The ALSA Driver API¶
Management of Cards and Devices¶
Card Management¶
-
void
snd_device_initialize
(struct device * dev, struct snd_card * card)¶ Initialize struct device for sound devices
Parameters
struct device * dev
- device to initialize
struct snd_card * card
- card to assign, optional
-
int
snd_card_new
(struct device * parent, int idx, const char * xid, struct module * module, int extra_size, struct snd_card ** card_ret)¶ create and initialize a soundcard structure
Parameters
struct device * parent
- the parent device object
int idx
- card index (address) [0 ... (SNDRV_CARDS-1)]
const char * xid
- card identification (ASCII string)
struct module * module
- top level module for locking
int extra_size
- allocate this extra size after the main soundcard structure
struct snd_card ** card_ret
- the pointer to store the created card instance
Description
Creates and initializes a soundcard structure.
The function allocates snd_card instance via kzalloc with the given space for the driver to use freely. The allocated struct is stored in the given card_ret pointer.
Return
Zero if successful or a negative error code.
-
int
snd_card_disconnect
(struct snd_card * card)¶ disconnect all APIs from the file-operations (user space)
Parameters
struct snd_card * card
- soundcard structure
Description
Disconnects all APIs from the file-operations (user space).
Return
Zero, otherwise a negative error code.
Note
- The current implementation replaces all active file->f_op with special
- dummy file operations (they do nothing except release).
-
void
snd_card_disconnect_sync
(struct snd_card * card)¶ disconnect card and wait until files get closed
Parameters
struct snd_card * card
- card object to disconnect
Description
This calls snd_card_disconnect()
for disconnecting all belonging components
and waits until all pending files get closed.
It assures that all accesses from user-space finished so that the driver
can release its resources gracefully.
-
int
snd_card_free_when_closed
(struct snd_card * card)¶ Disconnect the card, free it later eventually
Parameters
struct snd_card * card
- soundcard structure
Description
Unlike snd_card_free()
, this function doesn’t try to release the card
resource immediately, but tries to disconnect at first. When the card
is still in use, the function returns before freeing the resources.
The card resources will be freed when the refcount gets to zero.
-
int
snd_card_free
(struct snd_card * card)¶ frees given soundcard structure
Parameters
struct snd_card * card
- soundcard structure
Description
This function releases the soundcard structure and the all assigned devices automatically. That is, you don’t have to release the devices by yourself.
This function waits until the all resources are properly released.
Return
Zero. Frees all associated devices and frees the control interface associated to given soundcard.
-
void
snd_card_set_id
(struct snd_card * card, const char * nid)¶ set card identification name
Parameters
struct snd_card * card
- soundcard structure
const char * nid
- new identification string
Description
This function sets the card identification and checks for name collisions.
-
int
snd_card_add_dev_attr
(struct snd_card * card, const struct attribute_group * group)¶ Append a new sysfs attribute group to card
Parameters
struct snd_card * card
- card instance
const struct attribute_group * group
- attribute group to append
-
int
snd_card_register
(struct snd_card * card)¶ register the soundcard
Parameters
struct snd_card * card
- soundcard structure
Description
This function registers all the devices assigned to the soundcard. Until calling this, the ALSA control interface is blocked from the external accesses. Thus, you should call this function at the end of the initialization of the card.
Return
Zero otherwise a negative error code if the registration failed.
-
int
snd_component_add
(struct snd_card * card, const char * component)¶ add a component string
Parameters
struct snd_card * card
- soundcard structure
const char * component
- the component id string
Description
This function adds the component id string to the supported list. The component can be referred from the alsa-lib.
Return
Zero otherwise a negative error code.
-
int
snd_card_file_add
(struct snd_card * card, struct file * file)¶ add the file to the file list of the card
Parameters
struct snd_card * card
- soundcard structure
struct file * file
- file pointer
Description
This function adds the file to the file linked-list of the card. This linked-list is used to keep tracking the connection state, and to avoid the release of busy resources by hotplug.
Return
zero or a negative error code.
-
int
snd_card_file_remove
(struct snd_card * card, struct file * file)¶ remove the file from the file list
Parameters
struct snd_card * card
- soundcard structure
struct file * file
- file pointer
Description
This function removes the file formerly added to the card viasnd_card_file_add()
function. If all files are removed andsnd_card_free_when_closed()
was called beforehand, it processes the pending release of resources.
Return
Zero or a negative error code.
-
int
snd_power_wait
(struct snd_card * card, unsigned int power_state)¶ wait until the power-state is changed.
Parameters
struct snd_card * card
- soundcard structure
unsigned int power_state
- expected power state
Description
Waits until the power-state is changed.
Return
Zero if successful, or a negative error code.
Device Components¶
-
int
snd_device_new
(struct snd_card * card, enum snd_device_type type, void * device_data, struct snd_device_ops * ops)¶ create an ALSA device component
Parameters
struct snd_card * card
- the card instance
enum snd_device_type type
- the device type, SNDRV_DEV_XXX
void * device_data
- the data pointer of this device
struct snd_device_ops * ops
- the operator table
Description
Creates a new device component for the given data pointer. The device will be assigned to the card and managed together by the card.
The data pointer plays a role as the identifier, too, so the pointer address must be unique and unchanged.
Return
Zero if successful, or a negative error code on failure.
-
void
snd_device_disconnect
(struct snd_card * card, void * device_data)¶ disconnect the device
Parameters
struct snd_card * card
- the card instance
void * device_data
- the data pointer to disconnect
Description
Turns the device into the disconnection state, invoking dev_disconnect callback, if the device was already registered.
Usually called from snd_card_disconnect()
.
Return
Zero if successful, or a negative error code on failure or if the device not found.
-
void
snd_device_free
(struct snd_card * card, void * device_data)¶ release the device from the card
Parameters
struct snd_card * card
- the card instance
void * device_data
- the data pointer to release
Description
Removes the device from the list on the card and invokes the callbacks, dev_disconnect and dev_free, corresponding to the state. Then release the device.
-
int
snd_device_register
(struct snd_card * card, void * device_data)¶ register the device
Parameters
struct snd_card * card
- the card instance
void * device_data
- the data pointer to register
Description
Registers the device which was already created via
snd_device_new()
. Usually this is called from snd_card_register()
,
but it can be called later if any new devices are created after
invocation of snd_card_register()
.
Return
Zero if successful, or a negative error code on failure or if the device not found.
Module requests and Device File Entries¶
-
void
snd_request_card
(int card)¶ try to load the card module
Parameters
int card
- the card number
Description
Tries to load the module “snd-card-X” for the given card number via request_module. Returns immediately if already loaded.
-
void *
snd_lookup_minor_data
(unsigned int minor, int type)¶ get user data of a registered device
Parameters
unsigned int minor
- the minor number
int type
- device type (SNDRV_DEVICE_TYPE_XXX)
Description
Checks that a minor device with the specified type is registered, and returns its user data pointer.
This function increments the reference counter of the card instance
if an associated instance with the given minor number and type is found.
The caller must call snd_card_unref()
appropriately later.
Return
The user data pointer if the specified device is found. NULL
otherwise.
-
int
snd_register_device
(int type, struct snd_card * card, int dev, const struct file_operations * f_ops, void * private_data, struct device * device)¶ Register the ALSA device file for the card
Parameters
int type
- the device type, SNDRV_DEVICE_TYPE_XXX
struct snd_card * card
- the card instance
int dev
- the device index
const struct file_operations * f_ops
- the file operations
void * private_data
- user pointer for f_ops->:c:func:open()
struct device * device
- the device to register
Description
Registers an ALSA device file for the given card. The operators have to be set in reg parameter.
Return
Zero if successful, or a negative error code on failure.
Parameters
struct device * dev
- the device instance
Description
Unregisters the device file already registered via
snd_register_device()
.
Return
Zero if successful, or a negative error code on failure.
Memory Management Helpers¶
-
int
copy_to_user_fromio
(void __user * dst, const volatile void __iomem * src, size_t count)¶ copy data from mmio-space to user-space
Parameters
void __user * dst
- the destination pointer on user-space
const volatile void __iomem * src
- the source pointer on mmio
size_t count
- the data size to copy in bytes
Description
Copies the data from mmio-space to user-space.
Return
Zero if successful, or non-zero on failure.
-
int
copy_from_user_toio
(volatile void __iomem * dst, const void __user * src, size_t count)¶ copy data from user-space to mmio-space
Parameters
volatile void __iomem * dst
- the destination pointer on mmio-space
const void __user * src
- the source pointer on user-space
size_t count
- the data size to copy in bytes
Description
Copies the data from user-space to mmio-space.
Return
Zero if successful, or non-zero on failure.
-
void *
snd_malloc_pages
(size_t size, gfp_t gfp_flags)¶ allocate pages with the given size
Parameters
size_t size
- the size to allocate in bytes
gfp_t gfp_flags
- the allocation conditions, GFP_XXX
Description
Allocates the physically contiguous pages with the given size.
Return
The pointer of the buffer, or NULL
if no enough memory.
-
void
snd_free_pages
(void * ptr, size_t size)¶ release the pages
Parameters
void * ptr
- the buffer pointer to release
size_t size
- the allocated buffer size
Description
Releases the buffer allocated via snd_malloc_pages()
.
-
void
snd_malloc_dev_iram
(struct snd_dma_buffer * dmab, size_t size)¶ allocate memory from on-chip internal ram
Parameters
struct snd_dma_buffer * dmab
- buffer allocation record to store the allocated data
size_t size
- number of bytes to allocate from the iram
Description
This function requires iram phandle provided via of_node
-
void
snd_free_dev_iram
(struct snd_dma_buffer * dmab)¶ free allocated specific memory from on-chip internal ram
Parameters
struct snd_dma_buffer * dmab
- buffer allocation record to store the allocated data
-
int
snd_dma_alloc_pages
(int type, struct device * device, size_t size, struct snd_dma_buffer * dmab)¶ allocate the buffer area according to the given type
Parameters
int type
- the DMA buffer type
struct device * device
- the device pointer
size_t size
- the buffer size to allocate
struct snd_dma_buffer * dmab
- buffer allocation record to store the allocated data
Description
Calls the memory-allocator function for the corresponding buffer type.
Return
Zero if the buffer with the given size is allocated successfully, otherwise a negative value on error.
-
int
snd_dma_alloc_pages_fallback
(int type, struct device * device, size_t size, struct snd_dma_buffer * dmab)¶ allocate the buffer area according to the given type with fallback
Parameters
int type
- the DMA buffer type
struct device * device
- the device pointer
size_t size
- the buffer size to allocate
struct snd_dma_buffer * dmab
- buffer allocation record to store the allocated data
Description
Calls the memory-allocator function for the corresponding buffer type. When no space is left, this function reduces the size and tries to allocate again. The size actually allocated is stored in res_size argument.
Return
Zero if the buffer with the given size is allocated successfully, otherwise a negative value on error.
-
void
snd_dma_free_pages
(struct snd_dma_buffer * dmab)¶ release the allocated buffer
Parameters
struct snd_dma_buffer * dmab
- the buffer allocation record to release
Description
Releases the allocated buffer via snd_dma_alloc_pages()
.
PCM API¶
PCM Core¶
-
const char *
snd_pcm_format_name
(snd_pcm_format_t format)¶ Return a name string for the given PCM format
Parameters
snd_pcm_format_t format
- PCM format
-
int
snd_pcm_new_stream
(struct snd_pcm * pcm, int stream, int substream_count)¶ create a new PCM stream
Parameters
struct snd_pcm * pcm
- the pcm instance
int stream
- the stream direction, SNDRV_PCM_STREAM_XXX
int substream_count
- the number of substreams
Description
Creates a new stream for the pcm.
The corresponding stream on the pcm must have been empty before
calling this, i.e. zero must be given to the argument of
snd_pcm_new()
.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_new
(struct snd_card * card, const char * id, int device, int playback_count, int capture_count, struct snd_pcm ** rpcm)¶ create a new PCM instance
Parameters
struct snd_card * card
- the card instance
const char * id
- the id string
int device
- the device index (zero based)
int playback_count
- the number of substreams for playback
int capture_count
- the number of substreams for capture
struct snd_pcm ** rpcm
- the pointer to store the new pcm instance
Description
Creates a new PCM instance.
The pcm operators have to be set afterwards to the new instance
via snd_pcm_set_ops()
.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_new_internal
(struct snd_card * card, const char * id, int device, int playback_count, int capture_count, struct snd_pcm ** rpcm)¶ create a new internal PCM instance
Parameters
struct snd_card * card
- the card instance
const char * id
- the id string
int device
- the device index (zero based - shared with normal PCMs)
int playback_count
- the number of substreams for playback
int capture_count
- the number of substreams for capture
struct snd_pcm ** rpcm
- the pointer to store the new pcm instance
Description
Creates a new internal PCM instance with no userspace device or procfs entries. This is used by ASoC Back End PCMs in order to create a PCM that will only be used internally by kernel drivers. i.e. it cannot be opened by userspace. It provides existing ASoC components drivers with a substream and access to any private data.
The pcm operators have to be set afterwards to the new instance
via snd_pcm_set_ops()
.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_notify
(struct snd_pcm_notify * notify, int nfree)¶ Add/remove the notify list
Parameters
struct snd_pcm_notify * notify
- PCM notify list
int nfree
- 0 = register, 1 = unregister
Description
This adds the given notifier to the global list so that the callback is called for each registered PCM devices. This exists only for PCM OSS emulation, so far.
-
void
snd_pcm_set_ops
(struct snd_pcm * pcm, int direction, const struct snd_pcm_ops * ops)¶ set the PCM operators
Parameters
struct snd_pcm * pcm
- the pcm instance
int direction
- stream direction, SNDRV_PCM_STREAM_XXX
const struct snd_pcm_ops * ops
- the operator table
Description
Sets the given PCM operators to the pcm instance.
-
void
snd_pcm_set_sync
(struct snd_pcm_substream * substream)¶ set the PCM sync id
Parameters
struct snd_pcm_substream * substream
- the pcm substream
Description
Sets the PCM sync identifier for the card.
-
int
snd_interval_refine
(struct snd_interval * i, const struct snd_interval * v)¶ refine the interval value of configurator
Parameters
struct snd_interval * i
- the interval value to refine
const struct snd_interval * v
- the interval value to refer to
Description
Refines the interval value with the reference value. The interval is changed to the range satisfying both intervals. The interval status (min, max, integer, etc.) are evaluated.
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
void
snd_interval_div
(const struct snd_interval * a, const struct snd_interval * b, struct snd_interval * c)¶ refine the interval value with division
Parameters
const struct snd_interval * a
- dividend
const struct snd_interval * b
- divisor
struct snd_interval * c
- quotient
Description
c = a / b
Returns non-zero if the value is changed, zero if not changed.
-
void
snd_interval_muldivk
(const struct snd_interval * a, const struct snd_interval * b, unsigned int k, struct snd_interval * c)¶ refine the interval value
Parameters
const struct snd_interval * a
- dividend 1
const struct snd_interval * b
- dividend 2
unsigned int k
- divisor (as integer)
struct snd_interval * c
- result
Description
c = a * b / k
Returns non-zero if the value is changed, zero if not changed.
-
void
snd_interval_mulkdiv
(const struct snd_interval * a, unsigned int k, const struct snd_interval * b, struct snd_interval * c)¶ refine the interval value
Parameters
const struct snd_interval * a
- dividend 1
unsigned int k
- dividend 2 (as integer)
const struct snd_interval * b
- divisor
struct snd_interval * c
- result
Description
c = a * k / b
Returns non-zero if the value is changed, zero if not changed.
-
int
snd_interval_ratnum
(struct snd_interval * i, unsigned int rats_count, const struct snd_ratnum * rats, unsigned int * nump, unsigned int * denp)¶ refine the interval value
Parameters
struct snd_interval * i
- interval to refine
unsigned int rats_count
- number of ratnum_t
const struct snd_ratnum * rats
- ratnum_t array
unsigned int * nump
- pointer to store the resultant numerator
unsigned int * denp
- pointer to store the resultant denominator
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_interval_ratden
(struct snd_interval * i, unsigned int rats_count, const struct snd_ratden * rats, unsigned int * nump, unsigned int * denp)¶ refine the interval value
Parameters
struct snd_interval * i
- interval to refine
unsigned int rats_count
- number of struct ratden
const struct snd_ratden * rats
- struct ratden array
unsigned int * nump
- pointer to store the resultant numerator
unsigned int * denp
- pointer to store the resultant denominator
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_interval_list
(struct snd_interval * i, unsigned int count, const unsigned int * list, unsigned int mask)¶ refine the interval value from the list
Parameters
struct snd_interval * i
- the interval value to refine
unsigned int count
- the number of elements in the list
const unsigned int * list
- the value list
unsigned int mask
- the bit-mask to evaluate
Description
Refines the interval value from the list. When mask is non-zero, only the elements corresponding to bit 1 are evaluated.
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_interval_ranges
(struct snd_interval * i, unsigned int count, const struct snd_interval * ranges, unsigned int mask)¶ refine the interval value from the list of ranges
Parameters
struct snd_interval * i
- the interval value to refine
unsigned int count
- the number of elements in the list of ranges
const struct snd_interval * ranges
- the ranges list
unsigned int mask
- the bit-mask to evaluate
Description
Refines the interval value from the list of ranges. When mask is non-zero, only the elements corresponding to bit 1 are evaluated.
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_pcm_hw_rule_add
(struct snd_pcm_runtime * runtime, unsigned int cond, int var, snd_pcm_hw_rule_func_t func, void * private, int dep, ...)¶ add the hw-constraint rule
Parameters
struct snd_pcm_runtime * runtime
- the pcm runtime instance
unsigned int cond
- condition bits
int var
- the variable to evaluate
snd_pcm_hw_rule_func_t func
- the evaluation function
void * private
- the private data pointer passed to function
int dep
- the dependent variables
...
- variable arguments
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_mask
(struct snd_pcm_runtime * runtime, snd_pcm_hw_param_t var, u_int32_t mask)¶ apply the given bitmap mask constraint
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
snd_pcm_hw_param_t var
- hw_params variable to apply the mask
u_int32_t mask
- the bitmap mask
Description
Apply the constraint of the given bitmap mask to a 32-bit mask parameter.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_mask64
(struct snd_pcm_runtime * runtime, snd_pcm_hw_param_t var, u_int64_t mask)¶ apply the given bitmap mask constraint
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
snd_pcm_hw_param_t var
- hw_params variable to apply the mask
u_int64_t mask
- the 64bit bitmap mask
Description
Apply the constraint of the given bitmap mask to a 64-bit mask parameter.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_integer
(struct snd_pcm_runtime * runtime, snd_pcm_hw_param_t var)¶ apply an integer constraint to an interval
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
snd_pcm_hw_param_t var
- hw_params variable to apply the integer constraint
Description
Apply the constraint of integer to an interval parameter.
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_pcm_hw_constraint_minmax
(struct snd_pcm_runtime * runtime, snd_pcm_hw_param_t var, unsigned int min, unsigned int max)¶ apply a min/max range constraint to an interval
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
snd_pcm_hw_param_t var
- hw_params variable to apply the range
unsigned int min
- the minimal value
unsigned int max
- the maximal value
Description
Apply the min/max range constraint to an interval parameter.
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_pcm_hw_constraint_list
(struct snd_pcm_runtime * runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_list * l)¶ apply a list of constraints to a parameter
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
snd_pcm_hw_param_t var
- hw_params variable to apply the list constraint
const struct snd_pcm_hw_constraint_list * l
- list
Description
Apply the list of constraints to an interval parameter.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_ranges
(struct snd_pcm_runtime * runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_ranges * r)¶ apply list of range constraints to a parameter
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
snd_pcm_hw_param_t var
- hw_params variable to apply the list of range constraints
const struct snd_pcm_hw_constraint_ranges * r
- ranges
Description
Apply the list of range constraints to an interval parameter.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_ratnums
(struct snd_pcm_runtime * runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_ratnums * r)¶ apply ratnums constraint to a parameter
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
snd_pcm_hw_param_t var
- hw_params variable to apply the ratnums constraint
const struct snd_pcm_hw_constraint_ratnums * r
- struct snd_ratnums constriants
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_ratdens
(struct snd_pcm_runtime * runtime, unsigned int cond, snd_pcm_hw_param_t var, const struct snd_pcm_hw_constraint_ratdens * r)¶ apply ratdens constraint to a parameter
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
snd_pcm_hw_param_t var
- hw_params variable to apply the ratdens constraint
const struct snd_pcm_hw_constraint_ratdens * r
- struct snd_ratdens constriants
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_msbits
(struct snd_pcm_runtime * runtime, unsigned int cond, unsigned int width, unsigned int msbits)¶ add a hw constraint msbits rule
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
unsigned int width
- sample bits width
unsigned int msbits
- msbits width
Description
This constraint will set the number of most significant bits (msbits) if a sample format with the specified width has been select. If width is set to 0 the msbits will be set for any sample format with a width larger than the specified msbits.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_step
(struct snd_pcm_runtime * runtime, unsigned int cond, snd_pcm_hw_param_t var, unsigned long step)¶ add a hw constraint step rule
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
snd_pcm_hw_param_t var
- hw_params variable to apply the step constraint
unsigned long step
- step size
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_constraint_pow2
(struct snd_pcm_runtime * runtime, unsigned int cond, snd_pcm_hw_param_t var)¶ add a hw constraint power-of-2 rule
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int cond
- condition bits
snd_pcm_hw_param_t var
- hw_params variable to apply the power-of-2 constraint
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_rule_noresample
(struct snd_pcm_runtime * runtime, unsigned int base_rate)¶ add a rule to allow disabling hw resampling
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
unsigned int base_rate
- the rate at which the hardware does not resample
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_hw_param_value
(const struct snd_pcm_hw_params * params, snd_pcm_hw_param_t var, int * dir)¶ return params field var value
Parameters
const struct snd_pcm_hw_params * params
- the hw_params instance
snd_pcm_hw_param_t var
- parameter to retrieve
int * dir
- pointer to the direction (-1,0,1) or
NULL
Return
The value for field var if it’s fixed in configuration space
defined by params. -EINVAL
otherwise.
-
int
snd_pcm_hw_param_first
(struct snd_pcm_substream * pcm, struct snd_pcm_hw_params * params, snd_pcm_hw_param_t var, int * dir)¶ refine config space and return minimum value
Parameters
struct snd_pcm_substream * pcm
- PCM instance
struct snd_pcm_hw_params * params
- the hw_params instance
snd_pcm_hw_param_t var
- parameter to retrieve
int * dir
- pointer to the direction (-1,0,1) or
NULL
Description
Inside configuration space defined by params remove from var all values > minimum. Reduce configuration space accordingly.
Return
The minimum, or a negative error code on failure.
-
int
snd_pcm_hw_param_last
(struct snd_pcm_substream * pcm, struct snd_pcm_hw_params * params, snd_pcm_hw_param_t var, int * dir)¶ refine config space and return maximum value
Parameters
struct snd_pcm_substream * pcm
- PCM instance
struct snd_pcm_hw_params * params
- the hw_params instance
snd_pcm_hw_param_t var
- parameter to retrieve
int * dir
- pointer to the direction (-1,0,1) or
NULL
Description
Inside configuration space defined by params remove from var all values < maximum. Reduce configuration space accordingly.
Return
The maximum, or a negative error code on failure.
-
int
snd_pcm_lib_ioctl
(struct snd_pcm_substream * substream, unsigned int cmd, void * arg)¶ a generic PCM ioctl callback
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
unsigned int cmd
- ioctl command
void * arg
- ioctl argument
Description
Processes the generic ioctl commands for PCM. Can be passed as the ioctl callback for PCM ops.
Return
Zero if successful, or a negative error code on failure.
-
void
snd_pcm_period_elapsed
(struct snd_pcm_substream * substream)¶ update the pcm status for the next period
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
This function is called from the interrupt handler when the PCM has processed the period size. It will update the current pointer, wake up sleepers, etc.
Even if more than one periods have elapsed since the last call, you have to call this only once.
-
int
snd_pcm_add_chmap_ctls
(struct snd_pcm * pcm, int stream, const struct snd_pcm_chmap_elem * chmap, int max_channels, unsigned long private_value, struct snd_pcm_chmap ** info_ret)¶ create channel-mapping control elements
Parameters
struct snd_pcm * pcm
- the assigned PCM instance
int stream
- stream direction
const struct snd_pcm_chmap_elem * chmap
- channel map elements (for query)
int max_channels
- the max number of channels for the stream
unsigned long private_value
- the value passed to each kcontrol’s private_value field
struct snd_pcm_chmap ** info_ret
- store struct snd_pcm_chmap instance if non-NULL
Description
Create channel-mapping control elements assigned to the given PCM stream(s).
Return
Zero if successful, or a negative error value.
-
void
snd_pcm_stream_lock
(struct snd_pcm_substream * substream)¶ Lock the PCM stream
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
This locks the PCM stream’s spinlock or mutex depending on the nonatomic flag of the given substream. This also takes the global link rw lock (or rw sem), too, for avoiding the race with linked streams.
-
void
snd_pcm_stream_unlock
(struct snd_pcm_substream * substream)¶ Unlock the PCM stream
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
This unlocks the PCM stream that has been locked via snd_pcm_stream_lock()
.
-
void
snd_pcm_stream_lock_irq
(struct snd_pcm_substream * substream)¶ Lock the PCM stream
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
This locks the PCM stream like snd_pcm_stream_lock()
and disables the local
IRQ (only when nonatomic is false). In nonatomic case, this is identical
as snd_pcm_stream_lock()
.
-
void
snd_pcm_stream_unlock_irq
(struct snd_pcm_substream * substream)¶ Unlock the PCM stream
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
This is a counter-part of snd_pcm_stream_lock_irq()
.
-
void
snd_pcm_stream_unlock_irqrestore
(struct snd_pcm_substream * substream, unsigned long flags)¶ Unlock the PCM stream
Parameters
struct snd_pcm_substream * substream
- PCM substream
unsigned long flags
- irq flags
Description
This is a counter-part of snd_pcm_stream_lock_irqsave()
.
-
int
snd_pcm_hw_params_choose
(struct snd_pcm_substream * pcm, struct snd_pcm_hw_params * params)¶ choose a configuration defined by params
Parameters
struct snd_pcm_substream * pcm
- PCM instance
struct snd_pcm_hw_params * params
- the hw_params instance
Description
Choose one configuration from configuration space defined by params. The configuration chosen is that obtained fixing in this order: first access, first format, first subformat, min channels, min rate, min period time, max buffer size, min tick time
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_start
(struct snd_pcm_substream * substream)¶ start all linked streams
Parameters
struct snd_pcm_substream * substream
- the PCM substream instance
Return
Zero if successful, or a negative error code. The stream lock must be acquired before calling this function.
-
int
snd_pcm_stop
(struct snd_pcm_substream * substream, snd_pcm_state_t state)¶ try to stop all running streams in the substream group
Parameters
struct snd_pcm_substream * substream
- the PCM substream instance
snd_pcm_state_t state
- PCM state after stopping the stream
Description
The state of each stream is then changed to the given state unconditionally.
Return
Zero if successful, or a negative error code.
-
int
snd_pcm_drain_done
(struct snd_pcm_substream * substream)¶ stop the DMA only when the given stream is playback
Parameters
struct snd_pcm_substream * substream
- the PCM substream
Description
After stopping, the state is changed to SETUP.
Unlike snd_pcm_stop()
, this affects only the given stream.
Return
Zero if succesful, or a negative error code.
-
int
snd_pcm_stop_xrun
(struct snd_pcm_substream * substream)¶ stop the running streams as XRUN
Parameters
struct snd_pcm_substream * substream
- the PCM substream instance
Description
This stops the given running substream (and all linked substreams) as XRUN.
Unlike snd_pcm_stop()
, this function takes the substream lock by itself.
Return
Zero if successful, or a negative error code.
-
int
snd_pcm_suspend
(struct snd_pcm_substream * substream)¶ trigger SUSPEND to all linked streams
Parameters
struct snd_pcm_substream * substream
- the PCM substream
Description
After this call, all streams are changed to SUSPENDED state.
Return
Zero if successful (or substream is NULL
), or a negative error
code.
-
int
snd_pcm_suspend_all
(struct snd_pcm * pcm)¶ trigger SUSPEND to all substreams in the given pcm
Parameters
struct snd_pcm * pcm
- the PCM instance
Description
After this call, all streams are changed to SUSPENDED state.
Return
Zero if successful (or pcm is NULL
), or a negative error code.
-
int
snd_pcm_prepare
(struct snd_pcm_substream * substream, struct file * file)¶ prepare the PCM substream to be triggerable
Parameters
struct snd_pcm_substream * substream
- the PCM substream instance
struct file * file
- file to refer f_flags
Return
Zero if successful, or a negative error code.
-
int
snd_pcm_kernel_ioctl
(struct snd_pcm_substream * substream, unsigned int cmd, void * arg)¶ Execute PCM ioctl in the kernel-space
Parameters
struct snd_pcm_substream * substream
- PCM substream
unsigned int cmd
- IOCTL cmd
void * arg
- IOCTL argument
Description
The function is provided primarily for OSS layer and USB gadget drivers, and it allows only the limited set of ioctls (hw_params, sw_params, prepare, start, drain, drop, forward).
-
int
snd_pcm_lib_default_mmap
(struct snd_pcm_substream * substream, struct vm_area_struct * area)¶ Default PCM data mmap function
Parameters
struct snd_pcm_substream * substream
- PCM substream
struct vm_area_struct * area
- VMA
Description
This is the default mmap handler for PCM data. When mmap pcm_ops is NULL, this function is invoked implicitly.
-
int
snd_pcm_lib_mmap_iomem
(struct snd_pcm_substream * substream, struct vm_area_struct * area)¶ Default PCM data mmap function for I/O mem
Parameters
struct snd_pcm_substream * substream
- PCM substream
struct vm_area_struct * area
- VMA
Description
When your hardware uses the iomapped pages as the hardware buffer and wants to mmap it, pass this function as mmap pcm_ops. Note that this is supposed to work only on limited architectures.
-
int
snd_pcm_stream_linked
(struct snd_pcm_substream * substream)¶ Check whether the substream is linked with others
Parameters
struct snd_pcm_substream * substream
- substream to check
Description
Returns true if the given substream is being linked with others.
-
snd_pcm_stream_lock_irqsave
(substream, flags)¶ Lock the PCM stream
Parameters
substream
- PCM substream
flags
- irq flags
Description
This locks the PCM stream like snd_pcm_stream_lock()
but with the local
IRQ (only when nonatomic is false). In nonatomic case, this is identical
as snd_pcm_stream_lock()
.
-
snd_pcm_group_for_each_entry
(s, substream)¶ iterate over the linked substreams
Parameters
s
- the iterator
substream
- the substream
Description
Iterate over the all linked substreams to the given substream. When substream isn’t linked with any others, this gives returns substream itself once.
-
int
snd_pcm_running
(struct snd_pcm_substream * substream)¶ Check whether the substream is in a running state
Parameters
struct snd_pcm_substream * substream
- substream to check
Description
Returns true if the given substream is in the state RUNNING, or in the state DRAINING for playback.
-
ssize_t
bytes_to_samples
(struct snd_pcm_runtime * runtime, ssize_t size)¶ Unit conversion of the size from bytes to samples
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
ssize_t size
- size in bytes
-
snd_pcm_sframes_t
bytes_to_frames
(struct snd_pcm_runtime * runtime, ssize_t size)¶ Unit conversion of the size from bytes to frames
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
ssize_t size
- size in bytes
-
ssize_t
samples_to_bytes
(struct snd_pcm_runtime * runtime, ssize_t size)¶ Unit conversion of the size from samples to bytes
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
ssize_t size
- size in samples
-
ssize_t
frames_to_bytes
(struct snd_pcm_runtime * runtime, snd_pcm_sframes_t size)¶ Unit conversion of the size from frames to bytes
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
snd_pcm_sframes_t size
- size in frames
-
int
frame_aligned
(struct snd_pcm_runtime * runtime, ssize_t bytes)¶ Check whether the byte size is aligned to frames
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
ssize_t bytes
- size in bytes
-
size_t
snd_pcm_lib_buffer_bytes
(struct snd_pcm_substream * substream)¶ Get the buffer size of the current PCM in bytes
Parameters
struct snd_pcm_substream * substream
- PCM substream
-
size_t
snd_pcm_lib_period_bytes
(struct snd_pcm_substream * substream)¶ Get the period size of the current PCM in bytes
Parameters
struct snd_pcm_substream * substream
- PCM substream
-
snd_pcm_uframes_t
snd_pcm_playback_avail
(struct snd_pcm_runtime * runtime)¶ Get the available (writable) space for playback
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
Description
Result is between 0 ... (boundary - 1)
-
snd_pcm_uframes_t
snd_pcm_capture_avail
(struct snd_pcm_runtime * runtime)¶ Get the available (readable) space for capture
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
Description
Result is between 0 ... (boundary - 1)
-
snd_pcm_sframes_t
snd_pcm_playback_hw_avail
(struct snd_pcm_runtime * runtime)¶ Get the queued space for playback
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
-
snd_pcm_sframes_t
snd_pcm_capture_hw_avail
(struct snd_pcm_runtime * runtime)¶ Get the free space for capture
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
-
int
snd_pcm_playback_ready
(struct snd_pcm_substream * substream)¶ check whether the playback buffer is available
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
Checks whether enough free space is available on the playback buffer.
Return
Non-zero if available, or zero if not.
-
int
snd_pcm_capture_ready
(struct snd_pcm_substream * substream)¶ check whether the capture buffer is available
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
Checks whether enough capture data is available on the capture buffer.
Return
Non-zero if available, or zero if not.
-
int
snd_pcm_playback_data
(struct snd_pcm_substream * substream)¶ check whether any data exists on the playback buffer
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
Checks whether any data exists on the playback buffer.
Return
Non-zero if any data exists, or zero if not. If stop_threshold is bigger or equal to boundary, then this function returns always non-zero.
-
int
snd_pcm_playback_empty
(struct snd_pcm_substream * substream)¶ check whether the playback buffer is empty
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
Checks whether the playback buffer is empty.
Return
Non-zero if empty, or zero if not.
-
int
snd_pcm_capture_empty
(struct snd_pcm_substream * substream)¶ check whether the capture buffer is empty
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
Checks whether the capture buffer is empty.
Return
Non-zero if empty, or zero if not.
-
void
snd_pcm_trigger_done
(struct snd_pcm_substream * substream, struct snd_pcm_substream * master)¶ Mark the master substream
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
struct snd_pcm_substream * master
- the linked master substream
Description
When multiple substreams of the same card are linked and the hardware
supports the single-shot operation, the driver calls this in the loop
in snd_pcm_group_for_each_entry()
for marking the substream as “done”.
Then most of trigger operations are performed only to the given master
substream.
The trigger_master mark is cleared at timestamp updates at the end of trigger operations.
-
unsigned int
params_channels
(const struct snd_pcm_hw_params * p)¶ Get the number of channels from the hw params
Parameters
const struct snd_pcm_hw_params * p
- hw params
-
unsigned int
params_rate
(const struct snd_pcm_hw_params * p)¶ Get the sample rate from the hw params
Parameters
const struct snd_pcm_hw_params * p
- hw params
-
unsigned int
params_period_size
(const struct snd_pcm_hw_params * p)¶ Get the period size (in frames) from the hw params
Parameters
const struct snd_pcm_hw_params * p
- hw params
-
unsigned int
params_periods
(const struct snd_pcm_hw_params * p)¶ Get the number of periods from the hw params
Parameters
const struct snd_pcm_hw_params * p
- hw params
-
unsigned int
params_buffer_size
(const struct snd_pcm_hw_params * p)¶ Get the buffer size (in frames) from the hw params
Parameters
const struct snd_pcm_hw_params * p
- hw params
-
unsigned int
params_buffer_bytes
(const struct snd_pcm_hw_params * p)¶ Get the buffer size (in bytes) from the hw params
Parameters
const struct snd_pcm_hw_params * p
- hw params
-
int
snd_pcm_hw_constraint_single
(struct snd_pcm_runtime * runtime, snd_pcm_hw_param_t var, unsigned int val)¶ Constrain parameter to a single value
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
snd_pcm_hw_param_t var
- The hw_params variable to constrain
unsigned int val
- The value to constrain to
Return
Positive if the value is changed, zero if it’s not changed, or a negative error code.
-
int
snd_pcm_format_cpu_endian
(snd_pcm_format_t format)¶ Check the PCM format is CPU-endian
Parameters
snd_pcm_format_t format
- the format to check
Return
1 if the given PCM format is CPU-endian, 0 if opposite, or a negative error code if endian not specified.
-
void
snd_pcm_set_runtime_buffer
(struct snd_pcm_substream * substream, struct snd_dma_buffer * bufp)¶ Set the PCM runtime buffer
Parameters
struct snd_pcm_substream * substream
- PCM substream to set
struct snd_dma_buffer * bufp
- the buffer information, NULL to clear
Description
Copy the buffer information to runtime->dma_buffer when bufp is non-NULL. Otherwise it clears the current buffer information.
-
void
snd_pcm_gettime
(struct snd_pcm_runtime * runtime, struct timespec * tv)¶ Fill the timespec depending on the timestamp mode
Parameters
struct snd_pcm_runtime * runtime
- PCM runtime instance
struct timespec * tv
- timespec to fill
-
int
snd_pcm_lib_alloc_vmalloc_buffer
(struct snd_pcm_substream * substream, size_t size)¶ allocate virtual DMA buffer
Parameters
struct snd_pcm_substream * substream
- the substream to allocate the buffer to
size_t size
- the requested buffer size, in bytes
Description
Allocates the PCM substream buffer using vmalloc()
, i.e., the memory is
contiguous in kernel virtual space, but not in physical memory. Use this
if the buffer is accessed by kernel code but not by device DMA.
Return
1 if the buffer was changed, 0 if not changed, or a negative error code.
-
int
snd_pcm_lib_alloc_vmalloc_32_buffer
(struct snd_pcm_substream * substream, size_t size)¶ allocate 32-bit-addressable buffer
Parameters
struct snd_pcm_substream * substream
- the substream to allocate the buffer to
size_t size
- the requested buffer size, in bytes
Description
This function works like snd_pcm_lib_alloc_vmalloc_buffer()
, but uses
vmalloc_32()
, i.e., the pages are allocated from 32-bit-addressable memory.
Return
1 if the buffer was changed, 0 if not changed, or a negative error code.
-
dma_addr_t
snd_pcm_sgbuf_get_addr
(struct snd_pcm_substream * substream, unsigned int ofs)¶ Get the DMA address at the corresponding offset
Parameters
struct snd_pcm_substream * substream
- PCM substream
unsigned int ofs
- byte offset
-
void *
snd_pcm_sgbuf_get_ptr
(struct snd_pcm_substream * substream, unsigned int ofs)¶ Get the virtual address at the corresponding offset
Parameters
struct snd_pcm_substream * substream
- PCM substream
unsigned int ofs
- byte offset
-
unsigned int
snd_pcm_sgbuf_get_chunk_size
(struct snd_pcm_substream * substream, unsigned int ofs, unsigned int size)¶ Compute the max size that fits within the contig. page from the given size
Parameters
struct snd_pcm_substream * substream
- PCM substream
unsigned int ofs
- byte offset
unsigned int size
- byte size to examine
-
void
snd_pcm_mmap_data_open
(struct vm_area_struct * area)¶ increase the mmap counter
Parameters
struct vm_area_struct * area
- VMA
Description
PCM mmap callback should handle this counter properly
-
void
snd_pcm_mmap_data_close
(struct vm_area_struct * area)¶ decrease the mmap counter
Parameters
struct vm_area_struct * area
- VMA
Description
PCM mmap callback should handle this counter properly
-
void
snd_pcm_limit_isa_dma_size
(int dma, size_t * max)¶ Get the max size fitting with ISA DMA transfer
Parameters
int dma
- DMA number
size_t * max
- pointer to store the max size
-
const char *
snd_pcm_stream_str
(struct snd_pcm_substream * substream)¶ Get a string naming the direction of a stream
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Return
A string naming the direction of the stream.
-
struct snd_pcm_substream *
snd_pcm_chmap_substream
(struct snd_pcm_chmap * info, unsigned int idx)¶ get the PCM substream assigned to the given chmap info
Parameters
struct snd_pcm_chmap * info
- chmap information
unsigned int idx
- the substream number index
-
u64
pcm_format_to_bits
(snd_pcm_format_t pcm_format)¶ Strong-typed conversion of pcm_format to bitwise
Parameters
snd_pcm_format_t pcm_format
- PCM format
PCM Format Helpers¶
-
int
snd_pcm_format_signed
(snd_pcm_format_t format)¶ Check the PCM format is signed linear
Parameters
snd_pcm_format_t format
- the format to check
Return
1 if the given PCM format is signed linear, 0 if unsigned linear, and a negative error code for non-linear formats.
-
int
snd_pcm_format_unsigned
(snd_pcm_format_t format)¶ Check the PCM format is unsigned linear
Parameters
snd_pcm_format_t format
- the format to check
Return
1 if the given PCM format is unsigned linear, 0 if signed linear, and a negative error code for non-linear formats.
-
int
snd_pcm_format_linear
(snd_pcm_format_t format)¶ Check the PCM format is linear
Parameters
snd_pcm_format_t format
- the format to check
Return
1 if the given PCM format is linear, 0 if not.
-
int
snd_pcm_format_little_endian
(snd_pcm_format_t format)¶ Check the PCM format is little-endian
Parameters
snd_pcm_format_t format
- the format to check
Return
1 if the given PCM format is little-endian, 0 if big-endian, or a negative error code if endian not specified.
-
int
snd_pcm_format_big_endian
(snd_pcm_format_t format)¶ Check the PCM format is big-endian
Parameters
snd_pcm_format_t format
- the format to check
Return
1 if the given PCM format is big-endian, 0 if little-endian, or a negative error code if endian not specified.
-
int
snd_pcm_format_width
(snd_pcm_format_t format)¶ return the bit-width of the format
Parameters
snd_pcm_format_t format
- the format to check
Return
The bit-width of the format, or a negative error code if unknown format.
-
int
snd_pcm_format_physical_width
(snd_pcm_format_t format)¶ return the physical bit-width of the format
Parameters
snd_pcm_format_t format
- the format to check
Return
The physical bit-width of the format, or a negative error code if unknown format.
-
ssize_t
snd_pcm_format_size
(snd_pcm_format_t format, size_t samples)¶ return the byte size of samples on the given format
Parameters
snd_pcm_format_t format
- the format to check
size_t samples
- sampling rate
Return
The byte size of the given samples for the format, or a negative error code if unknown format.
-
const unsigned char *
snd_pcm_format_silence_64
(snd_pcm_format_t format)¶ return the silent data in 8 bytes array
Parameters
snd_pcm_format_t format
- the format to check
Return
The format pattern to fill or NULL
if error.
-
int
snd_pcm_format_set_silence
(snd_pcm_format_t format, void * data, unsigned int samples)¶ set the silence data on the buffer
Parameters
snd_pcm_format_t format
- the PCM format
void * data
- the buffer pointer
unsigned int samples
- the number of samples to set silence
Description
Sets the silence data on the buffer for the given samples.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_limit_hw_rates
(struct snd_pcm_runtime * runtime)¶ determine rate_min/rate_max fields
Parameters
struct snd_pcm_runtime * runtime
- the runtime instance
Description
Determines the rate_min and rate_max fields from the rates bits of the given runtime->hw.
Return
Zero if successful.
-
unsigned int
snd_pcm_rate_to_rate_bit
(unsigned int rate)¶ converts sample rate to SNDRV_PCM_RATE_xxx bit
Parameters
unsigned int rate
- the sample rate to convert
Return
The SNDRV_PCM_RATE_xxx flag that corresponds to the given rate, or SNDRV_PCM_RATE_KNOT for an unknown rate.
-
unsigned int
snd_pcm_rate_bit_to_rate
(unsigned int rate_bit)¶ converts SNDRV_PCM_RATE_xxx bit to sample rate
Parameters
unsigned int rate_bit
- the rate bit to convert
Return
The sample rate that corresponds to the given SNDRV_PCM_RATE_xxx flag or 0 for an unknown rate bit.
-
unsigned int
snd_pcm_rate_mask_intersect
(unsigned int rates_a, unsigned int rates_b)¶ computes the intersection between two rate masks
Parameters
unsigned int rates_a
- The first rate mask
unsigned int rates_b
- The second rate mask
Description
This function computes the rates that are supported by both rate masks passed to the function. It will take care of the special handling of SNDRV_PCM_RATE_CONTINUOUS and SNDRV_PCM_RATE_KNOT.
Return
A rate mask containing the rates that are supported by both rates_a and rates_b.
-
unsigned int
snd_pcm_rate_range_to_bits
(unsigned int rate_min, unsigned int rate_max)¶ converts rate range to SNDRV_PCM_RATE_xxx bit
Parameters
unsigned int rate_min
- the minimum sample rate
unsigned int rate_max
- the maximum sample rate
Description
This function has an implicit assumption: the rates in the given range have only the pre-defined rates like 44100 or 16000.
Return
The SNDRV_PCM_RATE_xxx flag that corresponds to the given rate range, or SNDRV_PCM_RATE_KNOT for an unknown range.
PCM Memory Management¶
-
int
snd_pcm_lib_preallocate_free
(struct snd_pcm_substream * substream)¶ release the preallocated buffer of the specified substream.
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
Description
Releases the pre-allocated buffer of the given substream.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_lib_preallocate_free_for_all
(struct snd_pcm * pcm)¶ release all pre-allocated buffers on the pcm
Parameters
struct snd_pcm * pcm
- the pcm instance
Description
Releases all the pre-allocated buffers on the given pcm.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_lib_preallocate_pages
(struct snd_pcm_substream * substream, int type, struct device * data, size_t size, size_t max)¶ pre-allocation for the given DMA type
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
int type
- DMA type (SNDRV_DMA_TYPE_*)
struct device * data
- DMA type dependent data
size_t size
- the requested pre-allocation size in bytes
size_t max
- the max. allowed pre-allocation size
Description
Do pre-allocation for the given DMA buffer type.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_lib_preallocate_pages_for_all
(struct snd_pcm * pcm, int type, void * data, size_t size, size_t max)¶ pre-allocation for continuous memory type (all substreams)
Parameters
struct snd_pcm * pcm
- the pcm instance
int type
- DMA type (SNDRV_DMA_TYPE_*)
void * data
- DMA type dependent data
size_t size
- the requested pre-allocation size in bytes
size_t max
- the max. allowed pre-allocation size
Description
Do pre-allocation to all substreams of the given pcm for the specified DMA type.
Return
Zero if successful, or a negative error code on failure.
-
struct page *
snd_pcm_sgbuf_ops_page
(struct snd_pcm_substream * substream, unsigned long offset)¶ get the page struct at the given offset
Parameters
struct snd_pcm_substream * substream
- the pcm substream instance
unsigned long offset
- the buffer offset
Description
Used as the page callback of PCM ops.
Return
The page struct at the given buffer offset. NULL
on failure.
-
int
snd_pcm_lib_malloc_pages
(struct snd_pcm_substream * substream, size_t size)¶ allocate the DMA buffer
Parameters
struct snd_pcm_substream * substream
- the substream to allocate the DMA buffer to
size_t size
- the requested buffer size in bytes
Description
Allocates the DMA buffer on the BUS type given earlier to
snd_pcm_lib_preallocate_xxx_pages()
.
Return
1 if the buffer is changed, 0 if not changed, or a negative code on failure.
-
int
snd_pcm_lib_free_pages
(struct snd_pcm_substream * substream)¶ release the allocated DMA buffer.
Parameters
struct snd_pcm_substream * substream
- the substream to release the DMA buffer
Description
Releases the DMA buffer allocated via snd_pcm_lib_malloc_pages()
.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_pcm_lib_free_vmalloc_buffer
(struct snd_pcm_substream * substream)¶ free vmalloc buffer
Parameters
struct snd_pcm_substream * substream
- the substream with a buffer allocated by
snd_pcm_lib_alloc_vmalloc_buffer()
Return
Zero if successful, or a negative error code on failure.
-
struct page *
snd_pcm_lib_get_vmalloc_page
(struct snd_pcm_substream * substream, unsigned long offset)¶ map vmalloc buffer offset to page struct
Parameters
struct snd_pcm_substream * substream
- the substream with a buffer allocated by
snd_pcm_lib_alloc_vmalloc_buffer()
unsigned long offset
- offset in the buffer
Description
This function is to be used as the page callback in the PCM ops.
Return
The page struct, or NULL
on failure.
PCM DMA Engine API¶
-
int
snd_hwparams_to_dma_slave_config
(const struct snd_pcm_substream * substream, const struct snd_pcm_hw_params * params, struct dma_slave_config * slave_config)¶ Convert hw_params to dma_slave_config
Parameters
const struct snd_pcm_substream * substream
- PCM substream
const struct snd_pcm_hw_params * params
- hw_params
struct dma_slave_config * slave_config
- DMA slave config
Description
This function can be used to initialize a dma_slave_config from a substream and hw_params in a dmaengine based PCM driver implementation.
-
void
snd_dmaengine_pcm_set_config_from_dai_data
(const struct snd_pcm_substream * substream, const struct snd_dmaengine_dai_dma_data * dma_data, struct dma_slave_config * slave_config)¶ Initializes a dma slave config using DAI DMA data.
Parameters
const struct snd_pcm_substream * substream
- PCM substream
const struct snd_dmaengine_dai_dma_data * dma_data
- DAI DMA data
struct dma_slave_config * slave_config
- DMA slave configuration
Description
Initializes the {dst,src}_addr, {dst,src}_maxburst, {dst,src}_addr_width and slave_id fields of the DMA slave config from the same fields of the DAI DMA data struct. The src and dst fields will be initialized depending on the direction of the substream. If the substream is a playback stream the dst fields will be initialized, if it is a capture stream the src fields will be initialized. The {dst,src}_addr_width field will only be initialized if the SND_DMAENGINE_PCM_DAI_FLAG_PACK flag is set or if the addr_width field of the DAI DMA data struct is not equal to DMA_SLAVE_BUSWIDTH_UNDEFINED. If both conditions are met the latter takes priority.
-
int
snd_dmaengine_pcm_trigger
(struct snd_pcm_substream * substream, int cmd)¶ dmaengine based PCM trigger implementation
Parameters
struct snd_pcm_substream * substream
- PCM substream
int cmd
- Trigger command
Description
Returns 0 on success, a negative error code otherwise.
This function can be used as the PCM trigger callback for dmaengine based PCM driver implementations.
-
snd_pcm_uframes_t
snd_dmaengine_pcm_pointer_no_residue
(struct snd_pcm_substream * substream)¶ dmaengine based PCM pointer implementation
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
This function is deprecated and should not be used by new drivers, as its results may be unreliable.
-
snd_pcm_uframes_t
snd_dmaengine_pcm_pointer
(struct snd_pcm_substream * substream)¶ dmaengine based PCM pointer implementation
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
This function can be used as the PCM pointer callback for dmaengine based PCM driver implementations.
-
struct dma_chan *
snd_dmaengine_pcm_request_channel
(dma_filter_fn filter_fn, void * filter_data)¶ Request channel for the dmaengine PCM
Parameters
dma_filter_fn filter_fn
- Filter function used to request the DMA channel
void * filter_data
- Data passed to the DMA filter function
Description
Returns NULL or the requested DMA channel.
This function request a DMA channel for usage with dmaengine PCM.
-
int
snd_dmaengine_pcm_open
(struct snd_pcm_substream * substream, struct dma_chan * chan)¶ Open a dmaengine based PCM substream
Parameters
struct snd_pcm_substream * substream
- PCM substream
struct dma_chan * chan
- DMA channel to use for data transfers
Description
Returns 0 on success, a negative error code otherwise.
The function should usually be called from the pcm open callback. Note that this function will use private_data field of the substream’s runtime. So it is not available to your pcm driver implementation.
-
int
snd_dmaengine_pcm_open_request_chan
(struct snd_pcm_substream * substream, dma_filter_fn filter_fn, void * filter_data)¶ Open a dmaengine based PCM substream and request channel
Parameters
struct snd_pcm_substream * substream
- PCM substream
dma_filter_fn filter_fn
- Filter function used to request the DMA channel
void * filter_data
- Data passed to the DMA filter function
Description
Returns 0 on success, a negative error code otherwise.
This function will request a DMA channel using the passed filter function and data. The function should usually be called from the pcm open callback. Note that this function will use private_data field of the substream’s runtime. So it is not available to your pcm driver implementation.
-
int
snd_dmaengine_pcm_close
(struct snd_pcm_substream * substream)¶ Close a dmaengine based PCM substream
Parameters
struct snd_pcm_substream * substream
- PCM substream
-
int
snd_dmaengine_pcm_close_release_chan
(struct snd_pcm_substream * substream)¶ Close a dmaengine based PCM substream and release channel
Parameters
struct snd_pcm_substream * substream
- PCM substream
Description
Releases the DMA channel associated with the PCM substream.
-
enum dma_transfer_direction
snd_pcm_substream_to_dma_direction
(const struct snd_pcm_substream * substream)¶ Get dma_transfer_direction for a PCM substream
Parameters
const struct snd_pcm_substream * substream
- PCM substream
-
struct
snd_dmaengine_dai_dma_data
¶ DAI DMA configuration data
Definition
struct snd_dmaengine_dai_dma_data {
dma_addr_t addr;
enum dma_slave_buswidth addr_width;
u32 maxburst;
unsigned int slave_id;
void *filter_data;
const char *chan_name;
unsigned int fifo_size;
unsigned int flags;
};
Members
addr
- Address of the DAI data source or destination register.
addr_width
- Width of the DAI data source or destination register.
maxburst
- Maximum number of words(note: words, as in units of the src_addr_width member, not bytes) that can be send to or received from the DAI in one burst.
slave_id
- Slave requester id for the DMA channel.
filter_data
- Custom DMA channel filter data, this will usually be used when requesting the DMA channel.
chan_name
- Custom channel name to use when requesting DMA channel.
fifo_size
- FIFO size of the DAI controller in bytes
flags
- PCM_DAI flags, only SND_DMAENGINE_PCM_DAI_FLAG_PACK for now
-
struct
snd_dmaengine_pcm_config
¶ Configuration data for dmaengine based PCM
Definition
struct snd_dmaengine_pcm_config {
int (*prepare_slave_config)(struct snd_pcm_substream *substream,struct snd_pcm_hw_params *params, struct dma_slave_config *slave_config);
struct dma_chan *(*compat_request_channel)(struct snd_soc_pcm_runtime *rtd, struct snd_pcm_substream *substream);
int (*process)(struct snd_pcm_substream *substream,int channel, unsigned long hwoff, void *buf, unsigned long bytes);
dma_filter_fn compat_filter_fn;
struct device *dma_dev;
const char *chan_names[SNDRV_PCM_STREAM_LAST + 1];
const struct snd_pcm_hardware *pcm_hardware;
unsigned int prealloc_buffer_size;
};
Members
prepare_slave_config
- Callback used to fill in the DMA slave_config for a PCM substream. Will be called from the PCM drivers hwparams callback.
compat_request_channel
- Callback to request a DMA channel for platforms which do not use devicetree.
process
- Callback used to apply processing on samples transferred from/to user space.
compat_filter_fn
- Will be used as the filter function when requesting a channel for platforms which do not use devicetree. The filter parameter will be the DAI’s DMA data.
dma_dev
- If set, request DMA channel on this device rather than the DAI device.
chan_names
- If set, these custom DMA channel names will be requested at registration time.
pcm_hardware
- snd_pcm_hardware struct to be used for the PCM.
prealloc_buffer_size
- Size of the preallocated audio buffer.
Note
If both compat_request_channel and compat_filter_fn are set compat_request_channel will be used to request the channel and compat_filter_fn will be ignored. Otherwise the channel will be requested using dma_request_channel with compat_filter_fn as the filter function.
Control/Mixer API¶
General Control Interface¶
-
void
snd_ctl_notify
(struct snd_card * card, unsigned int mask, struct snd_ctl_elem_id * id)¶ Send notification to user-space for a control change
Parameters
struct snd_card * card
- the card to send notification
unsigned int mask
- the event mask, SNDRV_CTL_EVENT_*
struct snd_ctl_elem_id * id
- the ctl element id to send notification
Description
This function adds an event record with the given id and mask, appends to the list and wakes up the user-space for notification. This can be called in the atomic context.
-
int
snd_ctl_new
(struct snd_kcontrol ** kctl, unsigned int count, unsigned int access, struct snd_ctl_file * file)¶ create a new control instance with some elements
Parameters
struct snd_kcontrol ** kctl
- the pointer to store new control instance
unsigned int count
- the number of elements in this control
unsigned int access
- the default access flags for elements in this control
struct snd_ctl_file * file
- given when locking these elements
Description
Allocates a memory object for a new control instance. The instance has elements as many as the given number (count). Each element has given access permissions (access). Each element is locked when file is given.
Return
0 on success, error code on failure
-
struct snd_kcontrol *
snd_ctl_new1
(const struct snd_kcontrol_new * ncontrol, void * private_data)¶ create a control instance from the template
Parameters
const struct snd_kcontrol_new * ncontrol
- the initialization record
void * private_data
- the private data to set
Description
Allocates a new struct snd_kcontrol instance and initialize from the given template. When the access field of ncontrol is 0, it’s assumed as READWRITE access. When the count field is 0, it’s assumes as one.
Return
The pointer of the newly generated instance, or NULL
on failure.
-
void
snd_ctl_free_one
(struct snd_kcontrol * kcontrol)¶ release the control instance
Parameters
struct snd_kcontrol * kcontrol
- the control instance
Description
Releases the control instance created via snd_ctl_new()
or snd_ctl_new1()
.
Don’t call this after the control was added to the card.
-
int
snd_ctl_add
(struct snd_card * card, struct snd_kcontrol * kcontrol)¶ add the control instance to the card
Parameters
struct snd_card * card
- the card instance
struct snd_kcontrol * kcontrol
- the control instance to add
Description
Adds the control instance created via snd_ctl_new()
or
snd_ctl_new1()
to the given card. Assigns also an unique
numid used for fast search.
It frees automatically the control which cannot be added.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ctl_replace
(struct snd_card * card, struct snd_kcontrol * kcontrol, bool add_on_replace)¶ replace the control instance of the card
Parameters
struct snd_card * card
- the card instance
struct snd_kcontrol * kcontrol
- the control instance to replace
bool add_on_replace
- add the control if not already added
Description
Replaces the given control. If the given control does not exist and the add_on_replace flag is set, the control is added. If the control exists, it is destroyed first.
It frees automatically the control which cannot be added or replaced.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ctl_remove
(struct snd_card * card, struct snd_kcontrol * kcontrol)¶ remove the control from the card and release it
Parameters
struct snd_card * card
- the card instance
struct snd_kcontrol * kcontrol
- the control instance to remove
Description
Removes the control from the card and then releases the instance.
You don’t need to call snd_ctl_free_one()
. You must be in
the write lock - down_write(card->controls_rwsem
).
Return
0 if successful, or a negative error code on failure.
-
int
snd_ctl_remove_id
(struct snd_card * card, struct snd_ctl_elem_id * id)¶ remove the control of the given id and release it
Parameters
struct snd_card * card
- the card instance
struct snd_ctl_elem_id * id
- the control id to remove
Description
Finds the control instance with the given id, removes it from the card list and releases it.
Return
0 if successful, or a negative error code on failure.
-
int
snd_ctl_remove_user_ctl
(struct snd_ctl_file * file, struct snd_ctl_elem_id * id)¶ remove and release the unlocked user control
Parameters
struct snd_ctl_file * file
- active control handle
struct snd_ctl_elem_id * id
- the control id to remove
Description
Finds the control instance with the given id, removes it from the card list and releases it.
Return
0 if successful, or a negative error code on failure.
-
int
snd_ctl_activate_id
(struct snd_card * card, struct snd_ctl_elem_id * id, int active)¶ activate/inactivate the control of the given id
Parameters
struct snd_card * card
- the card instance
struct snd_ctl_elem_id * id
- the control id to activate/inactivate
int active
- non-zero to activate
Description
Finds the control instance with the given id, and activate or inactivate the control together with notification, if changed. The given ID data is filled with full information.
Return
0 if unchanged, 1 if changed, or a negative error code on failure.
-
int
snd_ctl_rename_id
(struct snd_card * card, struct snd_ctl_elem_id * src_id, struct snd_ctl_elem_id * dst_id)¶ replace the id of a control on the card
Parameters
struct snd_card * card
- the card instance
struct snd_ctl_elem_id * src_id
- the old id
struct snd_ctl_elem_id * dst_id
- the new id
Description
Finds the control with the old id from the card, and replaces the id with the new one.
Return
Zero if successful, or a negative error code on failure.
-
struct snd_kcontrol *
snd_ctl_find_numid
(struct snd_card * card, unsigned int numid)¶ find the control instance with the given number-id
Parameters
struct snd_card * card
- the card instance
unsigned int numid
- the number-id to search
Description
Finds the control instance with the given number-id from the card.
The caller must down card->controls_rwsem before calling this function (if the race condition can happen).
Return
The pointer of the instance if found, or NULL
if not.
-
struct snd_kcontrol *
snd_ctl_find_id
(struct snd_card * card, struct snd_ctl_elem_id * id)¶ find the control instance with the given id
Parameters
struct snd_card * card
- the card instance
struct snd_ctl_elem_id * id
- the id to search
Description
Finds the control instance with the given id from the card.
The caller must down card->controls_rwsem before calling this function (if the race condition can happen).
Return
The pointer of the instance if found, or NULL
if not.
-
int
snd_ctl_register_ioctl
(snd_kctl_ioctl_func_t fcn)¶ register the device-specific control-ioctls
Parameters
snd_kctl_ioctl_func_t fcn
- ioctl callback function
Description
called from each device manager like pcm.c, hwdep.c, etc.
-
int
snd_ctl_register_ioctl_compat
(snd_kctl_ioctl_func_t fcn)¶ register the device-specific 32bit compat control-ioctls
Parameters
snd_kctl_ioctl_func_t fcn
- ioctl callback function
-
int
snd_ctl_unregister_ioctl
(snd_kctl_ioctl_func_t fcn)¶ de-register the device-specific control-ioctls
Parameters
snd_kctl_ioctl_func_t fcn
- ioctl callback function to unregister
-
int
snd_ctl_unregister_ioctl_compat
(snd_kctl_ioctl_func_t fcn)¶ de-register the device-specific compat 32bit control-ioctls
Parameters
snd_kctl_ioctl_func_t fcn
- ioctl callback function to unregister
-
int
snd_ctl_boolean_mono_info
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ Helper function for a standard boolean info callback with a mono channel
Parameters
struct snd_kcontrol * kcontrol
- the kcontrol instance
struct snd_ctl_elem_info * uinfo
- info to store
Description
This is a function that can be used as info callback for a standard boolean control with a single mono channel.
-
int
snd_ctl_boolean_stereo_info
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ Helper function for a standard boolean info callback with stereo two channels
Parameters
struct snd_kcontrol * kcontrol
- the kcontrol instance
struct snd_ctl_elem_info * uinfo
- info to store
Description
This is a function that can be used as info callback for a standard boolean control with stereo two channels.
-
int
snd_ctl_enum_info
(struct snd_ctl_elem_info * info, unsigned int channels, unsigned int items, const char *const names)¶ fills the info structure for an enumerated control
Parameters
struct snd_ctl_elem_info * info
- the structure to be filled
unsigned int channels
- the number of the control’s channels; often one
unsigned int items
- the number of control values; also the size of names
const char *const names
- an array containing the names of all control values
Description
Sets all required fields in info to their appropriate values. If the control’s accessibility is not the default (readable and writable), the caller has to fill info->access.
Return
Zero.
AC97 Codec API¶
-
void
snd_ac97_write
(struct snd_ac97 * ac97, unsigned short reg, unsigned short value)¶ write a value on the given register
Parameters
struct snd_ac97 * ac97
- the ac97 instance
unsigned short reg
- the register to change
unsigned short value
- the value to set
Description
Writes a value on the given register. This will invoke the write callback directly after the register check. This function doesn’t change the register cache unlike #:c:func:snd_ca97_write_cache(), so use this only when you don’t want to reflect the change to the suspend/resume state.
-
unsigned short
snd_ac97_read
(struct snd_ac97 * ac97, unsigned short reg)¶ read a value from the given register
Parameters
struct snd_ac97 * ac97
- the ac97 instance
unsigned short reg
- the register to read
Description
Reads a value from the given register. This will invoke the read callback directly after the register check.
Return
The read value.
-
void
snd_ac97_write_cache
(struct snd_ac97 * ac97, unsigned short reg, unsigned short value)¶ write a value on the given register and update the cache
Parameters
struct snd_ac97 * ac97
- the ac97 instance
unsigned short reg
- the register to change
unsigned short value
- the value to set
Description
Writes a value on the given register and updates the register cache. The cached values are used for the cached-read and the suspend/resume.
-
int
snd_ac97_update
(struct snd_ac97 * ac97, unsigned short reg, unsigned short value)¶ update the value on the given register
Parameters
struct snd_ac97 * ac97
- the ac97 instance
unsigned short reg
- the register to change
unsigned short value
- the value to set
Description
Compares the value with the register cache and updates the value only when the value is changed.
Return
1 if the value is changed, 0 if no change, or a negative code on failure.
-
int
snd_ac97_update_bits
(struct snd_ac97 * ac97, unsigned short reg, unsigned short mask, unsigned short value)¶ update the bits on the given register
Parameters
struct snd_ac97 * ac97
- the ac97 instance
unsigned short reg
- the register to change
unsigned short mask
- the bit-mask to change
unsigned short value
- the value to set
Description
Updates the masked-bits on the given register only when the value is changed.
Return
1 if the bits are changed, 0 if no change, or a negative code on failure.
-
const char *
snd_ac97_get_short_name
(struct snd_ac97 * ac97)¶ retrieve codec name
Parameters
struct snd_ac97 * ac97
- the codec instance
Return
The short identifying name of the codec.
-
int
snd_ac97_bus
(struct snd_card * card, int num, struct snd_ac97_bus_ops * ops, void * private_data, struct snd_ac97_bus ** rbus)¶ create an AC97 bus component
Parameters
struct snd_card * card
- the card instance
int num
- the bus number
struct snd_ac97_bus_ops * ops
- the bus callbacks table
void * private_data
- private data pointer for the new instance
struct snd_ac97_bus ** rbus
- the pointer to store the new AC97 bus instance.
Description
Creates an AC97 bus component. An struct snd_ac97_bus instance is newly allocated and initialized.
The ops table must include valid callbacks (at least read and write). The other callbacks, wait and reset, are not mandatory.
The clock is set to 48000. If another clock is needed, set
(*rbus)->clock
manually.
The AC97 bus instance is registered as a low-level device, so you don’t have to release it manually.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ac97_mixer
(struct snd_ac97_bus * bus, struct snd_ac97_template * template, struct snd_ac97 ** rac97)¶ create an Codec97 component
Parameters
struct snd_ac97_bus * bus
- the AC97 bus which codec is attached to
struct snd_ac97_template * template
- the template of ac97, including index, callbacks and the private data.
struct snd_ac97 ** rac97
- the pointer to store the new ac97 instance.
Description
Creates an Codec97 component. An struct snd_ac97 instance is newly allocated and initialized from the template. The codec is then initialized by the standard procedure.
The template must include the codec number (num) and address (addr), and the private data (private_data).
The ac97 instance is registered as a low-level device, so you don’t have to release it manually.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ac97_update_power
(struct snd_ac97 * ac97, int reg, int powerup)¶ update the powerdown register
Parameters
struct snd_ac97 * ac97
- the codec instance
int reg
- the rate register, e.g. AC97_PCM_FRONT_DAC_RATE
int powerup
- non-zero when power up the part
Description
Update the AC97 powerdown register bits of the given part.
Return
Zero.
-
void
snd_ac97_suspend
(struct snd_ac97 * ac97)¶ General suspend function for AC97 codec
Parameters
struct snd_ac97 * ac97
- the ac97 instance
Description
Suspends the codec, power down the chip.
-
void
snd_ac97_resume
(struct snd_ac97 * ac97)¶ General resume function for AC97 codec
Parameters
struct snd_ac97 * ac97
- the ac97 instance
Description
Do the standard resume procedure, power up and restoring the old register values.
-
int
snd_ac97_tune_hardware
(struct snd_ac97 * ac97, const struct ac97_quirk * quirk, const char * override)¶ tune up the hardware
Parameters
struct snd_ac97 * ac97
- the ac97 instance
const struct ac97_quirk * quirk
- quirk list
const char * override
- explicit quirk value (overrides the list if non-NULL)
Description
Do some workaround for each pci device, such as renaming of the headphone (true line-out) control as “Master”. The quirk-list must be terminated with a zero-filled entry.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ac97_set_rate
(struct snd_ac97 * ac97, int reg, unsigned int rate)¶ change the rate of the given input/output.
Parameters
struct snd_ac97 * ac97
- the ac97 instance
int reg
- the register to change
unsigned int rate
- the sample rate to set
Description
Changes the rate of the given input/output on the codec. If the codec doesn’t support VAR, the rate must be 48000 (except for SPDIF).
The valid registers are AC97_PMC_MIC_ADC_RATE, AC97_PCM_FRONT_DAC_RATE, AC97_PCM_LR_ADC_RATE. AC97_PCM_SURR_DAC_RATE and AC97_PCM_LFE_DAC_RATE are accepted if the codec supports them. AC97_SPDIF is accepted as a pseudo register to modify the SPDIF status bits.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ac97_pcm_assign
(struct snd_ac97_bus * bus, unsigned short pcms_count, const struct ac97_pcm * pcms)¶ assign AC97 slots to given PCM streams
Parameters
struct snd_ac97_bus * bus
- the ac97 bus instance
unsigned short pcms_count
- count of PCMs to be assigned
const struct ac97_pcm * pcms
- PCMs to be assigned
Description
It assigns available AC97 slots for given PCMs. If none or only some slots are available, pcm->xxx.slots and pcm->xxx.rslots[] members are reduced and might be zero.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ac97_pcm_open
(struct ac97_pcm * pcm, unsigned int rate, enum ac97_pcm_cfg cfg, unsigned short slots)¶ opens the given AC97 pcm
Parameters
struct ac97_pcm * pcm
- the ac97 pcm instance
unsigned int rate
- rate in Hz, if codec does not support VRA, this value must be 48000Hz
enum ac97_pcm_cfg cfg
- output stream characteristics
unsigned short slots
- a subset of allocated slots (snd_ac97_pcm_assign) for this pcm
Description
It locks the specified slots and sets the given rate to AC97 registers.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_ac97_pcm_close
(struct ac97_pcm * pcm)¶ closes the given AC97 pcm
Parameters
struct ac97_pcm * pcm
- the ac97 pcm instance
Description
It frees the locked AC97 slots.
Return
Zero.
-
int
snd_ac97_pcm_double_rate_rules
(struct snd_pcm_runtime * runtime)¶ set double rate constraints
Parameters
struct snd_pcm_runtime * runtime
- the runtime of the ac97 front playback pcm
Description
Installs the hardware constraint rules to prevent using double rates and more than two channels at the same time.
Return
Zero if successful, or a negative error code on failure.
Virtual Master Control API¶
-
struct snd_kcontrol *
snd_ctl_make_virtual_master
(char * name, const unsigned int * tlv)¶ Create a virtual master control
Parameters
char * name
- name string of the control element to create
const unsigned int * tlv
- optional TLV int array for dB information
Description
Creates a virtual master control with the given name string.
After creating a vmaster element, you can add the slave controls
via snd_ctl_add_slave()
or snd_ctl_add_slave_uncached()
.
The optional argument tlv can be used to specify the TLV information for dB scale of the master control. It should be a single element with #SNDRV_CTL_TLVT_DB_SCALE, #SNDRV_CTL_TLV_DB_MINMAX or #SNDRV_CTL_TLVT_DB_MINMAX_MUTE type, and should be the max 0dB.
Return
The created control element, or NULL
for errors (ENOMEM).
-
int
snd_ctl_add_vmaster_hook
(struct snd_kcontrol * kcontrol, void (*hook) (void *private_data, int, void * private_data)¶ Add a hook to a vmaster control
Parameters
struct snd_kcontrol * kcontrol
- vmaster kctl element
void (*)(void *private_data, int) hook
- the hook function
void * private_data
- the private_data pointer to be saved
Description
Adds the given hook to the vmaster control element so that it’s called at each time when the value is changed.
Return
Zero.
-
void
snd_ctl_sync_vmaster
(struct snd_kcontrol * kcontrol, bool hook_only)¶ Sync the vmaster slaves and hook
Parameters
struct snd_kcontrol * kcontrol
- vmaster kctl element
bool hook_only
- sync only the hook
Description
Forcibly call the put callback of each slave and call the hook function to synchronize with the current value of the given vmaster element. NOP when NULL is passed to kcontrol.
-
int
snd_ctl_apply_vmaster_slaves
(struct snd_kcontrol * kctl, int (*func) (struct snd_kcontrol *vslave, struct snd_kcontrol *slave, void *arg, void * arg)¶ Apply function to each vmaster slave
Parameters
struct snd_kcontrol * kctl
- vmaster kctl element
int (*)(struct snd_kcontrol *vslave, struct snd_kcontrol *slave, void *arg) func
- function to apply
void * arg
- optional function argument
Description
Apply the function func to each slave kctl of the given vmaster kctl. Returns 0 if successful, or a negative error code.
-
int
snd_ctl_add_slave
(struct snd_kcontrol * master, struct snd_kcontrol * slave)¶ Add a virtual slave control
Parameters
struct snd_kcontrol * master
- vmaster element
struct snd_kcontrol * slave
- slave element to add
Description
Add a virtual slave control to the given master element created via
snd_ctl_create_virtual_master()
beforehand.
All slaves must be the same type (returning the same information via info callback). The function doesn’t check it, so it’s your responsibility.
Also, some additional limitations: at most two channels, logarithmic volume control (dB level) thus no linear volume, master can only attenuate the volume without gain
Return
Zero if successful or a negative error code.
-
int
snd_ctl_add_slave_uncached
(struct snd_kcontrol * master, struct snd_kcontrol * slave)¶ Add a virtual slave control
Parameters
struct snd_kcontrol * master
- vmaster element
struct snd_kcontrol * slave
- slave element to add
Description
Add a virtual slave control to the given master.
Unlike snd_ctl_add_slave()
, the element added via this function
is supposed to have volatile values, and get callback is called
at each time queried from the master.
When the control peeks the hardware values directly and the value can be changed by other means than the put callback of the element, this function should be used to keep the value always up-to-date.
Return
Zero if successful or a negative error code.
MIDI API¶
Raw MIDI API¶
-
int
snd_rawmidi_receive
(struct snd_rawmidi_substream * substream, const unsigned char * buffer, int count)¶ receive the input data from the device
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
const unsigned char * buffer
- the buffer pointer
int count
- the data size to read
Description
Reads the data from the internal buffer.
Return
The size of read data, or a negative error code on failure.
-
int
snd_rawmidi_transmit_empty
(struct snd_rawmidi_substream * substream)¶ check whether the output buffer is empty
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
Return
1 if the internal output buffer is empty, 0 if not.
-
int
__snd_rawmidi_transmit_peek
(struct snd_rawmidi_substream * substream, unsigned char * buffer, int count)¶ copy data from the internal buffer
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
unsigned char * buffer
- the buffer pointer
int count
- data size to transfer
Description
This is a variant of snd_rawmidi_transmit_peek()
without spinlock.
-
int
snd_rawmidi_transmit_peek
(struct snd_rawmidi_substream * substream, unsigned char * buffer, int count)¶ copy data from the internal buffer
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
unsigned char * buffer
- the buffer pointer
int count
- data size to transfer
Description
Copies data from the internal output buffer to the given buffer.
Call this in the interrupt handler when the midi output is ready,
and call snd_rawmidi_transmit_ack()
after the transmission is
finished.
Return
The size of copied data, or a negative error code on failure.
-
int
__snd_rawmidi_transmit_ack
(struct snd_rawmidi_substream * substream, int count)¶ acknowledge the transmission
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
int count
- the transferred count
Description
This is a variant of __snd_rawmidi_transmit_ack()
without spinlock.
-
int
snd_rawmidi_transmit_ack
(struct snd_rawmidi_substream * substream, int count)¶ acknowledge the transmission
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
int count
- the transferred count
Description
Advances the hardware pointer for the internal output buffer with the given size and updates the condition. Call after the transmission is finished.
Return
The advanced size if successful, or a negative error code on failure.
-
int
snd_rawmidi_transmit
(struct snd_rawmidi_substream * substream, unsigned char * buffer, int count)¶ copy from the buffer to the device
Parameters
struct snd_rawmidi_substream * substream
- the rawmidi substream
unsigned char * buffer
- the buffer pointer
int count
- the data size to transfer
Description
Copies data from the buffer to the device and advances the pointer.
Return
The copied size if successful, or a negative error code on failure.
-
int
snd_rawmidi_proceed
(struct snd_rawmidi_substream * substream)¶ Discard the all pending bytes and proceed
Parameters
struct snd_rawmidi_substream * substream
- rawmidi substream
Return
the number of discarded bytes
-
int
snd_rawmidi_new
(struct snd_card * card, char * id, int device, int output_count, int input_count, struct snd_rawmidi ** rrawmidi)¶ create a rawmidi instance
Parameters
struct snd_card * card
- the card instance
char * id
- the id string
int device
- the device index
int output_count
- the number of output streams
int input_count
- the number of input streams
struct snd_rawmidi ** rrawmidi
- the pointer to store the new rawmidi instance
Description
Creates a new rawmidi instance.
Use snd_rawmidi_set_ops()
to set the operators to the new instance.
Return
Zero if successful, or a negative error code on failure.
-
void
snd_rawmidi_set_ops
(struct snd_rawmidi * rmidi, int stream, const struct snd_rawmidi_ops * ops)¶ set the rawmidi operators
Parameters
struct snd_rawmidi * rmidi
- the rawmidi instance
int stream
- the stream direction, SNDRV_RAWMIDI_STREAM_XXX
const struct snd_rawmidi_ops * ops
- the operator table
Description
Sets the rawmidi operators for the given stream direction.
MPU401-UART API¶
-
irqreturn_t
snd_mpu401_uart_interrupt
(int irq, void * dev_id)¶ generic MPU401-UART interrupt handler
Parameters
int irq
- the irq number
void * dev_id
- mpu401 instance
Description
Processes the interrupt for MPU401-UART i/o.
Return
IRQ_HANDLED
if the interrupt was handled. IRQ_NONE
otherwise.
-
irqreturn_t
snd_mpu401_uart_interrupt_tx
(int irq, void * dev_id)¶ generic MPU401-UART transmit irq handler
Parameters
int irq
- the irq number
void * dev_id
- mpu401 instance
Description
Processes the interrupt for MPU401-UART output.
Return
IRQ_HANDLED
if the interrupt was handled. IRQ_NONE
otherwise.
-
int
snd_mpu401_uart_new
(struct snd_card * card, int device, unsigned short hardware, unsigned long port, unsigned int info_flags, int irq, struct snd_rawmidi ** rrawmidi)¶ create an MPU401-UART instance
Parameters
struct snd_card * card
- the card instance
int device
- the device index, zero-based
unsigned short hardware
- the hardware type, MPU401_HW_XXXX
unsigned long port
- the base address of MPU401 port
unsigned int info_flags
- bitflags MPU401_INFO_XXX
int irq
- the ISA irq number, -1 if not to be allocated
struct snd_rawmidi ** rrawmidi
- the pointer to store the new rawmidi instance
Description
Creates a new MPU-401 instance.
Note that the rawmidi instance is returned on the rrawmidi argument, not the mpu401 instance itself. To access to the mpu401 instance, cast from rawmidi->private_data (with struct snd_mpu401 magic-cast).
Return
Zero if successful, or a negative error code.
Proc Info API¶
Proc Info Interface¶
-
int
snd_info_get_line
(struct snd_info_buffer * buffer, char * line, int len)¶ read one line from the procfs buffer
Parameters
struct snd_info_buffer * buffer
- the procfs buffer
char * line
- the buffer to store
int len
- the max. buffer size
Description
Reads one line from the buffer and stores the string.
Return
Zero if successful, or 1 if error or EOF.
-
const char *
snd_info_get_str
(char * dest, const char * src, int len)¶ parse a string token
Parameters
char * dest
- the buffer to store the string token
const char * src
- the original string
int len
- the max. length of token - 1
Description
Parses the original string and copy a token to the given string buffer.
Return
The updated pointer of the original string so that it can be used for the next call.
-
struct snd_info_entry *
snd_info_create_module_entry
(struct module * module, const char * name, struct snd_info_entry * parent)¶ create an info entry for the given module
Parameters
struct module * module
- the module pointer
const char * name
- the file name
struct snd_info_entry * parent
- the parent directory
Description
Creates a new info entry and assigns it to the given module.
Return
The pointer of the new instance, or NULL
on failure.
-
struct snd_info_entry *
snd_info_create_card_entry
(struct snd_card * card, const char * name, struct snd_info_entry * parent)¶ create an info entry for the given card
Parameters
struct snd_card * card
- the card instance
const char * name
- the file name
struct snd_info_entry * parent
- the parent directory
Description
Creates a new info entry and assigns it to the given card.
Return
The pointer of the new instance, or NULL
on failure.
-
void
snd_info_free_entry
(struct snd_info_entry * entry)¶ release the info entry
Parameters
struct snd_info_entry * entry
- the info entry
Description
Releases the info entry.
-
int
snd_info_register
(struct snd_info_entry * entry)¶ register the info entry
Parameters
struct snd_info_entry * entry
- the info entry
Description
Registers the proc info entry.
Return
Zero if successful, or a negative error code on failure.
Compress Offload¶
Compress Offload API¶
Parameters
struct snd_compr * device
- compressed device to register
-
struct
snd_compressed_buffer
¶ compressed buffer
Definition
struct snd_compressed_buffer {
__u32 fragment_size;
__u32 fragments;
};
Members
fragment_size
- size of buffer fragment in bytes
fragments
- number of such fragments
-
struct
snd_compr_params
¶ compressed stream params
Definition
struct snd_compr_params {
struct snd_compressed_buffer buffer;
struct snd_codec codec;
__u8 no_wake_mode;
};
Members
buffer
- buffer description
codec
- codec parameters
no_wake_mode
- dont wake on fragment elapsed
-
struct
snd_compr_tstamp
¶ timestamp descriptor
Definition
struct snd_compr_tstamp {
__u32 byte_offset;
__u32 copied_total;
__u32 pcm_frames;
__u32 pcm_io_frames;
__u32 sampling_rate;
};
Members
byte_offset
- Byte offset in ring buffer to DSP
copied_total
- Total number of bytes copied from/to ring buffer to/by DSP
pcm_frames
- Frames decoded or encoded by DSP. This field will evolve by large steps and should only be used to monitor encoding/decoding progress. It shall not be used for timing estimates.
pcm_io_frames
- Frames rendered or received by DSP into a mixer or an audio output/input. This field should be used for A/V sync or time estimates.
sampling_rate
- sampling rate of audio
-
struct
snd_compr_avail
¶ avail descriptor
Definition
struct snd_compr_avail {
__u64 avail;
struct snd_compr_tstamp tstamp;
};
Members
avail
- Number of bytes available in ring buffer for writing/reading
tstamp
- timestamp information
-
struct
snd_compr_caps
¶ caps descriptor
Definition
struct snd_compr_caps {
__u32 num_codecs;
__u32 direction;
__u32 min_fragment_size;
__u32 max_fragment_size;
__u32 min_fragments;
__u32 max_fragments;
__u32 codecs[MAX_NUM_CODECS];
__u32 reserved[11];
};
Members
num_codecs
- number of codecs supported
direction
- direction supported. Of type snd_compr_direction
min_fragment_size
- minimum fragment supported by DSP
max_fragment_size
- maximum fragment supported by DSP
min_fragments
- min fragments supported by DSP
max_fragments
- max fragments supported by DSP
codecs
- pointer to array of codecs
reserved
- reserved field
-
struct
snd_compr_codec_caps
¶ query capability of codec
Definition
struct snd_compr_codec_caps {
__u32 codec;
__u32 num_descriptors;
struct snd_codec_desc descriptor[MAX_NUM_CODEC_DESCRIPTORS];
};
Members
codec
- codec for which capability is queried
num_descriptors
- number of codec descriptors
descriptor
- array of codec capability descriptor
-
enum
sndrv_compress_encoder
¶
Constants
SNDRV_COMPRESS_ENCODER_PADDING
- no of samples appended by the encoder at the end of the track
SNDRV_COMPRESS_ENCODER_DELAY
- no of samples inserted by the encoder at the beginning of the track
-
struct
snd_compr_metadata
¶ compressed stream metadata
Definition
struct snd_compr_metadata {
__u32 key;
__u32 value[8];
};
Members
key
- key id
value
- key value
-
SNDRV_COMPRESS_IOCTL_VERSION
()¶
Parameters
Description
SNDRV_COMPRESS_GET_CAPS: Query capability of DSP SNDRV_COMPRESS_GET_CODEC_CAPS: Query capability of a codec SNDRV_COMPRESS_SET_PARAMS: Set codec and stream parameters
Note
only codec params can be changed runtime and stream params cant be SNDRV_COMPRESS_GET_PARAMS: Query codec params SNDRV_COMPRESS_TSTAMP: get the current timestamp value SNDRV_COMPRESS_AVAIL: get the current buffer avail value. This also queries the tstamp properties SNDRV_COMPRESS_PAUSE: Pause the running stream SNDRV_COMPRESS_RESUME: resume a paused stream SNDRV_COMPRESS_START: Start a stream SNDRV_COMPRESS_STOP: stop a running stream, discarding ring buffer content and the buffers currently with DSP SNDRV_COMPRESS_DRAIN: Play till end of buffers and stop after that SNDRV_COMPRESS_IOCTL_VERSION: Query the API version
-
struct
snd_enc_vorbis
¶
Definition
struct snd_enc_vorbis {
__s32 quality;
__u32 managed;
__u32 max_bit_rate;
__u32 min_bit_rate;
__u32 downmix;
};
Members
quality
- Sets encoding quality to n, between -1 (low) and 10 (high). In the default mode of operation, the quality level is 3. Normal quality range is 0 - 10.
managed
- Boolean. Set bitrate management mode. This turns off the normal VBR encoding, but allows hard or soft bitrate constraints to be enforced by the encoder. This mode can be slower, and may also be lower quality. It is primarily useful for streaming.
max_bit_rate
- Enabled only if managed is TRUE
min_bit_rate
- Enabled only if managed is TRUE
downmix
- Boolean. Downmix input from stereo to mono (has no effect on non-stereo streams). Useful for lower-bitrate encoding.
Description
These options were extracted from the OpenMAX IL spec and Gstreamer vorbisenc properties
For best quality users should specify VBR mode and set quality levels.
-
struct
snd_enc_real
¶
Definition
struct snd_enc_real {
__u32 quant_bits;
__u32 start_region;
__u32 num_regions;
};
Members
quant_bits
- number of coupling quantization bits in the stream
start_region
- coupling start region in the stream
num_regions
- number of regions value
Description
These options were extracted from the OpenMAX IL spec
-
struct
snd_enc_flac
¶
Definition
struct snd_enc_flac {
__u32 num;
__u32 gain;
};
Members
num
- serial number, valid only for OGG formats needs to be set by application
gain
- Add replay gain tags
Description
These options were extracted from the FLAC online documentation at http://flac.sourceforge.net/documentation_tools_flac.html
To make the API simpler, it is assumed that the user will select quality profiles. Additional options that affect encoding quality and speed can be added at a later stage if needed.
By default the Subset format is used by encoders.
TAGS such as pictures, etc, cannot be handled by an offloaded encoder and are not supported in this API.
-
struct
snd_compr_runtime
¶
Definition
struct snd_compr_runtime {
snd_pcm_state_t state;
struct snd_compr_ops *ops;
void *buffer;
u64 buffer_size;
u32 fragment_size;
u32 fragments;
u64 total_bytes_available;
u64 total_bytes_transferred;
wait_queue_head_t sleep;
void *private_data;
};
Members
state
- stream state
ops
- pointer to DSP callbacks
buffer
- pointer to kernel buffer, valid only when not in mmap mode or DSP doesn’t implement copy
buffer_size
- size of the above buffer
fragment_size
- size of buffer fragment in bytes
fragments
- number of such fragments
total_bytes_available
- cumulative number of bytes made available in the ring buffer
total_bytes_transferred
- cumulative bytes transferred by offload DSP
sleep
- poll sleep
private_data
- driver private data pointer
-
struct
snd_compr_stream
¶
Definition
struct snd_compr_stream {
const char *name;
struct snd_compr_ops *ops;
struct snd_compr_runtime *runtime;
struct snd_compr *device;
struct delayed_work error_work;
enum snd_compr_direction direction;
bool metadata_set;
bool next_track;
void *private_data;
};
Members
name
- device name
ops
- pointer to DSP callbacks
runtime
- pointer to runtime structure
device
- device pointer
error_work
- delayed work used when closing the stream due to an error
direction
- stream direction, playback/recording
metadata_set
- metadata set flag, true when set
next_track
- has userspace signal next track transition, true when set
private_data
- pointer to DSP private data
-
struct
snd_compr_ops
¶
Definition
struct snd_compr_ops {
int (*open)(struct snd_compr_stream *stream);
int (*free)(struct snd_compr_stream *stream);
int (*set_params)(struct snd_compr_stream *stream, struct snd_compr_params *params);
int (*get_params)(struct snd_compr_stream *stream, struct snd_codec *params);
int (*set_metadata)(struct snd_compr_stream *stream, struct snd_compr_metadata *metadata);
int (*get_metadata)(struct snd_compr_stream *stream, struct snd_compr_metadata *metadata);
int (*trigger)(struct snd_compr_stream *stream, int cmd);
int (*pointer)(struct snd_compr_stream *stream, struct snd_compr_tstamp *tstamp);
int (*copy)(struct snd_compr_stream *stream, char __user *buf, size_t count);
int (*mmap)(struct snd_compr_stream *stream, struct vm_area_struct *vma);
int (*ack)(struct snd_compr_stream *stream, size_t bytes);
int (*get_caps) (struct snd_compr_stream *stream, struct snd_compr_caps *caps);
int (*get_codec_caps) (struct snd_compr_stream *stream, struct snd_compr_codec_caps *codec);
};
Members
open
- Open the compressed stream This callback is mandatory and shall keep dsp ready to receive the stream parameter
free
- Close the compressed stream, mandatory
set_params
- Sets the compressed stream parameters, mandatory This can be called in during stream creation only to set codec params and the stream properties
get_params
- retrieve the codec parameters, mandatory
set_metadata
- Set the metadata values for a stream
get_metadata
- retrieves the requested metadata values from stream
trigger
- Trigger operations like start, pause, resume, drain, stop. This callback is mandatory
pointer
- Retrieve current h/w pointer information. Mandatory
copy
- Copy the compressed data to/from userspace, Optional Can’t be implemented if DSP supports mmap
mmap
- DSP mmap method to mmap DSP memory
ack
- Ack for DSP when data is written to audio buffer, Optional Not valid if copy is implemented
get_caps
- Retrieve DSP capabilities, mandatory
get_codec_caps
- Retrieve capabilities for a specific codec, mandatory
-
struct
snd_compr
¶
Definition
struct snd_compr {
const char *name;
struct device dev;
struct snd_compr_ops *ops;
void *private_data;
struct snd_card *card;
unsigned int direction;
struct mutex lock;
int device;
#ifdef CONFIG_SND_VERBOSE_PROCFS;
};
Members
name
- DSP device name
dev
- associated device instance
ops
- pointer to DSP callbacks
private_data
- pointer to DSP pvt data
card
- sound card pointer
direction
- Playback or capture direction
lock
- device lock
device
- device id
ASoC¶
ASoC Core API¶
-
struct
snd_soc_jack_pin
¶ Describes a pin to update based on jack detection
Definition
struct snd_soc_jack_pin {
struct list_head list;
const char *pin;
int mask;
bool invert;
};
Members
list
- internal list entry
pin
- name of the pin to update
mask
- bits to check for in reported jack status
invert
- if non-zero then pin is enabled when status is not reported
-
struct
snd_soc_jack_zone
¶ Describes voltage zones of jack detection
Definition
struct snd_soc_jack_zone {
unsigned int min_mv;
unsigned int max_mv;
unsigned int jack_type;
unsigned int debounce_time;
struct list_head list;
};
Members
min_mv
- start voltage in mv
max_mv
- end voltage in mv
jack_type
- type of jack that is expected for this voltage
debounce_time
- debounce_time for jack, codec driver should wait for this duration before reading the adc for voltages
list
- internal list entry
-
struct
snd_soc_jack_gpio
¶ Describes a gpio pin for jack detection
Definition
struct snd_soc_jack_gpio {
unsigned int gpio;
unsigned int idx;
struct device *gpiod_dev;
const char *name;
int report;
int invert;
int debounce_time;
bool wake;
int (*jack_status_check)(void *data);
};
Members
gpio
- legacy gpio number
idx
- gpio descriptor index within the function of the GPIO consumer device
gpiod_dev
- GPIO consumer device
name
- gpio name. Also as connection ID for the GPIO consumer device function name lookup
report
- value to report when jack detected
invert
- report presence in low state
debounce_time
- debounce time in ms
wake
- enable as wake source
jack_status_check
- callback function which overrides the detection to provide more complex checks (eg, reading an ADC).
-
struct snd_soc_component *
snd_soc_dapm_to_component
(struct snd_soc_dapm_context * dapm)¶ Casts a DAPM context to the component it is embedded in
Parameters
struct snd_soc_dapm_context * dapm
- The DAPM context to cast to the component
Description
This function must only be used on DAPM contexts that are known to be part of a component (e.g. in a component driver). Otherwise the behavior is undefined.
-
struct snd_soc_dapm_context *
snd_soc_component_get_dapm
(struct snd_soc_component * component)¶ Returns the DAPM context associated with a component
Parameters
struct snd_soc_component * component
- The component for which to get the DAPM context
-
void
snd_soc_component_init_bias_level
(struct snd_soc_component * component, enum snd_soc_bias_level level)¶ Initialize COMPONENT DAPM bias level
Parameters
struct snd_soc_component * component
- The COMPONENT for which to initialize the DAPM bias level
enum snd_soc_bias_level level
- The DAPM level to initialize to
Description
Initializes the COMPONENT DAPM bias level. See snd_soc_dapm_init_bias_level()
.
-
enum snd_soc_bias_level
snd_soc_component_get_bias_level
(struct snd_soc_component * component)¶ Get current COMPONENT DAPM bias level
Parameters
struct snd_soc_component * component
- The COMPONENT for which to get the DAPM bias level
Return
The current DAPM bias level of the COMPONENT.
-
int
snd_soc_component_force_bias_level
(struct snd_soc_component * component, enum snd_soc_bias_level level)¶ Set the COMPONENT DAPM bias level
Parameters
struct snd_soc_component * component
- The COMPONENT for which to set the level
enum snd_soc_bias_level level
- The level to set to
Description
Forces the COMPONENT bias level to a specific state. See
snd_soc_dapm_force_bias_level()
.
-
struct snd_soc_component *
snd_soc_dapm_kcontrol_component
(struct snd_kcontrol * kcontrol)¶ Returns the component associated to a kcontrol
Parameters
struct snd_kcontrol * kcontrol
- The kcontrol
Description
This function must only be used on DAPM contexts that are known to be part of a COMPONENT (e.g. in a COMPONENT driver). Otherwise the behavior is undefined.
-
int
snd_soc_component_cache_sync
(struct snd_soc_component * component)¶ Sync the register cache with the hardware
Parameters
struct snd_soc_component * component
- COMPONENT to sync
Note
This function will call regcache_sync()
-
struct snd_soc_component *
snd_soc_kcontrol_component
(struct snd_kcontrol * kcontrol)¶ Returns the component that registered the control
Parameters
struct snd_kcontrol * kcontrol
- The control for which to get the component
Note
This function will work correctly if the control has been registered
for a component. With snd_soc_add_codec_controls()
or via table based
setup for either a CODEC or component driver. Otherwise the behavior is
undefined.
-
struct snd_soc_dai *
snd_soc_find_dai
(const struct snd_soc_dai_link_component * dlc)¶ Find a registered DAI
Parameters
const struct snd_soc_dai_link_component * dlc
- name of the DAI or the DAI driver and optional component info to match
Description
This function will search all registered components and their DAIs to find the DAI of the same name. The component’s of_node and name should also match if being specified.
Return
pointer of DAI, or NULL if not found.
-
struct snd_soc_dai_link *
snd_soc_find_dai_link
(struct snd_soc_card * card, int id, const char * name, const char * stream_name)¶ Find a DAI link
Parameters
struct snd_soc_card * card
- soc card
int id
- DAI link ID to match
const char * name
- DAI link name to match, optional
const char * stream_name
- DAI link stream name to match, optional
Description
This function will search all existing DAI links of the soc card to find the link of the same ID. Since DAI links may not have their unique ID, so name and stream name should also match if being specified.
Return
pointer of DAI link, or NULL if not found.
-
int
snd_soc_add_dai_link
(struct snd_soc_card * card, struct snd_soc_dai_link * dai_link)¶ Add a DAI link dynamically
Parameters
struct snd_soc_card * card
- The ASoC card to which the DAI link is added
struct snd_soc_dai_link * dai_link
- The new DAI link to add
Description
This function adds a DAI link to the ASoC card’s link list.
Note
Topology can use this API to add DAI links when probing the topology component. And machine drivers can still define static DAI links in dai_link array.
-
void
snd_soc_remove_dai_link
(struct snd_soc_card * card, struct snd_soc_dai_link * dai_link)¶ Remove a DAI link from the list
Parameters
struct snd_soc_card * card
- The ASoC card that owns the link
struct snd_soc_dai_link * dai_link
- The DAI link to remove
Description
This function removes a DAI link from the ASoC card’s link list.
For DAI links previously added by topology, topology should remove them by using the dobj embedded in the link.
-
int
snd_soc_runtime_set_dai_fmt
(struct snd_soc_pcm_runtime * rtd, unsigned int dai_fmt)¶ Change DAI link format for a ASoC runtime
Parameters
struct snd_soc_pcm_runtime * rtd
- The runtime for which the DAI link format should be changed
unsigned int dai_fmt
- The new DAI link format
Description
This function updates the DAI link format for all DAIs connected to the DAI link for the specified runtime.
Note
For setups with a static format set the dai_fmt field in the corresponding snd_dai_link struct instead of using this function.
Returns 0 on success, otherwise a negative error code.
-
int
snd_soc_set_dmi_name
(struct snd_soc_card * card, const char * flavour)¶ Register DMI names to card
Parameters
struct snd_soc_card * card
- The card to register DMI names
const char * flavour
- The flavour “differentiator” for the card amongst its peers.
Description
An Intel machine driver may be used by many different devices but are difficult for userspace to differentiate, since machine drivers ususally use their own name as the card short name and leave the card long name blank. To differentiate such devices and fix bugs due to lack of device-specific configurations, this function allows DMI info to be used as the sound card long name, in the format of “vendor-product-version-board” (Character ‘-‘ is used to separate different DMI fields here). This will help the user space to load the device-specific Use Case Manager (UCM) configurations for the card.
Possible card long names may be: DellInc.-XPS139343-01-0310JH ASUSTeKCOMPUTERINC.-T100TA-1.0-T100TA Circuitco-MinnowboardMaxD0PLATFORM-D0-MinnowBoardMAX
This function also supports flavoring the card longname to provide the extra differentiation, like “vendor-product-version-board-flavor”.
We only keep number and alphabet characters and a few separator characters in the card long name since UCM in the user space uses the card long names as card configuration directory names and AudoConf cannot support special charactors like SPACE.
Returns 0 on success, otherwise a negative error code.
-
struct snd_kcontrol *
snd_soc_cnew
(const struct snd_kcontrol_new * _template, void * data, const char * long_name, const char * prefix)¶ create new control
Parameters
const struct snd_kcontrol_new * _template
- control template
void * data
- control private data
const char * long_name
- control long name
const char * prefix
- control name prefix
Description
Create a new mixer control from a template control.
Returns 0 for success, else error.
-
int
snd_soc_add_component_controls
(struct snd_soc_component * component, const struct snd_kcontrol_new * controls, unsigned int num_controls)¶ Add an array of controls to a component.
Parameters
struct snd_soc_component * component
- Component to add controls to
const struct snd_kcontrol_new * controls
- Array of controls to add
unsigned int num_controls
- Number of elements in the array
Return
0 for success, else error.
-
int
snd_soc_add_card_controls
(struct snd_soc_card * soc_card, const struct snd_kcontrol_new * controls, int num_controls)¶ add an array of controls to a SoC card. Convenience function to add a list of controls.
Parameters
struct snd_soc_card * soc_card
- SoC card to add controls to
const struct snd_kcontrol_new * controls
- array of controls to add
int num_controls
- number of elements in the array
Description
Return 0 for success, else error.
-
int
snd_soc_add_dai_controls
(struct snd_soc_dai * dai, const struct snd_kcontrol_new * controls, int num_controls)¶ add an array of controls to a DAI. Convienience function to add a list of controls.
Parameters
struct snd_soc_dai * dai
- DAI to add controls to
const struct snd_kcontrol_new * controls
- array of controls to add
int num_controls
- number of elements in the array
Description
Return 0 for success, else error.
-
int
snd_soc_dai_set_sysclk
(struct snd_soc_dai * dai, int clk_id, unsigned int freq, int dir)¶ configure DAI system or master clock.
Parameters
struct snd_soc_dai * dai
- DAI
int clk_id
- DAI specific clock ID
unsigned int freq
- new clock frequency in Hz
int dir
- new clock direction - input/output.
Description
Configures the DAI master (MCLK) or system (SYSCLK) clocking.
-
int
snd_soc_component_set_sysclk
(struct snd_soc_component * component, int clk_id, int source, unsigned int freq, int dir)¶ configure COMPONENT system or master clock.
Parameters
struct snd_soc_component * component
- COMPONENT
int clk_id
- DAI specific clock ID
int source
- Source for the clock
unsigned int freq
- new clock frequency in Hz
int dir
- new clock direction - input/output.
Description
Configures the CODEC master (MCLK) or system (SYSCLK) clocking.
-
int
snd_soc_dai_set_clkdiv
(struct snd_soc_dai * dai, int div_id, int div)¶ configure DAI clock dividers.
Parameters
struct snd_soc_dai * dai
- DAI
int div_id
- DAI specific clock divider ID
int div
- new clock divisor.
Description
Configures the clock dividers. This is used to derive the best DAI bit and frame clocks from the system or master clock. It’s best to set the DAI bit and frame clocks as low as possible to save system power.
-
int
snd_soc_dai_set_pll
(struct snd_soc_dai * dai, int pll_id, int source, unsigned int freq_in, unsigned int freq_out)¶ configure DAI PLL.
Parameters
struct snd_soc_dai * dai
- DAI
int pll_id
- DAI specific PLL ID
int source
- DAI specific source for the PLL
unsigned int freq_in
- PLL input clock frequency in Hz
unsigned int freq_out
- requested PLL output clock frequency in Hz
Description
Configures and enables PLL to generate output clock based on input clock.
-
int
snd_soc_dai_set_bclk_ratio
(struct snd_soc_dai * dai, unsigned int ratio)¶ configure BCLK to sample rate ratio.
Parameters
struct snd_soc_dai * dai
- DAI
unsigned int ratio
- Ratio of BCLK to Sample rate.
Description
Configures the DAI for a preset BCLK to sample rate ratio.
-
int
snd_soc_dai_set_fmt
(struct snd_soc_dai * dai, unsigned int fmt)¶ configure DAI hardware audio format.
Parameters
struct snd_soc_dai * dai
- DAI
unsigned int fmt
- SND_SOC_DAIFMT_* format value.
Description
Configures the DAI hardware format and clocking.
-
int
snd_soc_xlate_tdm_slot_mask
(unsigned int slots, unsigned int * tx_mask, unsigned int * rx_mask)¶ generate tx/rx slot mask.
Parameters
unsigned int slots
- Number of slots in use.
unsigned int * tx_mask
- bitmask representing active TX slots.
unsigned int * rx_mask
- bitmask representing active RX slots.
Description
Generates the TDM tx and rx slot default masks for DAI.
-
int
snd_soc_dai_set_tdm_slot
(struct snd_soc_dai * dai, unsigned int tx_mask, unsigned int rx_mask, int slots, int slot_width)¶ Configures a DAI for TDM operation
Parameters
struct snd_soc_dai * dai
- The DAI to configure
unsigned int tx_mask
- bitmask representing active TX slots.
unsigned int rx_mask
- bitmask representing active RX slots.
int slots
- Number of slots in use.
int slot_width
- Width in bits for each slot.
Description
This function configures the specified DAI for TDM operation. slot contains the total number of slots of the TDM stream and slot_with the width of each slot in bit clock cycles. tx_mask and rx_mask are bitmasks specifying the active slots of the TDM stream for the specified DAI, i.e. which slots the DAI should write to or read from. If a bit is set the corresponding slot is active, if a bit is cleared the corresponding slot is inactive. Bit 0 maps to the first slot, bit 1 to the second slot and so on. The first active slot maps to the first channel of the DAI, the second active slot to the second channel and so on.
TDM mode can be disabled by passing 0 for slots. In this case tx_mask, rx_mask and slot_width will be ignored.
Returns 0 on success, a negative error code otherwise.
-
int
snd_soc_dai_set_channel_map
(struct snd_soc_dai * dai, unsigned int tx_num, unsigned int * tx_slot, unsigned int rx_num, unsigned int * rx_slot)¶ configure DAI audio channel map
Parameters
struct snd_soc_dai * dai
- DAI
unsigned int tx_num
- how many TX channels
unsigned int * tx_slot
- pointer to an array which imply the TX slot number channel 0~num-1 uses
unsigned int rx_num
- how many RX channels
unsigned int * rx_slot
- pointer to an array which imply the RX slot number channel 0~num-1 uses
Description
configure the relationship between channel number and TDM slot number.
-
int
snd_soc_dai_get_channel_map
(struct snd_soc_dai * dai, unsigned int * tx_num, unsigned int * tx_slot, unsigned int * rx_num, unsigned int * rx_slot)¶ Get DAI audio channel map
Parameters
struct snd_soc_dai * dai
- DAI
unsigned int * tx_num
- how many TX channels
unsigned int * tx_slot
- pointer to an array which imply the TX slot number channel 0~num-1 uses
unsigned int * rx_num
- how many RX channels
unsigned int * rx_slot
- pointer to an array which imply the RX slot number channel 0~num-1 uses
-
int
snd_soc_dai_set_tristate
(struct snd_soc_dai * dai, int tristate)¶ configure DAI system or master clock.
Parameters
struct snd_soc_dai * dai
- DAI
int tristate
- tristate enable
Description
Tristates the DAI so that others can use it.
-
int
snd_soc_dai_digital_mute
(struct snd_soc_dai * dai, int mute, int direction)¶ configure DAI system or master clock.
Parameters
struct snd_soc_dai * dai
- DAI
int mute
- mute enable
int direction
- stream to mute
Description
Mutes the DAI DAC.
-
int
snd_soc_register_card
(struct snd_soc_card * card)¶ Register a card with the ASoC core
Parameters
struct snd_soc_card * card
- Card to register
-
int
snd_soc_unregister_card
(struct snd_soc_card * card)¶ Unregister a card with the ASoC core
Parameters
struct snd_soc_card * card
- Card to unregister
-
void
snd_soc_unregister_dais
(struct snd_soc_component * component)¶ Unregister DAIs from the ASoC core
Parameters
struct snd_soc_component * component
- The component for which the DAIs should be unregistered
-
int
snd_soc_register_dais
(struct snd_soc_component * component, struct snd_soc_dai_driver * dai_drv, size_t count)¶ Register a DAI with the ASoC core
Parameters
struct snd_soc_component * component
- The component the DAIs are registered for
struct snd_soc_dai_driver * dai_drv
- DAI driver to use for the DAIs
size_t count
- Number of DAIs
-
int
snd_soc_register_dai
(struct snd_soc_component * component, struct snd_soc_dai_driver * dai_drv)¶ Register a DAI dynamically & create its widgets
Parameters
struct snd_soc_component * component
- The component the DAIs are registered for
struct snd_soc_dai_driver * dai_drv
- DAI driver to use for the DAI
Description
Topology can use this API to register DAIs when probing a component. These DAIs’s widgets will be freed in the card cleanup and the DAIs will be freed in the component cleanup.
-
void
snd_soc_component_init_regmap
(struct snd_soc_component * component, struct regmap * regmap)¶ Initialize regmap instance for the component
Parameters
struct snd_soc_component * component
- The component for which to initialize the regmap instance
struct regmap * regmap
- The regmap instance that should be used by the component
Description
This function allows deferred assignment of the regmap instance that is associated with the component. Only use this if the regmap instance is not yet ready when the component is registered. The function must also be called before the first IO attempt of the component.
-
void
snd_soc_component_exit_regmap
(struct snd_soc_component * component)¶ De-initialize regmap instance for the component
Parameters
struct snd_soc_component * component
- The component for which to de-initialize the regmap instance
Description
Calls regmap_exit()
on the regmap instance associated to the component and
removes the regmap instance from the component.
This function should only be used if snd_soc_component_init_regmap()
was used
to initialize the regmap instance.
-
int
__snd_soc_unregister_component
(struct device * dev)¶ Unregister all related component from the ASoC core
Parameters
struct device * dev
- The device to unregister
-
int
devm_snd_soc_register_component
(struct device * dev, const struct snd_soc_component_driver * cmpnt_drv, struct snd_soc_dai_driver * dai_drv, int num_dai)¶ resource managed component registration
Parameters
struct device * dev
- Device used to manage component
const struct snd_soc_component_driver * cmpnt_drv
- Component driver
struct snd_soc_dai_driver * dai_drv
- DAI driver
int num_dai
- Number of DAIs to register
Description
Register a component with automatic unregistration when the device is unregistered.
-
int
devm_snd_soc_register_card
(struct device * dev, struct snd_soc_card * card)¶ resource managed card registration
Parameters
struct device * dev
- Device used to manage card
struct snd_soc_card * card
- Card to register
Description
Register a card with automatic unregistration when the device is unregistered.
-
int
devm_snd_dmaengine_pcm_register
(struct device * dev, const struct snd_dmaengine_pcm_config * config, unsigned int flags)¶ resource managed dmaengine PCM registration
Parameters
struct device * dev
- The parent device for the PCM device
const struct snd_dmaengine_pcm_config * config
- Platform specific PCM configuration
unsigned int flags
- Platform specific quirks
Description
Register a dmaengine based PCM device with automatic unregistration when the device is unregistered.
-
int
snd_soc_component_read
(struct snd_soc_component * component, unsigned int reg, unsigned int * val)¶ Read register value
Parameters
struct snd_soc_component * component
- Component to read from
unsigned int reg
- Register to read
unsigned int * val
- Pointer to where the read value is stored
Return
0 on success, a negative error code otherwise.
-
int
snd_soc_component_write
(struct snd_soc_component * component, unsigned int reg, unsigned int val)¶ Write register value
Parameters
struct snd_soc_component * component
- Component to write to
unsigned int reg
- Register to write
unsigned int val
- Value to write to the register
Return
0 on success, a negative error code otherwise.
-
int
snd_soc_component_update_bits
(struct snd_soc_component * component, unsigned int reg, unsigned int mask, unsigned int val)¶ Perform read/modify/write cycle
Parameters
struct snd_soc_component * component
- Component to update
unsigned int reg
- Register to update
unsigned int mask
- Mask that specifies which bits to update
unsigned int val
- New value for the bits specified by mask
Return
1 if the operation was successful and the value of the register changed, 0 if the operation was successful, but the value did not change. Returns a negative error code otherwise.
-
int
snd_soc_component_update_bits_async
(struct snd_soc_component * component, unsigned int reg, unsigned int mask, unsigned int val)¶ Perform asynchronous read/modify/write cycle
Parameters
struct snd_soc_component * component
- Component to update
unsigned int reg
- Register to update
unsigned int mask
- Mask that specifies which bits to update
unsigned int val
- New value for the bits specified by mask
Description
This function is similar to snd_soc_component_update_bits()
, but the update
operation is scheduled asynchronously. This means it may not be completed
when the function returns. To make sure that all scheduled updates have been
completed snd_soc_component_async_complete()
must be called.
Return
1 if the operation was successful and the value of the register changed, 0 if the operation was successful, but the value did not change. Returns a negative error code otherwise.
-
void
snd_soc_component_async_complete
(struct snd_soc_component * component)¶ Ensure asynchronous I/O has completed
Parameters
struct snd_soc_component * component
- Component for which to wait
Description
This function blocks until all asynchronous I/O which has previously been
scheduled using snd_soc_component_update_bits_async()
has completed.
-
int
snd_soc_component_test_bits
(struct snd_soc_component * component, unsigned int reg, unsigned int mask, unsigned int value)¶ Test register for change
Parameters
struct snd_soc_component * component
- component
unsigned int reg
- Register to test
unsigned int mask
- Mask that specifies which bits to test
unsigned int value
- Value to test against
Description
Tests a register with a new value and checks if the new value is different from the old value.
Return
1 for change, otherwise 0.
-
void
snd_soc_runtime_activate
(struct snd_soc_pcm_runtime * rtd, int stream)¶ Increment active count for PCM runtime components
Parameters
struct snd_soc_pcm_runtime * rtd
- ASoC PCM runtime that is activated
int stream
- Direction of the PCM stream
Description
Increments the active count for all the DAIs and components attached to a PCM runtime. Should typically be called when a stream is opened.
Must be called with the rtd->pcm_mutex being held
-
void
snd_soc_runtime_deactivate
(struct snd_soc_pcm_runtime * rtd, int stream)¶ Decrement active count for PCM runtime components
Parameters
struct snd_soc_pcm_runtime * rtd
- ASoC PCM runtime that is deactivated
int stream
- Direction of the PCM stream
Description
Decrements the active count for all the DAIs and components attached to a PCM runtime. Should typically be called when a stream is closed.
Must be called with the rtd->pcm_mutex being held
-
bool
snd_soc_runtime_ignore_pmdown_time
(struct snd_soc_pcm_runtime * rtd)¶ Check whether to ignore the power down delay
Parameters
struct snd_soc_pcm_runtime * rtd
- The ASoC PCM runtime that should be checked.
Description
This function checks whether the power down delay should be ignored for a specific PCM runtime. Returns true if the delay is 0, if it the DAI link has been configured to ignore the delay, or if none of the components benefits from having the delay.
-
int
snd_soc_set_runtime_hwparams
(struct snd_pcm_substream * substream, const struct snd_pcm_hardware * hw)¶ set the runtime hardware parameters
Parameters
struct snd_pcm_substream * substream
- the pcm substream
const struct snd_pcm_hardware * hw
- the hardware parameters
Description
Sets the substream runtime hardware parameters.
-
int
snd_soc_info_enum_double
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ enumerated double mixer info callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_info * uinfo
- control element information
Description
Callback to provide information about a double enumerated mixer control.
Returns 0 for success.
-
int
snd_soc_get_enum_double
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ enumerated double mixer get callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value of a double enumerated mixer.
Returns 0 for success.
-
int
snd_soc_put_enum_double
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ enumerated double mixer put callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value of a double enumerated mixer.
Returns 0 for success.
-
int
snd_soc_read_signed
(struct snd_soc_component * component, unsigned int reg, unsigned int mask, unsigned int shift, unsigned int sign_bit, int * signed_val)¶ Read a codec register and interpret as signed value
Parameters
struct snd_soc_component * component
- component
unsigned int reg
- Register to read
unsigned int mask
- Mask to use after shifting the register value
unsigned int shift
- Right shift of register value
unsigned int sign_bit
- Bit that describes if a number is negative or not.
int * signed_val
- Pointer to where the read value should be stored
Description
This functions reads a codec register. The register value is shifted right by ‘shift’ bits and masked with the given ‘mask’. Afterwards it translates the given registervalue into a signed integer if sign_bit is non-zero.
Returns 0 on sucess, otherwise an error value
-
int
snd_soc_info_volsw
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ single mixer info callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_info * uinfo
- control element information
Description
Callback to provide information about a single mixer control, or a double mixer control that spans 2 registers.
Returns 0 for success.
-
int
snd_soc_info_volsw_sx
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ Mixer info callback for SX TLV controls
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_info * uinfo
- control element information
Description
Callback to provide information about a single mixer control, or a double mixer control that spans 2 registers of the SX TLV type. SX TLV controls have a range that represents both positive and negative values either side of zero but without a sign bit.
Returns 0 for success.
-
int
snd_soc_get_volsw
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ single mixer get callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value of a single mixer control, or a double mixer control that spans 2 registers.
Returns 0 for success.
-
int
snd_soc_put_volsw
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ single mixer put callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value of a single mixer control, or a double mixer control that spans 2 registers.
Returns 0 for success.
-
int
snd_soc_get_volsw_sx
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ single mixer get callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value of a single mixer control, or a double mixer control that spans 2 registers.
Returns 0 for success.
-
int
snd_soc_put_volsw_sx
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ double mixer set callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value of a double mixer control that spans 2 registers.
Returns 0 for success.
-
int
snd_soc_info_volsw_range
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ single mixer info callback with range.
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_info * uinfo
- control element information
Description
Callback to provide information, within a range, about a single mixer control.
returns 0 for success.
-
int
snd_soc_put_volsw_range
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ single mixer put value callback with range.
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value, within a range, for a single mixer control.
Returns 0 for success.
-
int
snd_soc_get_volsw_range
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ single mixer get callback with range
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value, within a range, of a single mixer control.
Returns 0 for success.
-
int
snd_soc_limit_volume
(struct snd_soc_card * card, const char * name, int max)¶ Set new limit to an existing volume control.
Parameters
struct snd_soc_card * card
- where to look for the control
const char * name
- Name of the control
int max
- new maximum limit
Description
Return 0 for success, else error.
-
int
snd_soc_info_xr_sx
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ signed multi register info callback
Parameters
struct snd_kcontrol * kcontrol
- mreg control
struct snd_ctl_elem_info * uinfo
- control element information
Description
Callback to provide information of a control that can span multiple codec registers which together forms a single signed value in a MSB/LSB manner.
Returns 0 for success.
-
int
snd_soc_get_xr_sx
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ signed multi register get callback
Parameters
struct snd_kcontrol * kcontrol
- mreg control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value of a control that can span multiple codec registers which together forms a single signed value in a MSB/LSB manner. The control supports specifying total no of bits used to allow for bitfields across the multiple codec registers.
Returns 0 for success.
-
int
snd_soc_put_xr_sx
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ signed multi register get callback
Parameters
struct snd_kcontrol * kcontrol
- mreg control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value of a control that can span multiple codec registers which together forms a single signed value in a MSB/LSB manner. The control supports specifying total no of bits used to allow for bitfields across the multiple codec registers.
Returns 0 for success.
-
int
snd_soc_get_strobe
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ strobe get callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback get the value of a strobe mixer control.
Returns 0 for success.
-
int
snd_soc_put_strobe
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ strobe put callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback strobe a register bit to high then low (or the inverse) in one pass of a single mixer enum control.
Returns 1 for success.
-
int
snd_soc_new_compress
(struct snd_soc_pcm_runtime * rtd, int num)¶ create a new compress.
Parameters
struct snd_soc_pcm_runtime * rtd
- The runtime for which we will create compress
int num
- the device index number (zero based - shared with normal PCMs)
Return
0 for success, else error.
ASoC DAPM API¶
-
struct snd_soc_dapm_widget *
snd_soc_dapm_kcontrol_widget
(struct snd_kcontrol * kcontrol)¶ Returns the widget associated to a kcontrol
Parameters
struct snd_kcontrol * kcontrol
- The kcontrol
-
struct snd_soc_dapm_context *
snd_soc_dapm_kcontrol_dapm
(struct snd_kcontrol * kcontrol)¶ Returns the dapm context associated to a kcontrol
Parameters
struct snd_kcontrol * kcontrol
- The kcontrol
Note
This function must only be used on kcontrols that are known to have been registered for a CODEC. Otherwise the behaviour is undefined.
-
int
snd_soc_dapm_force_bias_level
(struct snd_soc_dapm_context * dapm, enum snd_soc_bias_level level)¶ Sets the DAPM bias level
Parameters
struct snd_soc_dapm_context * dapm
- The DAPM context for which to set the level
enum snd_soc_bias_level level
- The level to set
Description
Forces the DAPM bias level to a specific state. It will call the bias level callback of DAPM context with the specified level. This will even happen if the context is already at the same level. Furthermore it will not go through the normal bias level sequencing, meaning any intermediate states between the current and the target state will not be entered.
Note that the change in bias level is only temporary and the next time
snd_soc_dapm_sync()
is called the state will be set to the level as
determined by the DAPM core. The function is mainly intended to be used to
used during probe or resume from suspend to power up the device so
initialization can be done, before the DAPM core takes over.
-
int
snd_soc_dapm_set_bias_level
(struct snd_soc_dapm_context * dapm, enum snd_soc_bias_level level)¶ set the bias level for the system
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
enum snd_soc_bias_level level
- level to configure
Description
Configure the bias (power) levels for the SoC audio device.
Returns 0 for success else error.
-
int
snd_soc_dapm_dai_get_connected_widgets
(struct snd_soc_dai * dai, int stream, struct snd_soc_dapm_widget_list ** list, bool (*custom_stop_condition) (struct snd_soc_dapm_widget *, enum snd_soc_dapm_direction)¶ query audio path and it’s widgets.
Parameters
struct snd_soc_dai * dai
- the soc DAI.
int stream
- stream direction.
struct snd_soc_dapm_widget_list ** list
- list of active widgets for this stream.
bool (*)(struct snd_soc_dapm_widget *, enum snd_soc_dapm_direction) custom_stop_condition
- (optional) a function meant to stop the widget graph walk based on custom logic.
Description
Queries DAPM graph as to whether a valid audio stream path exists for the initial stream specified by name. This takes into account current mixer and mux kcontrol settings. Creates list of valid widgets.
Optionally, can be supplied with a function acting as a stopping condition. This function takes the dapm widget currently being examined and the walk direction as an arguments, it should return true if the walk should be stopped and false otherwise.
Returns the number of valid paths or negative error.
-
int
snd_soc_dapm_sync_unlocked
(struct snd_soc_dapm_context * dapm)¶ scan and power dapm paths
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
Description
Walks all dapm audio paths and powers widgets according to their stream or path usage.
Requires external locking.
Returns 0 for success.
-
int
snd_soc_dapm_sync
(struct snd_soc_dapm_context * dapm)¶ scan and power dapm paths
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
Description
Walks all dapm audio paths and powers widgets according to their stream or path usage.
Returns 0 for success.
-
int
snd_soc_dapm_add_routes
(struct snd_soc_dapm_context * dapm, const struct snd_soc_dapm_route * route, int num)¶ Add routes between DAPM widgets
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const struct snd_soc_dapm_route * route
- audio routes
int num
- number of routes
Description
Connects 2 dapm widgets together via a named audio path. The sink is the widget receiving the audio signal, whilst the source is the sender of the audio signal.
Returns 0 for success else error. On error all resources can be freed
with a call to snd_soc_card_free()
.
-
int
snd_soc_dapm_del_routes
(struct snd_soc_dapm_context * dapm, const struct snd_soc_dapm_route * route, int num)¶ Remove routes between DAPM widgets
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const struct snd_soc_dapm_route * route
- audio routes
int num
- number of routes
Description
Removes routes from the DAPM context.
-
int
snd_soc_dapm_weak_routes
(struct snd_soc_dapm_context * dapm, const struct snd_soc_dapm_route * route, int num)¶ Mark routes between DAPM widgets as weak
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const struct snd_soc_dapm_route * route
- audio routes
int num
- number of routes
Description
Mark existing routes matching those specified in the passed array as being weak, meaning that they are ignored for the purpose of power decisions. The main intended use case is for sidetone paths which couple audio between other independent paths if they are both active in order to make the combination work better at the user level but which aren’t intended to be “used”.
Note that CODEC drivers should not use this as sidetone type paths can frequently also be used as bypass paths.
-
int
snd_soc_dapm_new_widgets
(struct snd_soc_card * card)¶ add new dapm widgets
Parameters
struct snd_soc_card * card
- card to be checked for new dapm widgets
Description
Checks the codec for any new dapm widgets and creates them if found.
Returns 0 for success.
-
int
snd_soc_dapm_get_volsw
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ dapm mixer get callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value of a dapm mixer control.
Returns 0 for success.
-
int
snd_soc_dapm_put_volsw
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ dapm mixer set callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value of a dapm mixer control.
Returns 0 for success.
-
int
snd_soc_dapm_get_enum_double
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ dapm enumerated double mixer get callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to get the value of a dapm enumerated double mixer control.
Returns 0 for success.
-
int
snd_soc_dapm_put_enum_double
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ dapm enumerated double mixer set callback
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- control element information
Description
Callback to set the value of a dapm enumerated double mixer control.
Returns 0 for success.
-
int
snd_soc_dapm_info_pin_switch
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_info * uinfo)¶ Info for a pin switch
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_info * uinfo
- control element information
Description
Callback to provide information about a pin switch control.
-
int
snd_soc_dapm_get_pin_switch
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ Get information for a pin switch
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- Value
-
int
snd_soc_dapm_put_pin_switch
(struct snd_kcontrol * kcontrol, struct snd_ctl_elem_value * ucontrol)¶ Set information for a pin switch
Parameters
struct snd_kcontrol * kcontrol
- mixer control
struct snd_ctl_elem_value * ucontrol
- Value
-
struct snd_soc_dapm_widget *
snd_soc_dapm_new_control
(struct snd_soc_dapm_context * dapm, const struct snd_soc_dapm_widget * widget)¶ create new dapm control
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const struct snd_soc_dapm_widget * widget
- widget template
Description
Creates new DAPM control based upon a template.
Returns a widget pointer on success or an error pointer on failure
-
int
snd_soc_dapm_new_controls
(struct snd_soc_dapm_context * dapm, const struct snd_soc_dapm_widget * widget, int num)¶ create new dapm controls
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const struct snd_soc_dapm_widget * widget
- widget array
int num
- number of widgets
Description
Creates new DAPM controls based upon the templates.
Returns 0 for success else error.
-
void
snd_soc_dapm_stream_event
(struct snd_soc_pcm_runtime * rtd, int stream, int event)¶ send a stream event to the dapm core
Parameters
struct snd_soc_pcm_runtime * rtd
- PCM runtime data
int stream
- stream name
int event
- stream event
Description
Sends a stream event to the dapm core. The core then makes any necessary widget power changes.
Returns 0 for success else error.
-
int
snd_soc_dapm_enable_pin_unlocked
(struct snd_soc_dapm_context * dapm, const char * pin)¶ enable pin.
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Enables input/output pin and its parents or children widgets iff there is a valid audio route and active audio stream.
Requires external locking.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_enable_pin
(struct snd_soc_dapm_context * dapm, const char * pin)¶ enable pin.
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Enables input/output pin and its parents or children widgets iff there is a valid audio route and active audio stream.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_force_enable_pin_unlocked
(struct snd_soc_dapm_context * dapm, const char * pin)¶ force a pin to be enabled
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Enables input/output pin regardless of any other state. This is intended for use with microphone bias supplies used in microphone jack detection.
Requires external locking.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_force_enable_pin
(struct snd_soc_dapm_context * dapm, const char * pin)¶ force a pin to be enabled
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Enables input/output pin regardless of any other state. This is intended for use with microphone bias supplies used in microphone jack detection.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_disable_pin_unlocked
(struct snd_soc_dapm_context * dapm, const char * pin)¶ disable pin.
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Disables input/output pin and its parents or children widgets.
Requires external locking.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_disable_pin
(struct snd_soc_dapm_context * dapm, const char * pin)¶ disable pin.
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Disables input/output pin and its parents or children widgets.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_nc_pin_unlocked
(struct snd_soc_dapm_context * dapm, const char * pin)¶ permanently disable pin.
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Marks the specified pin as being not connected, disabling it along
any parent or child widgets. At present this is identical to
snd_soc_dapm_disable_pin()
but in future it will be extended to do
additional things such as disabling controls which only affect
paths through the pin.
Requires external locking.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_nc_pin
(struct snd_soc_dapm_context * dapm, const char * pin)¶ permanently disable pin.
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- pin name
Description
Marks the specified pin as being not connected, disabling it along
any parent or child widgets. At present this is identical to
snd_soc_dapm_disable_pin()
but in future it will be extended to do
additional things such as disabling controls which only affect
paths through the pin.
NOTE
snd_soc_dapm_sync()
needs to be called after this for DAPM to
do any widget power switching.
-
int
snd_soc_dapm_get_pin_status
(struct snd_soc_dapm_context * dapm, const char * pin)¶ get audio pin status
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- audio signal pin endpoint (or start point)
Description
Get audio pin status - connected or disconnected.
Returns 1 for connected otherwise 0.
-
int
snd_soc_dapm_ignore_suspend
(struct snd_soc_dapm_context * dapm, const char * pin)¶ ignore suspend status for DAPM endpoint
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
const char * pin
- audio signal pin endpoint (or start point)
Description
Mark the given endpoint or pin as ignoring suspend. When the system is disabled a path between two endpoints flagged as ignoring suspend will not be disabled. The path must already be enabled via normal means at suspend time, it will not be turned on if it was not already enabled.
-
void
snd_soc_dapm_free
(struct snd_soc_dapm_context * dapm)¶ free dapm resources
Parameters
struct snd_soc_dapm_context * dapm
- DAPM context
Description
Free all dapm widgets and resources.
ASoC DMA Engine API¶
-
int
snd_dmaengine_pcm_prepare_slave_config
(struct snd_pcm_substream * substream, struct snd_pcm_hw_params * params, struct dma_slave_config * slave_config)¶ Generic prepare_slave_config callback
Parameters
struct snd_pcm_substream * substream
- PCM substream
struct snd_pcm_hw_params * params
- hw_params
struct dma_slave_config * slave_config
- DMA slave config to prepare
Description
This function can be used as a generic prepare_slave_config callback for platforms which make use of the snd_dmaengine_dai_dma_data struct for their DAI DMA data. Internally the function will first call snd_hwparams_to_dma_slave_config to fill in the slave config based on the hw_params, followed by snd_dmaengine_set_config_from_dai_data to fill in the remaining fields based on the DAI DMA data.
-
int
snd_dmaengine_pcm_register
(struct device * dev, const struct snd_dmaengine_pcm_config * config, unsigned int flags)¶ Register a dmaengine based PCM device
Parameters
struct device * dev
- The parent device for the PCM device
const struct snd_dmaengine_pcm_config * config
- Platform specific PCM configuration
unsigned int flags
- Platform specific quirks
Parameters
struct device * dev
- Parent device the PCM was register with
Description
Removes a dmaengine based PCM device previously registered with snd_dmaengine_pcm_register.
Miscellaneous Functions¶
Hardware-Dependent Devices API¶
-
int
snd_hwdep_new
(struct snd_card * card, char * id, int device, struct snd_hwdep ** rhwdep)¶ create a new hwdep instance
Parameters
struct snd_card * card
- the card instance
char * id
- the id string
int device
- the device index (zero-based)
struct snd_hwdep ** rhwdep
- the pointer to store the new hwdep instance
Description
Creates a new hwdep instance with the given index on the card. The callbacks (hwdep->ops) must be set on the returned instance after this call manually by the caller.
Return
Zero if successful, or a negative error code on failure.
Jack Abstraction Layer API¶
-
enum
snd_jack_types
¶ Jack types which can be reported
Constants
SND_JACK_HEADPHONE
- Headphone
SND_JACK_MICROPHONE
- Microphone
SND_JACK_HEADSET
- Headset
SND_JACK_LINEOUT
- Line out
SND_JACK_MECHANICAL
- Mechanical switch
SND_JACK_VIDEOOUT
- Video out
SND_JACK_AVOUT
- AV (Audio Video) out
SND_JACK_LINEIN
- Line in
SND_JACK_BTN_0
- Button 0
SND_JACK_BTN_1
- Button 1
SND_JACK_BTN_2
- Button 2
SND_JACK_BTN_3
- Button 3
SND_JACK_BTN_4
- Button 4
SND_JACK_BTN_5
- Button 5
Description
These values are used as a bitmask.
Note that this must be kept in sync with the lookup table in sound/core/jack.c.
-
int
snd_jack_add_new_kctl
(struct snd_jack * jack, const char * name, int mask)¶ Create a new snd_jack_kctl and add it to jack
Parameters
struct snd_jack * jack
- the jack instance which the kctl will attaching to
const char * name
- the name for the snd_kcontrol object
int mask
- a bitmask of enum snd_jack_type values that can be detected by this snd_jack_kctl object.
Description
Creates a new snd_kcontrol object and adds it to the jack kctl_list.
Return
Zero if successful, or a negative error code on failure.
-
int
snd_jack_new
(struct snd_card * card, const char * id, int type, struct snd_jack ** jjack, bool initial_kctl, bool phantom_jack)¶ Create a new jack
Parameters
struct snd_card * card
- the card instance
const char * id
- an identifying string for this jack
int type
- a bitmask of enum snd_jack_type values that can be detected by this jack
struct snd_jack ** jjack
- Used to provide the allocated jack object to the caller.
bool initial_kctl
- if true, create a kcontrol and add it to the jack list.
bool phantom_jack
- Don’t create a input device for phantom jacks.
Description
Creates a new jack object.
Return
Zero if successful, or a negative error code on failure. On success jjack will be initialised.
-
void
snd_jack_set_parent
(struct snd_jack * jack, struct device * parent)¶ Set the parent device for a jack
Parameters
struct snd_jack * jack
- The jack to configure
struct device * parent
- The device to set as parent for the jack.
Description
Set the parent for the jack devices in the device tree. This function is only valid prior to registration of the jack. If no parent is configured then the parent device will be the sound card.
-
int
snd_jack_set_key
(struct snd_jack * jack, enum snd_jack_types type, int keytype)¶ Set a key mapping on a jack
Parameters
struct snd_jack * jack
- The jack to configure
enum snd_jack_types type
- Jack report type for this key
int keytype
- Input layer key type to be reported
Description
Map a SND_JACK_BTN_* button type to an input layer key, allowing reporting of keys on accessories via the jack abstraction. If no mapping is provided but keys are enabled in the jack type then BTN_n numeric buttons will be reported.
If jacks are not reporting via the input API this call will have no effect.
Note that this is intended to be use by simple devices with small numbers of keys that can be reported. It is also possible to access the input device directly - devices with complex input capabilities on accessories should consider doing this rather than using this abstraction.
This function may only be called prior to registration of the jack.
Return
Zero if successful, or a negative error code on failure.
-
void
snd_jack_report
(struct snd_jack * jack, int status)¶ Report the current status of a jack
Parameters
struct snd_jack * jack
- The jack to report status for
int status
- The current status of the jack
-
int
snd_soc_component_set_jack
(struct snd_soc_component * component, struct snd_soc_jack * jack, void * data)¶ configure component jack.
Parameters
struct snd_soc_component * component
- COMPONENTs
struct snd_soc_jack * jack
- structure to use for the jack
void * data
- can be used if codec driver need extra data for configuring jack
Description
Configures and enables jack detection function.
-
int
snd_soc_card_jack_new
(struct snd_soc_card * card, const char * id, int type, struct snd_soc_jack * jack, struct snd_soc_jack_pin * pins, unsigned int num_pins)¶ Create a new jack
Parameters
struct snd_soc_card * card
- ASoC card
const char * id
- an identifying string for this jack
int type
- a bitmask of enum snd_jack_type values that can be detected by this jack
struct snd_soc_jack * jack
- structure to use for the jack
struct snd_soc_jack_pin * pins
- Array of jack pins to be added to the jack or NULL
unsigned int num_pins
- Number of elements in the pins array
Description
Creates a new jack object.
Returns zero if successful, or a negative error code on failure. On success jack will be initialised.
-
void
snd_soc_jack_report
(struct snd_soc_jack * jack, int status, int mask)¶ Report the current status for a jack
Parameters
struct snd_soc_jack * jack
- the jack
int status
- a bitmask of enum snd_jack_type values that are currently detected.
int mask
- a bitmask of enum snd_jack_type values that being reported.
Description
If configured using snd_soc_jack_add_pins()
then the associated
DAPM pins will be enabled or disabled as appropriate and DAPM
synchronised.
Note
This function uses mutexes and should be called from a context which can sleep (such as a workqueue).
-
int
snd_soc_jack_add_zones
(struct snd_soc_jack * jack, int count, struct snd_soc_jack_zone * zones)¶ Associate voltage zones with jack
Parameters
struct snd_soc_jack * jack
- ASoC jack
int count
- Number of zones
struct snd_soc_jack_zone * zones
- Array of zones
Description
After this function has been called the zones specified in the array will be associated with the jack.
-
int
snd_soc_jack_get_type
(struct snd_soc_jack * jack, int micbias_voltage)¶ Based on the mic bias value, this function returns the type of jack from the zones declared in the jack type
Parameters
struct snd_soc_jack * jack
- ASoC jack
int micbias_voltage
- mic bias voltage at adc channel when jack is plugged in
Description
Based on the mic bias value passed, this function helps identify the type of jack from the already declared jack zones
-
int
snd_soc_jack_add_pins
(struct snd_soc_jack * jack, int count, struct snd_soc_jack_pin * pins)¶ Associate DAPM pins with an ASoC jack
Parameters
struct snd_soc_jack * jack
- ASoC jack
int count
- Number of pins
struct snd_soc_jack_pin * pins
- Array of pins
Description
After this function has been called the DAPM pins specified in the pins array will have their status updated to reflect the current state of the jack whenever the jack status is updated.
-
void
snd_soc_jack_notifier_register
(struct snd_soc_jack * jack, struct notifier_block * nb)¶ Register a notifier for jack status
Parameters
struct snd_soc_jack * jack
- ASoC jack
struct notifier_block * nb
- Notifier block to register
Description
Register for notification of the current status of the jack. Note that it is not possible to report additional jack events in the callback from the notifier, this is intended to support applications such as enabling electrical detection only when a mechanical detection event has occurred.
-
void
snd_soc_jack_notifier_unregister
(struct snd_soc_jack * jack, struct notifier_block * nb)¶ Unregister a notifier for jack status
Parameters
struct snd_soc_jack * jack
- ASoC jack
struct notifier_block * nb
- Notifier block to unregister
Description
Stop notifying for status changes.
-
int
snd_soc_jack_add_gpios
(struct snd_soc_jack * jack, int count, struct snd_soc_jack_gpio * gpios)¶ Associate GPIO pins with an ASoC jack
Parameters
struct snd_soc_jack * jack
- ASoC jack
int count
- number of pins
struct snd_soc_jack_gpio * gpios
- array of gpio pins
Description
This function will request gpio, set data direction and request irq for each gpio in the array.
-
int
snd_soc_jack_add_gpiods
(struct device * gpiod_dev, struct snd_soc_jack * jack, int count, struct snd_soc_jack_gpio * gpios)¶ Associate GPIO descriptor pins with an ASoC jack
Parameters
struct device * gpiod_dev
- GPIO consumer device
struct snd_soc_jack * jack
- ASoC jack
int count
- number of pins
struct snd_soc_jack_gpio * gpios
- array of gpio pins
Description
This function will request gpio, set data direction and request irq for each gpio in the array.
-
void
snd_soc_jack_free_gpios
(struct snd_soc_jack * jack, int count, struct snd_soc_jack_gpio * gpios)¶ Release GPIO pins’ resources of an ASoC jack
Parameters
struct snd_soc_jack * jack
- ASoC jack
int count
- number of pins
struct snd_soc_jack_gpio * gpios
- array of gpio pins
Description
Release gpio and irq resources for gpio pins associated with an ASoC jack.
ISA DMA Helpers¶
-
void
snd_dma_program
(unsigned long dma, unsigned long addr, unsigned int size, unsigned short mode)¶ program an ISA DMA transfer
Parameters
unsigned long dma
- the dma number
unsigned long addr
- the physical address of the buffer
unsigned int size
- the DMA transfer size
unsigned short mode
- the DMA transfer mode, DMA_MODE_XXX
Description
Programs an ISA DMA transfer for the given buffer.
-
void
snd_dma_disable
(unsigned long dma)¶ stop the ISA DMA transfer
Parameters
unsigned long dma
- the dma number
Description
Stops the ISA DMA transfer.
-
unsigned int
snd_dma_pointer
(unsigned long dma, unsigned int size)¶ return the current pointer to DMA transfer buffer in bytes
Parameters
unsigned long dma
- the dma number
unsigned int size
- the dma transfer size
Return
The current pointer in DMA transfer buffer in bytes.
Other Helper Macros¶
-
snd_printk
(fmt, ...)¶ printk wrapper
Parameters
fmt
- format string
...
- variable arguments
Description
Works like printk()
but prints the file and the line of the caller
when configured with CONFIG_SND_VERBOSE_PRINTK.
-
snd_printd
(fmt, ...)¶ debug printk
Parameters
fmt
- format string
...
- variable arguments
Description
Works like snd_printk()
for debugging purposes.
Ignored when CONFIG_SND_DEBUG is not set.
-
snd_BUG
()¶ give a BUG warning message and stack trace
Parameters
Description
Calls WARN()
if CONFIG_SND_DEBUG is set.
Ignored when CONFIG_SND_DEBUG is not set.
-
snd_printd_ratelimit
()¶
Parameters
-
snd_BUG_ON
(cond)¶ debugging check macro
Parameters
cond
- condition to evaluate
Description
Has the same behavior as WARN_ON when CONFIG_SND_DEBUG is set, otherwise just evaluates the conditional and returns the value.
-
snd_printdd
(format, ...)¶ debug printk
Parameters
format
- format string
...
- variable arguments
Description
Works like snd_printk()
for debugging purposes.
Ignored when CONFIG_SND_DEBUG_VERBOSE is not set.