Sound Devices
-
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.
-
int register_sound_special_device(const struct file_operations * fops, int unit, struct device * dev)
register a special sound node
Parameters
- const struct file_operations * fops
- File operations for the driver
- int unit
- Unit number to allocate
- struct device * dev
- device pointer
Description
Allocate a special sound device by minor number from the sound
subsystem.
Return
- The allocated number is returned on success. On failure,
- a negative error code is returned.
-
int register_sound_mixer(const struct file_operations * fops, int dev)
register a mixer device
Parameters
- const struct file_operations * fops
- File operations for the driver
- int dev
- Unit number to allocate
Description
Allocate a mixer device. Unit is the number of the mixer requested.
Pass -1 to request the next free mixer unit.
Return
- On success, the allocated number is returned. On failure,
- a negative error code is returned.
-
int register_sound_midi(const struct file_operations * fops, int dev)
register a midi device
Parameters
- const struct file_operations * fops
- File operations for the driver
- int dev
- Unit number to allocate
Description
Allocate a midi device. Unit is the number of the midi device requested.
Pass -1 to request the next free midi unit.
Return
- On success, the allocated number is returned. On failure,
- a negative error code is returned.
-
int register_sound_dsp(const struct file_operations * fops, int dev)
register a DSP device
Parameters
- const struct file_operations * fops
- File operations for the driver
- int dev
- Unit number to allocate
Description
Allocate a DSP device. Unit is the number of the DSP requested.
Pass -1 to request the next free DSP unit.
This function allocates both the audio and dsp device entries together
and will always allocate them as a matching pair - eg dsp3/audio3
Return
- On success, the allocated number is returned. On failure,
- a negative error code is returned.
-
void unregister_sound_special(int unit)
unregister a special sound device
Parameters
- int unit
- unit number to allocate
Description
Release a sound device that was allocated with
register_sound_special(). The unit passed is the return value from
the register function.
-
void unregister_sound_mixer(int unit)
unregister a mixer
Parameters
- int unit
- unit number to allocate
Description
Release a sound device that was allocated with
register_sound_mixer().
The unit passed is the return value from the register function.
-
void unregister_sound_midi(int unit)
unregister a midi device
Parameters
- int unit
- unit number to allocate
Description
Release a sound device that was allocated with
register_sound_midi().
The unit passed is the return value from the register function.
-
void unregister_sound_dsp(int unit)
unregister a DSP device
Parameters
- int unit
- unit number to allocate
Description
Release a sound device that was allocated with register_sound_dsp().
The unit passed is the return value from the register function.
Both of the allocated units are released together automatically.
-
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
-
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.
-
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.
-
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.
-
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_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.
-
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.
-
int snd_unregister_device(struct device * dev)
unregister the device on the given card
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.
-
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.
-
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.
-
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).
-
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
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.
Note
the power lock must be active before call.
-
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.
-
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.
-
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_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.
-
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.
-
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_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_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.
-
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.
-
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_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_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_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.
-
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().
-
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().