include/sound/dmaengine_pcm.h

Source file repositories/reference/linux-study-clean/include/sound/dmaengine_pcm.h

File Facts

System
Linux kernel
Corpus path
include/sound/dmaengine_pcm.h
Extension
.h
Size
7133 bytes
Lines
187
Domain
Driver Families
Bucket
include/sound
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct snd_dmaengine_dai_dma_data {
	dma_addr_t addr;
	enum dma_slave_buswidth addr_width;
	u32 maxburst;
	void *filter_data;
	const char *chan_name;
	unsigned int fifo_size;
	unsigned int flags;
	void *peripheral_config;
	size_t peripheral_size;
	u32 port_window_size;
};

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 *config);

int snd_dmaengine_pcm_refine_runtime_hwparams(
	struct snd_pcm_substream *substream,
	struct snd_dmaengine_dai_dma_data *dma_data,
	struct snd_pcm_hardware *hw,
	struct dma_chan *chan);

/*
 * Try to request the DMA channel using compat_request_channel or
 * compat_filter_fn if it couldn't be requested through devicetree.
 */
#define SND_DMAENGINE_PCM_FLAG_COMPAT BIT(0)
/*
 * Don't try to request the DMA channels through devicetree. This flag only
 * makes sense if SND_DMAENGINE_PCM_FLAG_COMPAT is set as well.
 */
#define SND_DMAENGINE_PCM_FLAG_NO_DT BIT(1)
/*
 * The PCM is half duplex and the DMA channel is shared between capture and
 * playback.
 */
#define SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX BIT(3)

/**
 * struct snd_dmaengine_pcm_config - Configuration data for dmaengine based PCM
 * @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.
 * @name: Component name. If null, dev_name will be used.
 * @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.
 */
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,
		       unsigned long bytes);
	const char *name;
	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;
};

int snd_dmaengine_pcm_register(struct device *dev,
	const struct snd_dmaengine_pcm_config *config,
	unsigned int flags);
void snd_dmaengine_pcm_unregister(struct device *dev);

int devm_snd_dmaengine_pcm_register(struct device *dev,
	const struct snd_dmaengine_pcm_config *config,

Annotation

Implementation Notes