sound/firewire/tascam/amdtp-tascam.c

Source file repositories/reference/linux-study-clean/sound/firewire/tascam/amdtp-tascam.c

File Facts

System
Linux kernel
Corpus path
sound/firewire/tascam/amdtp-tascam.c
Extension
.c
Size
6312 bytes
Lines
253
Domain
Driver Families
Bucket
sound/firewire
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 amdtp_tscm {
	unsigned int pcm_channels;
};

int amdtp_tscm_set_parameters(struct amdtp_stream *s, unsigned int rate)
{
	struct amdtp_tscm *p = s->protocol;
	unsigned int data_channels;

	if (amdtp_stream_running(s))
		return -EBUSY;

	data_channels = p->pcm_channels;

	/* Packets in in-stream have extra 2 data channels. */
	if (s->direction == AMDTP_IN_STREAM)
		data_channels += 2;

	return amdtp_stream_set_parameters(s, rate, data_channels, 1);
}

static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
			  __be32 *buffer, unsigned int frames,
			  unsigned int pcm_frames)
{
	struct amdtp_tscm *p = s->protocol;
	unsigned int channels = p->pcm_channels;
	struct snd_pcm_runtime *runtime = pcm->runtime;
	unsigned int pcm_buffer_pointer;
	int remaining_frames;
	const u32 *src;
	int i, c;

	pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
	pcm_buffer_pointer %= runtime->buffer_size;

	src = (void *)runtime->dma_area +
				frames_to_bytes(runtime, pcm_buffer_pointer);
	remaining_frames = runtime->buffer_size - pcm_buffer_pointer;

	for (i = 0; i < frames; ++i) {
		for (c = 0; c < channels; ++c) {
			buffer[c] = cpu_to_be32(*src);
			src++;
		}
		buffer += s->data_block_quadlets;
		if (--remaining_frames == 0)
			src = (void *)runtime->dma_area;
	}
}

static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
			 __be32 *buffer, unsigned int frames,
			 unsigned int pcm_frames)
{
	struct amdtp_tscm *p = s->protocol;
	unsigned int channels = p->pcm_channels;
	struct snd_pcm_runtime *runtime = pcm->runtime;
	unsigned int pcm_buffer_pointer;
	int remaining_frames;
	u32 *dst;
	int i, c;

	pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
	pcm_buffer_pointer %= runtime->buffer_size;

	dst  = (void *)runtime->dma_area +
				frames_to_bytes(runtime, pcm_buffer_pointer);
	remaining_frames = runtime->buffer_size - pcm_buffer_pointer;

	/* The first data channel is for event counter. */
	buffer += 1;

	for (i = 0; i < frames; ++i) {
		for (c = 0; c < channels; ++c) {
			*dst = be32_to_cpu(buffer[c]);
			dst++;
		}
		buffer += s->data_block_quadlets;
		if (--remaining_frames == 0)
			dst = (void *)runtime->dma_area;
	}
}

static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,
			      unsigned int data_blocks)
{
	struct amdtp_tscm *p = s->protocol;
	unsigned int channels, i, c;

Annotation

Implementation Notes