1. 根目录:
2. drivers
3. media
4. pci
5. ivtv
6. ivtv-alsa-pcm.c

/*
 *  ALSA PCM device for the
 *  ALSA interface to ivtv PCM capture streams
 *
 *  Copyright (C) 2009,2012  Andy Walls <awalls@md.metrocast.net>
 *  Copyright (C) 2009  Devin Heitmueller <dheitmueller@kernellabs.com>
 *
 *  Portions of this work were sponsored by ONELAN Limited for the cx18 driver
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 *  02111-1307  USA
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/vmalloc.h>

#include <media/v4l2-device.h>

#include <sound/core.h>
#include <sound/pcm.h>

#include "ivtv-driver.h"
#include "ivtv-queue.h"
#include "ivtv-streams.h"
#include "ivtv-fileops.h"
#include "ivtv-alsa.h"
#include "ivtv-alsa-pcm.h"

static unsigned int pcm_debug;
module_param(pcm_debug, int, 0644);
MODULE_PARM_DESC(pcm_debug, "enable debug messages for pcm");

#define dprintk(fmt, arg...) \
	do { \
		if (pcm_debug) \
			pr_info("ivtv-alsa-pcm %s: " fmt, __func__, ##arg); \
	} while (0)

static struct snd_pcm_hardware snd_ivtv_hw_capture = {
	.info = SNDRV_PCM_INFO_BLOCK_TRANSFER |
		SNDRV_PCM_INFO_MMAP           |
		SNDRV_PCM_INFO_INTERLEAVED    |
		SNDRV_PCM_INFO_MMAP_VALID,

	.formats = SNDRV_PCM_FMTBIT_S16_LE,

	.rates = SNDRV_PCM_RATE_48000,

	.rate_min = 48000,
	.rate_max = 48000,
	.channels_min = 2,
	.channels_max = 2,
	.buffer_bytes_max = 62720 * 8,	/* just about the value in usbaudio.c */
	.period_bytes_min = 64,		/* 12544/2, */
	.period_bytes_max = 12544,
	.periods_min = 2,
	.periods_max = 98,		/* 12544, */
};

static void ivtv_alsa_announce_pcm_data(struct snd_ivtv_card *itvsc,
					u8 *pcm_data,
					size_t num_bytes)
{
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	unsigned int oldptr;
	unsigned int stride;
	int period_elapsed = 0;
	int length;

	dprintk("ivtv alsa announce ptr=%p data=%p num_bytes=%zd\n", itvsc,
		pcm_data, num_bytes);

	substream = itvsc->capture_pcm_substream;
	if (substream == NULL) {
		dprintk("substream was NULL\n");
		return;
	}

	runtime = substream->runtime;
	if (runtime == NULL) {
		dprintk("runtime was NULL\n");
		return;
	}

	stride = runtime->frame_bits >> 3;
	if (stride == 0) {
		dprintk("stride is zero\n");
		return;
	}

	length = num_bytes / stride;
	if (length == 0) {
		dprintk("%s: length was zero\n", __func__);
		return;
	}

	if (runtime->dma_area == NULL) {
		dprintk("dma area was NULL - ignoring\n");
		return;
	}

	oldptr = itvsc->hwptr_done_capture;
	if (oldptr + length >= runtime->buffer_size) {
		unsigned int cnt =
			runtime->buffer_size - oldptr;
		memcpy(runtime->dma_area + oldptr * stride, pcm_data,
		       cnt * stride);
		memcpy(runtime->dma_area, pcm_data + cnt * stride,
		       length * stride - cnt * stride);
	} else {
		memcpy(runtime->dma_area + oldptr * stride, pcm_data,
		       length * stride);
	}
	snd_pcm_stream_lock(substream);

	itvsc->hwptr_done_capture += length;
	if (itvsc->hwptr_done_capture >=
	    runtime->buffer_size)
		itvsc->hwptr_done_capture -=
			runtime->buffer_size;

	itvsc->capture_transfer_done += length;
	if (itvsc->capture_transfer_done >=
	    runtime->period_size) {
		itvsc->capture_transfer_done -=
			runtime->period_size;
		period_elapsed = 1;
	}

	snd_pcm_stream_unlock(substream);

	if (period_elapsed)
		snd_pcm_period_elapsed(substream);
}

static int snd_ivtv_pcm_capture_open(struct snd_pcm_substream *substream)
{
	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
	struct ivtv *itv = to_ivtv(v4l2_dev);
	struct ivtv_stream *s;
	struct ivtv_open_id item;
	int ret;

	/* Instruct the CX2341[56] to start sending packets */
	snd_ivtv_lock(itvsc);
	s = &itv->streams[IVTV_ENC_STREAM_TYPE_PCM];

	v4l2_fh_init(&item.fh, s->vdev);
	item.itv = itv;
	item.type = s->type;

	/* See if the stream is available */
	if (ivtv_claim_stream(&item, item.type)) {
		/* No, it's already in use */
		snd_ivtv_unlock(itvsc);
		return -EBUSY;
	}

	if (test_bit(IVTV_F_S_STREAMOFF, &s->s_flags) ||
	    test_and_set_bit(IVTV_F_S_STREAMING, &s->s_flags)) {
		/* We're already streaming.  No additional action required */
		snd_ivtv_unlock(itvsc);
		return 0;
	}


	runtime->hw = snd_ivtv_hw_capture;
	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
	itvsc->capture_pcm_substream = substream;
	runtime->private_data = itv;

	itv->pcm_announce_callback = ivtv_alsa_announce_pcm_data;

	/* Not currently streaming, so start it up */
	set_bit(IVTV_F_S_STREAMING, &s->s_flags);
	ret = ivtv_start_v4l2_encode_stream(s);
	snd_ivtv_unlock(itvsc);

	return ret;
}

static int snd_ivtv_pcm_capture_close(struct snd_pcm_substream *substream)
{
	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
	struct ivtv *itv = to_ivtv(v4l2_dev);
	struct ivtv_stream *s;

	/* Instruct the ivtv to stop sending packets */
	snd_ivtv_lock(itvsc);
	s = &itv->streams[IVTV_ENC_STREAM_TYPE_PCM];
	ivtv_stop_v4l2_encode_stream(s, 0);
	clear_bit(IVTV_F_S_STREAMING, &s->s_flags);

	ivtv_release_stream(s);

	itv->pcm_announce_callback = NULL;
	snd_ivtv_unlock(itvsc);

	return 0;
}

static int snd_ivtv_pcm_ioctl(struct snd_pcm_substream *substream,
		     unsigned int cmd, void *arg)
{
	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
	int ret;

	snd_ivtv_lock(itvsc);
	ret = snd_pcm_lib_ioctl(substream, cmd, arg);
	snd_ivtv_unlock(itvsc);
	return ret;
}


static int snd_pcm_alloc_vmalloc_buffer(struct snd_pcm_substream *subs,
					size_t size)
{
	struct snd_pcm_runtime *runtime = subs->runtime;

	dprintk("Allocating vbuffer\n");
	if (runtime->dma_area) {
		if (runtime->dma_bytes > size)
			return 0;

		vfree(runtime->dma_area);
	}
	runtime->dma_area = vmalloc(size);
	if (!runtime->dma_area)
		return -ENOMEM;

	runtime->dma_bytes = size;

	return 0;
}

static int snd_ivtv_pcm_hw_params(struct snd_pcm_substream *substream,
			 struct snd_pcm_hw_params *params)
{
	dprintk("%s called\n", __func__);

	return snd_pcm_alloc_vmalloc_buffer(substream,
					   params_buffer_bytes(params));
}

static int snd_ivtv_pcm_hw_free(struct snd_pcm_substream *substream)
{
	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
	unsigned long flags;

	spin_lock_irqsave(&itvsc->slock, flags);
	if (substream->runtime->dma_area) {
		dprintk("freeing pcm capture region\n");
		vfree(substream->runtime->dma_area);
		substream->runtime->dma_area = NULL;
	}
	spin_unlock_irqrestore(&itvsc->slock, flags);

	return 0;
}

static int snd_ivtv_pcm_prepare(struct snd_pcm_substream *substream)
{
	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);

	itvsc->hwptr_done_capture = 0;
	itvsc->capture_transfer_done = 0;

	return 0;
}

static int snd_ivtv_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
	return 0;
}

static
snd_pcm_uframes_t snd_ivtv_pcm_pointer(struct snd_pcm_substream *substream)
{
	unsigned long flags;
	snd_pcm_uframes_t hwptr_done;
	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);

	spin_lock_irqsave(&itvsc->slock, flags);
	hwptr_done = itvsc->hwptr_done_capture;
	spin_unlock_irqrestore(&itvsc->slock, flags);

	return hwptr_done;
}

static struct page *snd_pcm_get_vmalloc_page(struct snd_pcm_substream *subs,
					     unsigned long offset)
{
	void *pageptr = subs->runtime->dma_area + offset;

	return vmalloc_to_page(pageptr);
}

static struct snd_pcm_ops snd_ivtv_pcm_capture_ops = {
	.open		= snd_ivtv_pcm_capture_open,
	.close		= snd_ivtv_pcm_capture_close,
	.ioctl		= snd_ivtv_pcm_ioctl,
	.hw_params	= snd_ivtv_pcm_hw_params,
	.hw_free	= snd_ivtv_pcm_hw_free,
	.prepare	= snd_ivtv_pcm_prepare,
	.trigger	= snd_ivtv_pcm_trigger,
	.pointer	= snd_ivtv_pcm_pointer,
	.page		= snd_pcm_get_vmalloc_page,
};

int snd_ivtv_pcm_create(struct snd_ivtv_card *itvsc)
{
	struct snd_pcm *sp;
	struct snd_card *sc = itvsc->sc;
	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
	struct ivtv *itv = to_ivtv(v4l2_dev);
	int ret;

	ret = snd_pcm_new(sc, "CX2341[56] PCM",
			  0, /* PCM device 0, the only one for this card */
			  0, /* 0 playback substreams */
			  1, /* 1 capture substream */
			  &sp);
	if (ret) {
		IVTV_ALSA_ERR("%s: snd_ivtv_pcm_create() failed with err %d\n",
			      __func__, ret);
		goto err_exit;
	}

	spin_lock_init(&itvsc->slock);

	snd_pcm_set_ops(sp, SNDRV_PCM_STREAM_CAPTURE,
			&snd_ivtv_pcm_capture_ops);
	sp->info_flags = 0;
	sp->private_data = itvsc;
	strlcpy(sp->name, itv->card_name, sizeof(sp->name));

	return 0;

err_exit:
	return ret;
}