usbaudio.c

linux 内核源代码

 *
 * retrieve the current 12.13 frequency from pipe, and set it.
 * the value is referred in prepare_playback_urb().
 */
static int retire_playback_sync_urb_hs(struct snd_usb_substream *subs,
				       struct snd_pcm_runtime *runtime,
				       struct urb *urb)
{
	unsigned int f;
	unsigned long flags;

	if (urb->iso_frame_desc[0].status == 0 &&
	    urb->iso_frame_desc[0].actual_length == 4) {
		f = combine_quad((u8*)urb->transfer_buffer) & 0x0fffffff;
		if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
			spin_lock_irqsave(&subs->lock, flags);
			subs->freqm = f;
			spin_unlock_irqrestore(&subs->lock, flags);
		}
	}

	return 0;
}

/* determine the number of frames in the next packet */
static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs)
{
	if (subs->fill_max)
		return subs->maxframesize;
	else {
		subs->phase = (subs->phase & 0xffff)
			+ (subs->freqm << subs->datainterval);
		return min(subs->phase >> 16, subs->maxframesize);
	}
}

/*
 * Prepare urb for streaming before playback starts or when paused.
 *
 * We don't have any data, so we send a frame of silence.
 */
static int prepare_nodata_playback_urb(struct snd_usb_substream *subs,
				       struct snd_pcm_runtime *runtime,
				       struct urb *urb)
{
	unsigned int i, offs, counts;
	struct snd_urb_ctx *ctx = urb->context;
	int stride = runtime->frame_bits >> 3;

	offs = 0;
	urb->dev = ctx->subs->dev;
	urb->number_of_packets = subs->packs_per_ms;
	for (i = 0; i < subs->packs_per_ms; ++i) {
		counts = snd_usb_audio_next_packet_size(subs);
		urb->iso_frame_desc[i].offset = offs * stride;
		urb->iso_frame_desc[i].length = counts * stride;
		offs += counts;
	}
	urb->transfer_buffer_length = offs * stride;
	memset(urb->transfer_buffer,
	       subs->cur_audiofmt->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0,
	       offs * stride);
	return 0;
}

/*
 * prepare urb for playback data pipe
 *
 * Since a URB can handle only a single linear buffer, we must use double
 * buffering when the data to be transferred overflows the buffer boundary.
 * To avoid inconsistencies when updating hwptr_done, we use double buffering
 * for all URBs.
 */
static int prepare_playback_urb(struct snd_usb_substream *subs,
				struct snd_pcm_runtime *runtime,
				struct urb *urb)
{
	int i, stride, offs;
	unsigned int counts;
	unsigned long flags;
	int period_elapsed = 0;
	struct snd_urb_ctx *ctx = urb->context;

	stride = runtime->frame_bits >> 3;

	offs = 0;
	urb->dev = ctx->subs->dev; /* we need to set this at each time */
	urb->number_of_packets = 0;
	spin_lock_irqsave(&subs->lock, flags);
	for (i = 0; i < ctx->packets; i++) {
		counts = snd_usb_audio_next_packet_size(subs);
		/* set up descriptor */
		urb->iso_frame_desc[i].offset = offs * stride;
		urb->iso_frame_desc[i].length = counts * stride;
		offs += counts;
		urb->number_of_packets++;
		subs->transfer_done += counts;
		if (subs->transfer_done >= runtime->period_size) {
			subs->transfer_done -= runtime->period_size;
			period_elapsed = 1;
			if (subs->fmt_type == USB_FORMAT_TYPE_II) {
				if (subs->transfer_done > 0) {
					/* FIXME: fill-max mode is not
					 * supported yet */
					offs -= subs->transfer_done;
					counts -= subs->transfer_done;
					urb->iso_frame_desc[i].length =
						counts * stride;
					subs->transfer_done = 0;
				}
				i++;
				if (i < ctx->packets) {
					/* add a transfer delimiter */
					urb->iso_frame_desc[i].offset =
						offs * stride;
					urb->iso_frame_desc[i].length = 0;
					urb->number_of_packets++;
				}
				break;
			}
 		}
		/* finish at the frame boundary at/after the period boundary */
		if (period_elapsed &&
		    (i & (subs->packs_per_ms - 1)) == subs->packs_per_ms - 1)
			break;
	}
	if (subs->hwptr_done + offs > runtime->buffer_size) {
		/* err, the transferred area goes over buffer boundary. */
		unsigned int len = runtime->buffer_size - subs->hwptr_done;
		memcpy(urb->transfer_buffer,
		       runtime->dma_area + subs->hwptr_done * stride,
		       len * stride);
		memcpy(urb->transfer_buffer + len * stride,
		       runtime->dma_area,
		       (offs - len) * stride);
	} else {
		memcpy(urb->transfer_buffer,
		       runtime->dma_area + subs->hwptr_done * stride,
		       offs * stride);
	}
	subs->hwptr_done += offs;
	if (subs->hwptr_done >= runtime->buffer_size)
		subs->hwptr_done -= runtime->buffer_size;
	spin_unlock_irqrestore(&subs->lock, flags);
	urb->transfer_buffer_length = offs * stride;
	if (period_elapsed)
		snd_pcm_period_elapsed(subs->pcm_substream);
	return 0;
}

/*
 * process after playback data complete
 * - nothing to do
 */
static int retire_playback_urb(struct snd_usb_substream *subs,
			       struct snd_pcm_runtime *runtime,
			       struct urb *urb)
{
	return 0;
}


/*
 */
static struct snd_urb_ops audio_urb_ops[2] = {
	{
		.prepare =	prepare_nodata_playback_urb,
		.retire =	retire_playback_urb,
		.prepare_sync =	prepare_playback_sync_urb,
		.retire_sync =	retire_playback_sync_urb,
	},
	{
		.prepare =	prepare_capture_urb,
		.retire =	retire_capture_urb,
		.prepare_sync =	prepare_capture_sync_urb,
		.retire_sync =	retire_capture_sync_urb,
	},
};

static struct snd_urb_ops audio_urb_ops_high_speed[2] = {
	{
		.prepare =	prepare_nodata_playback_urb,
		.retire =	retire_playback_urb,
		.prepare_sync =	prepare_playback_sync_urb_hs,
		.retire_sync =	retire_playback_sync_urb_hs,
	},
	{
		.prepare =	prepare_capture_urb,
		.retire =	retire_capture_urb,
		.prepare_sync =	prepare_capture_sync_urb_hs,
		.retire_sync =	retire_capture_sync_urb,
	},
};

/*
 * complete callback from data urb
 */
static void snd_complete_urb(struct urb *urb)
{
	struct snd_urb_ctx *ctx = urb->context;
	struct snd_usb_substream *subs = ctx->subs;
	struct snd_pcm_substream *substream = ctx->subs->pcm_substream;
	int err = 0;

	if ((subs->running && subs->ops.retire(subs, substream->runtime, urb)) ||
	    ! subs->running || /* can be stopped during retire callback */
	    (err = subs->ops.prepare(subs, substream->runtime, urb)) < 0 ||
	    (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
		clear_bit(ctx->index, &subs->active_mask);
		if (err < 0) {
			snd_printd(KERN_ERR "cannot submit urb (err = %d)\n", err);
			snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
		}
	}
}


/*
 * complete callback from sync urb
 */
static void snd_complete_sync_urb(struct urb *urb)
{
	struct snd_urb_ctx *ctx = urb->context;
	struct snd_usb_substream *subs = ctx->subs;
	struct snd_pcm_substream *substream = ctx->subs->pcm_substream;
	int err = 0;

	if ((subs->running && subs->ops.retire_sync(subs, substream->runtime, urb)) ||
	    ! subs->running || /* can be stopped during retire callback */
	    (err = subs->ops.prepare_sync(subs, substream->runtime, urb)) < 0 ||
	    (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
		clear_bit(ctx->index + 16, &subs->active_mask);
		if (err < 0) {
			snd_printd(KERN_ERR "cannot submit sync urb (err = %d)\n", err);
			snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
		}
	}
}


/* get the physical page pointer at the given offset */
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);
}

/* allocate virtual buffer; may be called more than once */
static int snd_pcm_alloc_vmalloc_buffer(struct snd_pcm_substream *subs, size_t size)
{
	struct snd_pcm_runtime *runtime = subs->runtime;
	if (runtime->dma_area) {
		if (runtime->dma_bytes >= size)
			return 0; /* already large enough */
		vfree(runtime->dma_area);
	}
	runtime->dma_area = vmalloc(size);
	if (! runtime->dma_area)
		return -ENOMEM;
	runtime->dma_bytes = size;
	return 0;
}

/* free virtual buffer; may be called more than once */
static int snd_pcm_free_vmalloc_buffer(struct snd_pcm_substream *subs)
{
	struct snd_pcm_runtime *runtime = subs->runtime;

	vfree(runtime->dma_area);
	runtime->dma_area = NULL;
	return 0;
}


/*
 * unlink active urbs.
 */
static int deactivate_urbs(struct snd_usb_substream *subs, int force, int can_sleep)
{
	unsigned int i;
	int async;

	subs->running = 0;

	if (!force && subs->stream->chip->shutdown) /* to be sure... */
		return -EBADFD;

	async = !can_sleep && async_unlink;

	if (! async && in_interrupt())
		return 0;

	for (i = 0; i < subs->nurbs; i++) {
		if (test_bit(i, &subs->active_mask)) {
			if (! test_and_set_bit(i, &subs->unlink_mask)) {
				struct urb *u = subs->dataurb[i].urb;
				if (async)
					usb_unlink_urb(u);
				else
					usb_kill_urb(u);
			}
		}
	}
	if (subs->syncpipe) {
		for (i = 0; i < SYNC_URBS; i++) {
			if (test_bit(i+16, &subs->active_mask)) {
 				if (! test_and_set_bit(i+16, &subs->unlink_mask)) {
					struct urb *u = subs->syncurb[i].urb;
					if (async)
						usb_unlink_urb(u);
					else
						usb_kill_urb(u);
				}
			}
		}
	}
	return 0;
}


static const char *usb_error_string(int err)
{
	switch (err) {
	case -ENODEV:
		return "no device";
	case -ENOENT:
		return "endpoint not enabled";
	case -EPIPE:
		return "endpoint stalled";
	case -ENOSPC:
		return "not enough bandwidth";
	case -ESHUTDOWN:
		return "device disabled";
	case -EHOSTUNREACH:
		return "device suspended";
#ifndef CONFIG_USB_EHCI_SPLIT_ISO
	case -ENOSYS:
		return "enable CONFIG_USB_EHCI_SPLIT_ISO to play through a hub";
#endif
	case -EINVAL:
	case -EAGAIN:
	case -EFBIG:
	case -EMSGSIZE:
		return "internal error";
	default:
		return "unknown error";
	}
}

/*
 * set up and start data/sync urbs
 */
static int start_urbs(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime)
{
	unsigned int i;
	int err;

	if (subs->stream->chip->shutdown)
		return -EBADFD;

	for (i = 0; i < subs->nurbs; i++) {
		snd_assert(subs->dataurb[i].urb, return -EINVAL);
		if (subs->ops.prepare(subs, runtime, subs->dataurb[i].urb) < 0) {
			snd_printk(KERN_ERR "cannot prepare datapipe for urb %d\n", i);
			goto __error;
		}
	}
	if (subs->syncpipe) {
		for (i = 0; i < SYNC_URBS; i++) {
			snd_assert(subs->syncurb[i].urb, return -EINVAL);
			if (subs->ops.prepare_sync(subs, runtime, subs->syncurb[i].urb) < 0) {
				snd_printk(KERN_ERR "cannot prepare syncpipe for urb %d\n", i);
				goto __error;
			}
		}
	}

	subs->active_mask = 0;
	subs->unlink_mask = 0;
	subs->running = 1;
	for (i = 0; i < subs->nurbs; i++) {
		err = usb_submit_urb(subs->dataurb[i].urb, GFP_ATOMIC);
		if (err < 0) {
			snd_printk(KERN_ERR "cannot submit datapipe "
				   "for urb %d, error %d: %s\n",
				   i, err, usb_error_string(err));
			goto __error;
		}
		set_bit(i, &subs->active_mask);
	}
	if (subs->syncpipe) {
		for (i = 0; i < SYNC_URBS; i++) {
			err = usb_submit_urb(subs->syncurb[i].urb, GFP_ATOMIC);
			if (err < 0) {
				snd_printk(KERN_ERR "cannot submit syncpipe "
					   "for urb %d, error %d: %s\n",
					   i, err, usb_error_string(err));
				goto __error;
			}
			set_bit(i + 16, &subs->active_mask);
		}
	}
	return 0;

 __error:
	// snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN);
	deactivate_urbs(subs, 0, 0);
	return -EPIPE;
}


/*
 *  wait until all urbs are processed.
 */
static int wait_clear_urbs(struct snd_usb_substream *subs)
{
	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
	unsigned int i;
	int alive;

	do {
		alive = 0;
		for (i = 0; i < subs->nurbs; i++) {
			if (test_bit(i, &subs->active_mask))
				alive++;
		}
		if (subs->syncpipe) {
			for (i = 0; i < SYNC_URBS; i++) {
				if (test_bit(i + 16, &subs->active_mask))
					alive++;
			}
		}
		if (! alive)
			break;
		schedule_timeout_uninterruptible(1);
	} while (time_before(jiffies, end_time));
	if (alive)
		snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive);
	return 0;
}


/*
 * return the current pcm pointer.  just return the hwptr_done value.
 */
static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream)
{
	struct snd_usb_substream *subs;
	snd_pcm_uframes_t hwptr_done;
	
	subs = (struct snd_usb_substream *)substream->runtime->private_data;
	spin_lock(&subs->lock);
	hwptr_done = subs->hwptr_done;
	spin_unlock(&subs->lock);
	return hwptr_done;
}