usbaudio.c

linux 内核源代码

/*
 * start/stop playback substream
 */
static int snd_usb_pcm_playback_trigger(struct snd_pcm_substream *substream,
					int cmd)
{
	struct snd_usb_substream *subs = substream->runtime->private_data;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
		subs->ops.prepare = prepare_playback_urb;
		return 0;
	case SNDRV_PCM_TRIGGER_STOP:
		return deactivate_urbs(subs, 0, 0);
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
		subs->ops.prepare = prepare_nodata_playback_urb;
		return 0;
	default:
		return -EINVAL;
	}
}

/*
 * start/stop capture substream
 */
static int snd_usb_pcm_capture_trigger(struct snd_pcm_substream *substream,
				       int cmd)
{
	struct snd_usb_substream *subs = substream->runtime->private_data;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
		subs->ops.retire = retire_capture_urb;
		return start_urbs(subs, substream->runtime);
	case SNDRV_PCM_TRIGGER_STOP:
		return deactivate_urbs(subs, 0, 0);
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
		subs->ops.retire = retire_paused_capture_urb;
		return 0;
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
		subs->ops.retire = retire_capture_urb;
		return 0;
	default:
		return -EINVAL;
	}
}


/*
 * release a urb data
 */
static void release_urb_ctx(struct snd_urb_ctx *u)
{
	if (u->urb) {
		if (u->buffer_size)
			usb_buffer_free(u->subs->dev, u->buffer_size,
					u->urb->transfer_buffer,
					u->urb->transfer_dma);
		usb_free_urb(u->urb);
		u->urb = NULL;
	}
}

/*
 * release a substream
 */
static void release_substream_urbs(struct snd_usb_substream *subs, int force)
{
	int i;

	/* stop urbs (to be sure) */
	deactivate_urbs(subs, force, 1);
	wait_clear_urbs(subs);

	for (i = 0; i < MAX_URBS; i++)
		release_urb_ctx(&subs->dataurb[i]);
	for (i = 0; i < SYNC_URBS; i++)
		release_urb_ctx(&subs->syncurb[i]);
	usb_buffer_free(subs->dev, SYNC_URBS * 4,
			subs->syncbuf, subs->sync_dma);
	subs->syncbuf = NULL;
	subs->nurbs = 0;
}

/*
 * initialize a substream for plaback/capture
 */
static int init_substream_urbs(struct snd_usb_substream *subs, unsigned int period_bytes,
			       unsigned int rate, unsigned int frame_bits)
{
	unsigned int maxsize, n, i;
	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
	unsigned int npacks[MAX_URBS], urb_packs, total_packs, packs_per_ms;

	/* calculate the frequency in 16.16 format */
	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
		subs->freqn = get_usb_full_speed_rate(rate);
	else
		subs->freqn = get_usb_high_speed_rate(rate);
	subs->freqm = subs->freqn;
	/* calculate max. frequency */
	if (subs->maxpacksize) {
		/* whatever fits into a max. size packet */
		maxsize = subs->maxpacksize;
		subs->freqmax = (maxsize / (frame_bits >> 3))
				<< (16 - subs->datainterval);
	} else {
		/* no max. packet size: just take 25% higher than nominal */
		subs->freqmax = subs->freqn + (subs->freqn >> 2);
		maxsize = ((subs->freqmax + 0xffff) * (frame_bits >> 3))
				>> (16 - subs->datainterval);
	}
	subs->phase = 0;

	if (subs->fill_max)
		subs->curpacksize = subs->maxpacksize;
	else
		subs->curpacksize = maxsize;

	if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH)
		packs_per_ms = 8 >> subs->datainterval;
	else
		packs_per_ms = 1;
	subs->packs_per_ms = packs_per_ms;

	if (is_playback) {
		urb_packs = nrpacks;
		urb_packs = max(urb_packs, (unsigned int)MIN_PACKS_URB);
		urb_packs = min(urb_packs, (unsigned int)MAX_PACKS);
	} else
		urb_packs = 1;
	urb_packs *= packs_per_ms;

	/* decide how many packets to be used */
	if (is_playback) {
		unsigned int minsize;
		/* determine how small a packet can be */
		minsize = (subs->freqn >> (16 - subs->datainterval))
			  * (frame_bits >> 3);
		/* with sync from device, assume it can be 12% lower */
		if (subs->syncpipe)
			minsize -= minsize >> 3;
		minsize = max(minsize, 1u);
		total_packs = (period_bytes + minsize - 1) / minsize;
		/* round up to multiple of packs_per_ms */
		total_packs = (total_packs + packs_per_ms - 1)
				& ~(packs_per_ms - 1);
		/* we need at least two URBs for queueing */
		if (total_packs < 2 * MIN_PACKS_URB * packs_per_ms)
			total_packs = 2 * MIN_PACKS_URB * packs_per_ms;
	} else {
		total_packs = MAX_URBS * urb_packs;
	}
	subs->nurbs = (total_packs + urb_packs - 1) / urb_packs;
	if (subs->nurbs > MAX_URBS) {
		/* too much... */
		subs->nurbs = MAX_URBS;
		total_packs = MAX_URBS * urb_packs;
	}
	n = total_packs;
	for (i = 0; i < subs->nurbs; i++) {
		npacks[i] = n > urb_packs ? urb_packs : n;
		n -= urb_packs;
	}
	if (subs->nurbs <= 1) {
		/* too little - we need at least two packets
		 * to ensure contiguous playback/capture
		 */
		subs->nurbs = 2;
		npacks[0] = (total_packs + 1) / 2;
		npacks[1] = total_packs - npacks[0];
	} else if (npacks[subs->nurbs-1] < MIN_PACKS_URB * packs_per_ms) {
		/* the last packet is too small.. */
		if (subs->nurbs > 2) {
			/* merge to the first one */
			npacks[0] += npacks[subs->nurbs - 1];
			subs->nurbs--;
		} else {
			/* divide to two */
			subs->nurbs = 2;
			npacks[0] = (total_packs + 1) / 2;
			npacks[1] = total_packs - npacks[0];
		}
	}

	/* allocate and initialize data urbs */
	for (i = 0; i < subs->nurbs; i++) {
		struct snd_urb_ctx *u = &subs->dataurb[i];
		u->index = i;
		u->subs = subs;
		u->packets = npacks[i];
		u->buffer_size = maxsize * u->packets;
		if (subs->fmt_type == USB_FORMAT_TYPE_II)
			u->packets++; /* for transfer delimiter */
		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
		if (! u->urb)
			goto out_of_memory;
		u->urb->transfer_buffer =
			usb_buffer_alloc(subs->dev, u->buffer_size, GFP_KERNEL,
					 &u->urb->transfer_dma);
		if (! u->urb->transfer_buffer)
			goto out_of_memory;
		u->urb->pipe = subs->datapipe;
		u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
		u->urb->interval = 1 << subs->datainterval;
		u->urb->context = u;
		u->urb->complete = snd_complete_urb;
	}

	if (subs->syncpipe) {
		/* allocate and initialize sync urbs */
		subs->syncbuf = usb_buffer_alloc(subs->dev, SYNC_URBS * 4,
						 GFP_KERNEL, &subs->sync_dma);
		if (! subs->syncbuf)
			goto out_of_memory;
		for (i = 0; i < SYNC_URBS; i++) {
			struct snd_urb_ctx *u = &subs->syncurb[i];
			u->index = i;
			u->subs = subs;
			u->packets = 1;
			u->urb = usb_alloc_urb(1, GFP_KERNEL);
			if (! u->urb)
				goto out_of_memory;
			u->urb->transfer_buffer = subs->syncbuf + i * 4;
			u->urb->transfer_dma = subs->sync_dma + i * 4;
			u->urb->transfer_buffer_length = 4;
			u->urb->pipe = subs->syncpipe;
			u->urb->transfer_flags = URB_ISO_ASAP |
						 URB_NO_TRANSFER_DMA_MAP;
			u->urb->number_of_packets = 1;
			u->urb->interval = 1 << subs->syncinterval;
			u->urb->context = u;
			u->urb->complete = snd_complete_sync_urb;
		}
	}
	return 0;

out_of_memory:
	release_substream_urbs(subs, 0);
	return -ENOMEM;
}


/*
 * find a matching audio format
 */
static struct audioformat *find_format(struct snd_usb_substream *subs, unsigned int format,
				       unsigned int rate, unsigned int channels)
{
	struct list_head *p;
	struct audioformat *found = NULL;
	int cur_attr = 0, attr;

	list_for_each(p, &subs->fmt_list) {
		struct audioformat *fp;
		fp = list_entry(p, struct audioformat, list);
		if (fp->format != format || fp->channels != channels)
			continue;
		if (rate < fp->rate_min || rate > fp->rate_max)
			continue;
		if (! (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)) {
			unsigned int i;
			for (i = 0; i < fp->nr_rates; i++)
				if (fp->rate_table[i] == rate)
					break;
			if (i >= fp->nr_rates)
				continue;
		}
		attr = fp->ep_attr & EP_ATTR_MASK;
		if (! found) {
			found = fp;
			cur_attr = attr;
			continue;
		}
		/* avoid async out and adaptive in if the other method
		 * supports the same format.
		 * this is a workaround for the case like
		 * M-audio audiophile USB.
		 */
		if (attr != cur_attr) {
			if ((attr == EP_ATTR_ASYNC &&
			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
			    (attr == EP_ATTR_ADAPTIVE &&
			     subs->direction == SNDRV_PCM_STREAM_CAPTURE))
				continue;
			if ((cur_attr == EP_ATTR_ASYNC &&
			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
			    (cur_attr == EP_ATTR_ADAPTIVE &&
			     subs->direction == SNDRV_PCM_STREAM_CAPTURE)) {
				found = fp;
				cur_attr = attr;
				continue;
			}
		}
		/* find the format with the largest max. packet size */
		if (fp->maxpacksize > found->maxpacksize) {
			found = fp;
			cur_attr = attr;
		}
	}
	return found;
}


/*
 * initialize the picth control and sample rate
 */
static int init_usb_pitch(struct usb_device *dev, int iface,
			  struct usb_host_interface *alts,
			  struct audioformat *fmt)
{
	unsigned int ep;
	unsigned char data[1];
	int err;

	ep = get_endpoint(alts, 0)->bEndpointAddress;
	/* if endpoint has pitch control, enable it */
	if (fmt->attributes & EP_CS_ATTR_PITCH_CONTROL) {
		data[0] = 1;
		if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), SET_CUR,
					   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
					   PITCH_CONTROL << 8, ep, data, 1, 1000)) < 0) {
			snd_printk(KERN_ERR "%d:%d:%d: cannot set enable PITCH\n",
				   dev->devnum, iface, ep);
			return err;
		}
	}
	return 0;
}

static int init_usb_sample_rate(struct usb_device *dev, int iface,
				struct usb_host_interface *alts,
				struct audioformat *fmt, int rate)
{
	unsigned int ep;
	unsigned char data[3];
	int err;

	ep = get_endpoint(alts, 0)->bEndpointAddress;
	/* if endpoint has sampling rate control, set it */
	if (fmt->attributes & EP_CS_ATTR_SAMPLE_RATE) {
		int crate;
		data[0] = rate;
		data[1] = rate >> 8;
		data[2] = rate >> 16;
		if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), SET_CUR,
					   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
					   SAMPLING_FREQ_CONTROL << 8, ep, data, 3, 1000)) < 0) {
			snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d to ep 0x%x\n",
				   dev->devnum, iface, fmt->altsetting, rate, ep);
			return err;
		}
		if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), GET_CUR,
					   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_IN,
					   SAMPLING_FREQ_CONTROL << 8, ep, data, 3, 1000)) < 0) {
			snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq at ep 0x%x\n",
				   dev->devnum, iface, fmt->altsetting, ep);
			return 0; /* some devices don't support reading */
		}
		crate = data[0] | (data[1] << 8) | (data[2] << 16);
		if (crate != rate) {
			snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
			// runtime->rate = crate;
		}
	}
	return 0;
}

/*
 * find a matching format and set up the interface
 */
static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
{
	struct usb_device *dev = subs->dev;
	struct usb_host_interface *alts;
	struct usb_interface_descriptor *altsd;
	struct usb_interface *iface;
	unsigned int ep, attr;
	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
	int err;

	iface = usb_ifnum_to_if(dev, fmt->iface);
	snd_assert(iface, return -EINVAL);
	alts = &iface->altsetting[fmt->altset_idx];
	altsd = get_iface_desc(alts);
	snd_assert(altsd->bAlternateSetting == fmt->altsetting, return -EINVAL);

	if (fmt == subs->cur_audiofmt)
		return 0;

	/* close the old interface */
	if (subs->interface >= 0 && subs->interface != fmt->iface) {
		if (usb_set_interface(subs->dev, subs->interface, 0) < 0) {
			snd_printk(KERN_ERR "%d:%d:%d: return to setting 0 failed\n",
				dev->devnum, fmt->iface, fmt->altsetting);
			return -EIO;
		}
		subs->interface = -1;
		subs->format = 0;
	}

	/* set interface */
	if (subs->interface != fmt->iface || subs->format != fmt->altset_idx) {
		if (usb_set_interface(dev, fmt->iface, fmt->altsetting) < 0) {
			snd_printk(KERN_ERR "%d:%d:%d: usb_set_interface failed\n",
				   dev->devnum, fmt->iface, fmt->altsetting);
			return -EIO;
		}
		snd_printdd(KERN_INFO "setting usb interface %d:%d\n", fmt->iface, fmt->altsetting);
		subs->interface = fmt->iface;
		subs->format = fmt->altset_idx;
	}

	/* create a data pipe */
	ep = fmt->endpoint & USB_ENDPOINT_NUMBER_MASK;
	if (is_playback)
		subs->datapipe = usb_sndisocpipe(dev, ep);
	else
		subs->datapipe = usb_rcvisocpipe(dev, ep);
	if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH &&
	    get_endpoint(alts, 0)->bInterval >= 1 &&
	    get_endpoint(alts, 0)->bInterval <= 4)
		subs->datainterval = get_endpoint(alts, 0)->bInterval - 1;
	else
		subs->datainterval = 0;
	subs->syncpipe = subs->syncinterval = 0;
	subs->maxpacksize = fmt->maxpacksize;
	subs->fill_max = 0;

	/* we need a sync pipe in async OUT or adaptive IN mode */
	/* check the number of EP, since some devices have broken
	 * descriptors which fool us.  if it has only one EP,
	 * assume it as adaptive-out or sync-in.
	 */
	attr = fmt->ep_attr & EP_ATTR_MASK;
	if (((is_playback && attr == EP_ATTR_ASYNC) ||
	     (! is_playback && attr == EP_ATTR_ADAPTIVE)) &&
	    altsd->bNumEndpoints >= 2) {
		/* check sync-pipe endpoint */
		/* ... and check descriptor size before accessing bSynchAddress
		   because there is a version of the SB Audigy 2 NX firmware lacking
		   the audio fields in the endpoint descriptors */
		if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != 0x01 ||
		    (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
		     get_endpoint(alts, 1)->bSynchAddress != 0)) {
			snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
				   dev->devnum, fmt->iface, fmt->altsetting);
			return -EINVAL;
		}
		ep = get_endpoint(alts, 1)->bEndpointAddress;
		if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
		    (( is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
		     (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
			snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
				   dev->devnum, fmt->iface, fmt->altsetting);
			return -EINVAL;