[ALSA] Add missing source codes in the last hwdep-pcm patch.

USB USX2Y
The missing source files in the last hwdep-pcm patch are added.
Signed-off-by: Karsten Wiese <annabellesgarden@yahoo.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/usx2y/usx2yhwdeppcm.c

+/*
+ *   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
+ */
+
+/* USX2Y "rawusb" aka hwdep_pcm implementation
+
+ Its usb's unableness to atomically handle power of 2 period sized data chuncs
+ at standard samplerates,
+ what led to this part of the usx2y module: 
+ It provides the alsa kernel half of the usx2y-alsa-jack driver pair.
+ The pair uses a hardware dependant alsa-device for mmaped pcm transport.
+ Advantage achieved:
+         The usb_hcd places reads/writes pcm data into dma-memory.
+         That memory is mmaped by jack's usx2y driver.
+         Jack's usx2y driver is the first/last to read/write pcm data.
+         Read/write is a combination of power of 2 period shaping and
+         float/int conversation.
+         Compared to mainline alsa/jack we leave out power of 2 period shaping inside
+         snd-usb-usx2y which needs memcpy() and additional buffers.
+         As a side effect possible unwanted pcm-data coruption resulting of
+         standard alsa's snd-usb-usx2y period shaping scheme falls away.
+         Result is sane jack operation at buffering schemes down to 128frames,
+         2 periods.
+         plain usx2y alsa mode is able to achieve 64frames, 4periods, but only at the
+         cost of easier triggered i.e. aeolus xruns (128 or 256frames,
+         2periods works but is useless cause of crackling).
+ 
+ This is a first "proof of concept" implementation.
+ Later, funcionalities should migrate to more apropriate places:
+ Userland:
+ - The jackd could mmap its float-pcm buffers directly from alsa-lib.
+ - alsa-lib could provide power of 2 period sized shaping combined with int/float
+   conversation.
+   Currently the usx2y jack driver provides above 2 services.
+ Kernel:
+ - rawusb dma pcm buffer transport should go to snd-usb-lib, so also snd-usb-audio
+   devices can use it.
+   Currently rawusb dma pcm buffer transport (this file) is only available to snd-usb-usx2y. 
+*/
+
+#include "usbusx2yaudio.c"
+
+#if defined(USX2Y_NRPACKS_VARIABLE) || (!defined(USX2Y_NRPACKS_VARIABLE) &&  USX2Y_NRPACKS == 1)
+
+#include <sound/hwdep.h>
+
+
+static int usX2Y_usbpcm_urb_capt_retire(snd_usX2Y_substream_t *subs)
+{
+	struct urb	*urb = subs->completed_urb;
+	snd_pcm_runtime_t *runtime = subs->pcm_substream->runtime;
+	int 		i, lens = 0, hwptr_done = subs->hwptr_done;
+	usX2Ydev_t	*usX2Y = subs->usX2Y;
+	if (0 > usX2Y->hwdep_pcm_shm->capture_iso_start) { //FIXME
+		int head = usX2Y->hwdep_pcm_shm->captured_iso_head + 1;
+		if (head >= ARRAY_SIZE(usX2Y->hwdep_pcm_shm->captured_iso))
+			head = 0;
+		usX2Y->hwdep_pcm_shm->capture_iso_start = head;
+		snd_printdd("cap start %i\n", head);
+	}
+	for (i = 0; i < nr_of_packs(); i++) {
+		if (urb->iso_frame_desc[i].status) { /* active? hmm, skip this */
+			snd_printk("activ frame status %i. Most propably some hardware problem.\n", urb->iso_frame_desc[i].status);
+			return urb->iso_frame_desc[i].status;
+		}
+		lens += urb->iso_frame_desc[i].actual_length / usX2Y->stride;
+	}
+	if ((hwptr_done += lens) >= runtime->buffer_size)
+		hwptr_done -= runtime->buffer_size;
+	subs->hwptr_done = hwptr_done;
+	subs->transfer_done += lens;
+	/* update the pointer, call callback if necessary */
+	if (subs->transfer_done >= runtime->period_size) {
+		subs->transfer_done -= runtime->period_size;
+		snd_pcm_period_elapsed(subs->pcm_substream);
+	}
+	return 0;
+}
+
+static inline int usX2Y_iso_frames_per_buffer(snd_pcm_runtime_t *runtime, usX2Ydev_t * usX2Y)
+{
+	return (runtime->buffer_size * 1000) / usX2Y->rate + 1;	//FIXME: so far only correct period_size == 2^x ?
+}
+
+/*
+ * prepare urb for playback data pipe
+ *
+ * we copy the data directly from the pcm buffer.
+ * the current position to be copied is held in hwptr field.
+ * since a urb can handle only a single linear buffer, if the total
+ * transferred area overflows the buffer boundary, we cannot send
+ * it directly from the buffer.  thus the data is once copied to
+ * a temporary buffer and urb points to that.
+ */
+static int usX2Y_hwdep_urb_play_prepare(snd_usX2Y_substream_t *subs,
+				  struct urb *urb)
+{
+	int count, counts, pack;
+	usX2Ydev_t *usX2Y = subs->usX2Y;
+	struct snd_usX2Y_hwdep_pcm_shm *shm = usX2Y->hwdep_pcm_shm;
+	snd_pcm_runtime_t *runtime = subs->pcm_substream->runtime;
+
+	if (0 > shm->playback_iso_start) {
+		shm->playback_iso_start = shm->captured_iso_head -
+			usX2Y_iso_frames_per_buffer(runtime, usX2Y);
+		if (0 > shm->playback_iso_start)
+			shm->playback_iso_start += ARRAY_SIZE(shm->captured_iso);
+		shm->playback_iso_head = shm->playback_iso_start;
+	}
+
+	count = 0;
+	for (pack = 0; pack < nr_of_packs(); pack++) {
+		/* calculate the size of a packet */
+		counts = shm->captured_iso[shm->playback_iso_head].length / usX2Y->stride;
+		if (counts < 43 || counts > 50) {
+			snd_printk("should not be here with counts=%i\n", counts);
+			return -EPIPE;
+		}
+		/* set up descriptor */
+		urb->iso_frame_desc[pack].offset = shm->captured_iso[shm->playback_iso_head].offset;
+		urb->iso_frame_desc[pack].length = shm->captured_iso[shm->playback_iso_head].length;
+		if (atomic_read(&subs->state) != state_RUNNING)
+			memset((char *)urb->transfer_buffer + urb->iso_frame_desc[pack].offset, 0,
+			       urb->iso_frame_desc[pack].length);
+		if (++shm->playback_iso_head >= ARRAY_SIZE(shm->captured_iso))
+			shm->playback_iso_head = 0;
+		count += counts;
+	}
+	urb->transfer_buffer_length = count * usX2Y->stride;
+	return 0;
+}
+
+
+static inline void usX2Y_usbpcm_urb_capt_iso_advance(snd_usX2Y_substream_t *subs, struct urb *urb)
+{
+	int pack;
+	for (pack = 0; pack < nr_of_packs(); ++pack) {
+		struct usb_iso_packet_descriptor *desc = urb->iso_frame_desc + pack;
+		if (NULL != subs) {
+			snd_usX2Y_hwdep_pcm_shm_t *shm = subs->usX2Y->hwdep_pcm_shm;
+			int head = shm->captured_iso_head + 1;
+			if (head >= ARRAY_SIZE(shm->captured_iso))
+				head = 0;
+			shm->captured_iso[head].frame = urb->start_frame + pack;
+			shm->captured_iso[head].offset = desc->offset;
+			shm->captured_iso[head].length = desc->actual_length;
+			shm->captured_iso_head = head;
+			shm->captured_iso_frames++;
+		}
+		if ((desc->offset += desc->length * NRURBS*nr_of_packs()) +
+		    desc->length >= SSS)
+			desc->offset -= (SSS - desc->length);
+	}
+}
+
+static inline int usX2Y_usbpcm_usbframe_complete(snd_usX2Y_substream_t *capsubs,
+					   snd_usX2Y_substream_t *capsubs2,
+					   snd_usX2Y_substream_t *playbacksubs, int frame)
+{
+	int err, state;
+	struct urb *urb = playbacksubs->completed_urb;
+
+	state = atomic_read(&playbacksubs->state);
+	if (NULL != urb) {
+		if (state == state_RUNNING)
+			usX2Y_urb_play_retire(playbacksubs, urb);
+		else
+			if (state >= state_PRERUNNING) {
+				atomic_inc(&playbacksubs->state);
+			}
+	} else {
+		switch (state) {
+		case state_STARTING1:
+			urb = playbacksubs->urb[0];
+			atomic_inc(&playbacksubs->state);
+			break;
+		case state_STARTING2:
+			urb = playbacksubs->urb[1];
+			atomic_inc(&playbacksubs->state);
+			break;
+		}
+	}
+	if (urb) {
+		if ((err = usX2Y_hwdep_urb_play_prepare(playbacksubs, urb)) ||
+		    (err = usX2Y_urb_submit(playbacksubs, urb, frame))) {
+			return err;
+		}
+	}
+	
+	playbacksubs->completed_urb = NULL;
+
+	state = atomic_read(&capsubs->state);
+	if (state >= state_PREPARED) {
+		if (state == state_RUNNING) {
+			if ((err = usX2Y_usbpcm_urb_capt_retire(capsubs)))
+				return err;
+		} else {
+			if (state >= state_PRERUNNING)
+				atomic_inc(&capsubs->state);
+		}
+		usX2Y_usbpcm_urb_capt_iso_advance(capsubs, capsubs->completed_urb);
+		if (NULL != capsubs2)
+			usX2Y_usbpcm_urb_capt_iso_advance(NULL, capsubs2->completed_urb);
+		if ((err = usX2Y_urb_submit(capsubs, capsubs->completed_urb, frame)))
+			return err;
+		if (NULL != capsubs2)
+			if ((err = usX2Y_urb_submit(capsubs2, capsubs2->completed_urb, frame)))
+				return err;
+	}
+	capsubs->completed_urb = NULL;
+	if (NULL != capsubs2)
+		capsubs2->completed_urb = NULL;
+	return 0;
+}
+
+
+static void i_usX2Y_usbpcm_urb_complete(struct urb *urb, struct pt_regs *regs)
+{
+	snd_usX2Y_substream_t *subs = (snd_usX2Y_substream_t*)urb->context;
+	usX2Ydev_t *usX2Y = subs->usX2Y;
+	snd_usX2Y_substream_t *capsubs, *capsubs2, *playbacksubs;
+
+	if (unlikely(atomic_read(&subs->state) < state_PREPARED)) {
+		snd_printdd("hcd_frame=%i ep=%i%s status=%i start_frame=%i\n", usb_get_current_frame_number(usX2Y->chip.dev), subs->endpoint, usb_pipein(urb->pipe) ? "in" : "out", urb->status, urb->start_frame);
+		return;
+	}
+	if (unlikely(urb->status)) {
+		usX2Y_error_urb_status(usX2Y, subs, urb);
+		return;
+	}
+	if (likely((0xFFFF & urb->start_frame) == usX2Y->wait_iso_frame))
+		subs->completed_urb = urb;
+	else {
+		usX2Y_error_sequence(usX2Y, subs, urb);
+		return;
+	}
+
+	capsubs = usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE];
+	capsubs2 = usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE + 2];
+	playbacksubs = usX2Y->subs[SNDRV_PCM_STREAM_PLAYBACK];
+	if (capsubs->completed_urb && atomic_read(&capsubs->state) >= state_PREPARED &&
+	    (NULL == capsubs2 || capsubs2->completed_urb) &&
+	    (playbacksubs->completed_urb || atomic_read(&playbacksubs->state) < state_PREPARED)) {
+		if (!usX2Y_usbpcm_usbframe_complete(capsubs, capsubs2, playbacksubs, urb->start_frame)) {
+			if (nr_of_packs() <= urb->start_frame &&
+			    urb->start_frame <= (2 * nr_of_packs() - 1))	// uhci and ohci
+				usX2Y->wait_iso_frame = urb->start_frame - nr_of_packs();
+			else
+				usX2Y->wait_iso_frame +=  nr_of_packs();
+		} else {
+			snd_printdd("\n");
+			usX2Y_clients_stop(usX2Y);
+		}
+	}
+}
+
+
+static void usX2Y_hwdep_urb_release(struct urb** urb)
+{
+	usb_kill_urb(*urb);
+	usb_free_urb(*urb);
+	*urb = NULL;
+}
+
+/*
+ * release a substream
+ */
+static void usX2Y_usbpcm_urbs_release(snd_usX2Y_substream_t *subs)
+{
+	int i;
+	snd_printdd("snd_usX2Y_urbs_release() %i\n", subs->endpoint);
+	for (i = 0; i < NRURBS; i++)
+		usX2Y_hwdep_urb_release(subs->urb + i);
+}
+
+static void usX2Y_usbpcm_subs_startup_finish(usX2Ydev_t * usX2Y)
+{
+	usX2Y_urbs_set_complete(usX2Y, i_usX2Y_usbpcm_urb_complete);
+	usX2Y->prepare_subs = NULL;
+}
+
+static void i_usX2Y_usbpcm_subs_startup(struct urb *urb, struct pt_regs *regs)
+{
+	snd_usX2Y_substream_t *subs = (snd_usX2Y_substream_t*)urb->context;
+	usX2Ydev_t *usX2Y = subs->usX2Y;
+	snd_usX2Y_substream_t *prepare_subs = usX2Y->prepare_subs;
+	if (NULL != prepare_subs &&
+	    urb->start_frame == prepare_subs->urb[0]->start_frame) {
+		atomic_inc(&prepare_subs->state);
+		if (prepare_subs == usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE]) {
+			snd_usX2Y_substream_t *cap_subs2 = usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE + 2];
+			if (cap_subs2 != NULL)
+				atomic_inc(&cap_subs2->state);
+		}
+		usX2Y_usbpcm_subs_startup_finish(usX2Y);
+		wake_up(&usX2Y->prepare_wait_queue);
+	}
+
+	i_usX2Y_usbpcm_urb_complete(urb, regs);
+}
+
+/*
+ * initialize a substream's urbs
+ */
+static int usX2Y_usbpcm_urbs_allocate(snd_usX2Y_substream_t *subs)
+{
+	int i;
+	unsigned int pipe;
+	int is_playback = subs == subs->usX2Y->subs[SNDRV_PCM_STREAM_PLAYBACK];
+	struct usb_device *dev = subs->usX2Y->chip.dev;
+
+	pipe = is_playback ? usb_sndisocpipe(dev, subs->endpoint) :
+			usb_rcvisocpipe(dev, subs->endpoint);
+	subs->maxpacksize = usb_maxpacket(dev, pipe, is_playback);
+	if (!subs->maxpacksize)
+		return -EINVAL;
+
+	/* allocate and initialize data urbs */
+	for (i = 0; i < NRURBS; i++) {
+		struct urb** purb = subs->urb + i;
+		if (*purb) {
+			usb_kill_urb(*purb);
+			continue;
+		}
+		*purb = usb_alloc_urb(nr_of_packs(), GFP_KERNEL);
+		if (NULL == *purb) {
+			usX2Y_usbpcm_urbs_release(subs);
+			return -ENOMEM;
+		}
+		(*purb)->transfer_buffer = is_playback ?
+			subs->usX2Y->hwdep_pcm_shm->playback : (
+				subs->endpoint == 0x8 ?
+				subs->usX2Y->hwdep_pcm_shm->capture0x8 :
+				subs->usX2Y->hwdep_pcm_shm->capture0xA);
+
+		(*purb)->dev = dev;
+		(*purb)->pipe = pipe;
+		(*purb)->number_of_packets = nr_of_packs();
+		(*purb)->context = subs;
+		(*purb)->interval = 1;
+		(*purb)->complete = i_usX2Y_usbpcm_subs_startup;
+	}
+	return 0;
+}
+
+/*
+ * free the buffer
+ */
+static int snd_usX2Y_usbpcm_hw_free(snd_pcm_substream_t *substream)
+{
+	snd_pcm_runtime_t *runtime = substream->runtime;
+	snd_usX2Y_substream_t *subs = (snd_usX2Y_substream_t *)runtime->private_data,
+		*cap_subs2 = subs->usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE + 2];
+	down(&subs->usX2Y->prepare_mutex);
+	snd_printdd("snd_usX2Y_usbpcm_hw_free(%p)\n", substream);
+
+	if (SNDRV_PCM_STREAM_PLAYBACK == substream->stream) {
+		snd_usX2Y_substream_t *cap_subs = subs->usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE];
+		atomic_set(&subs->state, state_STOPPED);
+		usX2Y_usbpcm_urbs_release(subs);
+		if (!cap_subs->pcm_substream ||
+		    !cap_subs->pcm_substream->runtime ||
+		    !cap_subs->pcm_substream->runtime->status ||
+		    cap_subs->pcm_substream->runtime->status->state < SNDRV_PCM_STATE_PREPARED) {
+			atomic_set(&cap_subs->state, state_STOPPED);
+			if (NULL != cap_subs2)
+				atomic_set(&cap_subs2->state, state_STOPPED);
+			usX2Y_usbpcm_urbs_release(cap_subs);
+			if (NULL != cap_subs2)
+				usX2Y_usbpcm_urbs_release(cap_subs2);
+		}
+	} else {
+		snd_usX2Y_substream_t *playback_subs = subs->usX2Y->subs[SNDRV_PCM_STREAM_PLAYBACK];
+		if (atomic_read(&playback_subs->state) < state_PREPARED) {
+			atomic_set(&subs->state, state_STOPPED);
+			if (NULL != cap_subs2)
+				atomic_set(&cap_subs2->state, state_STOPPED);
+			usX2Y_usbpcm_urbs_release(subs);
+			if (NULL != cap_subs2)
+				usX2Y_usbpcm_urbs_release(cap_subs2);
+		}
+	}
+	up(&subs->usX2Y->prepare_mutex);
+	return snd_pcm_lib_free_pages(substream);
+}
+
+static void usX2Y_usbpcm_subs_startup(snd_usX2Y_substream_t *subs)
+{
+	usX2Ydev_t * usX2Y = subs->usX2Y;
+	usX2Y->prepare_subs = subs;
+	subs->urb[0]->start_frame = -1;
+	smp_wmb();	// Make shure above modifications are seen by i_usX2Y_subs_startup()
+	usX2Y_urbs_set_complete(usX2Y, i_usX2Y_usbpcm_subs_startup);
+}
+
+static int usX2Y_usbpcm_urbs_start(snd_usX2Y_substream_t *subs)
+{
+	int	p, u, err,
+		stream = subs->pcm_substream->stream;
+	usX2Ydev_t *usX2Y = subs->usX2Y;
+
+	if (SNDRV_PCM_STREAM_CAPTURE == stream) {
+		usX2Y->hwdep_pcm_shm->captured_iso_head = -1;
+		usX2Y->hwdep_pcm_shm->captured_iso_frames = 0;
+	}
+
+	for (p = 0; 3 >= (stream + p); p += 2) {
+		snd_usX2Y_substream_t *subs = usX2Y->subs[stream + p];
+		if (subs != NULL) {
+			if ((err = usX2Y_usbpcm_urbs_allocate(subs)) < 0)
+				return err;
+			subs->completed_urb = NULL;
+		}
+	}
+
+	for (p = 0; p < 4; p++) {
+		snd_usX2Y_substream_t *subs = usX2Y->subs[p];
+		if (subs != NULL && atomic_read(&subs->state) >= state_PREPARED)
+			goto start;
+	}
+	usX2Y->wait_iso_frame = -1;
+
+ start:
+	usX2Y_usbpcm_subs_startup(subs);
+	for (u = 0; u < NRURBS; u++) {
+		for (p = 0; 3 >= (stream + p); p += 2) {
+			snd_usX2Y_substream_t *subs = usX2Y->subs[stream + p];
+			if (subs != NULL) {
+				struct urb *urb = subs->urb[u];
+				if (usb_pipein(urb->pipe)) {
+					unsigned long pack;
+					if (0 == u)
+						atomic_set(&subs->state, state_STARTING3);
+					urb->dev = usX2Y->chip.dev;
+					urb->transfer_flags = URB_ISO_ASAP;
+					for (pack = 0; pack < nr_of_packs(); pack++) {
+						urb->iso_frame_desc[pack].offset = subs->maxpacksize * (pack + u * nr_of_packs());
+						urb->iso_frame_desc[pack].length = subs->maxpacksize;
+					}
+					urb->transfer_buffer_length = subs->maxpacksize * nr_of_packs(); 
+					if ((err = usb_submit_urb(urb, GFP_KERNEL)) < 0) {
+						snd_printk (KERN_ERR "cannot usb_submit_urb() for urb %d, err = %d\n", u, err);
+						err = -EPIPE;
+						goto cleanup;
+					}  else {
+						snd_printdd("%i\n", urb->start_frame);
+						if (0 > usX2Y->wait_iso_frame)
+							usX2Y->wait_iso_frame = urb->start_frame;
+					}
+					urb->transfer_flags = 0;
+				} else {
+					atomic_set(&subs->state, state_STARTING1);
+					break;
+				}			
+			}
+		}
+	}
+	err = 0;
+	wait_event(usX2Y->prepare_wait_queue, NULL == usX2Y->prepare_subs);
+	if (atomic_read(&subs->state) != state_PREPARED)
+		err = -EPIPE;
+		
+ cleanup:
+	if (err) {
+		usX2Y_subs_startup_finish(usX2Y);	// Call it now
+		usX2Y_clients_stop(usX2Y);		// something is completely wroong > stop evrything			
+	}
+	return err;
+}
+
+/*
+ * prepare callback
+ *
+ * set format and initialize urbs
+ */
+static int snd_usX2Y_usbpcm_prepare(snd_pcm_substream_t *substream)
+{
+	snd_pcm_runtime_t *runtime = substream->runtime;
+	snd_usX2Y_substream_t *subs = (snd_usX2Y_substream_t *)runtime->private_data;
+	usX2Ydev_t *usX2Y = subs->usX2Y;
+	snd_usX2Y_substream_t *capsubs = subs->usX2Y->subs[SNDRV_PCM_STREAM_CAPTURE];
+	int err = 0;
+	snd_printdd("snd_usX2Y_pcm_prepare(%p)\n", substream);
+
+	if (NULL == usX2Y->hwdep_pcm_shm) {
+		if (NULL == (usX2Y->hwdep_pcm_shm = snd_malloc_pages(sizeof(snd_usX2Y_hwdep_pcm_shm_t), GFP_KERNEL)))
+			return -ENOMEM;
+		memset(usX2Y->hwdep_pcm_shm, 0, sizeof(snd_usX2Y_hwdep_pcm_shm_t));
+	}
+
+	down(&usX2Y->prepare_mutex);
+	usX2Y_subs_prepare(subs);
+// Start hardware streams
+// SyncStream first....
+	if (atomic_read(&capsubs->state) < state_PREPARED) {
+		if (usX2Y->format != runtime->format)
+			if ((err = usX2Y_format_set(usX2Y, runtime->format)) < 0)
+				goto up_prepare_mutex;
+		if (usX2Y->rate != runtime->rate)
+			if ((err = usX2Y_rate_set(usX2Y, runtime->rate)) < 0)
+				goto up_prepare_mutex;
+		snd_printdd("starting capture pipe for %s\n", subs == capsubs ? "self" : "playpipe");
+		if (0 > (err = usX2Y_usbpcm_urbs_start(capsubs)))
+			goto up_prepare_mutex;
+	}
+
+	if (subs != capsubs) {
+		usX2Y->hwdep_pcm_shm->playback_iso_start = -1;
+		if (atomic_read(&subs->state) < state_PREPARED) {
+			while (usX2Y_iso_frames_per_buffer(runtime, usX2Y) > usX2Y->hwdep_pcm_shm->captured_iso_frames) {
+				signed long timeout;
+				snd_printd("Wait: iso_frames_per_buffer=%i,captured_iso_frames=%i\n", usX2Y_iso_frames_per_buffer(runtime, usX2Y), usX2Y->hwdep_pcm_shm->captured_iso_frames);
+				set_current_state(TASK_INTERRUPTIBLE);
+				timeout = schedule_timeout(HZ/100 + 1);
+				if (signal_pending(current)) {
+					err = -ERESTARTSYS;
+					goto up_prepare_mutex;
+				}
+			} 
+			if (0 > (err = usX2Y_usbpcm_urbs_start(subs)))
+				goto up_prepare_mutex;
+		}
+		snd_printd("Ready: iso_frames_per_buffer=%i,captured_iso_frames=%i\n", usX2Y_iso_frames_per_buffer(runtime, usX2Y), usX2Y->hwdep_pcm_shm->captured_iso_frames);
+	} else
+		usX2Y->hwdep_pcm_shm->capture_iso_start = -1;
+
+ up_prepare_mutex:
+	up(&usX2Y->prepare_mutex);
+	return err;
+}
+
+static snd_pcm_hardware_t snd_usX2Y_4c =
+{
+	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
+				 SNDRV_PCM_INFO_BLOCK_TRANSFER |
+				 SNDRV_PCM_INFO_MMAP_VALID),
+	.formats =                 SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S24_3LE,
+	.rates =                   SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000,
+	.rate_min =                44100,
+	.rate_max =                48000,
+	.channels_min =            2,
+	.channels_max =            4,
+	.buffer_bytes_max =	(2*128*1024),
+	.period_bytes_min =	64,
+	.period_bytes_max =	(128*1024),
+	.periods_min =		2,
+	.periods_max =		1024,
+	.fifo_size =              0
+};
+
+
+
+static int snd_usX2Y_usbpcm_open(snd_pcm_substream_t *substream)
+{
+	snd_usX2Y_substream_t	*subs = ((snd_usX2Y_substream_t **)
+					 snd_pcm_substream_chip(substream))[substream->stream];
+	snd_pcm_runtime_t	*runtime = substream->runtime;
+
+	if (!subs->usX2Y->chip_status & USX2Y_STAT_CHIP_MMAP_PCM_URBS)
+		return -EBUSY;
+
+	runtime->hw = SNDRV_PCM_STREAM_PLAYBACK == substream->stream ? snd_usX2Y_2c :
+		(subs->usX2Y->subs[3] ? snd_usX2Y_4c : snd_usX2Y_2c);
+	runtime->private_data = subs;
+	subs->pcm_substream = substream;
+	snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME, 1000, 200000);
+	return 0;
+}
+
+
+static int snd_usX2Y_usbpcm_close(snd_pcm_substream_t *substream)
+{
+	snd_pcm_runtime_t *runtime = substream->runtime;
+	snd_usX2Y_substream_t *subs = (snd_usX2Y_substream_t *)runtime->private_data;
+	int err = 0;
+	snd_printd("\n");
+	subs->pcm_substream = NULL;
+	return err;
+}
+
+
+static snd_pcm_ops_t snd_usX2Y_usbpcm_ops = 
+{
+	.open =		snd_usX2Y_usbpcm_open,
+	.close =	snd_usX2Y_usbpcm_close,
+	.ioctl =	snd_pcm_lib_ioctl,
+	.hw_params =	snd_usX2Y_pcm_hw_params,
+	.hw_free =	snd_usX2Y_usbpcm_hw_free,
+	.prepare =	snd_usX2Y_usbpcm_prepare,
+	.trigger =	snd_usX2Y_pcm_trigger,
+	.pointer =	snd_usX2Y_pcm_pointer,
+};
+
+
+static int usX2Y_pcms_lock_check(snd_card_t *card)
+{
+	struct list_head *list;
+	snd_device_t *dev;
+	snd_pcm_t *pcm;
+	int err = 0;
+	list_for_each(list, &card->devices) {
+		dev = snd_device(list);
+		if (dev->type != SNDRV_DEV_PCM)
+			continue;
+		pcm = dev->device_data;
+		down(&pcm->open_mutex);
+	}
+	list_for_each(list, &card->devices) {
+		int s;
+		dev = snd_device(list);
+		if (dev->type != SNDRV_DEV_PCM)
+			continue;
+		pcm = dev->device_data;
+		for (s = 0; s < 2; ++s) {
+			snd_pcm_substream_t *substream;
+			substream = pcm->streams[s].substream;
+			if (substream && substream->open_flag)
+				err = -EBUSY;
+		}
+	}
+	return err;
+}
+
+
+static void usX2Y_pcms_unlock(snd_card_t *card)
+{
+	struct list_head *list;
+	snd_device_t *dev;
+	snd_pcm_t *pcm;
+	list_for_each(list, &card->devices) {
+		dev = snd_device(list);
+		if (dev->type != SNDRV_DEV_PCM)
+			continue;
+		pcm = dev->device_data;
+		up(&pcm->open_mutex);
+	}
+}
+
+
+static int snd_usX2Y_hwdep_pcm_open(snd_hwdep_t *hw, struct file *file)
+{
+	// we need to be the first 
+	snd_card_t *card = hw->card;
+	int err = usX2Y_pcms_lock_check(card);
+	if (0 == err)
+		usX2Y(card)->chip_status |= USX2Y_STAT_CHIP_MMAP_PCM_URBS;
+	usX2Y_pcms_unlock(card);
+	return err;
+}
+
+
+static int snd_usX2Y_hwdep_pcm_release(snd_hwdep_t *hw, struct file *file)
+{
+	snd_card_t *card = hw->card;
+	int err = usX2Y_pcms_lock_check(card);
+	if (0 == err)
+		usX2Y(hw->card)->chip_status &= ~USX2Y_STAT_CHIP_MMAP_PCM_URBS;
+	usX2Y_pcms_unlock(card);
+	return err;
+}
+
+
+static void snd_usX2Y_hwdep_pcm_vm_open(struct vm_area_struct *area)
+{
+}
+
+
+static void snd_usX2Y_hwdep_pcm_vm_close(struct vm_area_struct *area)
+{
+}
+
+
+static struct page * snd_usX2Y_hwdep_pcm_vm_nopage(struct vm_area_struct *area, unsigned long address, int *type)
+{
+	unsigned long offset;
+	struct page *page;
+	void *vaddr;
+
+	offset = area->vm_pgoff << PAGE_SHIFT;
+	offset += address - area->vm_start;
+	snd_assert((offset % PAGE_SIZE) == 0, return NOPAGE_OOM);
+	vaddr = (char*)((usX2Ydev_t*)area->vm_private_data)->hwdep_pcm_shm + offset;
+	page = virt_to_page(vaddr);
+
+	if (type)
+		*type = VM_FAULT_MINOR;
+
+	return page;
+}
+
+
+static struct vm_operations_struct snd_usX2Y_hwdep_pcm_vm_ops = {
+	.open = snd_usX2Y_hwdep_pcm_vm_open,
+	.close = snd_usX2Y_hwdep_pcm_vm_close,
+	.nopage = snd_usX2Y_hwdep_pcm_vm_nopage,
+};
+
+
+static int snd_usX2Y_hwdep_pcm_mmap(snd_hwdep_t * hw, struct file *filp, struct vm_area_struct *area)
+{
+	unsigned long	size = (unsigned long)(area->vm_end - area->vm_start);
+	usX2Ydev_t	*usX2Y = (usX2Ydev_t*)hw->private_data;
+
+	if (!(((usX2Ydev_t*)hw->private_data)->chip_status & USX2Y_STAT_CHIP_INIT))
+		return -EBUSY;
+
+	/* if userspace tries to mmap beyond end of our buffer, fail */ 
+	if (size > PAGE_ALIGN(sizeof(snd_usX2Y_hwdep_pcm_shm_t))) {
+		snd_printd("%lu > %lu\n", size, (unsigned long)sizeof(snd_usX2Y_hwdep_pcm_shm_t)); 
+		return -EINVAL;
+	}
+
+	if (!usX2Y->hwdep_pcm_shm) {
+		return -ENODEV;
+	}
+	area->vm_ops = &snd_usX2Y_hwdep_pcm_vm_ops;
+	area->vm_flags |= VM_RESERVED;
+	snd_printd("vm_flags=0x%lX\n", area->vm_flags);
+	area->vm_private_data = hw->private_data;
+	return 0;
+}
+
+
+static void snd_usX2Y_hwdep_pcm_private_free(snd_hwdep_t *hwdep)
+{
+	usX2Ydev_t *usX2Y = (usX2Ydev_t *)hwdep->private_data;
+	if (NULL != usX2Y->hwdep_pcm_shm)
+		snd_free_pages(usX2Y->hwdep_pcm_shm, sizeof(snd_usX2Y_hwdep_pcm_shm_t));
+}
+
+
+static void snd_usX2Y_usbpcm_private_free(snd_pcm_t *pcm)
+{
+	snd_pcm_lib_preallocate_free_for_all(pcm);
+}
+
+
+int usX2Y_hwdep_pcm_new(snd_card_t* card)
+{
+	int err;
+	snd_hwdep_t *hw;
+	snd_pcm_t *pcm;
+	struct usb_device *dev = usX2Y(card)->chip.dev;
+	if (1 != nr_of_packs())
+		return 0;
+
+	if ((err = snd_hwdep_new(card, SND_USX2Y_USBPCM_ID, 1, &hw)) < 0) {
+		snd_printd("\n");
+		return err;
+	}
+	hw->iface = SNDRV_HWDEP_IFACE_USX2Y_PCM;
+	hw->private_data = usX2Y(card);
+	hw->private_free = snd_usX2Y_hwdep_pcm_private_free;
+	hw->ops.open = snd_usX2Y_hwdep_pcm_open;
+	hw->ops.release = snd_usX2Y_hwdep_pcm_release;
+	hw->ops.mmap = snd_usX2Y_hwdep_pcm_mmap;
+	hw->exclusive = 1;
+	sprintf(hw->name, "/proc/bus/usb/%03d/%03d/hwdeppcm", dev->bus->busnum, dev->devnum);
+
+	err = snd_pcm_new(card, NAME_ALLCAPS" hwdep Audio", 2, 1, 1, &pcm);
+	if (err < 0) {
+		return err;
+	}
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_usX2Y_usbpcm_ops);
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_usX2Y_usbpcm_ops);
+
+	pcm->private_data = usX2Y(card)->subs;
+	pcm->private_free = snd_usX2Y_usbpcm_private_free;
+	pcm->info_flags = 0;
+
+	sprintf(pcm->name, NAME_ALLCAPS" hwdep Audio");
+	if (0 > (err = snd_pcm_lib_preallocate_pages(pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream,
+						     SNDRV_DMA_TYPE_CONTINUOUS,
+						     snd_dma_continuous_data(GFP_KERNEL),
+						     64*1024, 128*1024)) ||
+	    0 > (err = snd_pcm_lib_preallocate_pages(pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream,
+	    					     SNDRV_DMA_TYPE_CONTINUOUS,
+	    					     snd_dma_continuous_data(GFP_KERNEL),
+						     64*1024, 128*1024))) {
+		snd_usX2Y_usbpcm_private_free(pcm);
+		return err;
+	}
+
+
+	return 0;
+}
+
+#else
+
+int usX2Y_hwdep_pcm_new(snd_card_t* card)
+{
+	return 0;
+}
+
+#endif

sound/usb/usx2y/usx2yhwdeppcm.h

+#define MAXPACK 50
+#define MAXBUFFERMS 100
+#define MAXSTRIDE 3
+
+#define SSS (((MAXPACK*MAXBUFFERMS*MAXSTRIDE + 4096) / 4096) * 4096)
+struct snd_usX2Y_hwdep_pcm_shm {
+	char playback[SSS];
+	char capture0x8[SSS];
+	char capture0xA[SSS];
+	volatile int playback_iso_head;
+	int playback_iso_start;
+	struct {
+		int	frame,
+			offset,
+			length;
+	} captured_iso[128];
+	volatile int captured_iso_head;
+	volatile unsigned captured_iso_frames;
+	int capture_iso_start;
+};
+typedef struct snd_usX2Y_hwdep_pcm_shm snd_usX2Y_hwdep_pcm_shm_t;