Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1233 insertions, 0 deletions

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
new file mode 100644
index 000000000..727ef9889
--- /dev/null
+++ b/sound/usb/endpoint.c
@@ -0,0 +1,1233 @@
+/*
+ *   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/gfp.h>
+#include <linux/init.h>
+#include <linux/ratelimit.h>
+#include <linux/usb.h>
+#include <linux/usb/audio.h>
+#include <linux/slab.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "usbaudio.h"
+#include "helper.h"
+#include "card.h"
+#include "endpoint.h"
+#include "pcm.h"
+#include "quirks.h"
+
+#define EP_FLAG_RUNNING		1
+#define EP_FLAG_STOPPING	2
+
+/*
+ * snd_usb_endpoint is a model that abstracts everything related to an
+ * USB endpoint and its streaming.
+ *
+ * There are functions to activate and deactivate the streaming URBs and
+ * optional callbacks to let the pcm logic handle the actual content of the
+ * packets for playback and record. Thus, the bus streaming and the audio
+ * handlers are fully decoupled.
+ *
+ * There are two different types of endpoints in audio applications.
+ *
+ * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
+ * inbound and outbound traffic.
+ *
+ * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
+ * expect the payload to carry Q10.14 / Q16.16 formatted sync information
+ * (3 or 4 bytes).
+ *
+ * Each endpoint has to be configured prior to being used by calling
+ * snd_usb_endpoint_set_params().
+ *
+ * The model incorporates a reference counting, so that multiple users
+ * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
+ * only the first user will effectively start the URBs, and only the last
+ * one to stop it will tear the URBs down again.
+ */
+
+/*
+ * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
+ * this will overflow at approx 524 kHz
+ */
+static inline unsigned get_usb_full_speed_rate(unsigned int rate)
+{
+	return ((rate << 13) + 62) / 125;
+}
+
+/*
+ * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
+ * this will overflow at approx 4 MHz
+ */
+static inline unsigned get_usb_high_speed_rate(unsigned int rate)
+{
+	return ((rate << 10) + 62) / 125;
+}
+
+/*
+ * release a urb data
+ */
+static void release_urb_ctx(struct snd_urb_ctx *u)
+{
+	if (u->buffer_size)
+		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
+				  u->urb->transfer_buffer,
+				  u->urb->transfer_dma);
+	usb_free_urb(u->urb);
+	u->urb = NULL;
+}
+
+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";
+	case -EINVAL:
+	case -EAGAIN:
+	case -EFBIG:
+	case -EMSGSIZE:
+		return "internal error";
+	default:
+		return "unknown error";
+	}
+}
+
+/**
+ * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
+ *
+ * @ep: The snd_usb_endpoint
+ *
+ * Determine whether an endpoint is driven by an implicit feedback
+ * data endpoint source.
+ */
+int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
+{
+	return  ep->sync_master &&
+		ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA &&
+		ep->type == SND_USB_ENDPOINT_TYPE_DATA &&
+		usb_pipeout(ep->pipe);
+}
+
+/*
+ * For streaming based on information derived from sync endpoints,
+ * prepare_outbound_urb_sizes() will call next_packet_size() to
+ * determine the number of samples to be sent in the next packet.
+ *
+ * For implicit feedback, next_packet_size() is unused.
+ */
+int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep)
+{
+	unsigned long flags;
+	int ret;
+
+	if (ep->fill_max)
+		return ep->maxframesize;
+
+	spin_lock_irqsave(&ep->lock, flags);
+	ep->phase = (ep->phase & 0xffff)
+		+ (ep->freqm << ep->datainterval);
+	ret = min(ep->phase >> 16, ep->maxframesize);
+	spin_unlock_irqrestore(&ep->lock, flags);
+
+	return ret;
+}
+
+static void retire_outbound_urb(struct snd_usb_endpoint *ep,
+				struct snd_urb_ctx *urb_ctx)
+{
+	if (ep->retire_data_urb)
+		ep->retire_data_urb(ep->data_subs, urb_ctx->urb);
+}
+
+static void retire_inbound_urb(struct snd_usb_endpoint *ep,
+			       struct snd_urb_ctx *urb_ctx)
+{
+	struct urb *urb = urb_ctx->urb;
+
+	if (unlikely(ep->skip_packets > 0)) {
+		ep->skip_packets--;
+		return;
+	}
+
+	if (ep->sync_slave)
+		snd_usb_handle_sync_urb(ep->sync_slave, ep, urb);
+
+	if (ep->retire_data_urb)
+		ep->retire_data_urb(ep->data_subs, urb);
+}
+
+static void prepare_silent_urb(struct snd_usb_endpoint *ep,
+			       struct snd_urb_ctx *ctx)
+{
+	struct urb *urb = ctx->urb;
+	unsigned int offs = 0;
+	unsigned int extra = 0;
+	__le32 packet_length;
+	int i;
+
+	/* For tx_length_quirk, put packet length at start of packet */
+	if (ep->chip->tx_length_quirk)
+		extra = sizeof(packet_length);
+
+	for (i = 0; i < ctx->packets; ++i) {
+		unsigned int offset;
+		unsigned int length;
+		int counts;
+
+		if (ctx->packet_size[i])
+			counts = ctx->packet_size[i];
+		else
+			counts = snd_usb_endpoint_next_packet_size(ep);
+
+		length = counts * ep->stride; /* number of silent bytes */
+		offset = offs * ep->stride + extra * i;
+		urb->iso_frame_desc[i].offset = offset;
+		urb->iso_frame_desc[i].length = length + extra;
+		if (extra) {
+			packet_length = cpu_to_le32(length);
+			memcpy(urb->transfer_buffer + offset,
+			       &packet_length, sizeof(packet_length));
+		}
+		memset(urb->transfer_buffer + offset + extra,
+		       ep->silence_value, length);
+		offs += counts;
+	}
+
+	urb->number_of_packets = ctx->packets;
+	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
+}
+
+/*
+ * Prepare a PLAYBACK urb for submission to the bus.
+ */
+static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
+				 struct snd_urb_ctx *ctx)
+{
+	struct urb *urb = ctx->urb;
+	unsigned char *cp = urb->transfer_buffer;
+
+	urb->dev = ep->chip->dev; /* we need to set this at each time */
+
+	switch (ep->type) {
+	case SND_USB_ENDPOINT_TYPE_DATA:
+		if (ep->prepare_data_urb) {
+			ep->prepare_data_urb(ep->data_subs, urb);
+		} else {
+			/* no data provider, so send silence */
+			prepare_silent_urb(ep, ctx);
+		}
+		break;
+
+	case SND_USB_ENDPOINT_TYPE_SYNC:
+		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
+			/*
+			 * fill the length and offset of each urb descriptor.
+			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
+			 */
+			urb->iso_frame_desc[0].length = 4;
+			urb->iso_frame_desc[0].offset = 0;
+			cp[0] = ep->freqn;
+			cp[1] = ep->freqn >> 8;
+			cp[2] = ep->freqn >> 16;
+			cp[3] = ep->freqn >> 24;
+		} else {
+			/*
+			 * fill the length and offset of each urb descriptor.
+			 * the fixed 10.14 frequency is passed through the pipe.
+			 */
+			urb->iso_frame_desc[0].length = 3;
+			urb->iso_frame_desc[0].offset = 0;
+			cp[0] = ep->freqn >> 2;
+			cp[1] = ep->freqn >> 10;
+			cp[2] = ep->freqn >> 18;
+		}
+
+		break;
+	}
+}
+
+/*
+ * Prepare a CAPTURE or SYNC urb for submission to the bus.
+ */
+static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
+				       struct snd_urb_ctx *urb_ctx)
+{
+	int i, offs;
+	struct urb *urb = urb_ctx->urb;
+
+	urb->dev = ep->chip->dev; /* we need to set this at each time */
+
+	switch (ep->type) {
+	case SND_USB_ENDPOINT_TYPE_DATA:
+		offs = 0;
+		for (i = 0; i < urb_ctx->packets; i++) {
+			urb->iso_frame_desc[i].offset = offs;
+			urb->iso_frame_desc[i].length = ep->curpacksize;
+			offs += ep->curpacksize;
+		}
+
+		urb->transfer_buffer_length = offs;
+		urb->number_of_packets = urb_ctx->packets;
+		break;
+
+	case SND_USB_ENDPOINT_TYPE_SYNC:
+		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
+		urb->iso_frame_desc[0].offset = 0;
+		break;
+	}
+}
+
+/*
+ * Send output urbs that have been prepared previously. URBs are dequeued
+ * from ep->ready_playback_urbs and in case there there aren't any available
+ * or there are no packets that have been prepared, this function does
+ * nothing.
+ *
+ * The reason why the functionality of sending and preparing URBs is separated
+ * is that host controllers don't guarantee the order in which they return
+ * inbound and outbound packets to their submitters.
+ *
+ * This function is only used for implicit feedback endpoints. For endpoints
+ * driven by dedicated sync endpoints, URBs are immediately re-submitted
+ * from their completion handler.
+ */
+static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
+{
+	while (test_bit(EP_FLAG_RUNNING, &ep->flags)) {
+
+		unsigned long flags;
+		struct snd_usb_packet_info *uninitialized_var(packet);
+		struct snd_urb_ctx *ctx = NULL;
+		int err, i;
+
+		spin_lock_irqsave(&ep->lock, flags);
+		if (ep->next_packet_read_pos != ep->next_packet_write_pos) {
+			packet = ep->next_packet + ep->next_packet_read_pos;
+			ep->next_packet_read_pos++;
+			ep->next_packet_read_pos %= MAX_URBS;
+
+			/* take URB out of FIFO */
+			if (!list_empty(&ep->ready_playback_urbs)) {
+				ctx = list_first_entry(&ep->ready_playback_urbs,
+					       struct snd_urb_ctx, ready_list);
+				list_del_init(&ctx->ready_list);
+			}
+		}
+		spin_unlock_irqrestore(&ep->lock, flags);
+
+		if (ctx == NULL)
+			return;
+
+		/* copy over the length information */
+		for (i = 0; i < packet->packets; i++)
+			ctx->packet_size[i] = packet->packet_size[i];
+
+		/* call the data handler to fill in playback data */
+		prepare_outbound_urb(ep, ctx);
+
+		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
+		if (err < 0)
+			usb_audio_err(ep->chip,
+				"Unable to submit urb #%d: %d (urb %p)\n",
+				ctx->index, err, ctx->urb);
+		else
+			set_bit(ctx->index, &ep->active_mask);
+	}
+}
+
+/*
+ * complete callback for urbs
+ */
+static void snd_complete_urb(struct urb *urb)
+{
+	struct snd_urb_ctx *ctx = urb->context;
+	struct snd_usb_endpoint *ep = ctx->ep;
+	struct snd_pcm_substream *substream;
+	unsigned long flags;
+	int err;
+
+	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
+		     urb->status == -ENODEV ||		/* device removed */
+		     urb->status == -ECONNRESET ||	/* unlinked */
+		     urb->status == -ESHUTDOWN))	/* device disabled */
+		goto exit_clear;
+	/* device disconnected */
+	if (unlikely(atomic_read(&ep->chip->shutdown)))
+		goto exit_clear;
+
+	if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+		goto exit_clear;
+
+	if (usb_pipeout(ep->pipe)) {
+		retire_outbound_urb(ep, ctx);
+		/* can be stopped during retire callback */
+		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+			goto exit_clear;
+
+		if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
+			spin_lock_irqsave(&ep->lock, flags);
+			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
+			spin_unlock_irqrestore(&ep->lock, flags);
+			queue_pending_output_urbs(ep);
+
+			goto exit_clear;
+		}
+
+		prepare_outbound_urb(ep, ctx);
+		/* can be stopped during prepare callback */
+		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+			goto exit_clear;
+	} else {
+		retire_inbound_urb(ep, ctx);
+		/* can be stopped during retire callback */
+		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+			goto exit_clear;
+
+		prepare_inbound_urb(ep, ctx);
+	}
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err == 0)
+		return;
+
+	usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
+	if (ep->data_subs && ep->data_subs->pcm_substream) {
+		substream = ep->data_subs->pcm_substream;
+		snd_pcm_stop_xrun(substream);
+	}
+
+exit_clear:
+	clear_bit(ctx->index, &ep->active_mask);
+}
+
+/**
+ * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
+ *
+ * @chip: The chip
+ * @alts: The USB host interface
+ * @ep_num: The number of the endpoint to use
+ * @direction: SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE
+ * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
+ *
+ * If the requested endpoint has not been added to the given chip before,
+ * a new instance is created. Otherwise, a pointer to the previoulsy
+ * created instance is returned. In case of any error, NULL is returned.
+ *
+ * New endpoints will be added to chip->ep_list and must be freed by
+ * calling snd_usb_endpoint_free().
+ *
+ * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
+ * bNumEndpoints > 1 beforehand.
+ */
+struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
+					      struct usb_host_interface *alts,
+					      int ep_num, int direction, int type)
+{
+	struct snd_usb_endpoint *ep;
+	int is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK;
+
+	if (WARN_ON(!alts))
+		return NULL;
+
+	mutex_lock(&chip->mutex);
+
+	list_for_each_entry(ep, &chip->ep_list, list) {
+		if (ep->ep_num == ep_num &&
+		    ep->iface == alts->desc.bInterfaceNumber &&
+		    ep->altsetting == alts->desc.bAlternateSetting) {
+			usb_audio_dbg(ep->chip,
+				      "Re-using EP %x in iface %d,%d @%p\n",
+					ep_num, ep->iface, ep->altsetting, ep);
+			goto __exit_unlock;
+		}
+	}
+
+	usb_audio_dbg(chip, "Creating new %s %s endpoint #%x\n",
+		    is_playback ? "playback" : "capture",
+		    type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync",
+		    ep_num);
+
+	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
+	if (!ep)
+		goto __exit_unlock;
+
+	ep->chip = chip;
+	spin_lock_init(&ep->lock);
+	ep->type = type;
+	ep->ep_num = ep_num;
+	ep->iface = alts->desc.bInterfaceNumber;
+	ep->altsetting = alts->desc.bAlternateSetting;
+	INIT_LIST_HEAD(&ep->ready_playback_urbs);
+	ep_num &= USB_ENDPOINT_NUMBER_MASK;
+
+	if (is_playback)
+		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
+	else
+		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
+
+	if (type == SND_USB_ENDPOINT_TYPE_SYNC) {
+		if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+		    get_endpoint(alts, 1)->bRefresh >= 1 &&
+		    get_endpoint(alts, 1)->bRefresh <= 9)
+			ep->syncinterval = get_endpoint(alts, 1)->bRefresh;
+		else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
+			ep->syncinterval = 1;
+		else if (get_endpoint(alts, 1)->bInterval >= 1 &&
+			 get_endpoint(alts, 1)->bInterval <= 16)
+			ep->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
+		else
+			ep->syncinterval = 3;
+
+		ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);
+	}
+
+	list_add_tail(&ep->list, &chip->ep_list);
+
+__exit_unlock:
+	mutex_unlock(&chip->mutex);
+
+	return ep;
+}
+
+/*
+ *  wait until all urbs are processed.
+ */
+static int wait_clear_urbs(struct snd_usb_endpoint *ep)
+{
+	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
+	int alive;
+
+	do {
+		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
+		if (!alive)
+			break;
+
+		schedule_timeout_uninterruptible(1);
+	} while (time_before(jiffies, end_time));
+
+	if (alive)
+		usb_audio_err(ep->chip,
+			"timeout: still %d active urbs on EP #%x\n",
+			alive, ep->ep_num);
+	clear_bit(EP_FLAG_STOPPING, &ep->flags);
+
+	ep->data_subs = NULL;
+	ep->sync_slave = NULL;
+	ep->retire_data_urb = NULL;
+	ep->prepare_data_urb = NULL;
+
+	return 0;
+}
+
+/* sync the pending stop operation;
+ * this function itself doesn't trigger the stop operation
+ */
+void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
+{
+	if (ep && test_bit(EP_FLAG_STOPPING, &ep->flags))
+		wait_clear_urbs(ep);
+}
+
+/*
+ * unlink active urbs.
+ */
+static int deactivate_urbs(struct snd_usb_endpoint *ep, bool force)
+{
+	unsigned int i;
+
+	if (!force && atomic_read(&ep->chip->shutdown)) /* to be sure... */
+		return -EBADFD;
+
+	clear_bit(EP_FLAG_RUNNING, &ep->flags);
+
+	INIT_LIST_HEAD(&ep->ready_playback_urbs);
+	ep->next_packet_read_pos = 0;
+	ep->next_packet_write_pos = 0;
+
+	for (i = 0; i < ep->nurbs; i++) {
+		if (test_bit(i, &ep->active_mask)) {
+			if (!test_and_set_bit(i, &ep->unlink_mask)) {
+				struct urb *u = ep->urb[i].urb;
+				usb_unlink_urb(u);
+			}
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * release an endpoint's urbs
+ */
+static void release_urbs(struct snd_usb_endpoint *ep, int force)
+{
+	int i;
+
+	/* route incoming urbs to nirvana */
+	ep->retire_data_urb = NULL;
+	ep->prepare_data_urb = NULL;
+
+	/* stop urbs */
+	deactivate_urbs(ep, force);
+	wait_clear_urbs(ep);
+
+	for (i = 0; i < ep->nurbs; i++)
+		release_urb_ctx(&ep->urb[i]);
+
+	if (ep->syncbuf)
+		usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
+				  ep->syncbuf, ep->sync_dma);
+
+	ep->syncbuf = NULL;
+	ep->nurbs = 0;
+}
+
+/*
+ * configure a data endpoint
+ */
+static int data_ep_set_params(struct snd_usb_endpoint *ep,
+			      snd_pcm_format_t pcm_format,
+			      unsigned int channels,
+			      unsigned int period_bytes,
+			      unsigned int frames_per_period,
+			      unsigned int periods_per_buffer,
+			      struct audioformat *fmt,
+			      struct snd_usb_endpoint *sync_ep)
+{
+	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
+	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
+	unsigned int max_urbs, i;
+	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
+	int tx_length_quirk = (ep->chip->tx_length_quirk &&
+			       usb_pipeout(ep->pipe));
+
+	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
+		/*
+		 * When operating in DSD DOP mode, the size of a sample frame
+		 * in hardware differs from the actual physical format width
+		 * because we need to make room for the DOP markers.
+		 */
+		frame_bits += channels << 3;
+	}
+
+	ep->datainterval = fmt->datainterval;
+	ep->stride = frame_bits >> 3;
+
+	switch (pcm_format) {
+	case SNDRV_PCM_FORMAT_U8:
+		ep->silence_value = 0x80;
+		break;
+	case SNDRV_PCM_FORMAT_DSD_U8:
+	case SNDRV_PCM_FORMAT_DSD_U16_LE:
+	case SNDRV_PCM_FORMAT_DSD_U32_LE:
+	case SNDRV_PCM_FORMAT_DSD_U16_BE:
+	case SNDRV_PCM_FORMAT_DSD_U32_BE:
+		ep->silence_value = 0x69;
+		break;
+	default:
+		ep->silence_value = 0;
+	}
+
+	/* assume max. frequency is 50% higher than nominal */
+	ep->freqmax = ep->freqn + (ep->freqn >> 1);
+	/* Round up freqmax to nearest integer in order to calculate maximum
+	 * packet size, which must represent a whole number of frames.
+	 * This is accomplished by adding 0x0.ffff before converting the
+	 * Q16.16 format into integer.
+	 * In order to accurately calculate the maximum packet size when
+	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
+	 * multiply by the data interval prior to rounding. For instance,
+	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
+	 * frames with a data interval of 1, but 11 (10.25) frames with a
+	 * data interval of 2.
+	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
+	 * maximum datainterval value of 3, at USB full speed, higher for
+	 * USB high speed, noting that ep->freqmax is in units of
+	 * frames per packet in Q16.16 format.)
+	 */
+	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
+			 (frame_bits >> 3);
+	if (tx_length_quirk)
+		maxsize += sizeof(__le32); /* Space for length descriptor */
+	/* but wMaxPacketSize might reduce this */
+	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
+		/* whatever fits into a max. size packet */
+		unsigned int data_maxsize = maxsize = ep->maxpacksize;
+
+		if (tx_length_quirk)
+			/* Need to remove the length descriptor to calc freq */
+			data_maxsize -= sizeof(__le32);
+		ep->freqmax = (data_maxsize / (frame_bits >> 3))
+				<< (16 - ep->datainterval);
+	}
+
+	if (ep->fill_max)
+		ep->curpacksize = ep->maxpacksize;
+	else
+		ep->curpacksize = maxsize;
+
+	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
+		packs_per_ms = 8 >> ep->datainterval;
+		max_packs_per_urb = MAX_PACKS_HS;
+	} else {
+		packs_per_ms = 1;
+		max_packs_per_urb = MAX_PACKS;
+	}
+	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
+		max_packs_per_urb = min(max_packs_per_urb,
+					1U << sync_ep->syncinterval);
+	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
+
+	/*
+	 * Capture endpoints need to use small URBs because there's no way
+	 * to tell in advance where the next period will end, and we don't
+	 * want the next URB to complete much after the period ends.
+	 *
+	 * Playback endpoints with implicit sync much use the same parameters
+	 * as their corresponding capture endpoint.
+	 */
+	if (usb_pipein(ep->pipe) ||
+			snd_usb_endpoint_implicit_feedback_sink(ep)) {
+
+		urb_packs = packs_per_ms;
+		/*
+		 * Wireless devices can poll at a max rate of once per 4ms.
+		 * For dataintervals less than 5, increase the packet count to
+		 * allow the host controller to use bursting to fill in the
+		 * gaps.
+		 */
+		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
+			int interval = ep->datainterval;
+			while (interval < 5) {
+				urb_packs <<= 1;
+				++interval;
+			}
+		}
+		/* make capture URBs <= 1 ms and smaller than a period */
+		urb_packs = min(max_packs_per_urb, urb_packs);
+		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
+			urb_packs >>= 1;
+		ep->nurbs = MAX_URBS;
+
+	/*
+	 * Playback endpoints without implicit sync are adjusted so that
+	 * a period fits as evenly as possible in the smallest number of
+	 * URBs.  The total number of URBs is adjusted to the size of the
+	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
+	 */
+	} else {
+		/* determine how small a packet can be */
+		minsize = (ep->freqn >> (16 - ep->datainterval)) *
+				(frame_bits >> 3);
+		/* with sync from device, assume it can be 12% lower */
+		if (sync_ep)
+			minsize -= minsize >> 3;
+		minsize = max(minsize, 1u);
+
+		/* how many packets will contain an entire ALSA period? */
+		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
+
+		/* how many URBs will contain a period? */
+		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
+				max_packs_per_urb);
+		/* how many packets are needed in each URB? */
+		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
+
+		/* limit the number of frames in a single URB */
+		ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
+					urbs_per_period);
+
+		/* try to use enough URBs to contain an entire ALSA buffer */
+		max_urbs = min((unsigned) MAX_URBS,
+				MAX_QUEUE * packs_per_ms / urb_packs);
+		ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
+	}
+
+	/* allocate and initialize data urbs */
+	for (i = 0; i < ep->nurbs; i++) {
+		struct snd_urb_ctx *u = &ep->urb[i];
+		u->index = i;
+		u->ep = ep;
+		u->packets = urb_packs;
+		u->buffer_size = maxsize * u->packets;
+
+		if (fmt->fmt_type == UAC_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_alloc_coherent(ep->chip->dev, u->buffer_size,
+					   GFP_KERNEL, &u->urb->transfer_dma);
+		if (!u->urb->transfer_buffer)
+			goto out_of_memory;
+		u->urb->pipe = ep->pipe;
+		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
+		u->urb->interval = 1 << ep->datainterval;
+		u->urb->context = u;
+		u->urb->complete = snd_complete_urb;
+		INIT_LIST_HEAD(&u->ready_list);
+	}
+
+	return 0;
+
+out_of_memory:
+	release_urbs(ep, 0);
+	return -ENOMEM;
+}
+
+/*
+ * configure a sync endpoint
+ */
+static int sync_ep_set_params(struct snd_usb_endpoint *ep)
+{
+	int i;
+
+	ep->syncbuf = usb_alloc_coherent(ep->chip->dev, SYNC_URBS * 4,
+					 GFP_KERNEL, &ep->sync_dma);
+	if (!ep->syncbuf)
+		return -ENOMEM;
+
+	for (i = 0; i < SYNC_URBS; i++) {
+		struct snd_urb_ctx *u = &ep->urb[i];
+		u->index = i;
+		u->ep = ep;
+		u->packets = 1;
+		u->urb = usb_alloc_urb(1, GFP_KERNEL);
+		if (!u->urb)
+			goto out_of_memory;
+		u->urb->transfer_buffer = ep->syncbuf + i * 4;
+		u->urb->transfer_dma = ep->sync_dma + i * 4;
+		u->urb->transfer_buffer_length = 4;
+		u->urb->pipe = ep->pipe;
+		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
+		u->urb->number_of_packets = 1;
+		u->urb->interval = 1 << ep->syncinterval;
+		u->urb->context = u;
+		u->urb->complete = snd_complete_urb;
+	}
+
+	ep->nurbs = SYNC_URBS;
+
+	return 0;
+
+out_of_memory:
+	release_urbs(ep, 0);
+	return -ENOMEM;
+}
+
+/**
+ * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
+ *
+ * @ep: the snd_usb_endpoint to configure
+ * @pcm_format: the audio fomat.
+ * @channels: the number of audio channels.
+ * @period_bytes: the number of bytes in one alsa period.
+ * @period_frames: the number of frames in one alsa period.
+ * @buffer_periods: the number of periods in one alsa buffer.
+ * @rate: the frame rate.
+ * @fmt: the USB audio format information
+ * @sync_ep: the sync endpoint to use, if any
+ *
+ * Determine the number of URBs to be used on this endpoint.
+ * An endpoint must be configured before it can be started.
+ * An endpoint that is already running can not be reconfigured.
+ */
+int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
+				snd_pcm_format_t pcm_format,
+				unsigned int channels,
+				unsigned int period_bytes,
+				unsigned int period_frames,
+				unsigned int buffer_periods,
+				unsigned int rate,
+				struct audioformat *fmt,
+				struct snd_usb_endpoint *sync_ep)
+{
+	int err;
+
+	if (ep->use_count != 0) {
+		usb_audio_warn(ep->chip,
+			 "Unable to change format on ep #%x: already in use\n",
+			 ep->ep_num);
+		return -EBUSY;
+	}
+
+	/* release old buffers, if any */
+	release_urbs(ep, 0);
+
+	ep->datainterval = fmt->datainterval;
+	ep->maxpacksize = fmt->maxpacksize;
+	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
+
+	if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_FULL)
+		ep->freqn = get_usb_full_speed_rate(rate);
+	else
+		ep->freqn = get_usb_high_speed_rate(rate);
+
+	/* calculate the frequency in 16.16 format */
+	ep->freqm = ep->freqn;
+	ep->freqshift = INT_MIN;
+
+	ep->phase = 0;
+
+	switch (ep->type) {
+	case  SND_USB_ENDPOINT_TYPE_DATA:
+		err = data_ep_set_params(ep, pcm_format, channels,
+					 period_bytes, period_frames,
+					 buffer_periods, fmt, sync_ep);
+		break;
+	case  SND_USB_ENDPOINT_TYPE_SYNC:
+		err = sync_ep_set_params(ep);
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	usb_audio_dbg(ep->chip,
+		"Setting params for ep #%x (type %d, %d urbs), ret=%d\n",
+		ep->ep_num, ep->type, ep->nurbs, err);
+
+	return err;
+}
+
+/**
+ * snd_usb_endpoint_start: start an snd_usb_endpoint
+ *
+ * @ep: the endpoint to start
+ *
+ * A call to this function will increment the use count of the endpoint.
+ * In case it is not already running, the URBs for this endpoint will be
+ * submitted. Otherwise, this function does nothing.
+ *
+ * Must be balanced to calls of snd_usb_endpoint_stop().
+ *
+ * Returns an error if the URB submission failed, 0 in all other cases.
+ */
+int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
+{
+	int err;
+	unsigned int i;
+
+	if (atomic_read(&ep->chip->shutdown))
+		return -EBADFD;
+
+	/* already running? */
+	if (++ep->use_count != 1)
+		return 0;
+
+	/* just to be sure */
+	deactivate_urbs(ep, false);
+
+	ep->active_mask = 0;
+	ep->unlink_mask = 0;
+	ep->phase = 0;
+
+	snd_usb_endpoint_start_quirk(ep);
+
+	/*
+	 * If this endpoint has a data endpoint as implicit feedback source,
+	 * don't start the urbs here. Instead, mark them all as available,
+	 * wait for the record urbs to return and queue the playback urbs
+	 * from that context.
+	 */
+
+	set_bit(EP_FLAG_RUNNING, &ep->flags);
+
+	if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
+		for (i = 0; i < ep->nurbs; i++) {
+			struct snd_urb_ctx *ctx = ep->urb + i;
+			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
+		}
+
+		return 0;
+	}
+
+	for (i = 0; i < ep->nurbs; i++) {
+		struct urb *urb = ep->urb[i].urb;
+
+		if (snd_BUG_ON(!urb))
+			goto __error;
+
+		if (usb_pipeout(ep->pipe)) {
+			prepare_outbound_urb(ep, urb->context);
+		} else {
+			prepare_inbound_urb(ep, urb->context);
+		}
+
+		err = usb_submit_urb(urb, GFP_ATOMIC);
+		if (err < 0) {
+			usb_audio_err(ep->chip,
+				"cannot submit urb %d, error %d: %s\n",
+				i, err, usb_error_string(err));
+			goto __error;
+		}
+		set_bit(i, &ep->active_mask);
+	}
+
+	return 0;
+
+__error:
+	clear_bit(EP_FLAG_RUNNING, &ep->flags);
+	ep->use_count--;
+	deactivate_urbs(ep, false);
+	return -EPIPE;
+}
+
+/**
+ * snd_usb_endpoint_stop: stop an snd_usb_endpoint
+ *
+ * @ep: the endpoint to stop (may be NULL)
+ *
+ * A call to this function will decrement the use count of the endpoint.
+ * In case the last user has requested the endpoint stop, the URBs will
+ * actually be deactivated.
+ *
+ * Must be balanced to calls of snd_usb_endpoint_start().
+ *
+ * The caller needs to synchronize the pending stop operation via
+ * snd_usb_endpoint_sync_pending_stop().
+ */
+void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep)
+{
+	if (!ep)
+		return;
+
+	if (snd_BUG_ON(ep->use_count == 0))
+		return;
+
+	if (--ep->use_count == 0) {
+		deactivate_urbs(ep, false);
+		set_bit(EP_FLAG_STOPPING, &ep->flags);
+	}
+}
+
+/**
+ * snd_usb_endpoint_deactivate: deactivate an snd_usb_endpoint
+ *
+ * @ep: the endpoint to deactivate
+ *
+ * If the endpoint is not currently in use, this functions will
+ * deactivate its associated URBs.
+ *
+ * In case of any active users, this functions does nothing.
+ */
+void snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep)
+{
+	if (!ep)
+		return;
+
+	if (ep->use_count != 0)
+		return;
+
+	deactivate_urbs(ep, true);
+	wait_clear_urbs(ep);
+}
+
+/**
+ * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
+ *
+ * @ep: the endpoint to release
+ *
+ * This function does not care for the endpoint's use count but will tear
+ * down all the streaming URBs immediately.
+ */
+void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
+{
+	release_urbs(ep, 1);
+}
+
+/**
+ * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
+ *
+ * @ep: the endpoint to free
+ *
+ * This free all resources of the given ep.
+ */
+void snd_usb_endpoint_free(struct snd_usb_endpoint *ep)
+{
+	kfree(ep);
+}
+
+/**
+ * snd_usb_handle_sync_urb: parse an USB sync packet
+ *
+ * @ep: the endpoint to handle the packet
+ * @sender: the sending endpoint
+ * @urb: the received packet
+ *
+ * This function is called from the context of an endpoint that received
+ * the packet and is used to let another endpoint object handle the payload.
+ */
+void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
+			     struct snd_usb_endpoint *sender,
+			     const struct urb *urb)
+{
+	int shift;
+	unsigned int f;
+	unsigned long flags;
+
+	snd_BUG_ON(ep == sender);
+
+	/*
+	 * In case the endpoint is operating in implicit feedback mode, prepare
+	 * a new outbound URB that has the same layout as the received packet
+	 * and add it to the list of pending urbs. queue_pending_output_urbs()
+	 * will take care of them later.
+	 */
+	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
+	    ep->use_count != 0) {
+
+		/* implicit feedback case */
+		int i, bytes = 0;
+		struct snd_urb_ctx *in_ctx;
+		struct snd_usb_packet_info *out_packet;
+
+		in_ctx = urb->context;
+
+		/* Count overall packet size */
+		for (i = 0; i < in_ctx->packets; i++)
+			if (urb->iso_frame_desc[i].status == 0)
+				bytes += urb->iso_frame_desc[i].actual_length;
+
+		/*
+		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
+		 * streaming once it received a 0-byte OUT URB
+		 */
+		if (bytes == 0)
+			return;
+
+		spin_lock_irqsave(&ep->lock, flags);
+		out_packet = ep->next_packet + ep->next_packet_write_pos;
+
+		/*
+		 * Iterate through the inbound packet and prepare the lengths
+		 * for the output packet. The OUT packet we are about to send
+		 * will have the same amount of payload bytes per stride as the
+		 * IN packet we just received. Since the actual size is scaled
+		 * by the stride, use the sender stride to calculate the length
+		 * in case the number of channels differ between the implicitly
+		 * fed-back endpoint and the synchronizing endpoint.
+		 */
+
+		out_packet->packets = in_ctx->packets;
+		for (i = 0; i < in_ctx->packets; i++) {
+			if (urb->iso_frame_desc[i].status == 0)
+				out_packet->packet_size[i] =
+					urb->iso_frame_desc[i].actual_length / sender->stride;
+			else
+				out_packet->packet_size[i] = 0;
+		}
+
+		ep->next_packet_write_pos++;
+		ep->next_packet_write_pos %= MAX_URBS;
+		spin_unlock_irqrestore(&ep->lock, flags);
+		queue_pending_output_urbs(ep);
+
+		return;
+	}
+
+	/*
+	 * process after playback sync complete
+	 *
+	 * Full speed devices report feedback values in 10.14 format as samples
+	 * per frame, high speed devices in 16.16 format as samples per
+	 * microframe.
+	 *
+	 * Because the Audio Class 1 spec was written before USB 2.0, many high
+	 * speed devices use a wrong interpretation, some others use an
+	 * entirely different format.
+	 *
+	 * Therefore, we cannot predict what format any particular device uses
+	 * and must detect it automatically.
+	 */
+
+	if (urb->iso_frame_desc[0].status != 0 ||
+	    urb->iso_frame_desc[0].actual_length < 3)
+		return;
+
+	f = le32_to_cpup(urb->transfer_buffer);
+	if (urb->iso_frame_desc[0].actual_length == 3)
+		f &= 0x00ffffff;
+	else
+		f &= 0x0fffffff;
+
+	if (f == 0)
+		return;
+
+	if (unlikely(sender->tenor_fb_quirk)) {
+		/*
+		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
+		 * and others) sometimes change the feedback value
+		 * by +/- 0x1.0000.
+		 */
+		if (f < ep->freqn - 0x8000)
+			f += 0xf000;
+		else if (f > ep->freqn + 0x8000)
+			f -= 0xf000;
+	} else if (unlikely(ep->freqshift == INT_MIN)) {
+		/*
+		 * The first time we see a feedback value, determine its format
+		 * by shifting it left or right until it matches the nominal
+		 * frequency value.  This assumes that the feedback does not
+		 * differ from the nominal value more than +50% or -25%.
+		 */
+		shift = 0;
+		while (f < ep->freqn - ep->freqn / 4) {
+			f <<= 1;
+			shift++;
+		}
+		while (f > ep->freqn + ep->freqn / 2) {
+			f >>= 1;
+			shift--;
+		}
+		ep->freqshift = shift;
+	} else if (ep->freqshift >= 0)
+		f <<= ep->freqshift;
+	else
+		f >>= -ep->freqshift;
+
+	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
+		/*
+		 * If the frequency looks valid, set it.
+		 * This value is referred to in prepare_playback_urb().
+		 */
+		spin_lock_irqsave(&ep->lock, flags);
+		ep->freqm = f;
+		spin_unlock_irqrestore(&ep->lock, flags);
+	} else {
+		/*
+		 * Out of range; maybe the shift value is wrong.
+		 * Reset it so that we autodetect again the next time.
+		 */
+		ep->freqshift = INT_MIN;
+	}
+}
+