sound/usb/clock.c - third_party/linux - Git at Google

 /*
  *   Clock domain and sample rate management functions
  *
  *   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/bitops.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/usb.h>
 #include <linux/usb/audio.h>
 #include <linux/usb/audio-v2.h>
 #include <linux/usb/audio-v3.h>

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

 #include "usbaudio.h"
 #include "card.h"
 #include "helper.h"
 #include "clock.h"
 #include "quirks.h"

 static void *find_uac_clock_desc(struct usb_host_interface *iface, int id,
 				 bool (*validator)(void *, int), u8 type)
 {
 	void *cs = NULL;

 	while ((cs = snd_usb_find_csint_desc(iface->extra, iface->extralen,
 					     cs, type))) {
 		if (validator(cs, id))
 			return cs;
 	}

 	return NULL;
 }

 static bool validate_clock_source_v2(void *p, int id)
 {
 	struct uac_clock_source_descriptor *cs = p;
 	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
 }

 static bool validate_clock_source_v3(void *p, int id)
 {
 	struct uac3_clock_source_descriptor *cs = p;
 	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
 }

 static bool validate_clock_selector_v2(void *p, int id)
 {
 	struct uac_clock_selector_descriptor *cs = p;
 	return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
 		cs->bLength == 7 + cs->bNrInPins;
 }

 static bool validate_clock_selector_v3(void *p, int id)
 {
 	struct uac3_clock_selector_descriptor *cs = p;
 	return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
 		cs->bLength == 11 + cs->bNrInPins;
 }

 static bool validate_clock_multiplier_v2(void *p, int id)
 {
 	struct uac_clock_multiplier_descriptor *cs = p;
 	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
 }

 static bool validate_clock_multiplier_v3(void *p, int id)
 {
 	struct uac3_clock_multiplier_descriptor *cs = p;
 	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
 }

 #define DEFINE_FIND_HELPER(name, obj, validator, type)		\
 static obj *name(struct usb_host_interface *iface, int id)	\
 {								\
 	return find_uac_clock_desc(iface, id, validator, type);	\
 }

 DEFINE_FIND_HELPER(snd_usb_find_clock_source,
 		   struct uac_clock_source_descriptor,
 		   validate_clock_source_v2, UAC2_CLOCK_SOURCE);
 DEFINE_FIND_HELPER(snd_usb_find_clock_source_v3,
 		   struct uac3_clock_source_descriptor,
 		   validate_clock_source_v3, UAC3_CLOCK_SOURCE);

 DEFINE_FIND_HELPER(snd_usb_find_clock_selector,
 		   struct uac_clock_selector_descriptor,
 		   validate_clock_selector_v2, UAC2_CLOCK_SELECTOR);
 DEFINE_FIND_HELPER(snd_usb_find_clock_selector_v3,
 		   struct uac3_clock_selector_descriptor,
 		   validate_clock_selector_v3, UAC3_CLOCK_SELECTOR);

 DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier,
 		   struct uac_clock_multiplier_descriptor,
 		   validate_clock_multiplier_v2, UAC2_CLOCK_MULTIPLIER);
 DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier_v3,
 		   struct uac3_clock_multiplier_descriptor,
 		   validate_clock_multiplier_v3, UAC3_CLOCK_MULTIPLIER);

 static int uac_clock_selector_get_val(struct snd_usb_audio *chip, int selector_id)
 {
 	unsigned char buf;
 	int ret;

 	ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0),
 			      UAC2_CS_CUR,
 			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 			      UAC2_CX_CLOCK_SELECTOR << 8,
 			      snd_usb_ctrl_intf(chip) | (selector_id << 8),
 			      &buf, sizeof(buf));

 	if (ret < 0)
 		return ret;

 	return buf;
 }

 static int uac_clock_selector_set_val(struct snd_usb_audio *chip, int selector_id,
 					unsigned char pin)
 {
 	int ret;

 	ret = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->dev, 0),
 			      UAC2_CS_CUR,
 			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
 			      UAC2_CX_CLOCK_SELECTOR << 8,
 			      snd_usb_ctrl_intf(chip) | (selector_id << 8),
 			      &pin, sizeof(pin));
 	if (ret < 0)
 		return ret;

 	if (ret != sizeof(pin)) {
 		usb_audio_err(chip,
 			"setting selector (id %d) unexpected length %d\n",
 			selector_id, ret);
 		return -EINVAL;
 	}

 	ret = uac_clock_selector_get_val(chip, selector_id);
 	if (ret < 0)
 		return ret;

 	if (ret != pin) {
 		usb_audio_err(chip,
 			"setting selector (id %d) to %x failed (current: %d)\n",
 			selector_id, pin, ret);
 		return -EINVAL;
 	}

 	return ret;
 }

 static bool uac_clock_source_is_valid(struct snd_usb_audio *chip,
 				      int protocol,
 				      int source_id)
 {
 	int err;
 	unsigned char data;
 	struct usb_device *dev = chip->dev;
 	u32 bmControls;

 	if (protocol == UAC_VERSION_3) {
 		struct uac3_clock_source_descriptor *cs_desc =
 			snd_usb_find_clock_source_v3(chip->ctrl_intf, source_id);

 		if (!cs_desc)
 			return 0;
 		bmControls = le32_to_cpu(cs_desc->bmControls);
 	} else { /* UAC_VERSION_1/2 */
 		struct uac_clock_source_descriptor *cs_desc =
 			snd_usb_find_clock_source(chip->ctrl_intf, source_id);

 		if (!cs_desc)
 			return 0;
 		bmControls = cs_desc->bmControls;
 	}

 	/* If a clock source can't tell us whether it's valid, we assume it is */
 	if (!uac_v2v3_control_is_readable(bmControls,
 				      UAC2_CS_CONTROL_CLOCK_VALID))
 		return 1;

 	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
 			      USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
 			      UAC2_CS_CONTROL_CLOCK_VALID << 8,
 			      snd_usb_ctrl_intf(chip) | (source_id << 8),
 			      &data, sizeof(data));

 	if (err < 0) {
 		dev_warn(&dev->dev,
 			 "%s(): cannot get clock validity for id %d\n",
 			   __func__, source_id);
 		return 0;
 	}

 	return !!data;
 }

 static int __uac_clock_find_source(struct snd_usb_audio *chip, int entity_id,
 				   unsigned long *visited, bool validate)
 {
 	struct uac_clock_source_descriptor *source;
 	struct uac_clock_selector_descriptor *selector;
 	struct uac_clock_multiplier_descriptor *multiplier;

 	entity_id &= 0xff;

 	if (test_and_set_bit(entity_id, visited)) {
 		usb_audio_warn(chip,
 			 "%s(): recursive clock topology detected, id %d.\n",
 			 __func__, entity_id);
 		return -EINVAL;
 	}

 	/* first, see if the ID we're looking for is a clock source already */
 	source = snd_usb_find_clock_source(chip->ctrl_intf, entity_id);
 	if (source) {
 		entity_id = source->bClockID;
 		if (validate && !uac_clock_source_is_valid(chip, UAC_VERSION_2,
 								entity_id)) {
 			usb_audio_err(chip,
 				"clock source %d is not valid, cannot use\n",
 				entity_id);
 			return -ENXIO;
 		}
 		return entity_id;
 	}

 	selector = snd_usb_find_clock_selector(chip->ctrl_intf, entity_id);
 	if (selector) {
 		int ret, i, cur;

 		/* the entity ID we are looking for is a selector.
 		 * find out what it currently selects */
 		ret = uac_clock_selector_get_val(chip, selector->bClockID);
 		if (ret < 0)
 			return ret;

 		/* Selector values are one-based */

 		if (ret > selector->bNrInPins || ret < 1) {
 			usb_audio_err(chip,
 				"%s(): selector reported illegal value, id %d, ret %d\n",
 				__func__, selector->bClockID, ret);

 			return -EINVAL;
 		}

 		cur = ret;
 		ret = __uac_clock_find_source(chip, selector->baCSourceID[ret - 1],
 					       visited, validate);
 		if (!validate || ret > 0 || !chip->autoclock)
 			return ret;

 		/* The current clock source is invalid, try others. */
 		for (i = 1; i <= selector->bNrInPins; i++) {
 			int err;

 			if (i == cur)
 				continue;

 			ret = __uac_clock_find_source(chip, selector->baCSourceID[i - 1],
 				visited, true);
 			if (ret < 0)
 				continue;

 			err = uac_clock_selector_set_val(chip, entity_id, i);
 			if (err < 0)
 				continue;

 			usb_audio_info(chip,
 				 "found and selected valid clock source %d\n",
 				 ret);
 			return ret;
 		}

 		return -ENXIO;
 	}

 	/* FIXME: multipliers only act as pass-thru element for now */
 	multiplier = snd_usb_find_clock_multiplier(chip->ctrl_intf, entity_id);
 	if (multiplier)
 		return __uac_clock_find_source(chip, multiplier->bCSourceID,
 						visited, validate);

 	return -EINVAL;
 }

 static int __uac3_clock_find_source(struct snd_usb_audio *chip, int entity_id,
 				   unsigned long *visited, bool validate)
 {
 	struct uac3_clock_source_descriptor *source;
 	struct uac3_clock_selector_descriptor *selector;
 	struct uac3_clock_multiplier_descriptor *multiplier;

 	entity_id &= 0xff;

 	if (test_and_set_bit(entity_id, visited)) {
 		usb_audio_warn(chip,
 			 "%s(): recursive clock topology detected, id %d.\n",
 			 __func__, entity_id);
 		return -EINVAL;
 	}

 	/* first, see if the ID we're looking for is a clock source already */
 	source = snd_usb_find_clock_source_v3(chip->ctrl_intf, entity_id);
 	if (source) {
 		entity_id = source->bClockID;
 		if (validate && !uac_clock_source_is_valid(chip, UAC_VERSION_3,
 								entity_id)) {
 			usb_audio_err(chip,
 				"clock source %d is not valid, cannot use\n",
 				entity_id);
 			return -ENXIO;
 		}
 		return entity_id;
 	}

 	selector = snd_usb_find_clock_selector_v3(chip->ctrl_intf, entity_id);
 	if (selector) {
 		int ret, i, cur;

 		/* the entity ID we are looking for is a selector.
 		 * find out what it currently selects */
 		ret = uac_clock_selector_get_val(chip, selector->bClockID);
 		if (ret < 0)
 			return ret;

 		/* Selector values are one-based */

 		if (ret > selector->bNrInPins || ret < 1) {
 			usb_audio_err(chip,
 				"%s(): selector reported illegal value, id %d, ret %d\n",
 				__func__, selector->bClockID, ret);

 			return -EINVAL;
 		}

 		cur = ret;
 		ret = __uac3_clock_find_source(chip, selector->baCSourceID[ret - 1],
 					       visited, validate);
 		if (!validate || ret > 0 || !chip->autoclock)
 			return ret;

 		/* The current clock source is invalid, try others. */
 		for (i = 1; i <= selector->bNrInPins; i++) {
 			int err;

 			if (i == cur)
 				continue;

 			ret = __uac3_clock_find_source(chip, selector->baCSourceID[i - 1],
 				visited, true);
 			if (ret < 0)
 				continue;

 			err = uac_clock_selector_set_val(chip, entity_id, i);
 			if (err < 0)
 				continue;

 			usb_audio_info(chip,
 				 "found and selected valid clock source %d\n",
 				 ret);
 			return ret;
 		}

 		return -ENXIO;
 	}

 	/* FIXME: multipliers only act as pass-thru element for now */
 	multiplier = snd_usb_find_clock_multiplier_v3(chip->ctrl_intf,
 						      entity_id);
 	if (multiplier)
 		return __uac3_clock_find_source(chip, multiplier->bCSourceID,
 						visited, validate);

 	return -EINVAL;
 }

 /*
  * For all kinds of sample rate settings and other device queries,
  * the clock source (end-leaf) must be used. However, clock selectors,
  * clock multipliers and sample rate converters may be specified as
  * clock source input to terminal. This functions walks the clock path
  * to its end and tries to find the source.
  *
  * The 'visited' bitfield is used internally to detect recursive loops.
  *
  * Returns the clock source UnitID (>=0) on success, or an error.
  */
 int snd_usb_clock_find_source(struct snd_usb_audio *chip, int protocol,
 			      int entity_id, bool validate)
 {
 	DECLARE_BITMAP(visited, 256);
 	memset(visited, 0, sizeof(visited));

 	switch (protocol) {
 	case UAC_VERSION_2:
 		return __uac_clock_find_source(chip, entity_id, visited,
 					       validate);
 	case UAC_VERSION_3:
 		return __uac3_clock_find_source(chip, entity_id, visited,
 					       validate);
 	default:
 		return -EINVAL;
 	}
 }

 static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
 			      struct usb_host_interface *alts,
 			      struct audioformat *fmt, int rate)
 {
 	struct usb_device *dev = chip->dev;
 	unsigned int ep;
 	unsigned char data[3];
 	int err, crate;

 	if (get_iface_desc(alts)->bNumEndpoints < 1)
 		return -EINVAL;
 	ep = get_endpoint(alts, 0)->bEndpointAddress;

 	/* if endpoint doesn't have sampling rate control, bail out */
 	if (!(fmt->attributes & UAC_EP_CS_ATTR_SAMPLE_RATE))
 		return 0;

 	data[0] = rate;
 	data[1] = rate >> 8;
 	data[2] = rate >> 16;
 	err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
 			      USB_TYPE_CLASS | USB_RECIP_ENDPOINT | USB_DIR_OUT,
 			      UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
 			      data, sizeof(data));
 	if (err < 0) {
 		dev_err(&dev->dev, "%d:%d: cannot set freq %d to ep %#x\n",
 			iface, fmt->altsetting, rate, ep);
 		return err;
 	}

 	/* Don't check the sample rate for devices which we know don't
 	 * support reading */
 	if (snd_usb_get_sample_rate_quirk(chip))
 		return 0;
 	/* the firmware is likely buggy, don't repeat to fail too many times */
 	if (chip->sample_rate_read_error > 2)
 		return 0;

 	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC_GET_CUR,
 			      USB_TYPE_CLASS | USB_RECIP_ENDPOINT | USB_DIR_IN,
 			      UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
 			      data, sizeof(data));
 	if (err < 0) {
 		dev_err(&dev->dev, "%d:%d: cannot get freq at ep %#x\n",
 			iface, fmt->altsetting, ep);
 		chip->sample_rate_read_error++;
 		return 0; /* some devices don't support reading */
 	}

 	crate = data[0] | (data[1] << 8) | (data[2] << 16);
 	if (crate != rate) {
 		dev_warn(&dev->dev, "current rate %d is different from the runtime rate %d\n", crate, rate);
 		// runtime->rate = crate;
 	}

 	return 0;
 }

 static int get_sample_rate_v2v3(struct snd_usb_audio *chip, int iface,
 			      int altsetting, int clock)
 {
 	struct usb_device *dev = chip->dev;
 	__le32 data;
 	int err;

 	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
 			      USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
 			      UAC2_CS_CONTROL_SAM_FREQ << 8,
 			      snd_usb_ctrl_intf(chip) | (clock << 8),
 			      &data, sizeof(data));
 	if (err < 0) {
 		dev_warn(&dev->dev, "%d:%d: cannot get freq (v2/v3): err %d\n",
 			 iface, altsetting, err);
 		return 0;
 	}

 	return le32_to_cpu(data);
 }

 static int set_sample_rate_v2v3(struct snd_usb_audio *chip, int iface,
 			      struct usb_host_interface *alts,
 			      struct audioformat *fmt, int rate)
 {
 	struct usb_device *dev = chip->dev;
 	__le32 data;
 	int err, cur_rate, prev_rate;
 	int clock;
 	bool writeable;
 	u32 bmControls;

 	clock = snd_usb_clock_find_source(chip, fmt->protocol,
 					  fmt->clock, true);
 	if (clock < 0)
 		return clock;

 	prev_rate = get_sample_rate_v2v3(chip, iface, fmt->altsetting, clock);
 	if (prev_rate == rate)
 		return 0;

 	if (fmt->protocol == UAC_VERSION_3) {
 		struct uac3_clock_source_descriptor *cs_desc;

 		cs_desc = snd_usb_find_clock_source_v3(chip->ctrl_intf, clock);
 		bmControls = le32_to_cpu(cs_desc->bmControls);
 	} else {
 		struct uac_clock_source_descriptor *cs_desc;

 		cs_desc = snd_usb_find_clock_source(chip->ctrl_intf, clock);
 		bmControls = cs_desc->bmControls;
 	}

 	writeable = uac_v2v3_control_is_writeable(bmControls,
 						  UAC2_CS_CONTROL_SAM_FREQ);
 	if (writeable) {
 		data = cpu_to_le32(rate);
 		err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC2_CS_CUR,
 				      USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
 				      UAC2_CS_CONTROL_SAM_FREQ << 8,
 				      snd_usb_ctrl_intf(chip) | (clock << 8),
 				      &data, sizeof(data));
 		if (err < 0) {
 			usb_audio_err(chip,
 				"%d:%d: cannot set freq %d (v2/v3): err %d\n",
 				iface, fmt->altsetting, rate, err);
 			return err;
 		}

 		cur_rate = get_sample_rate_v2v3(chip, iface,
 						fmt->altsetting, clock);
 	} else {
 		cur_rate = prev_rate;
 	}

 	if (cur_rate != rate) {
 		if (!writeable) {
 			usb_audio_warn(chip,
 				 "%d:%d: freq mismatch (RO clock): req %d, clock runs @%d\n",
 				 iface, fmt->altsetting, rate, cur_rate);
 			return -ENXIO;
 		}
 		usb_audio_dbg(chip,
 			"current rate %d is different from the runtime rate %d\n",
 			cur_rate, rate);
 	}

 	/* Some devices doesn't respond to sample rate changes while the
 	 * interface is active. */
 	if (rate != prev_rate) {
 		usb_set_interface(dev, iface, 0);
 		snd_usb_set_interface_quirk(dev);
 		usb_set_interface(dev, iface, fmt->altsetting);
 		snd_usb_set_interface_quirk(dev);
 	}

 	return 0;
 }

 int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface,
 			     struct usb_host_interface *alts,
 			     struct audioformat *fmt, int rate)
 {
 	switch (fmt->protocol) {
 	case UAC_VERSION_1:
 	default:
 		return set_sample_rate_v1(chip, iface, alts, fmt, rate);

 	case UAC_VERSION_3:
 		if (chip->badd_profile >= UAC3_FUNCTION_SUBCLASS_GENERIC_IO) {
 			if (rate != UAC3_BADD_SAMPLING_RATE)
 				return -ENXIO;
 			else
 				return 0;
 		}
 	/* fall through */
 	case UAC_VERSION_2:
 		return set_sample_rate_v2v3(chip, iface, alts, fmt, rate);
 	}
 }
	/*
	* Clock domain and sample rate management functions
	*
	* 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/bitops.h>
	#include <linux/init.h>
	#include <linux/string.h>
	#include <linux/usb.h>
	#include <linux/usb/audio.h>
	#include <linux/usb/audio-v2.h>
	#include <linux/usb/audio-v3.h>

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

	#include "usbaudio.h"
	#include "card.h"
	#include "helper.h"
	#include "clock.h"
	#include "quirks.h"

	static void find_uac_clock_desc(struct usb_host_interface iface, int id,
	bool (validator)(void , int), u8 type)
	{
	void *cs = NULL;

	while ((cs = snd_usb_find_csint_desc(iface->extra, iface->extralen,
	cs, type))) {
	if (validator(cs, id))
	return cs;
	}

	return NULL;
	}

	static bool validate_clock_source_v2(void *p, int id)
	{
	struct uac_clock_source_descriptor *cs = p;
	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
	}

	static bool validate_clock_source_v3(void *p, int id)
	{
	struct uac3_clock_source_descriptor *cs = p;
	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
	}

	static bool validate_clock_selector_v2(void *p, int id)
	{
	struct uac_clock_selector_descriptor *cs = p;
	return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
	cs->bLength == 7 + cs->bNrInPins;
	}

	static bool validate_clock_selector_v3(void *p, int id)
	{
	struct uac3_clock_selector_descriptor *cs = p;
	return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
	cs->bLength == 11 + cs->bNrInPins;
	}

	static bool validate_clock_multiplier_v2(void *p, int id)
	{
	struct uac_clock_multiplier_descriptor *cs = p;
	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
	}

	static bool validate_clock_multiplier_v3(void *p, int id)
	{
	struct uac3_clock_multiplier_descriptor *cs = p;
	return cs->bLength == sizeof(*cs) && cs->bClockID == id;
	}

	#define DEFINE_FIND_HELPER(name, obj, validator, type) \
	static obj name(struct usb_host_interface iface, int id) \
	{ \
	return find_uac_clock_desc(iface, id, validator, type); \
	}

	DEFINE_FIND_HELPER(snd_usb_find_clock_source,
	struct uac_clock_source_descriptor,
	validate_clock_source_v2, UAC2_CLOCK_SOURCE);
	DEFINE_FIND_HELPER(snd_usb_find_clock_source_v3,
	struct uac3_clock_source_descriptor,
	validate_clock_source_v3, UAC3_CLOCK_SOURCE);

	DEFINE_FIND_HELPER(snd_usb_find_clock_selector,
	struct uac_clock_selector_descriptor,
	validate_clock_selector_v2, UAC2_CLOCK_SELECTOR);
	DEFINE_FIND_HELPER(snd_usb_find_clock_selector_v3,
	struct uac3_clock_selector_descriptor,
	validate_clock_selector_v3, UAC3_CLOCK_SELECTOR);

	DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier,
	struct uac_clock_multiplier_descriptor,
	validate_clock_multiplier_v2, UAC2_CLOCK_MULTIPLIER);
	DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier_v3,
	struct uac3_clock_multiplier_descriptor,
	validate_clock_multiplier_v3, UAC3_CLOCK_MULTIPLIER);

	static int uac_clock_selector_get_val(struct snd_usb_audio *chip, int selector_id)
	{
	unsigned char buf;
	int ret;

	ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0),
	UAC2_CS_CUR,
	USB_RECIP_INTERFACE \| USB_TYPE_CLASS \| USB_DIR_IN,
	UAC2_CX_CLOCK_SELECTOR << 8,
	snd_usb_ctrl_intf(chip) \| (selector_id << 8),
	&buf, sizeof(buf));

	if (ret < 0)
	return ret;

	return buf;
	}

	static int uac_clock_selector_set_val(struct snd_usb_audio *chip, int selector_id,
	unsigned char pin)
	{
	int ret;

	ret = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->dev, 0),
	UAC2_CS_CUR,
	USB_RECIP_INTERFACE \| USB_TYPE_CLASS \| USB_DIR_OUT,
	UAC2_CX_CLOCK_SELECTOR << 8,
	snd_usb_ctrl_intf(chip) \| (selector_id << 8),
	&pin, sizeof(pin));
	if (ret < 0)
	return ret;

	if (ret != sizeof(pin)) {
	usb_audio_err(chip,
	"setting selector (id %d) unexpected length %d\n",
	selector_id, ret);
	return -EINVAL;
	}

	ret = uac_clock_selector_get_val(chip, selector_id);
	if (ret < 0)
	return ret;

	if (ret != pin) {
	usb_audio_err(chip,
	"setting selector (id %d) to %x failed (current: %d)\n",
	selector_id, pin, ret);
	return -EINVAL;
	}

	return ret;
	}

	static bool uac_clock_source_is_valid(struct snd_usb_audio *chip,
	int protocol,
	int source_id)
	{
	int err;
	unsigned char data;
	struct usb_device *dev = chip->dev;
	u32 bmControls;

	if (protocol == UAC_VERSION_3) {
	struct uac3_clock_source_descriptor *cs_desc =
	snd_usb_find_clock_source_v3(chip->ctrl_intf, source_id);

	if (!cs_desc)
	return 0;
	bmControls = le32_to_cpu(cs_desc->bmControls);
	} else { /* UAC_VERSION_1/2 */
	struct uac_clock_source_descriptor *cs_desc =
	snd_usb_find_clock_source(chip->ctrl_intf, source_id);

	if (!cs_desc)
	return 0;
	bmControls = cs_desc->bmControls;
	}

	/* If a clock source can't tell us whether it's valid, we assume it is */
	if (!uac_v2v3_control_is_readable(bmControls,
	UAC2_CS_CONTROL_CLOCK_VALID))
	return 1;

	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
	USB_TYPE_CLASS \| USB_RECIP_INTERFACE \| USB_DIR_IN,
	UAC2_CS_CONTROL_CLOCK_VALID << 8,
	snd_usb_ctrl_intf(chip) \| (source_id << 8),
	&data, sizeof(data));

	if (err < 0) {
	dev_warn(&dev->dev,
	"%s(): cannot get clock validity for id %d\n",
	__func__, source_id);
	return 0;
	}

	return !!data;
	}

	static int __uac_clock_find_source(struct snd_usb_audio *chip, int entity_id,
	unsigned long *visited, bool validate)
	{
	struct uac_clock_source_descriptor *source;
	struct uac_clock_selector_descriptor *selector;
	struct uac_clock_multiplier_descriptor *multiplier;

	entity_id &= 0xff;

	if (test_and_set_bit(entity_id, visited)) {
	usb_audio_warn(chip,
	"%s(): recursive clock topology detected, id %d.\n",
	__func__, entity_id);
	return -EINVAL;
	}

	/* first, see if the ID we're looking for is a clock source already */
	source = snd_usb_find_clock_source(chip->ctrl_intf, entity_id);
	if (source) {
	entity_id = source->bClockID;
	if (validate && !uac_clock_source_is_valid(chip, UAC_VERSION_2,
	entity_id)) {
	usb_audio_err(chip,
	"clock source %d is not valid, cannot use\n",
	entity_id);
	return -ENXIO;
	}
	return entity_id;
	}

	selector = snd_usb_find_clock_selector(chip->ctrl_intf, entity_id);
	if (selector) {
	int ret, i, cur;

	/* the entity ID we are looking for is a selector.
	* find out what it currently selects */
	ret = uac_clock_selector_get_val(chip, selector->bClockID);
	if (ret < 0)
	return ret;

	/* Selector values are one-based */

	if (ret > selector->bNrInPins \|\| ret < 1) {
	usb_audio_err(chip,
	"%s(): selector reported illegal value, id %d, ret %d\n",
	__func__, selector->bClockID, ret);

	return -EINVAL;
	}

	cur = ret;
	ret = __uac_clock_find_source(chip, selector->baCSourceID[ret - 1],
	visited, validate);
	if (!validate \|\| ret > 0 \|\| !chip->autoclock)
	return ret;

	/* The current clock source is invalid, try others. */
	for (i = 1; i <= selector->bNrInPins; i++) {
	int err;

	if (i == cur)
	continue;

	ret = __uac_clock_find_source(chip, selector->baCSourceID[i - 1],
	visited, true);
	if (ret < 0)
	continue;

	err = uac_clock_selector_set_val(chip, entity_id, i);
	if (err < 0)
	continue;

	usb_audio_info(chip,
	"found and selected valid clock source %d\n",
	ret);
	return ret;
	}

	return -ENXIO;
	}

	/* FIXME: multipliers only act as pass-thru element for now */
	multiplier = snd_usb_find_clock_multiplier(chip->ctrl_intf, entity_id);
	if (multiplier)
	return __uac_clock_find_source(chip, multiplier->bCSourceID,
	visited, validate);

	return -EINVAL;
	}

	static int __uac3_clock_find_source(struct snd_usb_audio *chip, int entity_id,
	unsigned long *visited, bool validate)
	{
	struct uac3_clock_source_descriptor *source;
	struct uac3_clock_selector_descriptor *selector;
	struct uac3_clock_multiplier_descriptor *multiplier;

	entity_id &= 0xff;

	if (test_and_set_bit(entity_id, visited)) {
	usb_audio_warn(chip,
	"%s(): recursive clock topology detected, id %d.\n",
	__func__, entity_id);
	return -EINVAL;
	}

	/* first, see if the ID we're looking for is a clock source already */
	source = snd_usb_find_clock_source_v3(chip->ctrl_intf, entity_id);
	if (source) {
	entity_id = source->bClockID;
	if (validate && !uac_clock_source_is_valid(chip, UAC_VERSION_3,
	entity_id)) {
	usb_audio_err(chip,
	"clock source %d is not valid, cannot use\n",
	entity_id);
	return -ENXIO;
	}
	return entity_id;
	}

	selector = snd_usb_find_clock_selector_v3(chip->ctrl_intf, entity_id);
	if (selector) {
	int ret, i, cur;

	/* the entity ID we are looking for is a selector.
	* find out what it currently selects */
	ret = uac_clock_selector_get_val(chip, selector->bClockID);
	if (ret < 0)
	return ret;

	/* Selector values are one-based */

	if (ret > selector->bNrInPins \|\| ret < 1) {
	usb_audio_err(chip,
	"%s(): selector reported illegal value, id %d, ret %d\n",
	__func__, selector->bClockID, ret);

	return -EINVAL;
	}

	cur = ret;
	ret = __uac3_clock_find_source(chip, selector->baCSourceID[ret - 1],
	visited, validate);
	if (!validate \|\| ret > 0 \|\| !chip->autoclock)
	return ret;

	/* The current clock source is invalid, try others. */
	for (i = 1; i <= selector->bNrInPins; i++) {
	int err;

	if (i == cur)
	continue;

	ret = __uac3_clock_find_source(chip, selector->baCSourceID[i - 1],
	visited, true);
	if (ret < 0)
	continue;

	err = uac_clock_selector_set_val(chip, entity_id, i);
	if (err < 0)
	continue;

	usb_audio_info(chip,
	"found and selected valid clock source %d\n",
	ret);
	return ret;
	}

	return -ENXIO;
	}

	/* FIXME: multipliers only act as pass-thru element for now */
	multiplier = snd_usb_find_clock_multiplier_v3(chip->ctrl_intf,
	entity_id);
	if (multiplier)
	return __uac3_clock_find_source(chip, multiplier->bCSourceID,
	visited, validate);

	return -EINVAL;
	}

	/*
	* For all kinds of sample rate settings and other device queries,
	* the clock source (end-leaf) must be used. However, clock selectors,
	* clock multipliers and sample rate converters may be specified as
	* clock source input to terminal. This functions walks the clock path
	* to its end and tries to find the source.
	*
	* The 'visited' bitfield is used internally to detect recursive loops.
	*
	* Returns the clock source UnitID (>=0) on success, or an error.
	*/
	int snd_usb_clock_find_source(struct snd_usb_audio *chip, int protocol,
	int entity_id, bool validate)
	{
	DECLARE_BITMAP(visited, 256);
	memset(visited, 0, sizeof(visited));

	switch (protocol) {
	case UAC_VERSION_2:
	return __uac_clock_find_source(chip, entity_id, visited,
	validate);
	case UAC_VERSION_3:
	return __uac3_clock_find_source(chip, entity_id, visited,
	validate);
	default:
	return -EINVAL;
	}
	}

	static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
	struct usb_host_interface *alts,
	struct audioformat *fmt, int rate)
	{
	struct usb_device *dev = chip->dev;
	unsigned int ep;
	unsigned char data[3];
	int err, crate;

	if (get_iface_desc(alts)->bNumEndpoints < 1)
	return -EINVAL;
	ep = get_endpoint(alts, 0)->bEndpointAddress;

	/* if endpoint doesn't have sampling rate control, bail out */
	if (!(fmt->attributes & UAC_EP_CS_ATTR_SAMPLE_RATE))
	return 0;

	data[0] = rate;
	data[1] = rate >> 8;
	data[2] = rate >> 16;
	err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
	USB_TYPE_CLASS \| USB_RECIP_ENDPOINT \| USB_DIR_OUT,
	UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
	data, sizeof(data));
	if (err < 0) {
	dev_err(&dev->dev, "%d:%d: cannot set freq %d to ep %#x\n",
	iface, fmt->altsetting, rate, ep);
	return err;
	}

	/* Don't check the sample rate for devices which we know don't
	* support reading */
	if (snd_usb_get_sample_rate_quirk(chip))
	return 0;
	/* the firmware is likely buggy, don't repeat to fail too many times */
	if (chip->sample_rate_read_error > 2)
	return 0;

	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC_GET_CUR,
	USB_TYPE_CLASS \| USB_RECIP_ENDPOINT \| USB_DIR_IN,
	UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
	data, sizeof(data));
	if (err < 0) {
	dev_err(&dev->dev, "%d:%d: cannot get freq at ep %#x\n",
	iface, fmt->altsetting, ep);
	chip->sample_rate_read_error++;
	return 0; /* some devices don't support reading */
	}

	crate = data[0] \| (data[1] << 8) \| (data[2] << 16);
	if (crate != rate) {
	dev_warn(&dev->dev, "current rate %d is different from the runtime rate %d\n", crate, rate);
	// runtime->rate = crate;
	}

	return 0;
	}

	static int get_sample_rate_v2v3(struct snd_usb_audio *chip, int iface,
	int altsetting, int clock)
	{
	struct usb_device *dev = chip->dev;
	__le32 data;
	int err;

	err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
	USB_TYPE_CLASS \| USB_RECIP_INTERFACE \| USB_DIR_IN,
	UAC2_CS_CONTROL_SAM_FREQ << 8,
	snd_usb_ctrl_intf(chip) \| (clock << 8),
	&data, sizeof(data));
	if (err < 0) {
	dev_warn(&dev->dev, "%d:%d: cannot get freq (v2/v3): err %d\n",
	iface, altsetting, err);
	return 0;
	}

	return le32_to_cpu(data);
	}

	static int set_sample_rate_v2v3(struct snd_usb_audio *chip, int iface,
	struct usb_host_interface *alts,
	struct audioformat *fmt, int rate)
	{
	struct usb_device *dev = chip->dev;
	__le32 data;
	int err, cur_rate, prev_rate;
	int clock;
	bool writeable;
	u32 bmControls;

	clock = snd_usb_clock_find_source(chip, fmt->protocol,
	fmt->clock, true);
	if (clock < 0)
	return clock;

	prev_rate = get_sample_rate_v2v3(chip, iface, fmt->altsetting, clock);
	if (prev_rate == rate)
	return 0;

	if (fmt->protocol == UAC_VERSION_3) {
	struct uac3_clock_source_descriptor *cs_desc;

	cs_desc = snd_usb_find_clock_source_v3(chip->ctrl_intf, clock);
	bmControls = le32_to_cpu(cs_desc->bmControls);
	} else {
	struct uac_clock_source_descriptor *cs_desc;

	cs_desc = snd_usb_find_clock_source(chip->ctrl_intf, clock);
	bmControls = cs_desc->bmControls;
	}

	writeable = uac_v2v3_control_is_writeable(bmControls,
	UAC2_CS_CONTROL_SAM_FREQ);
	if (writeable) {
	data = cpu_to_le32(rate);
	err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC2_CS_CUR,
	USB_TYPE_CLASS \| USB_RECIP_INTERFACE \| USB_DIR_OUT,
	UAC2_CS_CONTROL_SAM_FREQ << 8,
	snd_usb_ctrl_intf(chip) \| (clock << 8),
	&data, sizeof(data));
	if (err < 0) {
	usb_audio_err(chip,
	"%d:%d: cannot set freq %d (v2/v3): err %d\n",
	iface, fmt->altsetting, rate, err);
	return err;
	}

	cur_rate = get_sample_rate_v2v3(chip, iface,
	fmt->altsetting, clock);
	} else {
	cur_rate = prev_rate;
	}

	if (cur_rate != rate) {
	if (!writeable) {
	usb_audio_warn(chip,
	"%d:%d: freq mismatch (RO clock): req %d, clock runs @%d\n",
	iface, fmt->altsetting, rate, cur_rate);
	return -ENXIO;
	}
	usb_audio_dbg(chip,
	"current rate %d is different from the runtime rate %d\n",
	cur_rate, rate);
	}

	/* Some devices doesn't respond to sample rate changes while the
	* interface is active. */
	if (rate != prev_rate) {
	usb_set_interface(dev, iface, 0);
	snd_usb_set_interface_quirk(dev);
	usb_set_interface(dev, iface, fmt->altsetting);
	snd_usb_set_interface_quirk(dev);
	}

	return 0;
	}

	int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface,
	struct usb_host_interface *alts,
	struct audioformat *fmt, int rate)
	{
	switch (fmt->protocol) {
	case UAC_VERSION_1:
	default:
	return set_sample_rate_v1(chip, iface, alts, fmt, rate);

	case UAC_VERSION_3:
	if (chip->badd_profile >= UAC3_FUNCTION_SUBCLASS_GENERIC_IO) {
	if (rate != UAC3_BADD_SAMPLING_RATE)
	return -ENXIO;
	else
	return 0;
	}
	/* fall through */
	case UAC_VERSION_2:
	return set_sample_rate_v2v3(chip, iface, alts, fmt, rate);
	}
	}