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

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *   Clock domain and sample rate management functions
  */

 #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"

 union uac23_clock_source_desc {
 	struct uac_clock_source_descriptor v2;
 	struct uac3_clock_source_descriptor v3;
 };

 union uac23_clock_selector_desc {
 	struct uac_clock_selector_descriptor v2;
 	struct uac3_clock_selector_descriptor v3;
 };

 union uac23_clock_multiplier_desc {
 	struct uac_clock_multiplier_descriptor v2;
 	struct uac_clock_multiplier_descriptor v3;
 };

 #define GET_VAL(p, proto, field) \
 	((proto) == UAC_VERSION_3 ? (p)->v3.field : (p)->v2.field)

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

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

 	return NULL;
 }

 static bool validate_clock_source(void *p, int id, int proto)
 {
 	union uac23_clock_source_desc *cs = p;

 	return GET_VAL(cs, proto, bClockID) == id;
 }

 static bool validate_clock_selector(void *p, int id, int proto)
 {
 	union uac23_clock_selector_desc *cs = p;

 	return GET_VAL(cs, proto, bClockID) == id;
 }

 static bool validate_clock_multiplier(void *p, int id, int proto)
 {
 	union uac23_clock_multiplier_desc *cs = p;

 	return GET_VAL(cs, proto, bClockID) == id;
 }

 #define DEFINE_FIND_HELPER(name, obj, validator, type2, type3)		\
 static obj *name(struct snd_usb_audio *chip, int id, int proto)	\
 {									\
 	return find_uac_clock_desc(chip->ctrl_intf, id, validator,	\
 				   proto == UAC_VERSION_3 ? (type3) : (type2), \
 				   proto);				\
 }

 DEFINE_FIND_HELPER(snd_usb_find_clock_source,
 		   union uac23_clock_source_desc, validate_clock_source,
 		   UAC2_CLOCK_SOURCE, UAC3_CLOCK_SOURCE);
 DEFINE_FIND_HELPER(snd_usb_find_clock_selector,
 		   union uac23_clock_selector_desc, validate_clock_selector,
 		   UAC2_CLOCK_SELECTOR, UAC3_CLOCK_SELECTOR);
 DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier,
 		   union uac23_clock_multiplier_desc, validate_clock_multiplier,
 		   UAC2_CLOCK_MULTIPLIER, 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_quirk(struct snd_usb_audio *chip,
 					    const struct audioformat *fmt,
 					    int source_id)
 {
 	bool ret = false;
 	int count;
 	unsigned char data;
 	struct usb_device *dev = chip->dev;
 	union uac23_clock_source_desc *cs_desc;

 	cs_desc = snd_usb_find_clock_source(chip, source_id, fmt->protocol);
 	if (!cs_desc)
 		return false;

 	if (fmt->protocol == UAC_VERSION_2) {
 		/*
 		 * Assume the clock is valid if clock source supports only one
 		 * single sample rate, the terminal is connected directly to it
 		 * (there is no clock selector) and clock type is internal.
 		 * This is to deal with some Denon DJ controllers that always
 		 * reports that clock is invalid.
 		 */
 		if (fmt->nr_rates == 1 &&
 		    (fmt->clock & 0xff) == cs_desc->v2.bClockID &&
 		    (cs_desc->v2.bmAttributes & 0x3) !=
 				UAC_CLOCK_SOURCE_TYPE_EXT)
 			return true;
 	}

 	/*
 	 * MOTU MicroBook IIc
 	 * Sample rate changes takes more than 2 seconds for this device. Clock
 	 * validity request returns false during that period.
 	 */
 	if (chip->usb_id == USB_ID(0x07fd, 0x0004)) {
 		count = 0;

 		while ((!ret) && (count < 50)) {
 			int err;

 			msleep(100);

 			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 false;
 			}

 			ret = !!data;
 			count++;
 		}
 	}

 	return ret;
 }

 static bool uac_clock_source_is_valid(struct snd_usb_audio *chip,
 				      const struct audioformat *fmt,
 				      int source_id)
 {
 	int err;
 	unsigned char data;
 	struct usb_device *dev = chip->dev;
 	u32 bmControls;
 	union uac23_clock_source_desc *cs_desc;

 	cs_desc = snd_usb_find_clock_source(chip, source_id, fmt->protocol);
 	if (!cs_desc)
 		return false;

 	if (fmt->protocol == UAC_VERSION_3)
 		bmControls = le32_to_cpu(cs_desc->v3.bmControls);
 	else
 		bmControls = cs_desc->v2.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 true;

 	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 false;
 	}

 	if (data)
 		return true;
 	else
 		return uac_clock_source_is_valid_quirk(chip, fmt, source_id);
 }

 static int __uac_clock_find_source(struct snd_usb_audio *chip,
 				   const struct audioformat *fmt, int entity_id,
 				   unsigned long *visited, bool validate)
 {
 	union uac23_clock_source_desc *source;
 	union uac23_clock_selector_desc *selector;
 	union uac23_clock_multiplier_desc *multiplier;
 	int ret, i, cur, err, pins, clock_id;
 	const u8 *sources;
 	int proto = fmt->protocol;

 	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 at is a clock source already */
 	source = snd_usb_find_clock_source(chip, entity_id, proto);
 	if (source) {
 		entity_id = GET_VAL(source, proto, bClockID);
 		if (validate && !uac_clock_source_is_valid(chip, fmt,
 								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, entity_id, proto);
 	if (selector) {
 		pins = GET_VAL(selector, proto, bNrInPins);
 		clock_id = GET_VAL(selector, proto, bClockID);
 		sources = GET_VAL(selector, proto, baCSourceID);
 		cur = 0;

 		if (pins == 1) {
 			ret = 1;
 			goto find_source;
 		}

 		/* the entity ID we are looking at is a selector.
 		 * find out what it currently selects */
 		ret = uac_clock_selector_get_val(chip, clock_id);
 		if (ret < 0) {
 			if (!chip->autoclock)
 				return ret;
 			goto find_others;
 		}

 		/* Selector values are one-based */

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

 			if (!chip->autoclock)
 				return -EINVAL;
 			goto find_others;
 		}

 	find_source:
 		cur = ret;
 		ret = __uac_clock_find_source(chip, fmt,
 					      sources[ret - 1],
 					      visited, validate);
 		if (ret > 0) {
 			/* Skip setting clock selector again for some devices */
 			if (chip->quirk_flags & QUIRK_FLAG_SKIP_CLOCK_SELECTOR)
 				return ret;
 			err = uac_clock_selector_set_val(chip, entity_id, cur);
 			if (err < 0)
 				return err;
 		}

 		if (!validate || ret > 0 || !chip->autoclock)
 			return ret;

 	find_others:
 		/* The current clock source is invalid, try others. */
 		for (i = 1; i <= pins; i++) {
 			if (i == cur)
 				continue;

 			ret = __uac_clock_find_source(chip, fmt,
 						      sources[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, entity_id, proto);
 	if (multiplier)
 		return __uac_clock_find_source(chip, fmt,
 					       GET_VAL(multiplier, proto, 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,
 			      const struct audioformat *fmt, bool validate)
 {
 	DECLARE_BITMAP(visited, 256);
 	memset(visited, 0, sizeof(visited));

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

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

 	/* 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,
 			      fmt->endpoint, data, sizeof(data));
 	if (err < 0) {
 		dev_err(&dev->dev, "%d:%d: cannot set freq %d to ep %#x\n",
 			fmt->iface, fmt->altsetting, rate, fmt->endpoint);
 		return err;
 	}

 	/* Don't check the sample rate for devices which we know don't
 	 * support reading */
 	if (chip->quirk_flags & QUIRK_FLAG_GET_SAMPLE_RATE)
 		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,
 			      fmt->endpoint, data, sizeof(data));
 	if (err < 0) {
 		dev_err(&dev->dev, "%d:%d: cannot get freq at ep %#x\n",
 			fmt->iface, fmt->altsetting, fmt->endpoint);
 		chip->sample_rate_read_error++;
 		return 0; /* some devices don't support reading */
 	}

 	crate = data[0] | (data[1] << 8) | (data[2] << 16);
 	if (!crate) {
 		dev_info(&dev->dev, "failed to read current rate; disabling the check\n");
 		chip->sample_rate_read_error = 3; /* three strikes, see above */
 		return 0;
 	}

 	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);
 }

 /*
  * Try to set the given sample rate:
  *
  * Return 0 if the clock source is read-only, the actual rate on success,
  * or a negative error code.
  *
  * This function gets called from format.c to validate each sample rate, too.
  * Hence no message is shown upon error
  */
 int snd_usb_set_sample_rate_v2v3(struct snd_usb_audio *chip,
 				 const struct audioformat *fmt,
 				 int clock, int rate)
 {
 	bool writeable;
 	u32 bmControls;
 	__le32 data;
 	int err;
 	union uac23_clock_source_desc *cs_desc;

 	cs_desc = snd_usb_find_clock_source(chip, clock, fmt->protocol);

 	if (!cs_desc)
 		return 0;

 	if (fmt->protocol == UAC_VERSION_3)
 		bmControls = le32_to_cpu(cs_desc->v3.bmControls);
 	else
 		bmControls = cs_desc->v2.bmControls;

 	writeable = uac_v2v3_control_is_writeable(bmControls,
 						  UAC2_CS_CONTROL_SAM_FREQ);
 	if (!writeable)
 		return 0;

 	data = cpu_to_le32(rate);
 	err = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->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)
 		return err;

 	return get_sample_rate_v2v3(chip, fmt->iface, fmt->altsetting, clock);
 }

 static int set_sample_rate_v2v3(struct snd_usb_audio *chip,
 				const struct audioformat *fmt, int rate)
 {
 	int cur_rate, prev_rate;
 	int clock;

 	/* First, try to find a valid clock. This may trigger
 	 * automatic clock selection if the current clock is not
 	 * valid.
 	 */
 	clock = snd_usb_clock_find_source(chip, fmt, true);
 	if (clock < 0) {
 		/* We did not find a valid clock, but that might be
 		 * because the current sample rate does not match an
 		 * external clock source. Try again without validation
 		 * and we will do another validation after setting the
 		 * rate.
 		 */
 		clock = snd_usb_clock_find_source(chip, fmt, false);

 		/* Hardcoded sample rates */
 		if (chip->quirk_flags & QUIRK_FLAG_IGNORE_CLOCK_SOURCE)
 			return 0;

 		if (clock < 0)
 			return clock;
 	}

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

 	cur_rate = snd_usb_set_sample_rate_v2v3(chip, fmt, clock, rate);
 	if (cur_rate < 0) {
 		usb_audio_err(chip,
 			      "%d:%d: cannot set freq %d (v2/v3): err %d\n",
 			      fmt->iface, fmt->altsetting, rate, cur_rate);
 		return cur_rate;
 	}

 	if (!cur_rate)
 		cur_rate = prev_rate;

 	if (cur_rate != rate) {
 		usb_audio_dbg(chip,
 			      "%d:%d: freq mismatch: req %d, clock runs @%d\n",
 			      fmt->iface, fmt->altsetting, rate, cur_rate);
 		/* continue processing */
 	}

 validation:
 	/* validate clock after rate change */
 	if (!uac_clock_source_is_valid(chip, fmt, clock))
 		return -ENXIO;
 	return 0;
 }

 int snd_usb_init_sample_rate(struct snd_usb_audio *chip,
 			     const struct audioformat *fmt, int rate)
 {
 	usb_audio_dbg(chip, "%d:%d Set sample rate %d, clock %d\n",
 		      fmt->iface, fmt->altsetting, rate, fmt->clock);

 	switch (fmt->protocol) {
 	case UAC_VERSION_1:
 	default:
 		return set_sample_rate_v1(chip, 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;
 		}
 		fallthrough;
 	case UAC_VERSION_2:
 		return set_sample_rate_v2v3(chip, fmt, rate);
 	}
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Clock domain and sample rate management functions
	*/

	#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"

	union uac23_clock_source_desc {
	struct uac_clock_source_descriptor v2;
	struct uac3_clock_source_descriptor v3;
	};

	union uac23_clock_selector_desc {
	struct uac_clock_selector_descriptor v2;
	struct uac3_clock_selector_descriptor v3;
	};

	union uac23_clock_multiplier_desc {
	struct uac_clock_multiplier_descriptor v2;
	struct uac_clock_multiplier_descriptor v3;
	};

	#define GET_VAL(p, proto, field) \
	((proto) == UAC_VERSION_3 ? (p)->v3.field : (p)->v2.field)

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

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

	return NULL;
	}

	static bool validate_clock_source(void *p, int id, int proto)
	{
	union uac23_clock_source_desc *cs = p;

	return GET_VAL(cs, proto, bClockID) == id;
	}

	static bool validate_clock_selector(void *p, int id, int proto)
	{
	union uac23_clock_selector_desc *cs = p;

	return GET_VAL(cs, proto, bClockID) == id;
	}

	static bool validate_clock_multiplier(void *p, int id, int proto)
	{
	union uac23_clock_multiplier_desc *cs = p;

	return GET_VAL(cs, proto, bClockID) == id;
	}

	#define DEFINE_FIND_HELPER(name, obj, validator, type2, type3) \
	static obj name(struct snd_usb_audio chip, int id, int proto) \
	{ \
	return find_uac_clock_desc(chip->ctrl_intf, id, validator, \
	proto == UAC_VERSION_3 ? (type3) : (type2), \
	proto); \
	}

	DEFINE_FIND_HELPER(snd_usb_find_clock_source,
	union uac23_clock_source_desc, validate_clock_source,
	UAC2_CLOCK_SOURCE, UAC3_CLOCK_SOURCE);
	DEFINE_FIND_HELPER(snd_usb_find_clock_selector,
	union uac23_clock_selector_desc, validate_clock_selector,
	UAC2_CLOCK_SELECTOR, UAC3_CLOCK_SELECTOR);
	DEFINE_FIND_HELPER(snd_usb_find_clock_multiplier,
	union uac23_clock_multiplier_desc, validate_clock_multiplier,
	UAC2_CLOCK_MULTIPLIER, 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_quirk(struct snd_usb_audio *chip,
	const struct audioformat *fmt,
	int source_id)
	{
	bool ret = false;
	int count;
	unsigned char data;
	struct usb_device *dev = chip->dev;
	union uac23_clock_source_desc *cs_desc;

	cs_desc = snd_usb_find_clock_source(chip, source_id, fmt->protocol);
	if (!cs_desc)
	return false;

	if (fmt->protocol == UAC_VERSION_2) {
	/*
	* Assume the clock is valid if clock source supports only one
	* single sample rate, the terminal is connected directly to it
	* (there is no clock selector) and clock type is internal.
	* This is to deal with some Denon DJ controllers that always
	* reports that clock is invalid.
	*/
	if (fmt->nr_rates == 1 &&
	(fmt->clock & 0xff) == cs_desc->v2.bClockID &&
	(cs_desc->v2.bmAttributes & 0x3) !=
	UAC_CLOCK_SOURCE_TYPE_EXT)
	return true;
	}

	/*
	* MOTU MicroBook IIc
	* Sample rate changes takes more than 2 seconds for this device. Clock
	* validity request returns false during that period.
	*/
	if (chip->usb_id == USB_ID(0x07fd, 0x0004)) {
	count = 0;

	while ((!ret) && (count < 50)) {
	int err;

	msleep(100);

	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 false;
	}

	ret = !!data;
	count++;
	}
	}

	return ret;
	}

	static bool uac_clock_source_is_valid(struct snd_usb_audio *chip,
	const struct audioformat *fmt,
	int source_id)
	{
	int err;
	unsigned char data;
	struct usb_device *dev = chip->dev;
	u32 bmControls;
	union uac23_clock_source_desc *cs_desc;

	cs_desc = snd_usb_find_clock_source(chip, source_id, fmt->protocol);
	if (!cs_desc)
	return false;

	if (fmt->protocol == UAC_VERSION_3)
	bmControls = le32_to_cpu(cs_desc->v3.bmControls);
	else
	bmControls = cs_desc->v2.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 true;

	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 false;
	}

	if (data)
	return true;
	else
	return uac_clock_source_is_valid_quirk(chip, fmt, source_id);
	}

	static int __uac_clock_find_source(struct snd_usb_audio *chip,
	const struct audioformat *fmt, int entity_id,
	unsigned long *visited, bool validate)
	{
	union uac23_clock_source_desc *source;
	union uac23_clock_selector_desc *selector;
	union uac23_clock_multiplier_desc *multiplier;
	int ret, i, cur, err, pins, clock_id;
	const u8 *sources;
	int proto = fmt->protocol;

	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 at is a clock source already */
	source = snd_usb_find_clock_source(chip, entity_id, proto);
	if (source) {
	entity_id = GET_VAL(source, proto, bClockID);
	if (validate && !uac_clock_source_is_valid(chip, fmt,
	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, entity_id, proto);
	if (selector) {
	pins = GET_VAL(selector, proto, bNrInPins);
	clock_id = GET_VAL(selector, proto, bClockID);
	sources = GET_VAL(selector, proto, baCSourceID);
	cur = 0;

	if (pins == 1) {
	ret = 1;
	goto find_source;
	}

	/* the entity ID we are looking at is a selector.
	* find out what it currently selects */
	ret = uac_clock_selector_get_val(chip, clock_id);
	if (ret < 0) {
	if (!chip->autoclock)
	return ret;
	goto find_others;
	}

	/* Selector values are one-based */

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

	if (!chip->autoclock)
	return -EINVAL;
	goto find_others;
	}

	find_source:
	cur = ret;
	ret = __uac_clock_find_source(chip, fmt,
	sources[ret - 1],
	visited, validate);
	if (ret > 0) {
	/* Skip setting clock selector again for some devices */
	if (chip->quirk_flags & QUIRK_FLAG_SKIP_CLOCK_SELECTOR)
	return ret;
	err = uac_clock_selector_set_val(chip, entity_id, cur);
	if (err < 0)
	return err;
	}

	if (!validate \|\| ret > 0 \|\| !chip->autoclock)
	return ret;

	find_others:
	/* The current clock source is invalid, try others. */
	for (i = 1; i <= pins; i++) {
	if (i == cur)
	continue;

	ret = __uac_clock_find_source(chip, fmt,
	sources[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, entity_id, proto);
	if (multiplier)
	return __uac_clock_find_source(chip, fmt,
	GET_VAL(multiplier, proto, 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,
	const struct audioformat *fmt, bool validate)
	{
	DECLARE_BITMAP(visited, 256);
	memset(visited, 0, sizeof(visited));

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

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

	/* 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,
	fmt->endpoint, data, sizeof(data));
	if (err < 0) {
	dev_err(&dev->dev, "%d:%d: cannot set freq %d to ep %#x\n",
	fmt->iface, fmt->altsetting, rate, fmt->endpoint);
	return err;
	}

	/* Don't check the sample rate for devices which we know don't
	* support reading */
	if (chip->quirk_flags & QUIRK_FLAG_GET_SAMPLE_RATE)
	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,
	fmt->endpoint, data, sizeof(data));
	if (err < 0) {
	dev_err(&dev->dev, "%d:%d: cannot get freq at ep %#x\n",
	fmt->iface, fmt->altsetting, fmt->endpoint);
	chip->sample_rate_read_error++;
	return 0; /* some devices don't support reading */
	}

	crate = data[0] \| (data[1] << 8) \| (data[2] << 16);
	if (!crate) {
	dev_info(&dev->dev, "failed to read current rate; disabling the check\n");
	chip->sample_rate_read_error = 3; /* three strikes, see above */
	return 0;
	}

	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);
	}

	/*
	* Try to set the given sample rate:
	*
	* Return 0 if the clock source is read-only, the actual rate on success,
	* or a negative error code.
	*
	* This function gets called from format.c to validate each sample rate, too.
	* Hence no message is shown upon error
	*/
	int snd_usb_set_sample_rate_v2v3(struct snd_usb_audio *chip,
	const struct audioformat *fmt,
	int clock, int rate)
	{
	bool writeable;
	u32 bmControls;
	__le32 data;
	int err;
	union uac23_clock_source_desc *cs_desc;

	cs_desc = snd_usb_find_clock_source(chip, clock, fmt->protocol);

	if (!cs_desc)
	return 0;

	if (fmt->protocol == UAC_VERSION_3)
	bmControls = le32_to_cpu(cs_desc->v3.bmControls);
	else
	bmControls = cs_desc->v2.bmControls;

	writeable = uac_v2v3_control_is_writeable(bmControls,
	UAC2_CS_CONTROL_SAM_FREQ);
	if (!writeable)
	return 0;

	data = cpu_to_le32(rate);
	err = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->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)
	return err;

	return get_sample_rate_v2v3(chip, fmt->iface, fmt->altsetting, clock);
	}

	static int set_sample_rate_v2v3(struct snd_usb_audio *chip,
	const struct audioformat *fmt, int rate)
	{
	int cur_rate, prev_rate;
	int clock;

	/* First, try to find a valid clock. This may trigger
	* automatic clock selection if the current clock is not
	* valid.
	*/
	clock = snd_usb_clock_find_source(chip, fmt, true);
	if (clock < 0) {
	/* We did not find a valid clock, but that might be
	* because the current sample rate does not match an
	* external clock source. Try again without validation
	* and we will do another validation after setting the
	* rate.
	*/
	clock = snd_usb_clock_find_source(chip, fmt, false);

	/* Hardcoded sample rates */
	if (chip->quirk_flags & QUIRK_FLAG_IGNORE_CLOCK_SOURCE)
	return 0;

	if (clock < 0)
	return clock;
	}

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

	cur_rate = snd_usb_set_sample_rate_v2v3(chip, fmt, clock, rate);
	if (cur_rate < 0) {
	usb_audio_err(chip,
	"%d:%d: cannot set freq %d (v2/v3): err %d\n",
	fmt->iface, fmt->altsetting, rate, cur_rate);
	return cur_rate;
	}

	if (!cur_rate)
	cur_rate = prev_rate;

	if (cur_rate != rate) {
	usb_audio_dbg(chip,
	"%d:%d: freq mismatch: req %d, clock runs @%d\n",
	fmt->iface, fmt->altsetting, rate, cur_rate);
	/* continue processing */
	}

	validation:
	/* validate clock after rate change */
	if (!uac_clock_source_is_valid(chip, fmt, clock))
	return -ENXIO;
	return 0;
	}

	int snd_usb_init_sample_rate(struct snd_usb_audio *chip,
	const struct audioformat *fmt, int rate)
	{
	usb_audio_dbg(chip, "%d:%d Set sample rate %d, clock %d\n",
	fmt->iface, fmt->altsetting, rate, fmt->clock);

	switch (fmt->protocol) {
	case UAC_VERSION_1:
	default:
	return set_sample_rate_v1(chip, 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;
	}
	fallthrough;
	case UAC_VERSION_2:
	return set_sample_rate_v2v3(chip, fmt, rate);
	}
	}