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clock.c

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

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

static struct uac_clock_source_descriptor *
      snd_usb_find_clock_source(struct usb_host_interface *ctrl_iface,
                          int clock_id)
{
      struct uac_clock_source_descriptor *cs = NULL;

      while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
                                   ctrl_iface->extralen,
                                   cs, UAC2_CLOCK_SOURCE))) {
            if (cs->bClockID == clock_id)
                  return cs;
      }

      return NULL;
}

static struct uac_clock_selector_descriptor *
      snd_usb_find_clock_selector(struct usb_host_interface *ctrl_iface,
                            int clock_id)
{
      struct uac_clock_selector_descriptor *cs = NULL;

      while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
                                   ctrl_iface->extralen,
                                   cs, UAC2_CLOCK_SELECTOR))) {
            if (cs->bClockID == clock_id)
                  return cs;
      }

      return NULL;
}

static struct uac_clock_multiplier_descriptor *
      snd_usb_find_clock_multiplier(struct usb_host_interface *ctrl_iface,
                              int clock_id)
{
      struct uac_clock_multiplier_descriptor *cs = NULL;

      while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
                                   ctrl_iface->extralen,
                                   cs, UAC2_CLOCK_MULTIPLIER))) {
            if (cs->bClockID == clock_id)
                  return cs;
      }

      return NULL;
}

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), 1000);

      if (ret < 0)
            return ret;

      return buf;
}

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

      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), 1000);

      if (err < 0) {
            snd_printk(KERN_WARNING "%s(): cannot get clock validity for id %d\n",
                     __func__, source_id);
            return err;
      }

      return !!data;
}

static int __uac_clock_find_source(struct snd_usb_audio *chip,
                           int entity_id, unsigned long *visited)
{
      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)) {
            snd_printk(KERN_WARNING
                  "%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)
            return source->bClockID;

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

            /* 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) {
                  printk(KERN_ERR
                        "%s(): selector reported illegal value, id %d, ret %d\n",
                        __func__, selector->bClockID, ret);

                  return -EINVAL;
            }

            return __uac_clock_find_source(chip, selector->baCSourceID[ret-1],
                                     visited);
      }

      /* 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);

      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 entity_id)
{
      DECLARE_BITMAP(visited, 256);
      memset(visited, 0, sizeof(visited));
      return __uac_clock_find_source(chip, entity_id, visited);
}

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;

      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;
      if ((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), 1000)) < 0) {
            snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d to ep %#x\n",
                     dev->devnum, iface, fmt->altsetting, rate, ep);
            return err;
      }

      if ((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), 1000)) < 0) {
            snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq at ep %#x\n",
                     dev->devnum, iface, fmt->altsetting, ep);
            return 0; /* some devices don't support reading */
      }

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

      return 0;
}

static int set_sample_rate_v2(struct snd_usb_audio *chip, int iface,
                        struct usb_host_interface *alts,
                        struct audioformat *fmt, int rate)
{
      struct usb_device *dev = chip->dev;
      unsigned char data[4];
      int err, crate;
      int clock = snd_usb_clock_find_source(chip, fmt->clock);

      if (clock < 0)
            return clock;

      if (!uac_clock_source_is_valid(chip, clock)) {
            /* TODO: should we try to find valid clock setups by ourself? */
            snd_printk(KERN_ERR "%d:%d:%d: clock source %d is not valid, cannot use\n",
                     dev->devnum, iface, fmt->altsetting, clock);
            return -ENXIO;
      }

      data[0] = rate;
      data[1] = rate >> 8;
      data[2] = rate >> 16;
      data[3] = rate >> 24;
      if ((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), 1000)) < 0) {
            snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d (v2)\n",
                     dev->devnum, iface, fmt->altsetting, rate);
            return err;
      }

      if ((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), 1000)) < 0) {
            snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq (v2)\n",
                     dev->devnum, iface, fmt->altsetting);
            return err;
      }

      crate = data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
      if (crate != rate)
            snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);

      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)
{
      struct usb_interface_descriptor *altsd = get_iface_desc(alts);

      switch (altsd->bInterfaceProtocol) {
      case UAC_VERSION_1:
      default:
            return set_sample_rate_v1(chip, iface, alts, fmt, rate);

      case UAC_VERSION_2:
            return set_sample_rate_v2(chip, iface, alts, fmt, rate);
      }
}


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