clock.c

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/*
 *   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));

    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;
    struct uac_clock_source_descriptor *cs_desc =
        snd_usb_find_clock_source(chip->ctrl_intf, source_id);

    if (!cs_desc)
        return 0;

    /* If a clock source can't tell us whether it's valid, we assume it is */
    if (!uac2_control_is_readable(cs_desc->bmControls,
                      UAC2_CS_CONTROL_CLOCK_VALID - 1))
        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) {
        snd_printk(KERN_WARNING "%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)
{
    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))) < 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))) < 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))) < 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))) < 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);
    }
}