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));

	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);
	}
}