1. 根目录:
2. drivers
3. media
4. pci
5. ivtv
6. ivtv-alsa-mixer.c

/*
 *  ALSA mixer controls for the
 *  ALSA interface to ivtv PCM capture streams
 *
 *  Copyright (C) 2009,2012  Andy Walls <awalls@md.metrocast.net>
 *
 *  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/init.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/spinlock.h>
#include <linux/videodev2.h>

#include <media/v4l2-device.h>

#include <sound/core.h>
#include <sound/control.h>
#include <sound/tlv.h>

#include "ivtv-alsa.h"
#include "ivtv-driver.h"

/*
 * Note the cx25840-core volume scale is funny, due to the alignment of the
 * scale with another chip's range:
 *
 * v4l2_control value	/512	indicated dB	actual dB	reg 0x8d4
 * 0x0000 - 0x01ff	  0	-119		-96		228
 * 0x0200 - 0x02ff	  1	-118		-96		228
 * ...
 * 0x2c00 - 0x2dff	 22	 -97		-96		228
 * 0x2e00 - 0x2fff	 23	 -96		-96		228
 * 0x3000 - 0x31ff	 24	 -95		-95		226
 * ...
 * 0xee00 - 0xefff	119	   0		  0		 36
 * ...
 * 0xfe00 - 0xffff	127	  +8		 +8		 20
 */
static inline int dB_to_cx25840_vol(int dB)
{
	if (dB < -96)
		dB = -96;
	else if (dB > 8)
		dB = 8;
	return (dB + 119) << 9;
}

static inline int cx25840_vol_to_dB(int v)
{
	if (v < (23 << 9))
		v = (23 << 9);
	else if (v > (127 << 9))
		v = (127 << 9);
	return (v >> 9) - 119;
}

static int snd_ivtv_mixer_tv_vol_info(struct snd_kcontrol *kcontrol,
				      struct snd_ctl_elem_info *uinfo)
{
	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	uinfo->count = 1;
	/* We're already translating values, just keep this control in dB */
	uinfo->value.integer.min  = -96;
	uinfo->value.integer.max  =   8;
	uinfo->value.integer.step =   1;
	return 0;
}

static int snd_ivtv_mixer_tv_vol_get(struct snd_kcontrol *kctl,
				     struct snd_ctl_elem_value *uctl)
{
	struct snd_ivtv_card *itvsc = snd_kcontrol_chip(kctl);
	struct ivtv *itv = to_ivtv(itvsc->v4l2_dev);
	struct v4l2_control vctrl;
	int ret;

	vctrl.id = V4L2_CID_AUDIO_VOLUME;
	vctrl.value = dB_to_cx25840_vol(uctl->value.integer.value[0]);

	snd_ivtv_lock(itvsc);
	ret = v4l2_subdev_call(itv->sd_audio, core, g_ctrl, &vctrl);
	snd_ivtv_unlock(itvsc);

	if (!ret)
		uctl->value.integer.value[0] = cx25840_vol_to_dB(vctrl.value);
	return ret;
}

static int snd_ivtv_mixer_tv_vol_put(struct snd_kcontrol *kctl,
				     struct snd_ctl_elem_value *uctl)
{
	struct snd_ivtv_card *itvsc = snd_kcontrol_chip(kctl);
	struct ivtv *itv = to_ivtv(itvsc->v4l2_dev);
	struct v4l2_control vctrl;
	int ret;

	vctrl.id = V4L2_CID_AUDIO_VOLUME;
	vctrl.value = dB_to_cx25840_vol(uctl->value.integer.value[0]);

	snd_ivtv_lock(itvsc);

	/* Fetch current state */
	ret = v4l2_subdev_call(itv->sd_audio, core, g_ctrl, &vctrl);

	if (ret ||
	    (cx25840_vol_to_dB(vctrl.value) != uctl->value.integer.value[0])) {

		/* Set, if needed */
		vctrl.value = dB_to_cx25840_vol(uctl->value.integer.value[0]);
		ret = v4l2_subdev_call(itv->sd_audio, core, s_ctrl, &vctrl);
		if (!ret)
			ret = 1; /* Indicate control was changed w/o error */
	}
	snd_ivtv_unlock(itvsc);

	return ret;
}


/* This is a bit of overkill, the slider is already in dB internally */
static DECLARE_TLV_DB_SCALE(snd_ivtv_mixer_tv_vol_db_scale, -9600, 100, 0);

static struct snd_kcontrol_new snd_ivtv_mixer_tv_vol __initdata = {
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "Analog TV Capture Volume",
	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
		  SNDRV_CTL_ELEM_ACCESS_TLV_READ,
	.info = snd_ivtv_mixer_tv_volume_info,
	.get = snd_ivtv_mixer_tv_volume_get,
	.put = snd_ivtv_mixer_tv_volume_put,
	.tlv.p = snd_ivtv_mixer_tv_vol_db_scale
};

/* FIXME - add mute switch and balance, bass, treble sliders:
	V4L2_CID_AUDIO_MUTE

	V4L2_CID_AUDIO_BALANCE

	V4L2_CID_AUDIO_BASS
	V4L2_CID_AUDIO_TREBLE
*/

/* FIXME - add stereo, lang1, lang2, mono menu */
/* FIXME - add I2S volume */

int __init snd_ivtv_mixer_create(struct snd_ivtv_card *itvsc)
{
	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
	struct snd_card *sc = itvsc->sc;
	int ret;

	strlcpy(sc->mixername, "CX2341[56] Mixer", sizeof(sc->mixername));

	ret = snd_ctl_add(sc, snd_ctl_new1(snd_ivtv_mixer_tv_vol, itvsc));
	if (ret) {
		IVTV_ALSA_WARN("%s: failed to add %s control, err %d\n",
			       __func__, snd_ivtv_mixer_tv_vol.name, ret);
	}
	return ret;
}