[media] ivtv, ivtv-alsa: Add initial ivtv-alsa interface driver for ivtv

This is a cut-and-paste port of the cx18-alsa driver to
create an ivtv-alsa interface module for the ivtv driver.
It is not actually hooked-up to the PCM stream DMA buffers
from the ivtv driver yet.  That will be done in a coming change,
since that portion is so very different from the cx18 driver.
This code has all or more of the bugs and shortcomings of the
cx18-alsa interface driver: inconsistent use of itvsc->slock,
ivtv-alsa-mixer.c is dead code, assumes 48 ksps regardless
of the actual setting of the audio capture, problems with
proper struct ivtv and struct ivtv_stream housekeeping,
struct ivtv_open_id.v4l2_fh abuse, and $DIETY knows what else.

Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/pci/ivtv/Kconfig

@@ -28,6 +28,17 @@ config VIDEO_IVTV
 	  To compile this driver as a module, choose M here: the
 	  module will be called ivtv.
 
+config VIDEO_IVTV_ALSA
+	tristate "Conexant cx23415/cx23416 PCM audio capture support"
+	depends on VIDEO_IVTV && SND && EXPERIMENTAL
+	select SND_PCM
+	---help---
+	  This is an ALSA interface driver for direct PCM audio capture from
+	  Conexant cx23415/cx23416 based PCI TV cards using the ivtv driver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ivtv-alsa.
+
 config VIDEO_FB_IVTV
 	tristate "Conexant cx23415 framebuffer support"
 	depends on VIDEO_IVTV && FB

drivers/media/pci/ivtv/Makefile

@@ -3,8 +3,10 @@ ivtv-objs	:= ivtv-routing.o ivtv-cards.o ivtv-controls.o \
 		   ivtv-gpio.o ivtv-i2c.o ivtv-ioctl.o ivtv-irq.o \
 		   ivtv-mailbox.o ivtv-queue.o ivtv-streams.o ivtv-udma.o \
 		   ivtv-vbi.o ivtv-yuv.o
+ivtv-alsa-objs := ivtv-alsa-main.o ivtv-alsa-pcm.o
 
 obj-$(CONFIG_VIDEO_IVTV) += ivtv.o
+obj-$(CONFIG_VIDEO_IVTV_ALSA) += ivtv-alsa.o
 obj-$(CONFIG_VIDEO_FB_IVTV) += ivtvfb.o
 
 ccflags-y += -I$(srctree)/drivers/media/i2c

drivers/media/pci/ivtv/ivtv-alsa-main.c

@@ -0,0 +1,303 @@
+/*
+ *  ALSA interface to ivtv PCM capture streams
+ *
+ *  Copyright (C) 2009,2012  Andy Walls <awalls@md.metrocast.net>
+ *  Copyright (C) 2009  Devin Heitmueller <dheitmueller@kernellabs.com>
+ *
+ *  Portions of this work were sponsored by ONELAN Limited for the cx18 driver
+ *
+ *  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/slab.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/spinlock.h>
+
+#include <media/v4l2-device.h>
+
+#include <sound/core.h>
+#include <sound/initval.h>
+
+#include "ivtv-driver.h"
+#include "ivtv-version.h"
+#include "ivtv-alsa.h"
+#include "ivtv-alsa-mixer.h"
+#include "ivtv-alsa-pcm.h"
+
+int ivtv_alsa_debug;
+
+#define IVTV_DEBUG_ALSA_INFO(fmt, arg...) \
+	do { \
+		if (ivtv_alsa_debug & 2) \
+			pr_info("%s: " fmt, "ivtv-alsa", ## arg); \
+	} while (0)
+
+module_param_named(debug, ivtv_alsa_debug, int, 0644);
+MODULE_PARM_DESC(debug,
+		 "Debug level (bitmask). Default: 0\n"
+		 "\t\t\t  1/0x0001: warning\n"
+		 "\t\t\t  2/0x0002: info\n");
+
+MODULE_AUTHOR("Andy Walls");
+MODULE_DESCRIPTION("CX23415/CX23416 ALSA Interface");
+MODULE_SUPPORTED_DEVICE("CX23415/CX23416 MPEG2 encoder");
+MODULE_LICENSE("GPL");
+
+MODULE_VERSION(IVTV_VERSION);
+
+static inline
+struct snd_ivtv_card *to_snd_ivtv_card(struct v4l2_device *v4l2_dev)
+{
+	return to_ivtv(v4l2_dev)->alsa;
+}
+
+static inline
+struct snd_ivtv_card *p_to_snd_ivtv_card(struct v4l2_device **v4l2_dev)
+{
+	return container_of(v4l2_dev, struct snd_ivtv_card, v4l2_dev);
+}
+
+static void snd_ivtv_card_free(struct snd_ivtv_card *itvsc)
+{
+	if (itvsc == NULL)
+		return;
+
+	if (itvsc->v4l2_dev != NULL)
+		to_ivtv(itvsc->v4l2_dev)->alsa = NULL;
+
+	/* FIXME - take any other stopping actions needed */
+
+	kfree(itvsc);
+}
+
+static void snd_ivtv_card_private_free(struct snd_card *sc)
+{
+	if (sc == NULL)
+		return;
+	snd_ivtv_card_free(sc->private_data);
+	sc->private_data = NULL;
+	sc->private_free = NULL;
+}
+
+static int snd_ivtv_card_create(struct v4l2_device *v4l2_dev,
+				       struct snd_card *sc,
+				       struct snd_ivtv_card **itvsc)
+{
+	*itvsc = kzalloc(sizeof(struct snd_ivtv_card), GFP_KERNEL);
+	if (*itvsc == NULL)
+		return -ENOMEM;
+
+	(*itvsc)->v4l2_dev = v4l2_dev;
+	(*itvsc)->sc = sc;
+
+	sc->private_data = *itvsc;
+	sc->private_free = snd_ivtv_card_private_free;
+
+	return 0;
+}
+
+static int snd_ivtv_card_set_names(struct snd_ivtv_card *itvsc)
+{
+	struct ivtv *itv = to_ivtv(itvsc->v4l2_dev);
+	struct snd_card *sc = itvsc->sc;
+
+	/* sc->driver is used by alsa-lib's configurator: simple, unique */
+	strlcpy(sc->driver, "CX2341[56]", sizeof(sc->driver));
+
+	/* sc->shortname is a symlink in /proc/asound: IVTV-M -> cardN */
+	snprintf(sc->shortname,  sizeof(sc->shortname), "IVTV-%d",
+		 itv->instance);
+
+	/* sc->longname is read from /proc/asound/cards */
+	snprintf(sc->longname, sizeof(sc->longname),
+		 "CX2341[56] #%d %s TV/FM Radio/Line-In Capture",
+		 itv->instance, itv->card_name);
+
+	return 0;
+}
+
+static int snd_ivtv_init(struct v4l2_device *v4l2_dev)
+{
+	struct ivtv *itv = to_ivtv(v4l2_dev);
+	struct snd_card *sc = NULL;
+	struct snd_ivtv_card *itvsc;
+	int ret;
+
+	/* Numbrs steps from "Writing an ALSA Driver" by Takashi Iwai */
+
+	/* (1) Check and increment the device index */
+	/* This is a no-op for us.  We'll use the itv->instance */
+
+	/* (2) Create a card instance */
+	ret = snd_card_create(SNDRV_DEFAULT_IDX1, /* use first available id */
+			      SNDRV_DEFAULT_STR1, /* xid from end of shortname*/
+			      THIS_MODULE, 0, &sc);
+	if (ret) {
+		IVTV_ALSA_ERR("%s: snd_card_create() failed with err %d\n",
+			      __func__, ret);
+		goto err_exit;
+	}
+
+	/* (3) Create a main component */
+	ret = snd_ivtv_card_create(v4l2_dev, sc, &itvsc);
+	if (ret) {
+		IVTV_ALSA_ERR("%s: snd_ivtv_card_create() failed with err %d\n",
+			      __func__, ret);
+		goto err_exit_free;
+	}
+
+	/* (4) Set the driver ID and name strings */
+	snd_ivtv_card_set_names(itvsc);
+
+	/* (5) Create other components: mixer, PCM, & proc files */
+#if 0
+	ret = snd_ivtv_mixer_create(itvsc);
+	if (ret) {
+		IVTV_ALSA_WARN("%s: snd_ivtv_mixer_create() failed with err %d:"
+			       " proceeding anyway\n", __func__, ret);
+	}
+#endif
+
+	ret = snd_ivtv_pcm_create(itvsc);
+	if (ret) {
+		IVTV_ALSA_ERR("%s: snd_ivtv_pcm_create() failed with err %d\n",
+			      __func__, ret);
+		goto err_exit_free;
+	}
+	/* FIXME - proc files */
+
+	/* (7) Set the driver data and return 0 */
+	/* We do this out of normal order for PCI drivers to avoid races */
+	itv->alsa = itvsc;
+
+	/* (6) Register the card instance */
+	ret = snd_card_register(sc);
+	if (ret) {
+		itv->alsa = NULL;
+		IVTV_ALSA_ERR("%s: snd_card_register() failed with err %d\n",
+			      __func__, ret);
+		goto err_exit_free;
+	}
+
+	return 0;
+
+err_exit_free:
+	if (sc != NULL)
+		snd_card_free(sc);
+	kfree(itvsc);
+err_exit:
+	return ret;
+}
+
+int ivtv_alsa_load(struct ivtv *itv)
+{
+	struct v4l2_device *v4l2_dev = &itv->v4l2_dev;
+	struct ivtv_stream *s;
+
+	if (v4l2_dev == NULL) {
+		pr_err("ivtv-alsa: %s: struct v4l2_device * is NULL\n",
+		       __func__);
+		return 0;
+	}
+
+	itv = to_ivtv(v4l2_dev);
+	if (itv == NULL) {
+		pr_err("ivtv-alsa itv is NULL\n");
+		return 0;
+	}
+
+	s = &itv->streams[IVTV_ENC_STREAM_TYPE_PCM];
+	if (s->vdev == NULL) {
+		IVTV_DEBUG_ALSA_INFO("%s: PCM stream for card is disabled - "
+				     "skipping\n", __func__);
+		return 0;
+	}
+
+	if (itv->alsa != NULL) {
+		IVTV_ALSA_ERR("%s: struct snd_ivtv_card * already exists\n",
+			      __func__);
+		return 0;
+	}
+
+	if (snd_ivtv_init(v4l2_dev)) {
+		IVTV_ALSA_ERR("%s: failed to create struct snd_ivtv_card\n",
+			      __func__);
+	} else {
+		IVTV_DEBUG_ALSA_INFO("%s: created ivtv ALSA interface instance "
+				     "\n", __func__);
+	}
+	return 0;
+}
+
+static int __init ivtv_alsa_init(void)
+{
+	pr_info("ivtv-alsa: module loading...\n");
+	ivtv_ext_init = &ivtv_alsa_load;
+	return 0;
+}
+
+static void __exit snd_ivtv_exit(struct snd_ivtv_card *itvsc)
+{
+	struct ivtv *itv = to_ivtv(itvsc->v4l2_dev);
+
+	/* FIXME - pointer checks & shutdown itvsc */
+
+	snd_card_free(itvsc->sc);
+	itv->alsa = NULL;
+}
+
+static int __exit ivtv_alsa_exit_callback(struct device *dev, void *data)
+{
+	struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
+	struct snd_ivtv_card *itvsc;
+
+	if (v4l2_dev == NULL) {
+		pr_err("ivtv-alsa: %s: struct v4l2_device * is NULL\n",
+		       __func__);
+		return 0;
+	}
+
+	itvsc = to_snd_ivtv_card(v4l2_dev);
+	if (itvsc == NULL) {
+		IVTV_ALSA_WARN("%s: struct snd_ivtv_card * is NULL\n",
+			       __func__);
+		return 0;
+	}
+
+	snd_ivtv_exit(itvsc);
+	return 0;
+}
+
+static void __exit ivtv_alsa_exit(void)
+{
+	struct device_driver *drv;
+	int ret;
+
+	pr_info("ivtv-alsa: module unloading...\n");
+
+	drv = driver_find("ivtv", &pci_bus_type);
+	ret = driver_for_each_device(drv, NULL, NULL, ivtv_alsa_exit_callback);
+	(void)ret;	/* suppress compiler warning */
+
+	ivtv_ext_init = NULL;
+	pr_info("ivtv-alsa: module unload complete\n");
+}
+
+module_init(ivtv_alsa_init);
+module_exit(ivtv_alsa_exit);

drivers/media/pci/ivtv/ivtv-alsa-mixer.c

@@ -0,0 +1,175 @@
+/*
+ *  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;
+}

drivers/media/pci/ivtv/ivtv-alsa-mixer.h

@@ -0,0 +1,23 @@
+/*
+ *  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
+ */
+
+int __init snd_ivtv_mixer_create(struct snd_ivtv_card *itvsc);

drivers/media/pci/ivtv/ivtv-alsa-pcm.c

@@ -0,0 +1,357 @@
+/*
+ *  ALSA PCM device for the
+ *  ALSA interface to ivtv PCM capture streams
+ *
+ *  Copyright (C) 2009,2012  Andy Walls <awalls@md.metrocast.net>
+ *  Copyright (C) 2009  Devin Heitmueller <dheitmueller@kernellabs.com>
+ *
+ *  Portions of this work were sponsored by ONELAN Limited for the cx18 driver
+ *
+ *  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/vmalloc.h>
+#include <linux/printk.h>
+
+#include <media/v4l2-device.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+
+#include "ivtv-driver.h"
+#include "ivtv-queue.h"
+#include "ivtv-streams.h"
+#include "ivtv-fileops.h"
+#include "ivtv-alsa.h"
+
+static unsigned int pcm_debug;
+module_param(pcm_debug, int, 0644);
+MODULE_PARM_DESC(pcm_debug, "enable debug messages for pcm");
+
+#define dprintk(fmt, arg...) \
+	do { \
+		if (pcm_debug) \
+			pr_info("ivtv-alsa-pcm %s: " fmt, __func__, ##arg); \
+	} while (0)
+
+static struct snd_pcm_hardware snd_ivtv_hw_capture = {
+	.info = SNDRV_PCM_INFO_BLOCK_TRANSFER |
+		SNDRV_PCM_INFO_MMAP           |
+		SNDRV_PCM_INFO_INTERLEAVED    |
+		SNDRV_PCM_INFO_MMAP_VALID,
+
+	.formats = SNDRV_PCM_FMTBIT_S16_LE,
+
+	.rates = SNDRV_PCM_RATE_48000,
+
+	.rate_min = 48000,
+	.rate_max = 48000,
+	.channels_min = 2,
+	.channels_max = 2,
+	.buffer_bytes_max = 62720 * 8,	/* just about the value in usbaudio.c */
+	.period_bytes_min = 64,		/* 12544/2, */
+	.period_bytes_max = 12544,
+	.periods_min = 2,
+	.periods_max = 98,		/* 12544, */
+};
+
+void ivtv_alsa_announce_pcm_data(struct snd_ivtv_card *itvsc, u8 *pcm_data,
+				 size_t num_bytes)
+{
+	struct snd_pcm_substream *substream;
+	struct snd_pcm_runtime *runtime;
+	unsigned int oldptr;
+	unsigned int stride;
+	int period_elapsed = 0;
+	int length;
+
+	dprintk("ivtv alsa announce ptr=%p data=%p num_bytes=%zd\n", itvsc,
+		pcm_data, num_bytes);
+
+	substream = itvsc->capture_pcm_substream;
+	if (substream == NULL) {
+		dprintk("substream was NULL\n");
+		return;
+	}
+
+	runtime = substream->runtime;
+	if (runtime == NULL) {
+		dprintk("runtime was NULL\n");
+		return;
+	}
+
+	stride = runtime->frame_bits >> 3;
+	if (stride == 0) {
+		dprintk("stride is zero\n");
+		return;
+	}
+
+	length = num_bytes / stride;
+	if (length == 0) {
+		dprintk("%s: length was zero\n", __func__);
+		return;
+	}
+
+	if (runtime->dma_area == NULL) {
+		dprintk("dma area was NULL - ignoring\n");
+		return;
+	}
+
+	oldptr = itvsc->hwptr_done_capture;
+	if (oldptr + length >= runtime->buffer_size) {
+		unsigned int cnt =
+			runtime->buffer_size - oldptr;
+		memcpy(runtime->dma_area + oldptr * stride, pcm_data,
+		       cnt * stride);
+		memcpy(runtime->dma_area, pcm_data + cnt * stride,
+		       length * stride - cnt * stride);
+	} else {
+		memcpy(runtime->dma_area + oldptr * stride, pcm_data,
+		       length * stride);
+	}
+	snd_pcm_stream_lock(substream);
+
+	itvsc->hwptr_done_capture += length;
+	if (itvsc->hwptr_done_capture >=
+	    runtime->buffer_size)
+		itvsc->hwptr_done_capture -=
+			runtime->buffer_size;
+
+	itvsc->capture_transfer_done += length;
+	if (itvsc->capture_transfer_done >=
+	    runtime->period_size) {
+		itvsc->capture_transfer_done -=
+			runtime->period_size;
+		period_elapsed = 1;
+	}
+
+	snd_pcm_stream_unlock(substream);
+
+	if (period_elapsed)
+		snd_pcm_period_elapsed(substream);
+}
+
+static int snd_ivtv_pcm_capture_open(struct snd_pcm_substream *substream)
+{
+	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
+	struct ivtv *itv = to_ivtv(v4l2_dev);
+	struct ivtv_stream *s;
+	struct ivtv_open_id item;
+	int ret;
+
+	/* Instruct the CX2341[56] to start sending packets */
+	snd_ivtv_lock(itvsc);
+	s = &itv->streams[IVTV_ENC_STREAM_TYPE_PCM];
+
+	v4l2_fh_init(&item.fh, s->vdev);
+	item.itv = itv;
+	item.type = s->type;
+
+	/* See if the stream is available */
+	if (ivtv_claim_stream(&item, item.type)) {
+		/* No, it's already in use */
+		snd_ivtv_unlock(itvsc);
+		return -EBUSY;
+	}
+
+	if (test_bit(IVTV_F_S_STREAMOFF, &s->s_flags) ||
+	    test_and_set_bit(IVTV_F_S_STREAMING, &s->s_flags)) {
+		/* We're already streaming.  No additional action required */
+		snd_ivtv_unlock(itvsc);
+		return 0;
+	}
+
+
+	runtime->hw = snd_ivtv_hw_capture;
+	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
+	itvsc->capture_pcm_substream = substream;
+	runtime->private_data = itv;
+
+	itv->pcm_announce_callback = ivtv_alsa_announce_pcm_data;
+
+	/* Not currently streaming, so start it up */
+	set_bit(IVTV_F_S_STREAMING, &s->s_flags);
+	ret = ivtv_start_v4l2_encode_stream(s);
+	snd_ivtv_unlock(itvsc);
+
+	return ret;
+}
+
+static int snd_ivtv_pcm_capture_close(struct snd_pcm_substream *substream)
+{
+	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
+	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
+	struct ivtv *itv = to_ivtv(v4l2_dev);
+	struct ivtv_stream *s;
+
+	/* Instruct the ivtv to stop sending packets */
+	snd_ivtv_lock(itvsc);
+	s = &itv->streams[IVTV_ENC_STREAM_TYPE_PCM];
+	ivtv_stop_v4l2_encode_stream(s, 0);
+	clear_bit(IVTV_F_S_STREAMING, &s->s_flags);
+
+	ivtv_release_stream(s);
+
+	itv->pcm_announce_callback = NULL;
+	snd_ivtv_unlock(itvsc);
+
+	return 0;
+}
+
+static int snd_ivtv_pcm_ioctl(struct snd_pcm_substream *substream,
+		     unsigned int cmd, void *arg)
+{
+	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
+	int ret;
+
+	snd_ivtv_lock(itvsc);
+	ret = snd_pcm_lib_ioctl(substream, cmd, arg);
+	snd_ivtv_unlock(itvsc);
+	return ret;
+}
+
+
+static int snd_pcm_alloc_vmalloc_buffer(struct snd_pcm_substream *subs,
+					size_t size)
+{
+	struct snd_pcm_runtime *runtime = subs->runtime;
+
+	dprintk("Allocating vbuffer\n");
+	if (runtime->dma_area) {
+		if (runtime->dma_bytes > size)
+			return 0;
+
+		vfree(runtime->dma_area);
+	}
+	runtime->dma_area = vmalloc(size);
+	if (!runtime->dma_area)
+		return -ENOMEM;
+
+	runtime->dma_bytes = size;
+
+	return 0;
+}
+
+static int snd_ivtv_pcm_hw_params(struct snd_pcm_substream *substream,
+			 struct snd_pcm_hw_params *params)
+{
+	dprintk("%s called\n", __func__);
+
+	return snd_pcm_alloc_vmalloc_buffer(substream,
+					   params_buffer_bytes(params));
+}
+
+static int snd_ivtv_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
+	unsigned long flags;
+
+	spin_lock_irqsave(&itvsc->slock, flags);
+	if (substream->runtime->dma_area) {
+		dprintk("freeing pcm capture region\n");
+		vfree(substream->runtime->dma_area);
+		substream->runtime->dma_area = NULL;
+	}
+	spin_unlock_irqrestore(&itvsc->slock, flags);
+
+	return 0;
+}
+
+static int snd_ivtv_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
+
+	itvsc->hwptr_done_capture = 0;
+	itvsc->capture_transfer_done = 0;
+
+	return 0;
+}
+
+static int snd_ivtv_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	return 0;
+}
+
+static
+snd_pcm_uframes_t snd_ivtv_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	unsigned long flags;
+	snd_pcm_uframes_t hwptr_done;
+	struct snd_ivtv_card *itvsc = snd_pcm_substream_chip(substream);
+
+	spin_lock_irqsave(&itvsc->slock, flags);
+	hwptr_done = itvsc->hwptr_done_capture;
+	spin_unlock_irqrestore(&itvsc->slock, flags);
+
+	return hwptr_done;
+}
+
+static struct page *snd_pcm_get_vmalloc_page(struct snd_pcm_substream *subs,
+					     unsigned long offset)
+{
+	void *pageptr = subs->runtime->dma_area + offset;
+
+	return vmalloc_to_page(pageptr);
+}
+
+static struct snd_pcm_ops snd_ivtv_pcm_capture_ops = {
+	.open		= snd_ivtv_pcm_capture_open,
+	.close		= snd_ivtv_pcm_capture_close,
+	.ioctl		= snd_ivtv_pcm_ioctl,
+	.hw_params	= snd_ivtv_pcm_hw_params,
+	.hw_free	= snd_ivtv_pcm_hw_free,
+	.prepare	= snd_ivtv_pcm_prepare,
+	.trigger	= snd_ivtv_pcm_trigger,
+	.pointer	= snd_ivtv_pcm_pointer,
+	.page		= snd_pcm_get_vmalloc_page,
+};
+
+int snd_ivtv_pcm_create(struct snd_ivtv_card *itvsc)
+{
+	struct snd_pcm *sp;
+	struct snd_card *sc = itvsc->sc;
+	struct v4l2_device *v4l2_dev = itvsc->v4l2_dev;
+	struct ivtv *itv = to_ivtv(v4l2_dev);
+	int ret;
+
+	ret = snd_pcm_new(sc, "CX2341[56] PCM",
+			  0, /* PCM device 0, the only one for this card */
+			  0, /* 0 playback substreams */
+			  1, /* 1 capture substream */
+			  &sp);
+	if (ret) {
+		IVTV_ALSA_ERR("%s: snd_ivtv_pcm_create() failed with err %d\n",
+			      __func__, ret);
+		goto err_exit;
+	}
+
+	spin_lock_init(&itvsc->slock);
+
+	snd_pcm_set_ops(sp, SNDRV_PCM_STREAM_CAPTURE,
+			&snd_ivtv_pcm_capture_ops);
+	sp->info_flags = 0;
+	sp->private_data = itvsc;
+	strlcpy(sp->name, itv->card_name, sizeof(sp->name));
+
+	return 0;
+
+err_exit:
+	return ret;
+}

drivers/media/pci/ivtv/ivtv-alsa-pcm.h

@@ -0,0 +1,27 @@
+/*
+ *  ALSA PCM device 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
+ */
+
+int __init snd_ivtv_pcm_create(struct snd_ivtv_card *itvsc);
+
+/* Used by ivtv driver to announce the PCM data to the module */
+void ivtv_alsa_announce_pcm_data(struct snd_ivtv_card *card, u8 *pcm_data,
+				 size_t num_bytes);

drivers/media/pci/ivtv/ivtv-alsa.h

@@ -0,0 +1,75 @@
+/*
+ *  ALSA interface to ivtv PCM capture streams
+ *
+ *  Copyright (C) 2009,2012  Andy Walls <awalls@md.metrocast.net>
+ *  Copyright (C) 2009  Devin Heitmueller <dheitmueller@kernellabs.com>
+ *
+ *  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
+ */
+
+struct snd_card;
+
+struct snd_ivtv_card {
+	struct v4l2_device *v4l2_dev;
+	struct snd_card *sc;
+	unsigned int capture_transfer_done;
+	unsigned int hwptr_done_capture;
+	struct snd_pcm_substream *capture_pcm_substream;
+	spinlock_t slock;
+};
+
+extern int ivtv_alsa_debug;
+
+/*
+ * File operations that manipulate the encoder or video or audio subdevices
+ * need to be serialized.  Use the same lock we use for v4l2 file ops.
+ */
+static inline void snd_ivtv_lock(struct snd_ivtv_card *itvsc)
+{
+	struct ivtv *itv = to_ivtv(itvsc->v4l2_dev);
+	mutex_lock(&itv->serialize_lock);
+}
+
+static inline void snd_ivtv_unlock(struct snd_ivtv_card *itvsc)
+{
+	struct ivtv *itv = to_ivtv(itvsc->v4l2_dev);
+	mutex_unlock(&itv->serialize_lock);
+}
+
+#define IVTV_ALSA_DBGFLG_WARN  (1 << 0)
+#define IVTV_ALSA_DBGFLG_INFO  (1 << 1)
+
+#define IVTV_ALSA_DEBUG(x, type, fmt, args...) \
+	do { \
+		if ((x) & ivtv_alsa_debug) \
+			pr_info("%s-alsa: " type ": " fmt, \
+				v4l2_dev->name , ## args); \
+	} while (0)
+
+#define IVTV_ALSA_DEBUG_WARN(fmt, args...) \
+	IVTV_ALSA_DEBUG(IVTV_ALSA_DBGFLG_WARN, "warning", fmt , ## args)
+
+#define IVTV_ALSA_DEBUG_INFO(fmt, args...) \
+	IVTV_ALSA_DEBUG(IVTV_ALSA_DBGFLG_INFO, "info", fmt , ## args)
+
+#define IVTV_ALSA_ERR(fmt, args...) \
+	pr_err("%s-alsa: " fmt, v4l2_dev->name , ## args)
+
+#define IVTV_ALSA_WARN(fmt, args...) \
+	pr_warn("%s-alsa: " fmt, v4l2_dev->name , ## args)
+
+#define IVTV_ALSA_INFO(fmt, args...) \
+	pr_info("%s-alsa: " fmt, v4l2_dev->name , ## args)

drivers/media/pci/ivtv/ivtv-driver.c

@@ -68,6 +68,10 @@
    setting this to 1 you ensure that radio0 is now also radio1. */
 int ivtv_first_minor;
 
+/* Callback for registering extensions */
+int (*ivtv_ext_init)(struct ivtv *);
+EXPORT_SYMBOL(ivtv_ext_init);
+
 /* add your revision and whatnot here */
 static struct pci_device_id ivtv_pci_tbl[] __devinitdata = {
 	{PCI_VENDOR_ID_ICOMP, PCI_DEVICE_ID_IVTV15,
@@ -279,6 +283,34 @@ MODULE_LICENSE("GPL");
 
 MODULE_VERSION(IVTV_VERSION);
 
+#if defined(CONFIG_MODULES) && defined(MODULE)
+static void request_module_async(struct work_struct *work)
+{
+	struct ivtv *dev = container_of(work, struct ivtv, request_module_wk);
+
+	/* Make sure ivtv-alsa module is loaded */
+	request_module("ivtv-alsa");
+
+	/* Initialize ivtv-alsa for this instance of the cx18 device */
+	if (ivtv_ext_init != NULL)
+		ivtv_ext_init(dev);
+}
+
+static void request_modules(struct ivtv *dev)
+{
+	INIT_WORK(&dev->request_module_wk, request_module_async);
+	schedule_work(&dev->request_module_wk);
+}
+
+static void flush_request_modules(struct ivtv *dev)
+{
+	flush_work_sync(&dev->request_module_wk);
+}
+#else
+#define request_modules(dev)
+#define flush_request_modules(dev)
+#endif /* CONFIG_MODULES */
+
 void ivtv_clear_irq_mask(struct ivtv *itv, u32 mask)
 {
 	itv->irqmask &= ~mask;
@@ -1253,6 +1285,9 @@ static int __devinit ivtv_probe(struct pci_dev *pdev,
 		goto free_streams;
 	}
 	IVTV_INFO("Initialized card: %s\n", itv->card_name);
+
+	/* Load ivtv submodules (ivtv-alsa) */
+	request_modules(itv);
 	return 0;
 
 free_streams:
@@ -1380,6 +1415,8 @@ static void ivtv_remove(struct pci_dev *pdev)
 
 	IVTV_DEBUG_INFO("Removing card\n");
 
+	flush_request_modules(itv);
+
 	if (test_bit(IVTV_F_I_INITED, &itv->i_flags)) {
 		/* Stop all captures */
 		IVTV_DEBUG_INFO("Stopping all streams\n");

drivers/media/pci/ivtv/ivtv-driver.h

@@ -669,6 +669,13 @@ struct ivtv {
 	atomic_t capturing;		/* count number of active capture streams */
 	atomic_t decoding;		/* count number of active decoding streams */
 
+	/* ALSA interface for PCM capture stream */
+	struct snd_ivtv_card *alsa;
+	void (*pcm_announce_callback)(struct snd_ivtv_card *card, u8 *pcm_data,
+				      size_t num_bytes);
+
+	/* Used for ivtv-alsa module loading */
+	struct work_struct request_module_wk;
 
 	/* Interrupts & DMA */
 	u32 irqmask;                    /* active interrupts */
@@ -752,6 +759,9 @@ static inline struct ivtv *to_ivtv(struct v4l2_device *v4l2_dev)
 	return container_of(v4l2_dev, struct ivtv, v4l2_dev);
 }
 
+/* ivtv extensions to be loaded */
+extern int (*ivtv_ext_init)(struct ivtv *);
+
 /* Globals */
 extern int ivtv_first_minor;
 

drivers/media/pci/ivtv/ivtv-fileops.c

@@ -41,7 +41,7 @@
    associated VBI streams are also automatically claimed.
    Possible error returns: -EBUSY if someone else has claimed
    the stream or 0 on success. */
-static int ivtv_claim_stream(struct ivtv_open_id *id, int type)
+int ivtv_claim_stream(struct ivtv_open_id *id, int type)
 {
 	struct ivtv *itv = id->itv;
 	struct ivtv_stream *s = &itv->streams[type];
@@ -96,6 +96,7 @@ static int ivtv_claim_stream(struct ivtv_open_id *id, int type)
 	set_bit(IVTV_F_S_INTERNAL_USE, &s_vbi->s_flags);
 	return 0;
 }
+EXPORT_SYMBOL(ivtv_claim_stream);
 
 /* This function releases a previously claimed stream. It will take into
    account associated VBI streams. */
@@ -146,6 +147,7 @@ void ivtv_release_stream(struct ivtv_stream *s)
 	clear_bit(IVTV_F_S_CLAIMED, &s_vbi->s_flags);
 	ivtv_flush_queues(s_vbi);
 }
+EXPORT_SYMBOL(ivtv_release_stream);
 
 static void ivtv_dualwatch(struct ivtv *itv)
 {

drivers/media/pci/ivtv/ivtv-fileops.h

@@ -37,8 +37,8 @@ void ivtv_mute(struct ivtv *itv);
 void ivtv_unmute(struct ivtv *itv);
 
 /* Utilities */
-
-/* Release a previously claimed stream. */
+/* Shared with ivtv-alsa module */
+int ivtv_claim_stream(struct ivtv_open_id *id, int type);
 void ivtv_release_stream(struct ivtv_stream *s);
 
 #endif

drivers/media/pci/ivtv/ivtv-streams.c

@@ -629,6 +629,7 @@ int ivtv_start_v4l2_encode_stream(struct ivtv_stream *s)
 	atomic_inc(&itv->capturing);
 	return 0;
 }
+EXPORT_SYMBOL(ivtv_start_v4l2_encode_stream);
 
 static int ivtv_setup_v4l2_decode_stream(struct ivtv_stream *s)
 {
@@ -885,6 +886,7 @@ int ivtv_stop_v4l2_encode_stream(struct ivtv_stream *s, int gop_end)
 
 	return 0;
 }
+EXPORT_SYMBOL(ivtv_stop_v4l2_encode_stream);
 
 int ivtv_stop_v4l2_decode_stream(struct ivtv_stream *s, int flags, u64 pts)
 {