[media] media: Add stk1160 new driver (easycap replacement)

This driver adds support for stk1160 usb bridge as used in some
video/audio usb capture devices.
It is a complete rewrite of staging/media/easycap driver and
it's meant as a replacement.

As stk1160 allows communication with an ac97 codec chip, this
driver allows to register a control-only sound card to allow the user
to access ac97 controls.

Two devices have been used for testing:
* 1-cvbs video and 1-audio ac97 input,
* 4-cvbs inputs
Both of these devices reports with the same id [05e1:0408],
so the driver tries to support a superset of the capabilities.

By using keep_buffers module parameter it's possible to prevent
the driver from releasing urb buffers when streaming is stopped.
The usage of this parameter can avoid memory fragmentation that may
cause the driver to stop working on low memory systems.
A similar mechanism is implemented in em28xx driver (see commit 86d38d).
Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/Kconfig

@@ -748,6 +748,8 @@ source "drivers/media/video/tm6000/Kconfig"
 
 source "drivers/media/video/usbvision/Kconfig"
 
+source "drivers/media/video/stk1160/Kconfig"
+
 endif # V4L_USB_DRIVERS
 
 #

drivers/media/video/Makefile

@@ -126,6 +126,7 @@ obj-$(CONFIG_VIDEO_HEXIUM_ORION) += hexium_orion.o
 obj-$(CONFIG_VIDEO_HEXIUM_GEMINI) += hexium_gemini.o
 obj-$(CONFIG_STA2X11_VIP) += sta2x11_vip.o
 obj-$(CONFIG_VIDEO_TIMBERDALE)	+= timblogiw.o
+obj-$(CONFIG_VIDEO_STK1160) += stk1160/
 
 obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o
 obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o

drivers/media/video/stk1160/Kconfig

+config VIDEO_STK1160
+	tristate "STK1160 USB video capture support"
+	depends on VIDEO_DEV && I2C
+	select VIDEOBUF2_VMALLOC
+	select VIDEO_SAA711X
+
+	---help---
+	  This is a video4linux driver for STK1160 based video capture devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called stk1160
+
+config VIDEO_STK1160_AC97
+	bool "STK1160 AC97 codec support"
+	depends on VIDEO_STK1160 && SND
+	select SND_AC97_CODEC
+
+	---help---
+	  Enables AC97 codec support for stk1160 driver.
+.

drivers/media/video/stk1160/Makefile

+obj-stk1160-ac97-$(CONFIG_VIDEO_STK1160_AC97) := stk1160-ac97.o
+
+stk1160-y := 	stk1160-core.o \
+		stk1160-v4l.o \
+		stk1160-video.o \
+		stk1160-i2c.o \
+		$(obj-stk1160-ac97-y)
+
+obj-$(CONFIG_VIDEO_STK1160) += stk1160.o
+
+ccflags-y += -Idrivers/media/video

drivers/media/video/stk1160/stk1160-ac97.c

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/ac97_codec.h>
+
+#include "stk1160.h"
+#include "stk1160-reg.h"
+
+static struct snd_ac97 *stk1160_ac97;
+
+static void stk1160_write_ac97(struct snd_ac97 *ac97, u16 reg, u16 value)
+{
+	struct stk1160 *dev = ac97->private_data;
+
+	/* Set codec register address */
+	stk1160_write_reg(dev, STK1160_AC97_ADDR, reg);
+
+	/* Set codec command */
+	stk1160_write_reg(dev, STK1160_AC97_CMD, value & 0xff);
+	stk1160_write_reg(dev, STK1160_AC97_CMD + 1, (value & 0xff00) >> 8);
+
+	/*
+	 * Set command write bit to initiate write operation.
+	 * The bit will be cleared when transfer is done.
+	 */
+	stk1160_write_reg(dev, STK1160_AC97CTL_0, 0x8c);
+}
+
+static u16 stk1160_read_ac97(struct snd_ac97 *ac97, u16 reg)
+{
+	struct stk1160 *dev = ac97->private_data;
+	u8 vall = 0;
+	u8 valh = 0;
+
+	/* Set codec register address */
+	stk1160_write_reg(dev, STK1160_AC97_ADDR, reg);
+
+	/*
+	 * Set command read bit to initiate read operation.
+	 * The bit will be cleared when transfer is done.
+	 */
+	stk1160_write_reg(dev, STK1160_AC97CTL_0, 0x8b);
+
+	/* Retrieve register value */
+	stk1160_read_reg(dev, STK1160_AC97_CMD, &vall);
+	stk1160_read_reg(dev, STK1160_AC97_CMD + 1, &valh);
+
+	return (valh << 8) | vall;
+}
+
+static void stk1160_reset_ac97(struct snd_ac97 *ac97)
+{
+	struct stk1160 *dev = ac97->private_data;
+	/* Two-step reset AC97 interface and hardware codec */
+	stk1160_write_reg(dev, STK1160_AC97CTL_0, 0x94);
+	stk1160_write_reg(dev, STK1160_AC97CTL_0, 0x88);
+
+	/* Set 16-bit audio data and choose L&R channel*/
+	stk1160_write_reg(dev, STK1160_AC97CTL_1 + 2, 0x01);
+}
+
+static struct snd_ac97_bus_ops stk1160_ac97_ops = {
+	.read	= stk1160_read_ac97,
+	.write	= stk1160_write_ac97,
+	.reset	= stk1160_reset_ac97,
+};
+
+int stk1160_ac97_register(struct stk1160 *dev)
+{
+	struct snd_card *card = NULL;
+	struct snd_ac97_bus *ac97_bus;
+	struct snd_ac97_template ac97_template;
+	int rc;
+
+	/*
+	 * Just want a card to access ac96 controls,
+	 * the actual capture interface will be handled by snd-usb-audio
+	 */
+	rc = snd_card_create(SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1,
+			      THIS_MODULE, 0, &card);
+	if (rc < 0)
+		return rc;
+
+	snd_card_set_dev(card, dev->dev);
+
+	/* TODO: I'm not sure where should I get these names :-( */
+	snprintf(card->shortname, sizeof(card->shortname),
+		 "stk1160-mixer");
+	snprintf(card->longname, sizeof(card->longname),
+		 "stk1160 ac97 codec mixer control");
+	strncpy(card->driver, dev->dev->driver->name, sizeof(card->driver));
+
+	rc = snd_ac97_bus(card, 0, &stk1160_ac97_ops, NULL, &ac97_bus);
+	if (rc)
+		goto err;
+
+	/* We must set private_data before calling snd_ac97_mixer */
+	memset(&ac97_template, 0, sizeof(ac97_template));
+	ac97_template.private_data = dev;
+	ac97_template.scaps = AC97_SCAP_SKIP_MODEM;
+	rc = snd_ac97_mixer(ac97_bus, &ac97_template, &stk1160_ac97);
+	if (rc)
+		goto err;
+
+	dev->snd_card = card;
+	rc = snd_card_register(card);
+	if (rc)
+		goto err;
+
+	return 0;
+
+err:
+	dev->snd_card = NULL;
+	if (card)
+		snd_card_free(card);
+	return rc;
+}
+
+int stk1160_ac97_unregister(struct stk1160 *dev)
+{
+	struct snd_card *card = dev->snd_card;
+
+	/*
+	 * We need to check usb_device,
+	 * because ac97 release attempts to communicate with codec
+	 */
+	if (card && dev->udev)
+		snd_card_free(card);
+
+	return 0;
+}

drivers/media/video/stk1160/stk1160-core.c

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ * TODO:
+ *
+ * 1. (Try to) detect if we must register ac97 mixer
+ * 2. Support stream at lower speed: lower frame rate or lower frame size.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+#include <linux/usb.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <media/saa7115.h>
+
+#include "stk1160.h"
+#include "stk1160-reg.h"
+
+static unsigned int input;
+module_param(input, int, 0644);
+MODULE_PARM_DESC(input, "Set default input");
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ezequiel Garcia");
+MODULE_DESCRIPTION("STK1160 driver");
+
+/* Devices supported by this driver */
+static struct usb_device_id stk1160_id_table[] = {
+	{ USB_DEVICE(0x05e1, 0x0408) },
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, stk1160_id_table);
+
+/* saa7113 I2C address */
+static unsigned short saa7113_addrs[] = {
+	0x4a >> 1,
+	I2C_CLIENT_END
+};
+
+/*
+ * Read/Write stk registers
+ */
+int stk1160_read_reg(struct stk1160 *dev, u16 reg, u8 *value)
+{
+	int ret;
+	int pipe = usb_rcvctrlpipe(dev->udev, 0);
+
+	*value = 0;
+	ret = usb_control_msg(dev->udev, pipe, 0x00,
+			USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			0x00, reg, value, sizeof(u8), HZ);
+	if (ret < 0) {
+		stk1160_err("read failed on reg 0x%x (%d)\n",
+			reg, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+int stk1160_write_reg(struct stk1160 *dev, u16 reg, u16 value)
+{
+	int ret;
+	int pipe = usb_sndctrlpipe(dev->udev, 0);
+
+	ret =  usb_control_msg(dev->udev, pipe, 0x01,
+			USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			value, reg, NULL, 0, HZ);
+	if (ret < 0) {
+		stk1160_err("write failed on reg 0x%x (%d)\n",
+			reg, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+void stk1160_select_input(struct stk1160 *dev)
+{
+	static const u8 gctrl[] = {
+		0x98, 0x90, 0x88, 0x80
+	};
+
+	if (dev->ctl_input < ARRAY_SIZE(gctrl))
+		stk1160_write_reg(dev, STK1160_GCTRL, gctrl[dev->ctl_input]);
+}
+
+/* TODO: We should break this into pieces */
+static void stk1160_reg_reset(struct stk1160 *dev)
+{
+	int i;
+
+	static const struct regval ctl[] = {
+		{STK1160_GCTRL+2, 0x0078},
+
+		{STK1160_RMCTL+1, 0x0000},
+		{STK1160_RMCTL+3, 0x0002},
+
+		{STK1160_PLLSO,   0x0010},
+		{STK1160_PLLSO+1, 0x0000},
+		{STK1160_PLLSO+2, 0x0014},
+		{STK1160_PLLSO+3, 0x000E},
+
+		{STK1160_PLLFD,   0x0046},
+
+		/* Timing generator setup */
+		{STK1160_TIGEN,   0x0012},
+		{STK1160_TICTL,   0x002D},
+		{STK1160_TICTL+1, 0x0001},
+		{STK1160_TICTL+2, 0x0000},
+		{STK1160_TICTL+3, 0x0000},
+		{STK1160_TIGEN,   0x0080},
+
+		{0xffff, 0xffff}
+	};
+
+	for (i = 0; ctl[i].reg != 0xffff; i++)
+		stk1160_write_reg(dev, ctl[i].reg, ctl[i].val);
+}
+
+static void stk1160_release(struct v4l2_device *v4l2_dev)
+{
+	struct stk1160 *dev = container_of(v4l2_dev, struct stk1160, v4l2_dev);
+
+	stk1160_info("releasing all resources\n");
+
+	stk1160_i2c_unregister(dev);
+
+	v4l2_ctrl_handler_free(&dev->ctrl_handler);
+	v4l2_device_unregister(&dev->v4l2_dev);
+	kfree(dev->alt_max_pkt_size);
+	kfree(dev);
+}
+
+/* high bandwidth multiplier, as encoded in highspeed endpoint descriptors */
+#define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
+
+/*
+ * Scan usb interface and populate max_pkt_size array
+ * with information on each alternate setting.
+ * The array should be allocated by the caller.
+ */
+static int stk1160_scan_usb(struct usb_interface *intf, struct usb_device *udev,
+		unsigned int *max_pkt_size)
+{
+	int i, e, sizedescr, size, ifnum;
+	const struct usb_endpoint_descriptor *desc;
+
+	bool has_video = false, has_audio = false;
+	const char *speed;
+
+	ifnum = intf->altsetting[0].desc.bInterfaceNumber;
+
+	/* Get endpoints */
+	for (i = 0; i < intf->num_altsetting; i++) {
+
+		for (e = 0; e < intf->altsetting[i].desc.bNumEndpoints; e++) {
+
+			/* This isn't clear enough, at least to me */
+			desc = &intf->altsetting[i].endpoint[e].desc;
+			sizedescr = le16_to_cpu(desc->wMaxPacketSize);
+			size = sizedescr & 0x7ff;
+
+			if (udev->speed == USB_SPEED_HIGH)
+				size = size * hb_mult(sizedescr);
+
+			if (usb_endpoint_xfer_isoc(desc) &&
+			    usb_endpoint_dir_in(desc)) {
+				switch (desc->bEndpointAddress) {
+				case STK1160_EP_AUDIO:
+					has_audio = true;
+					break;
+				case STK1160_EP_VIDEO:
+					has_video = true;
+					max_pkt_size[i] = size;
+					break;
+				}
+			}
+		}
+	}
+
+	/* Is this even possible? */
+	if (!(has_audio || has_video)) {
+		dev_err(&udev->dev, "no audio or video endpoints found\n");
+		return -ENODEV;
+	}
+
+	switch (udev->speed) {
+	case USB_SPEED_LOW:
+		speed = "1.5";
+		break;
+	case USB_SPEED_FULL:
+		speed = "12";
+		break;
+	case USB_SPEED_HIGH:
+		speed = "480";
+		break;
+	default:
+		speed = "unknown";
+	}
+
+	dev_info(&udev->dev, "New device %s %s @ %s Mbps (%04x:%04x, interface %d, class %d)\n",
+		udev->manufacturer ? udev->manufacturer : "",
+		udev->product ? udev->product : "",
+		speed,
+		le16_to_cpu(udev->descriptor.idVendor),
+		le16_to_cpu(udev->descriptor.idProduct),
+		ifnum,
+		intf->altsetting->desc.bInterfaceNumber);
+
+	/* This should never happen, since we rejected audio interfaces */
+	if (has_audio)
+		dev_warn(&udev->dev, "audio interface %d found.\n\
+				This is not implemented by this driver,\
+				you should use snd-usb-audio instead\n", ifnum);
+
+	if (has_video)
+		dev_info(&udev->dev, "video interface %d found\n",
+				ifnum);
+
+	/*
+	 * Make sure we have 480 Mbps of bandwidth, otherwise things like
+	 * video stream wouldn't likely work, since 12 Mbps is generally
+	 * not enough even for most streams.
+	 */
+	if (udev->speed != USB_SPEED_HIGH)
+		dev_warn(&udev->dev, "must be connected to a high-speed USB 2.0 port\n\
+				You may not be able to stream video smoothly\n");
+
+	return 0;
+}
+
+static int stk1160_probe(struct usb_interface *interface,
+		const struct usb_device_id *id)
+{
+	int ifnum;
+	int rc = 0;
+
+	unsigned int *alt_max_pkt_size;	/* array of wMaxPacketSize */
+	struct usb_device *udev;
+	struct stk1160 *dev;
+
+	ifnum = interface->altsetting[0].desc.bInterfaceNumber;
+	udev = interface_to_usbdev(interface);
+
+	/*
+	 * Since usb audio class is supported by snd-usb-audio,
+	 * we reject audio interface.
+	 */
+	if (interface->altsetting[0].desc.bInterfaceClass == USB_CLASS_AUDIO)
+		return -ENODEV;
+
+	/* Alloc an array for all possible max_pkt_size */
+	alt_max_pkt_size = kmalloc(sizeof(alt_max_pkt_size[0]) *
+			interface->num_altsetting, GFP_KERNEL);
+	if (alt_max_pkt_size == NULL)
+		return -ENOMEM;
+
+	/*
+	 * Scan usb posibilities and populate alt_max_pkt_size array.
+	 * Also, check if device speed is fast enough.
+	 */
+	rc = stk1160_scan_usb(interface, udev, alt_max_pkt_size);
+	if (rc < 0) {
+		kfree(alt_max_pkt_size);
+		return rc;
+	}
+
+	dev = kzalloc(sizeof(struct stk1160), GFP_KERNEL);
+	if (dev == NULL) {
+		kfree(alt_max_pkt_size);
+		return -ENOMEM;
+	}
+
+	dev->alt_max_pkt_size = alt_max_pkt_size;
+	dev->udev = udev;
+	dev->num_alt = interface->num_altsetting;
+	dev->ctl_input = input;
+
+	/* We save struct device for debug purposes only */
+	dev->dev = &interface->dev;
+
+	usb_set_intfdata(interface, dev);
+
+	/* initialize videobuf2 stuff */
+	rc = stk1160_vb2_setup(dev);
+	if (rc < 0)
+		goto free_err;
+
+	/*
+	 * There is no need to take any locks here in probe
+	 * because we register the device node as the *last* thing.
+	 */
+	spin_lock_init(&dev->buf_lock);
+	mutex_init(&dev->v4l_lock);
+	mutex_init(&dev->vb_queue_lock);
+
+	rc = v4l2_ctrl_handler_init(&dev->ctrl_handler, 0);
+	if (rc) {
+		stk1160_err("v4l2_ctrl_handler_init failed (%d)\n", rc);
+		goto free_err;
+	}
+
+	/*
+	 * We obtain a v4l2_dev but defer
+	 * registration of video device node as the last thing.
+	 * There is no need to set the name if we give a device struct
+	 */
+	dev->v4l2_dev.release = stk1160_release;
+	dev->v4l2_dev.ctrl_handler = &dev->ctrl_handler;
+	rc = v4l2_device_register(dev->dev, &dev->v4l2_dev);
+	if (rc) {
+		stk1160_err("v4l2_device_register failed (%d)\n", rc);
+		goto free_ctrl;
+	}
+
+	rc = stk1160_i2c_register(dev);
+	if (rc < 0)
+		goto unreg_v4l2;
+
+	/*
+	 * To the best of my knowledge stk1160 boards only have
+	 * saa7113, but it doesn't hurt to support them all.
+	 */
+	dev->sd_saa7115 = v4l2_i2c_new_subdev(&dev->v4l2_dev, &dev->i2c_adap,
+		"saa7115_auto", 0, saa7113_addrs);
+
+	stk1160_info("driver ver %s successfully loaded\n",
+		STK1160_VERSION);
+
+	/* i2c reset saa711x */
+	v4l2_device_call_all(&dev->v4l2_dev, 0, core, reset, 0);
+	v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_routing,
+				0, 0, 0);
+	v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_stream, 0);
+
+	/* reset stk1160 to default values */
+	stk1160_reg_reset(dev);
+
+	/* select default input */
+	stk1160_select_input(dev);
+
+	stk1160_ac97_register(dev);
+
+	rc = stk1160_video_register(dev);
+	if (rc < 0)
+		goto unreg_i2c;
+
+	return 0;
+
+unreg_i2c:
+	stk1160_i2c_unregister(dev);
+unreg_v4l2:
+	v4l2_device_unregister(&dev->v4l2_dev);
+free_ctrl:
+	v4l2_ctrl_handler_free(&dev->ctrl_handler);
+free_err:
+	kfree(alt_max_pkt_size);
+	kfree(dev);
+
+	return rc;
+}
+
+static void stk1160_disconnect(struct usb_interface *interface)
+{
+	struct stk1160 *dev;
+
+	dev = usb_get_intfdata(interface);
+	usb_set_intfdata(interface, NULL);
+
+	/*
+	 * Wait until all current v4l2 operation are finished
+	 * then deallocate resources
+	 */
+	mutex_lock(&dev->vb_queue_lock);
+	mutex_lock(&dev->v4l_lock);
+
+	/* Here is the only place where isoc get released */
+	stk1160_uninit_isoc(dev);
+
+	/* ac97 unregister needs to be done before usb_device is cleared */
+	stk1160_ac97_unregister(dev);
+
+	stk1160_clear_queue(dev);
+
+	video_unregister_device(&dev->vdev);
+	v4l2_device_disconnect(&dev->v4l2_dev);
+
+	/* This way current users can detect device is gone */
+	dev->udev = NULL;
+
+	mutex_unlock(&dev->v4l_lock);
+	mutex_unlock(&dev->vb_queue_lock);
+
+	/*
+	 * This calls stk1160_release if it's the last reference.
+	 * therwise, release is posponed until there are no users left.
+	 */
+	v4l2_device_put(&dev->v4l2_dev);
+}
+
+static struct usb_driver stk1160_usb_driver = {
+	.name = "stk1160",
+	.id_table = stk1160_id_table,
+	.probe = stk1160_probe,
+	.disconnect = stk1160_disconnect,
+};
+
+module_usb_driver(stk1160_usb_driver);

drivers/media/video/stk1160/stk1160-i2c.c

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/i2c.h>
+
+#include "stk1160.h"
+#include "stk1160-reg.h"
+
+static unsigned int i2c_debug;
+module_param(i2c_debug, int, 0644);
+MODULE_PARM_DESC(i2c_debug, "enable debug messages [i2c]");
+
+#define dprintk_i2c(fmt, args...)				\
+do {								\
+	if (i2c_debug)						\
+		printk(KERN_DEBUG fmt, ##args);			\
+} while (0)
+
+static int stk1160_i2c_busy_wait(struct stk1160 *dev, u8 wait_bit_mask)
+{
+	unsigned long end;
+	u8 flag;
+
+	/* Wait until read/write finish bit is set */
+	end = jiffies + msecs_to_jiffies(STK1160_I2C_TIMEOUT);
+	while (time_is_after_jiffies(end)) {
+
+		stk1160_read_reg(dev, STK1160_SICTL+1, &flag);
+		/* read/write done? */
+		if (flag & wait_bit_mask)
+			goto done;
+
+		usleep_range(10 * USEC_PER_MSEC, 20 * USEC_PER_MSEC);
+	}
+
+	return -ETIMEDOUT;
+
+done:
+	return 0;
+}
+
+static int stk1160_i2c_write_reg(struct stk1160 *dev, u8 addr,
+		u8 reg, u8 value)
+{
+	int rc;
+
+	/* Set serial device address */
+	rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
+	if (rc < 0)
+		return rc;
+
+	/* Set i2c device register sub-address */
+	rc = stk1160_write_reg(dev, STK1160_SBUSW_WA, reg);
+	if (rc < 0)
+		return rc;
+
+	/* Set i2c device register value */
+	rc = stk1160_write_reg(dev, STK1160_SBUSW_WD, value);
+	if (rc < 0)
+		return rc;
+
+	/* Start write now */
+	rc = stk1160_write_reg(dev, STK1160_SICTL, 0x01);
+	if (rc < 0)
+		return rc;
+
+	rc = stk1160_i2c_busy_wait(dev, 0x04);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+static int stk1160_i2c_read_reg(struct stk1160 *dev, u8 addr,
+		u8 reg, u8 *value)
+{
+	int rc;
+
+	/* Set serial device address */
+	rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
+	if (rc < 0)
+		return rc;
+
+	/* Set i2c device register sub-address */
+	rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, reg);
+	if (rc < 0)
+		return rc;
+
+	/* Start read now */
+	rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
+	if (rc < 0)
+		return rc;
+
+	rc = stk1160_i2c_busy_wait(dev, 0x01);
+	if (rc < 0)
+		return rc;
+
+	stk1160_read_reg(dev, STK1160_SBUSR_RD, value);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+/*
+ * stk1160_i2c_check_for_device()
+ * check if there is a i2c_device at the supplied address
+ */
+static int stk1160_i2c_check_for_device(struct stk1160 *dev,
+		unsigned char addr)
+{
+	int rc;
+
+	/* Set serial device address */
+	rc = stk1160_write_reg(dev, STK1160_SICTL_SDA, addr);
+	if (rc < 0)
+		return rc;
+
+	/* Set device sub-address, we'll chip version reg */
+	rc = stk1160_write_reg(dev, STK1160_SBUSR_RA, 0x00);
+	if (rc < 0)
+		return rc;
+
+	/* Start read now */
+	rc = stk1160_write_reg(dev, STK1160_SICTL, 0x20);
+	if (rc < 0)
+		return rc;
+
+	rc = stk1160_i2c_busy_wait(dev, 0x01);
+	if (rc < 0)
+		return -ENODEV;
+
+	return 0;
+}
+
+/*
+ * stk1160_i2c_xfer()
+ * the main i2c transfer function
+ */
+static int stk1160_i2c_xfer(struct i2c_adapter *i2c_adap,
+			   struct i2c_msg msgs[], int num)
+{
+	struct stk1160 *dev = i2c_adap->algo_data;
+	int addr, rc, i;
+
+	for (i = 0; i < num; i++) {
+		addr = msgs[i].addr << 1;
+		dprintk_i2c("%s: addr=%x", __func__, addr);
+
+		if (!msgs[i].len) {
+			/* no len: check only for device presence */
+			rc = stk1160_i2c_check_for_device(dev, addr);
+			if (rc < 0) {
+				dprintk_i2c(" no device\n");
+				return rc;
+			}
+
+		} else if (msgs[i].flags & I2C_M_RD) {
+			/* read request without preceding register selection */
+			dprintk_i2c(" subaddr not selected");
+			rc = -EOPNOTSUPP;
+			goto err;
+
+		} else if (i + 1 < num && msgs[i].len <= 2 &&
+			   (msgs[i + 1].flags & I2C_M_RD) &&
+			   msgs[i].addr == msgs[i + 1].addr) {
+
+			if (msgs[i].len != 1 || msgs[i + 1].len != 1) {
+				dprintk_i2c(" len not supported");
+				rc = -EOPNOTSUPP;
+				goto err;
+			}
+
+			dprintk_i2c(" subaddr=%x", msgs[i].buf[0]);
+
+			rc = stk1160_i2c_read_reg(dev, addr, msgs[i].buf[0],
+				msgs[i + 1].buf);
+
+			dprintk_i2c(" read=%x", *msgs[i + 1].buf);
+
+			/* consumed two msgs, so we skip one of them */
+			i++;
+
+		} else {
+			if (msgs[i].len != 2) {
+				dprintk_i2c(" len not supported");
+				rc = -EOPNOTSUPP;
+				goto err;
+			}
+
+			dprintk_i2c(" subaddr=%x write=%x",
+				msgs[i].buf[0],  msgs[i].buf[1]);
+
+			rc = stk1160_i2c_write_reg(dev, addr, msgs[i].buf[0],
+				msgs[i].buf[1]);
+		}
+
+		if (rc < 0)
+			goto err;
+		dprintk_i2c(" OK\n");
+	}
+
+	return num;
+err:
+	dprintk_i2c(" ERROR: %d\n", rc);
+	return num;
+}
+
+/*
+ * functionality(), what da heck is this?
+ */
+static u32 functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm algo = {
+	.master_xfer   = stk1160_i2c_xfer,
+	.functionality = functionality,
+};
+
+static struct i2c_adapter adap_template = {
+	.owner = THIS_MODULE,
+	.name = "stk1160",
+	.algo = &algo,
+};
+
+static struct i2c_client client_template = {
+	.name = "stk1160 internal",
+};
+
+/*
+ * stk1160_i2c_register()
+ * register i2c bus
+ */
+int stk1160_i2c_register(struct stk1160 *dev)
+{
+	int rc;
+
+	dev->i2c_adap = adap_template;
+	dev->i2c_adap.dev.parent = dev->dev;
+	strcpy(dev->i2c_adap.name, "stk1160");
+	dev->i2c_adap.algo_data = dev;
+
+	i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
+
+	rc = i2c_add_adapter(&dev->i2c_adap);
+	if (rc < 0) {
+		stk1160_err("cannot add i2c adapter (%d)\n", rc);
+		return rc;
+	}
+
+	dev->i2c_client = client_template;
+	dev->i2c_client.adapter = &dev->i2c_adap;
+
+	/* Set i2c clock divider device address */
+	stk1160_write_reg(dev, STK1160_SICTL_CD,  0x0f);
+
+	/* ??? */
+	stk1160_write_reg(dev, STK1160_ASIC + 3,  0x00);
+
+	return 0;
+}
+
+/*
+ * stk1160_i2c_unregister()
+ * unregister i2c_bus
+ */
+int stk1160_i2c_unregister(struct stk1160 *dev)
+{
+	i2c_del_adapter(&dev->i2c_adap);
+	return 0;
+}

drivers/media/video/stk1160/stk1160-reg.h

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ */
+
+/* GPIO Control */
+#define STK1160_GCTRL			0x000
+
+/* Remote Wakup Control */
+#define STK1160_RMCTL			0x00c
+
+/*
+ * Decoder Control Register:
+ * This byte controls capture start/stop
+ * with bit #7 (0x?? OR 0x80 to activate).
+ */
+#define STK1160_DCTRL			0x100
+
+/* Capture Frame Start Position */
+#define STK116_CFSPO			0x110
+#define STK116_CFSPO_STX_L		0x110
+#define STK116_CFSPO_STX_H		0x111
+#define STK116_CFSPO_STY_L		0x112
+#define STK116_CFSPO_STY_H		0x113
+
+/* Capture Frame End Position */
+#define STK116_CFEPO			0x114
+#define STK116_CFEPO_ENX_L		0x114
+#define STK116_CFEPO_ENX_H		0x115
+#define STK116_CFEPO_ENY_L		0x116
+#define STK116_CFEPO_ENY_H		0x117
+
+/* Serial Interface Control  */
+#define STK1160_SICTL			0x200
+#define STK1160_SICTL_CD		0x202
+#define STK1160_SICTL_SDA		0x203
+
+/* Serial Bus Write */
+#define STK1160_SBUSW			0x204
+#define STK1160_SBUSW_WA		0x204
+#define STK1160_SBUSW_WD		0x205
+
+/* Serial Bus Read */
+#define STK1160_SBUSR			0x208
+#define STK1160_SBUSR_RA		0x208
+#define STK1160_SBUSR_RD		0x209
+
+/* Alternate Serial Inteface Control */
+#define STK1160_ASIC			0x2fc
+
+/* PLL Select Options */
+#define STK1160_PLLSO			0x018
+
+/* PLL Frequency Divider */
+#define STK1160_PLLFD			0x01c
+
+/* Timing Generator */
+#define STK1160_TIGEN			0x300
+
+/* Timing Control Parameter */
+#define STK1160_TICTL			0x350
+
+/* AC97 Audio Control */
+#define STK1160_AC97CTL_0		0x500
+#define STK1160_AC97CTL_1		0x504
+
+/* Use [0:6] bits of register 0x504 to set codec command address */
+#define STK1160_AC97_ADDR		0x504
+/* Use [16:31] bits of register 0x500 to set codec command data */
+#define STK1160_AC97_CMD		0x502
+
+/* Audio I2S Interface */
+#define STK1160_I2SCTL			0x50c
+
+/* EEPROM Interface */
+#define STK1160_EEPROM_SZ		0x5f0

drivers/media/video/stk1160/stk1160-v4l.c

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+#include <linux/videodev2.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-common.h>
+#include <media/v4l2-ioctl.h>
+#include <media/v4l2-fh.h>
+#include <media/v4l2-event.h>
+#include <media/v4l2-chip-ident.h>
+#include <media/videobuf2-vmalloc.h>
+
+#include <media/saa7115.h>
+
+#include "stk1160.h"
+#include "stk1160-reg.h"
+
+static unsigned int vidioc_debug;
+module_param(vidioc_debug, int, 0644);
+MODULE_PARM_DESC(vidioc_debug, "enable debug messages [vidioc]");
+
+static bool keep_buffers;
+module_param(keep_buffers, bool, 0644);
+MODULE_PARM_DESC(keep_buffers, "don't release buffers upon stop streaming");
+
+/* supported video standards */
+static struct stk1160_fmt format[] = {
+	{
+		.name     = "16 bpp YUY2, 4:2:2, packed",
+		.fourcc   = V4L2_PIX_FMT_UYVY,
+		.depth    = 16,
+	}
+};
+
+static void stk1160_set_std(struct stk1160 *dev)
+{
+	int i;
+
+	static struct regval std525[] = {
+
+		/* 720x480 */
+
+		/* Frame start */
+		{STK116_CFSPO_STX_L, 0x0000},
+		{STK116_CFSPO_STX_H, 0x0000},
+		{STK116_CFSPO_STY_L, 0x0003},
+		{STK116_CFSPO_STY_H, 0x0000},
+
+		/* Frame end */
+		{STK116_CFEPO_ENX_L, 0x05a0},
+		{STK116_CFEPO_ENX_H, 0x0005},
+		{STK116_CFEPO_ENY_L, 0x00f3},
+		{STK116_CFEPO_ENY_H, 0x0000},
+
+		{0xffff, 0xffff}
+	};
+
+	static struct regval std625[] = {
+
+		/* 720x576 */
+
+		/* TODO: Each line of frame has some junk at the end */
+		/* Frame start */
+		{STK116_CFSPO,   0x0000},
+		{STK116_CFSPO+1, 0x0000},
+		{STK116_CFSPO+2, 0x0001},
+		{STK116_CFSPO+3, 0x0000},
+
+		/* Frame end */
+		{STK116_CFEPO,   0x05a0},
+		{STK116_CFEPO+1, 0x0005},
+		{STK116_CFEPO+2, 0x0121},
+		{STK116_CFEPO+3, 0x0001},
+
+		{0xffff, 0xffff}
+	};
+
+	if (dev->norm & V4L2_STD_525_60) {
+		stk1160_dbg("registers to NTSC like standard\n");
+		for (i = 0; std525[i].reg != 0xffff; i++)
+			stk1160_write_reg(dev, std525[i].reg, std525[i].val);
+	} else {
+		stk1160_dbg("registers to PAL like standard\n");
+		for (i = 0; std625[i].reg != 0xffff; i++)
+			stk1160_write_reg(dev, std625[i].reg, std625[i].val);
+	}
+
+}
+
+/*
+ * Set a new alternate setting.
+ * Returns true is dev->max_pkt_size has changed, false otherwise.
+ */
+static bool stk1160_set_alternate(struct stk1160 *dev)
+{
+	int i, prev_alt = dev->alt;
+	unsigned int min_pkt_size;
+	bool new_pkt_size;
+
+	/*
+	 * If we don't set right alternate,
+	 * then we will get a green screen with junk.
+	 */
+	min_pkt_size = STK1160_MIN_PKT_SIZE;
+
+	for (i = 0; i < dev->num_alt; i++) {
+		/* stop when the selected alt setting offers enough bandwidth */
+		if (dev->alt_max_pkt_size[i] >= min_pkt_size) {
+			dev->alt = i;
+			break;
+		/*
+		 * otherwise make sure that we end up with the maximum bandwidth
+		 * because the min_pkt_size equation might be wrong...
+		 */
+		} else if (dev->alt_max_pkt_size[i] >
+			   dev->alt_max_pkt_size[dev->alt])
+			dev->alt = i;
+	}
+
+	stk1160_info("setting alternate %d\n", dev->alt);
+
+	if (dev->alt != prev_alt) {
+		stk1160_dbg("minimum isoc packet size: %u (alt=%d)\n",
+				min_pkt_size, dev->alt);
+		stk1160_dbg("setting alt %d with wMaxPacketSize=%u\n",
+			       dev->alt, dev->alt_max_pkt_size[dev->alt]);
+		usb_set_interface(dev->udev, 0, dev->alt);
+	}
+
+	new_pkt_size = dev->max_pkt_size != dev->alt_max_pkt_size[dev->alt];
+	dev->max_pkt_size = dev->alt_max_pkt_size[dev->alt];
+
+	return new_pkt_size;
+}
+
+static int stk1160_start_streaming(struct stk1160 *dev)
+{
+	int i, rc;
+	bool new_pkt_size;
+
+	/* Check device presence */
+	if (!dev->udev)
+		return -ENODEV;
+
+	if (mutex_lock_interruptible(&dev->v4l_lock))
+		return -ERESTARTSYS;
+	/*
+	 * For some reason it is mandatory to set alternate *first*
+	 * and only *then* initialize isoc urbs.
+	 * Someone please explain me why ;)
+	 */
+	new_pkt_size = stk1160_set_alternate(dev);
+
+	/*
+	 * We (re)allocate isoc urbs if:
+	 * there is no allocated isoc urbs, OR
+	 * a new dev->max_pkt_size is detected
+	 */
+	if (!dev->isoc_ctl.num_bufs || new_pkt_size) {
+		rc = stk1160_alloc_isoc(dev);
+		if (rc < 0)
+			return rc;
+	}
+
+	/* submit urbs and enables IRQ */
+	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
+		rc = usb_submit_urb(dev->isoc_ctl.urb[i], GFP_KERNEL);
+		if (rc) {
+			stk1160_err("cannot submit urb[%d] (%d)\n", i, rc);
+			stk1160_uninit_isoc(dev);
+			return rc;
+		}
+	}
+
+	/* Start saa711x */
+	v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_stream, 1);
+
+	/* Start stk1160 */
+	stk1160_write_reg(dev, STK1160_DCTRL, 0xb3);
+	stk1160_write_reg(dev, STK1160_DCTRL+3, 0x00);
+
+	stk1160_dbg("streaming started\n");
+
+	mutex_unlock(&dev->v4l_lock);
+
+	return 0;
+}
+
+/* Must be called with v4l_lock hold */
+static void stk1160_stop_hw(struct stk1160 *dev)
+{
+	/* If the device is not physically present, there is nothing to do */
+	if (!dev->udev)
+		return;
+
+	/* set alternate 0 */
+	dev->alt = 0;
+	stk1160_info("setting alternate %d\n", dev->alt);
+	usb_set_interface(dev->udev, 0, 0);
+
+	/* Stop stk1160 */
+	stk1160_write_reg(dev, STK1160_DCTRL, 0x00);
+	stk1160_write_reg(dev, STK1160_DCTRL+3, 0x00);
+
+	/* Stop saa711x */
+	v4l2_device_call_all(&dev->v4l2_dev, 0, video, s_stream, 0);
+}
+
+static int stk1160_stop_streaming(struct stk1160 *dev)
+{
+	if (mutex_lock_interruptible(&dev->v4l_lock))
+		return -ERESTARTSYS;
+
+	stk1160_cancel_isoc(dev);
+
+	/*
+	 * It is possible to keep buffers around using a module parameter.
+	 * This is intended to avoid memory fragmentation.
+	 */
+	if (!keep_buffers)
+		stk1160_free_isoc(dev);
+
+	stk1160_stop_hw(dev);
+
+	stk1160_clear_queue(dev);
+
+	stk1160_dbg("streaming stopped\n");
+
+	mutex_unlock(&dev->v4l_lock);
+
+	return 0;
+}
+
+static struct v4l2_file_operations stk1160_fops = {
+	.owner = THIS_MODULE,
+	.open = v4l2_fh_open,
+	.release = vb2_fop_release,
+	.read = vb2_fop_read,
+	.poll = vb2_fop_poll,
+	.mmap = vb2_fop_mmap,
+	.unlocked_ioctl = video_ioctl2,
+};
+
+/*
+ * vidioc ioctls
+ */
+static int vidioc_querycap(struct file *file,
+		void *priv, struct v4l2_capability *cap)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	strcpy(cap->driver, "stk1160");
+	strcpy(cap->card, "stk1160");
+	usb_make_path(dev->udev, cap->bus_info, sizeof(cap->bus_info));
+	cap->device_caps =
+		V4L2_CAP_VIDEO_CAPTURE |
+		V4L2_CAP_STREAMING |
+		V4L2_CAP_READWRITE;
+	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
+	return 0;
+}
+
+static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
+		struct v4l2_fmtdesc *f)
+{
+	if (f->index != 0)
+		return -EINVAL;
+
+	strlcpy(f->description, format[f->index].name, sizeof(f->description));
+	f->pixelformat = format[f->index].fourcc;
+	return 0;
+}
+
+static int vidioc_g_fmt_vid_cap(struct file *file, void *priv,
+					struct v4l2_format *f)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	f->fmt.pix.width = dev->width;
+	f->fmt.pix.height = dev->height;
+	f->fmt.pix.field = V4L2_FIELD_INTERLACED;
+	f->fmt.pix.pixelformat = dev->fmt->fourcc;
+	f->fmt.pix.bytesperline = dev->width * 2;
+	f->fmt.pix.sizeimage = dev->height * f->fmt.pix.bytesperline;
+	f->fmt.pix.colorspace = V4L2_COLORSPACE_SMPTE170M;
+
+	return 0;
+}
+
+static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
+			struct v4l2_format *f)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	if (f->fmt.pix.pixelformat != format[0].fourcc) {
+		stk1160_err("fourcc format 0x%08x invalid\n",
+			f->fmt.pix.pixelformat);
+		return -EINVAL;
+	}
+
+	/*
+	 * User can't choose size at his own will,
+	 * so we just return him the current size chosen
+	 * at standard selection.
+	 * TODO: Implement frame scaling?
+	 */
+
+	f->fmt.pix.width = dev->width;
+	f->fmt.pix.height = dev->height;
+	f->fmt.pix.field = V4L2_FIELD_INTERLACED;
+	f->fmt.pix.bytesperline = dev->width * 2;
+	f->fmt.pix.sizeimage = dev->height * f->fmt.pix.bytesperline;
+	f->fmt.pix.colorspace = V4L2_COLORSPACE_SMPTE170M;
+
+	return 0;
+}
+
+static int vidioc_s_fmt_vid_cap(struct file *file, void *priv,
+					struct v4l2_format *f)
+{
+	struct stk1160 *dev = video_drvdata(file);
+	struct vb2_queue *q = &dev->vb_vidq;
+	int rc;
+
+	if (vb2_is_busy(q))
+		return -EBUSY;
+
+	rc = vidioc_try_fmt_vid_cap(file, priv, f);
+	if (rc < 0)
+		return rc;
+
+	/* We don't support any format changes */
+
+	return 0;
+}
+
+static int vidioc_querystd(struct file *file, void *priv, v4l2_std_id *norm)
+{
+	struct stk1160 *dev = video_drvdata(file);
+	v4l2_device_call_all(&dev->v4l2_dev, 0, video, querystd, norm);
+	return 0;
+}
+
+static int vidioc_g_std(struct file *file, void *priv, v4l2_std_id *norm)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	*norm = dev->norm;
+	return 0;
+}
+
+static int vidioc_s_std(struct file *file, void *priv, v4l2_std_id *norm)
+{
+	struct stk1160 *dev = video_drvdata(file);
+	struct vb2_queue *q = &dev->vb_vidq;
+
+	if (vb2_is_busy(q))
+		return -EBUSY;
+
+	/* Check device presence */
+	if (!dev->udev)
+		return -ENODEV;
+
+	/* We need to set this now, before we call stk1160_set_std */
+	dev->norm = *norm;
+
+	/* This is taken from saa7115 video decoder */
+	if (dev->norm & V4L2_STD_525_60) {
+		dev->width = 720;
+		dev->height = 480;
+	} else if (dev->norm & V4L2_STD_625_50) {
+		dev->width = 720;
+		dev->height = 576;
+	} else {
+		stk1160_err("invalid standard\n");
+		return -EINVAL;
+	}
+
+	stk1160_set_std(dev);
+
+	v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_std,
+			dev->norm);
+
+	return 0;
+}
+
+
+static int vidioc_enum_input(struct file *file, void *priv,
+				struct v4l2_input *i)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	if (i->index > STK1160_MAX_INPUT)
+		return -EINVAL;
+
+	sprintf(i->name, "Composite%d", i->index);
+	i->type = V4L2_INPUT_TYPE_CAMERA;
+	i->std = dev->vdev.tvnorms;
+	return 0;
+}
+
+static int vidioc_g_input(struct file *file, void *priv, unsigned int *i)
+{
+	struct stk1160 *dev = video_drvdata(file);
+	*i = dev->ctl_input;
+	return 0;
+}
+
+static int vidioc_s_input(struct file *file, void *priv, unsigned int i)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	if (vb2_is_busy(&dev->vb_vidq))
+		return -EBUSY;
+
+	if (i > STK1160_MAX_INPUT)
+		return -EINVAL;
+
+	dev->ctl_input = i;
+
+	stk1160_select_input(dev);
+
+	return 0;
+}
+
+static int vidioc_g_chip_ident(struct file *file, void *priv,
+	       struct v4l2_dbg_chip_ident *chip)
+{
+	switch (chip->match.type) {
+	case V4L2_CHIP_MATCH_HOST:
+		chip->ident = V4L2_IDENT_NONE;
+		chip->revision = 0;
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+static int vidioc_g_register(struct file *file, void *priv,
+			     struct v4l2_dbg_register *reg)
+{
+	struct stk1160 *dev = video_drvdata(file);
+	int rc;
+	u8 val;
+
+	switch (reg->match.type) {
+	case V4L2_CHIP_MATCH_AC97:
+		/* TODO: Support me please :-( */
+		return -EINVAL;
+	case V4L2_CHIP_MATCH_I2C_DRIVER:
+		v4l2_device_call_all(&dev->v4l2_dev, 0, core, g_register, reg);
+		return 0;
+	case V4L2_CHIP_MATCH_I2C_ADDR:
+		/* TODO: is this correct? */
+		v4l2_device_call_all(&dev->v4l2_dev, 0, core, g_register, reg);
+		return 0;
+	default:
+		if (!v4l2_chip_match_host(&reg->match))
+			return -EINVAL;
+	}
+
+	/* Match host */
+	rc = stk1160_read_reg(dev, reg->reg, &val);
+	reg->val = val;
+	reg->size = 1;
+
+	return rc;
+}
+
+static int vidioc_s_register(struct file *file, void *priv,
+			     struct v4l2_dbg_register *reg)
+{
+	struct stk1160 *dev = video_drvdata(file);
+
+	switch (reg->match.type) {
+	case V4L2_CHIP_MATCH_AC97:
+		return -EINVAL;
+	case V4L2_CHIP_MATCH_I2C_DRIVER:
+		v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_register, reg);
+		return 0;
+	case V4L2_CHIP_MATCH_I2C_ADDR:
+		/* TODO: is this correct? */
+		v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_register, reg);
+		return 0;
+	default:
+		if (!v4l2_chip_match_host(&reg->match))
+			return -EINVAL;
+	}
+
+	/* Match host */
+	return stk1160_write_reg(dev, reg->reg, cpu_to_le16(reg->val));
+}
+#endif
+
+static const struct v4l2_ioctl_ops stk1160_ioctl_ops = {
+	.vidioc_querycap      = vidioc_querycap,
+	.vidioc_enum_fmt_vid_cap  = vidioc_enum_fmt_vid_cap,
+	.vidioc_g_fmt_vid_cap     = vidioc_g_fmt_vid_cap,
+	.vidioc_try_fmt_vid_cap   = vidioc_try_fmt_vid_cap,
+	.vidioc_s_fmt_vid_cap     = vidioc_s_fmt_vid_cap,
+	.vidioc_querystd      = vidioc_querystd,
+	.vidioc_g_std         = vidioc_g_std,
+	.vidioc_s_std         = vidioc_s_std,
+	.vidioc_enum_input    = vidioc_enum_input,
+	.vidioc_g_input       = vidioc_g_input,
+	.vidioc_s_input       = vidioc_s_input,
+
+	/* vb2 takes care of these */
+	.vidioc_reqbufs       = vb2_ioctl_reqbufs,
+	.vidioc_querybuf      = vb2_ioctl_querybuf,
+	.vidioc_qbuf          = vb2_ioctl_qbuf,
+	.vidioc_dqbuf         = vb2_ioctl_dqbuf,
+	.vidioc_streamon      = vb2_ioctl_streamon,
+	.vidioc_streamoff     = vb2_ioctl_streamoff,
+
+	.vidioc_log_status  = v4l2_ctrl_log_status,
+	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
+	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
+	.vidioc_g_chip_ident = vidioc_g_chip_ident,
+
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+	.vidioc_g_register = vidioc_g_register,
+	.vidioc_s_register = vidioc_s_register,
+#endif
+};
+
+/********************************************************************/
+
+/*
+ * Videobuf2 operations
+ */
+static int queue_setup(struct vb2_queue *vq, const struct v4l2_format *v4l_fmt,
+				unsigned int *nbuffers, unsigned int *nplanes,
+				unsigned int sizes[], void *alloc_ctxs[])
+{
+	struct stk1160 *dev = vb2_get_drv_priv(vq);
+	unsigned long size;
+
+	size = dev->width * dev->height * 2;
+
+	/*
+	 * Here we can change the number of buffers being requested.
+	 * So, we set a minimum and a maximum like this:
+	 */
+	*nbuffers = clamp_t(unsigned int, *nbuffers,
+			STK1160_MIN_VIDEO_BUFFERS, STK1160_MAX_VIDEO_BUFFERS);
+
+	/* This means a packed colorformat */
+	*nplanes = 1;
+
+	sizes[0] = size;
+
+	stk1160_info("%s: buffer count %d, each %ld bytes\n",
+			__func__, *nbuffers, size);
+
+	return 0;
+}
+
+static void buffer_queue(struct vb2_buffer *vb)
+{
+	unsigned long flags;
+	struct stk1160 *dev = vb2_get_drv_priv(vb->vb2_queue);
+	struct stk1160_buffer *buf =
+		container_of(vb, struct stk1160_buffer, vb);
+
+	spin_lock_irqsave(&dev->buf_lock, flags);
+	if (!dev->udev) {
+		/*
+		 * If the device is disconnected return the buffer to userspace
+		 * directly. The next QBUF call will fail with -ENODEV.
+		 */
+		vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
+	} else {
+
+		buf->mem = vb2_plane_vaddr(vb, 0);
+		buf->length = vb2_plane_size(vb, 0);
+		buf->bytesused = 0;
+		buf->pos = 0;
+
+		/*
+		 * If buffer length is less from expected then we return
+		 * the buffer to userspace directly.
+		 */
+		if (buf->length < dev->width * dev->height * 2)
+			vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
+		else
+			list_add_tail(&buf->list, &dev->avail_bufs);
+
+	}
+	spin_unlock_irqrestore(&dev->buf_lock, flags);
+}
+
+static int start_streaming(struct vb2_queue *vq, unsigned int count)
+{
+	struct stk1160 *dev = vb2_get_drv_priv(vq);
+	return stk1160_start_streaming(dev);
+}
+
+/* abort streaming and wait for last buffer */
+static int stop_streaming(struct vb2_queue *vq)
+{
+	struct stk1160 *dev = vb2_get_drv_priv(vq);
+	return stk1160_stop_streaming(dev);
+}
+
+static struct vb2_ops stk1160_video_qops = {
+	.queue_setup		= queue_setup,
+	.buf_queue		= buffer_queue,
+	.start_streaming	= start_streaming,
+	.stop_streaming		= stop_streaming,
+	.wait_prepare		= vb2_ops_wait_prepare,
+	.wait_finish		= vb2_ops_wait_finish,
+};
+
+static struct video_device v4l_template = {
+	.name = "stk1160",
+	.tvnorms = V4L2_STD_525_60 | V4L2_STD_625_50,
+	.fops = &stk1160_fops,
+	.ioctl_ops = &stk1160_ioctl_ops,
+	.release = video_device_release_empty,
+};
+
+/********************************************************************/
+
+/* Must be called with both v4l_lock and vb_queue_lock hold */
+void stk1160_clear_queue(struct stk1160 *dev)
+{
+	struct stk1160_buffer *buf;
+	unsigned long flags;
+
+	/* Release all active buffers */
+	spin_lock_irqsave(&dev->buf_lock, flags);
+	while (!list_empty(&dev->avail_bufs)) {
+		buf = list_first_entry(&dev->avail_bufs,
+			struct stk1160_buffer, list);
+		list_del(&buf->list);
+		vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
+		stk1160_info("buffer [%p/%d] aborted\n",
+				buf, buf->vb.v4l2_buf.index);
+	}
+	/* It's important to clear current buffer */
+	dev->isoc_ctl.buf = NULL;
+	spin_unlock_irqrestore(&dev->buf_lock, flags);
+}
+
+int stk1160_vb2_setup(struct stk1160 *dev)
+{
+	int rc;
+	struct vb2_queue *q;
+
+	q = &dev->vb_vidq;
+	memset(q, 0, sizeof(dev->vb_vidq));
+	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	q->io_modes = VB2_READ | VB2_MMAP | VB2_USERPTR;
+	q->drv_priv = dev;
+	q->buf_struct_size = sizeof(struct stk1160_buffer);
+	q->ops = &stk1160_video_qops;
+	q->mem_ops = &vb2_vmalloc_memops;
+
+	rc = vb2_queue_init(q);
+	if (rc < 0)
+		return rc;
+
+	/* initialize video dma queue */
+	INIT_LIST_HEAD(&dev->avail_bufs);
+
+	return 0;
+}
+
+int stk1160_video_register(struct stk1160 *dev)
+{
+	int rc;
+
+	/* Initialize video_device with a template structure */
+	dev->vdev = v4l_template;
+	dev->vdev.debug = vidioc_debug;
+	dev->vdev.queue = &dev->vb_vidq;
+
+	/*
+	 * Provide mutexes for v4l2 core and for videobuf2 queue.
+	 * It will be used to protect *only* v4l2 ioctls.
+	 */
+	dev->vdev.lock = &dev->v4l_lock;
+	dev->vdev.queue->lock = &dev->vb_queue_lock;
+
+	/* This will be used to set video_device parent */
+	dev->vdev.v4l2_dev = &dev->v4l2_dev;
+	set_bit(V4L2_FL_USE_FH_PRIO, &dev->vdev.flags);
+
+	/* NTSC is default */
+	dev->norm = V4L2_STD_NTSC_M;
+	dev->width = 720;
+	dev->height = 480;
+
+	/* set default format */
+	dev->fmt = &format[0];
+	stk1160_set_std(dev);
+
+	v4l2_device_call_all(&dev->v4l2_dev, 0, core, s_std,
+			dev->norm);
+
+	video_set_drvdata(&dev->vdev, dev);
+	rc = video_register_device(&dev->vdev, VFL_TYPE_GRABBER, -1);
+	if (rc < 0) {
+		stk1160_err("video_register_device failed (%d)\n", rc);
+		return rc;
+	}
+
+	v4l2_info(&dev->v4l2_dev, "V4L2 device registered as %s\n",
+		  video_device_node_name(&dev->vdev));
+
+	return 0;
+}

drivers/media/video/stk1160/stk1160-video.c

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/slab.h>
+#include <linux/ratelimit.h>
+
+#include "stk1160.h"
+
+static unsigned int debug;
+module_param(debug, int, 0644);
+MODULE_PARM_DESC(debug, "enable debug messages");
+
+static inline void print_err_status(struct stk1160 *dev,
+				     int packet, int status)
+{
+	char *errmsg = "Unknown";
+
+	switch (status) {
+	case -ENOENT:
+		errmsg = "unlinked synchronuously";
+		break;
+	case -ECONNRESET:
+		errmsg = "unlinked asynchronuously";
+		break;
+	case -ENOSR:
+		errmsg = "Buffer error (overrun)";
+		break;
+	case -EPIPE:
+		errmsg = "Stalled (device not responding)";
+		break;
+	case -EOVERFLOW:
+		errmsg = "Babble (bad cable?)";
+		break;
+	case -EPROTO:
+		errmsg = "Bit-stuff error (bad cable?)";
+		break;
+	case -EILSEQ:
+		errmsg = "CRC/Timeout (could be anything)";
+		break;
+	case -ETIME:
+		errmsg = "Device does not respond";
+		break;
+	}
+
+	if (packet < 0)
+		printk_ratelimited(KERN_WARNING "URB status %d [%s].\n",
+				status, errmsg);
+	else
+		printk_ratelimited(KERN_INFO "URB packet %d, status %d [%s].\n",
+			       packet, status, errmsg);
+}
+
+static inline
+struct stk1160_buffer *stk1160_next_buffer(struct stk1160 *dev)
+{
+	struct stk1160_buffer *buf = NULL;
+	unsigned long flags = 0;
+
+	/* Current buffer must be NULL when this functions gets called */
+	BUG_ON(dev->isoc_ctl.buf);
+
+	spin_lock_irqsave(&dev->buf_lock, flags);
+	if (!list_empty(&dev->avail_bufs)) {
+		buf = list_first_entry(&dev->avail_bufs,
+				struct stk1160_buffer, list);
+		list_del(&buf->list);
+	}
+	spin_unlock_irqrestore(&dev->buf_lock, flags);
+
+	return buf;
+}
+
+static inline
+void stk1160_buffer_done(struct stk1160 *dev)
+{
+	struct stk1160_buffer *buf = dev->isoc_ctl.buf;
+
+	dev->field_count++;
+
+	buf->vb.v4l2_buf.sequence = dev->field_count >> 1;
+	buf->vb.v4l2_buf.field = V4L2_FIELD_INTERLACED;
+	buf->vb.v4l2_buf.bytesused = buf->bytesused;
+	do_gettimeofday(&buf->vb.v4l2_buf.timestamp);
+
+	vb2_set_plane_payload(&buf->vb, 0, buf->bytesused);
+	vb2_buffer_done(&buf->vb, VB2_BUF_STATE_DONE);
+
+	dev->isoc_ctl.buf = NULL;
+}
+
+static inline
+void stk1160_copy_video(struct stk1160 *dev, u8 *src, int len)
+{
+	int linesdone, lineoff, lencopy;
+	int bytesperline = dev->width * 2;
+	struct stk1160_buffer *buf = dev->isoc_ctl.buf;
+	u8 *dst = buf->mem;
+	int remain;
+
+	/*
+	 * TODO: These stk1160_dbg are very spammy!
+	 * We should 1) check why we are getting them
+	 * and 2) add ratelimit.
+	 *
+	 * UPDATE: One of the reasons (the only one?) for getting these
+	 * is incorrect standard (mismatch between expected and configured).
+	 * So perhaps, we could add a counter for errors. When the counter
+	 * reaches some value, we simply stop streaming.
+	 */
+
+	len -= 4;
+	src += 4;
+
+	remain = len;
+
+	linesdone = buf->pos / bytesperline;
+	lineoff = buf->pos % bytesperline; /* offset in current line */
+
+	if (!buf->odd)
+		dst += bytesperline;
+
+	/* Multiply linesdone by two, to take account of the other field */
+	dst += linesdone * bytesperline * 2 + lineoff;
+
+	/* Copy the remaining of current line */
+	if (remain < (bytesperline - lineoff))
+		lencopy = remain;
+	else
+		lencopy = bytesperline - lineoff;
+
+	/*
+	 * Check if we have enough space left in the buffer.
+	 * In that case, we force loop exit after copy.
+	 */
+	if (lencopy > buf->bytesused - buf->length) {
+		lencopy = buf->bytesused - buf->length;
+		remain = lencopy;
+	}
+
+	/* Check if the copy is done */
+	if (lencopy == 0 || remain == 0)
+		return;
+
+	/* Let the bug hunt begin! sanity checks! */
+	if (lencopy < 0) {
+		stk1160_dbg("copy skipped: negative lencopy\n");
+		return;
+	}
+
+	if ((unsigned long)dst + lencopy >
+		(unsigned long)buf->mem + buf->length) {
+		printk_ratelimited(KERN_WARNING "stk1160: buffer overflow detected\n");
+		return;
+	}
+
+	memcpy(dst, src, lencopy);
+
+	buf->bytesused += lencopy;
+	buf->pos += lencopy;
+	remain -= lencopy;
+
+	/* Copy current field line by line, interlacing with the other field */
+	while (remain > 0) {
+
+		dst += lencopy + bytesperline;
+		src += lencopy;
+
+		/* Copy one line at a time */
+		if (remain < bytesperline)
+			lencopy = remain;
+		else
+			lencopy = bytesperline;
+
+		/*
+		 * Check if we have enough space left in the buffer.
+		 * In that case, we force loop exit after copy.
+		 */
+		if (lencopy > buf->bytesused - buf->length) {
+			lencopy = buf->bytesused - buf->length;
+			remain = lencopy;
+		}
+
+		/* Check if the copy is done */
+		if (lencopy == 0 || remain == 0)
+			return;
+
+		if (lencopy < 0) {
+			printk_ratelimited(KERN_WARNING "stk1160: negative lencopy detected\n");
+			return;
+		}
+
+		if ((unsigned long)dst + lencopy >
+			(unsigned long)buf->mem + buf->length) {
+			printk_ratelimited(KERN_WARNING "stk1160: buffer overflow detected\n");
+			return;
+		}
+
+		memcpy(dst, src, lencopy);
+		remain -= lencopy;
+
+		buf->bytesused += lencopy;
+		buf->pos += lencopy;
+	}
+}
+
+/*
+ * Controls the isoc copy of each urb packet
+ */
+static void stk1160_process_isoc(struct stk1160 *dev, struct urb *urb)
+{
+	int i, len, status;
+	u8 *p;
+
+	if (!dev) {
+		stk1160_warn("%s called with null device\n", __func__);
+		return;
+	}
+
+	if (urb->status < 0) {
+		/* Print status and drop current packet (or field?) */
+		print_err_status(dev, -1, urb->status);
+		return;
+	}
+
+	for (i = 0; i < urb->number_of_packets; i++) {
+		status = urb->iso_frame_desc[i].status;
+		if (status < 0) {
+			print_err_status(dev, i, status);
+			continue;
+		}
+
+		/* Get packet actual length and pointer to data */
+		p = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
+		len = urb->iso_frame_desc[i].actual_length;
+
+		/* Empty packet */
+		if (len <= 4)
+			continue;
+
+		/*
+		 * An 8-byte packet sequence means end of field.
+		 * So if we don't have any packet, we start receiving one now
+		 * and if we do have a packet, then we are done with it.
+		 *
+		 * These end of field packets are always 0xc0 or 0x80,
+		 * but not always 8-byte long so we don't check packet length.
+		 */
+		if (p[0] == 0xc0) {
+
+			/*
+			 * If first byte is 0xc0 then we received
+			 * second field, and frame has ended.
+			 */
+			if (dev->isoc_ctl.buf != NULL)
+				stk1160_buffer_done(dev);
+
+			dev->isoc_ctl.buf = stk1160_next_buffer(dev);
+			if (dev->isoc_ctl.buf == NULL)
+				return;
+		}
+
+		/*
+		 * If we don't have a buffer here, then it means we
+		 * haven't found the start mark sequence.
+		 */
+		if (dev->isoc_ctl.buf == NULL)
+			continue;
+
+		if (p[0] == 0xc0 || p[0] == 0x80) {
+
+			/* We set next packet parity and
+			 * continue to get next one
+			 */
+			dev->isoc_ctl.buf->odd = *p & 0x40;
+			dev->isoc_ctl.buf->pos = 0;
+			continue;
+		}
+
+		stk1160_copy_video(dev, p, len);
+	}
+}
+
+
+/*
+ * IRQ callback, called by URB callback
+ */
+static void stk1160_isoc_irq(struct urb *urb)
+{
+	int i, rc;
+	struct stk1160 *dev = urb->context;
+
+	switch (urb->status) {
+	case 0:
+		break;
+	case -ECONNRESET:   /* kill */
+	case -ENOENT:
+	case -ESHUTDOWN:
+		/* TODO: check uvc driver: he frees the queue here */
+		return;
+	default:
+		stk1160_err("urb error! status %d\n", urb->status);
+		return;
+	}
+
+	stk1160_process_isoc(dev, urb);
+
+	/* Reset urb buffers */
+	for (i = 0; i < urb->number_of_packets; i++) {
+		urb->iso_frame_desc[i].status = 0;
+		urb->iso_frame_desc[i].actual_length = 0;
+	}
+
+	rc = usb_submit_urb(urb, GFP_ATOMIC);
+	if (rc)
+		stk1160_err("urb re-submit failed (%d)\n", rc);
+}
+
+/*
+ * Cancel urbs
+ * This function can't be called in atomic context
+ */
+void stk1160_cancel_isoc(struct stk1160 *dev)
+{
+	int i;
+
+	/*
+	 * This check is not necessary, but we add it
+	 * to avoid a spurious debug message
+	 */
+	if (!dev->isoc_ctl.num_bufs)
+		return;
+
+	stk1160_dbg("killing urbs...\n");
+
+	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
+
+		/*
+		 * To kill urbs we can't be in atomic context.
+		 * We don't care for NULL pointer since
+		 * usb_kill_urb allows it.
+		 */
+		usb_kill_urb(dev->isoc_ctl.urb[i]);
+	}
+
+	stk1160_dbg("all urbs killed\n");
+}
+
+/*
+ * Releases urb and transfer buffers
+ * Obviusly, associated urb must be killed before releasing it.
+ */
+void stk1160_free_isoc(struct stk1160 *dev)
+{
+	struct urb *urb;
+	int i;
+
+	stk1160_dbg("freeing urb buffers...\n");
+
+	for (i = 0; i < dev->isoc_ctl.num_bufs; i++) {
+
+		urb = dev->isoc_ctl.urb[i];
+		if (urb) {
+
+			if (dev->isoc_ctl.transfer_buffer[i]) {
+#ifndef CONFIG_DMA_NONCOHERENT
+				usb_free_coherent(dev->udev,
+					urb->transfer_buffer_length,
+					dev->isoc_ctl.transfer_buffer[i],
+					urb->transfer_dma);
+#else
+				kfree(dev->isoc_ctl.transfer_buffer[i]);
+#endif
+			}
+			usb_free_urb(urb);
+			dev->isoc_ctl.urb[i] = NULL;
+		}
+		dev->isoc_ctl.transfer_buffer[i] = NULL;
+	}
+
+	kfree(dev->isoc_ctl.urb);
+	kfree(dev->isoc_ctl.transfer_buffer);
+
+	dev->isoc_ctl.urb = NULL;
+	dev->isoc_ctl.transfer_buffer = NULL;
+	dev->isoc_ctl.num_bufs = 0;
+
+	stk1160_dbg("all urb buffers freed\n");
+}
+
+/*
+ * Helper for cancelling and freeing urbs
+ * This function can't be called in atomic context
+ */
+void stk1160_uninit_isoc(struct stk1160 *dev)
+{
+	stk1160_cancel_isoc(dev);
+	stk1160_free_isoc(dev);
+}
+
+/*
+ * Allocate URBs
+ */
+int stk1160_alloc_isoc(struct stk1160 *dev)
+{
+	struct urb *urb;
+	int i, j, k, sb_size, max_packets, num_bufs;
+
+	/*
+	 * It may be necessary to release isoc here,
+	 * since isoc are only released on disconnection.
+	 * (see new_pkt_size flag)
+	 */
+	if (dev->isoc_ctl.num_bufs)
+		stk1160_uninit_isoc(dev);
+
+	stk1160_dbg("allocating urbs...\n");
+
+	num_bufs = STK1160_NUM_BUFS;
+	max_packets = STK1160_NUM_PACKETS;
+	sb_size = max_packets * dev->max_pkt_size;
+
+	dev->isoc_ctl.buf = NULL;
+	dev->isoc_ctl.max_pkt_size = dev->max_pkt_size;
+	dev->isoc_ctl.urb = kzalloc(sizeof(void *)*num_bufs, GFP_KERNEL);
+	if (!dev->isoc_ctl.urb) {
+		stk1160_err("out of memory for urb array\n");
+		return -ENOMEM;
+	}
+
+	dev->isoc_ctl.transfer_buffer = kzalloc(sizeof(void *)*num_bufs,
+					      GFP_KERNEL);
+	if (!dev->isoc_ctl.transfer_buffer) {
+		stk1160_err("out of memory for usb transfers\n");
+		kfree(dev->isoc_ctl.urb);
+		return -ENOMEM;
+	}
+
+	/* allocate urbs and transfer buffers */
+	for (i = 0; i < num_bufs; i++) {
+
+		urb = usb_alloc_urb(max_packets, GFP_KERNEL);
+		if (!urb) {
+			stk1160_err("cannot alloc urb[%d]\n", i);
+			stk1160_uninit_isoc(dev);
+			return -ENOMEM;
+		}
+		dev->isoc_ctl.urb[i] = urb;
+
+#ifndef CONFIG_DMA_NONCOHERENT
+		dev->isoc_ctl.transfer_buffer[i] = usb_alloc_coherent(dev->udev,
+			sb_size, GFP_KERNEL, &urb->transfer_dma);
+#else
+		dev->isoc_ctl.transfer_buffer[i] = kmalloc(sb_size, GFP_KERNEL);
+#endif
+		if (!dev->isoc_ctl.transfer_buffer[i]) {
+			stk1160_err("cannot alloc %d bytes for tx buffer\n",
+				sb_size);
+			stk1160_uninit_isoc(dev);
+			return -ENOMEM;
+		}
+		memset(dev->isoc_ctl.transfer_buffer[i], 0, sb_size);
+
+		/*
+		 * FIXME: Where can I get the endpoint?
+		 */
+		urb->dev = dev->udev;
+		urb->pipe = usb_rcvisocpipe(dev->udev, STK1160_EP_VIDEO);
+		urb->transfer_buffer = dev->isoc_ctl.transfer_buffer[i];
+		urb->transfer_buffer_length = sb_size;
+		urb->complete = stk1160_isoc_irq;
+		urb->context = dev;
+		urb->interval = 1;
+		urb->start_frame = 0;
+		urb->number_of_packets = max_packets;
+#ifndef CONFIG_DMA_NONCOHERENT
+		urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
+#else
+		urb->transfer_flags = URB_ISO_ASAP;
+#endif
+
+		k = 0;
+		for (j = 0; j < max_packets; j++) {
+			urb->iso_frame_desc[j].offset = k;
+			urb->iso_frame_desc[j].length =
+					dev->isoc_ctl.max_pkt_size;
+			k += dev->isoc_ctl.max_pkt_size;
+		}
+	}
+
+	stk1160_dbg("urbs allocated\n");
+
+	/* At last we can say we have some buffers */
+	dev->isoc_ctl.num_bufs = num_bufs;
+
+	return 0;
+}
+

drivers/media/video/stk1160/stk1160.h

+/*
+ * STK1160 driver
+ *
+ * Copyright (C) 2012 Ezequiel Garcia
+ * <elezegarcia--a.t--gmail.com>
+ *
+ * Based on Easycap driver by R.M. Thomas
+ *	Copyright (C) 2010 R.M. Thomas
+ *	<rmthomas--a.t--sciolus.org>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/i2c.h>
+#include <sound/core.h>
+#include <sound/ac97_codec.h>
+#include <media/videobuf2-core.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-ctrls.h>
+
+#define STK1160_VERSION		"0.9.5"
+#define STK1160_VERSION_NUM	0x000905
+
+/* TODO: Decide on number of packets for each buffer */
+#define STK1160_NUM_PACKETS 64
+
+/* Number of buffers for isoc transfers */
+#define STK1160_NUM_BUFS 16 /* TODO */
+
+/* TODO: This endpoint address should be retrieved */
+#define STK1160_EP_VIDEO 0x82
+#define STK1160_EP_AUDIO 0x81
+
+/* Max and min video buffers */
+#define STK1160_MIN_VIDEO_BUFFERS 8
+#define STK1160_MAX_VIDEO_BUFFERS 32
+
+#define STK1160_MIN_PKT_SIZE 3072
+
+#define STK1160_MAX_INPUT 3
+
+#define STK1160_I2C_TIMEOUT 100
+
+/* TODO: Print helpers
+ * I could use dev_xxx, pr_xxx, v4l2_xxx or printk.
+ * However, there isn't a solid consensus on which
+ * new drivers should use.
+ *
+ */
+#define DEBUG
+#ifdef DEBUG
+#define stk1160_dbg(fmt, args...) \
+	printk(KERN_DEBUG "stk1160: " fmt,  ## args)
+#else
+#define stk1160_dbg(fmt, args...)
+#endif
+
+#define stk1160_info(fmt, args...) \
+	pr_info("stk1160: " fmt, ## args)
+
+#define stk1160_warn(fmt, args...) \
+	pr_warn("stk1160: " fmt, ## args)
+
+#define stk1160_err(fmt, args...) \
+	pr_err("stk1160: " fmt, ## args)
+
+/* Buffer for one video frame */
+struct stk1160_buffer {
+	/* common v4l buffer stuff -- must be first */
+	struct vb2_buffer vb;
+	struct list_head list;
+
+	void *mem;
+	unsigned int length;		/* buffer length */
+	unsigned int bytesused;		/* bytes written */
+	int odd;			/* current oddity */
+
+	/*
+	 * Since we interlace two fields per frame,
+	 * this is different from bytesused.
+	 */
+	unsigned int pos;		/* current pos inside buffer */
+};
+
+struct stk1160_isoc_ctl {
+	/* max packet size of isoc transaction */
+	int max_pkt_size;
+
+	/* number of allocated urbs */
+	int num_bufs;
+
+	/* urb for isoc transfers */
+	struct urb **urb;
+
+	/* transfer buffers for isoc transfer */
+	char **transfer_buffer;
+
+	/* current buffer */
+	struct stk1160_buffer *buf;
+};
+
+struct stk1160_fmt {
+	char  *name;
+	u32   fourcc;          /* v4l2 format id */
+	int   depth;
+};
+
+struct stk1160 {
+	struct v4l2_device v4l2_dev;
+	struct video_device vdev;
+	struct v4l2_ctrl_handler ctrl_handler;
+
+	struct device *dev;
+	struct usb_device *udev;
+
+	/* saa7115 subdev */
+	struct v4l2_subdev *sd_saa7115;
+
+	/* isoc control struct */
+	struct list_head avail_bufs;
+
+	/* video capture */
+	struct vb2_queue vb_vidq;
+
+	/* max packet size of isoc transaction */
+	int max_pkt_size;
+	/* array of wMaxPacketSize */
+	unsigned int *alt_max_pkt_size;
+	/* alternate */
+	int alt;
+	/* Number of alternative settings */
+	int num_alt;
+
+	struct stk1160_isoc_ctl isoc_ctl;
+	char urb_buf[255];	 /* urb control msg buffer */
+
+	/* frame properties */
+	int width;		  /* current frame width */
+	int height;		  /* current frame height */
+	unsigned int ctl_input;	  /* selected input */
+	v4l2_std_id norm;	  /* current norm */
+	struct stk1160_fmt *fmt;  /* selected format */
+
+	unsigned int field_count; /* not sure ??? */
+	enum v4l2_field field;    /* also not sure :/ */
+
+	/* i2c i/o */
+	struct i2c_adapter i2c_adap;
+	struct i2c_client i2c_client;
+
+	struct mutex v4l_lock;
+	struct mutex vb_queue_lock;
+	spinlock_t buf_lock;
+
+	struct file *fh_owner;	/* filehandle ownership */
+
+	/* EXPERIMENTAL */
+	struct snd_card *snd_card;
+};
+
+struct regval {
+	u16 reg;
+	u16 val;
+};
+
+/* Provided by stk1160-v4l.c */
+int stk1160_vb2_setup(struct stk1160 *dev);
+int stk1160_video_register(struct stk1160 *dev);
+void stk1160_video_unregister(struct stk1160 *dev);
+void stk1160_clear_queue(struct stk1160 *dev);
+
+/* Provided by stk1160-video.c */
+int stk1160_alloc_isoc(struct stk1160 *dev);
+void stk1160_free_isoc(struct stk1160 *dev);
+void stk1160_cancel_isoc(struct stk1160 *dev);
+void stk1160_uninit_isoc(struct stk1160 *dev);
+
+/* Provided by stk1160-i2c.c */
+int stk1160_i2c_register(struct stk1160 *dev);
+int stk1160_i2c_unregister(struct stk1160 *dev);
+
+/* Provided by stk1160-core.c */
+int stk1160_read_reg(struct stk1160 *dev, u16 reg, u8 *value);
+int stk1160_write_reg(struct stk1160 *dev, u16 reg, u16 value);
+int stk1160_write_regs_req(struct stk1160 *dev, u8 req, u16 reg,
+		char *buf, int len);
+int stk1160_read_reg_req_len(struct stk1160 *dev, u8 req, u16 reg,
+		char *buf, int len);
+void stk1160_select_input(struct stk1160 *dev);
+
+/* Provided by stk1160-ac97.c */
+#ifdef CONFIG_VIDEO_STK1160_AC97
+int stk1160_ac97_register(struct stk1160 *dev);
+int stk1160_ac97_unregister(struct stk1160 *dev);
+#else
+static inline int stk1160_ac97_register(struct stk1160 *dev) { return 0; }
+static inline int stk1160_ac97_unregister(struct stk1160 *dev) { return 0; }
+#endif
+