V4L/DVB (8145a): USB Video Class driver

This driver supports video input devices compliant with the USB Video Class
specification. This means lots of currently manufactured webcams, and probably
most of the future ones.

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

11 files changed, 6877 insertions, 0 deletions

diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index 3b26fbd3e558..5ccb0aeca8cc 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -793,6 +793,14 @@ menuconfig V4L_USB_DRIVERS
 
 if V4L_USB_DRIVERS && USB
 
+config USB_VIDEO_CLASS
+	tristate "USB Video Class (UVC)"
+	---help---
+	  Support for the USB Video Class (UVC).  Currently only video
+	  input devices, such as webcams, are supported.
+
+	  For more information see: <http://linux-uvc.berlios.de/>
+
 source "drivers/media/video/pvrusb2/Kconfig"
 
 source "drivers/media/video/em28xx/Kconfig"
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index dff0d6abe917..ecbbfaab24d5 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -136,6 +136,8 @@ obj-$(CONFIG_SOC_CAMERA_MT9V022)	+= mt9v022.o
 
 obj-$(CONFIG_VIDEO_AU0828) += au0828/
 
+obj-$(CONFIG_USB_VIDEO_CLASS)	+= uvc/
+
 EXTRA_CFLAGS += -Idrivers/media/dvb/dvb-core
 EXTRA_CFLAGS += -Idrivers/media/dvb/frontends
 EXTRA_CFLAGS += -Idrivers/media/common/tuners
diff --git a/drivers/media/video/uvc/Makefile b/drivers/media/video/uvc/Makefile
new file mode 100644
index 000000000000..fb39bbf9b5ac
--- /dev/null
+++ b/drivers/media/video/uvc/Makefile
@@ -0,0 +1,3 @@
+uvcvideo-objs  := uvc_driver.o uvc_queue.o uvc_v4l2.o uvc_video.o uvc_ctrl.o \
+		  uvc_status.o uvc_isight.o
+obj-$(CONFIG_USB_VIDEO_CLASS) := uvcvideo.o
diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
new file mode 100644
index 000000000000..f0ee46d15540
--- /dev/null
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -0,0 +1,1256 @@
+/*
+ *      uvc_ctrl.c  --  USB Video Class driver - Controls
+ *
+ *      Copyright (C) 2005-2008
+ *          Laurent Pinchart (laurent.pinchart@skynet.be)
+ *
+ *      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.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/version.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/usb.h>
+#include <linux/videodev2.h>
+#include <linux/vmalloc.h>
+#include <linux/wait.h>
+#include <asm/atomic.h>
+
+#include "uvcvideo.h"
+
+#define UVC_CTRL_NDATA		2
+#define UVC_CTRL_DATA_CURRENT	0
+#define UVC_CTRL_DATA_BACKUP	1
+
+/* ------------------------------------------------------------------------
+ * Control, formats, ...
+ */
+
+static struct uvc_control_info uvc_ctrls[] = {
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_BRIGHTNESS_CONTROL,
+		.index		= 0,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_CONTRAST_CONTROL,
+		.index		= 1,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_HUE_CONTROL,
+		.index		= 2,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE | UVC_CONTROL_AUTO_UPDATE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_SATURATION_CONTROL,
+		.index		= 3,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_SHARPNESS_CONTROL,
+		.index		= 4,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_GAMMA_CONTROL,
+		.index		= 5,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_BACKLIGHT_COMPENSATION_CONTROL,
+		.index		= 8,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_GAIN_CONTROL,
+		.index		= 9,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_POWER_LINE_FREQUENCY_CONTROL,
+		.index		= 10,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_HUE_AUTO_CONTROL,
+		.index		= 11,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_CUR
+				| UVC_CONTROL_GET_DEF | UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_AE_MODE_CONTROL,
+		.index		= 1,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_CUR
+				| UVC_CONTROL_GET_DEF | UVC_CONTROL_GET_RES
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_AE_PRIORITY_CONTROL,
+		.index		= 2,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_CUR
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_EXPOSURE_TIME_ABSOLUTE_CONTROL,
+		.index		= 3,
+		.size		= 4,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_FOCUS_ABSOLUTE_CONTROL,
+		.index		= 5,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE | UVC_CONTROL_AUTO_UPDATE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_FOCUS_AUTO_CONTROL,
+		.index		= 17,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_CUR
+				| UVC_CONTROL_GET_DEF | UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_TEMPERATURE_AUTO_CONTROL,
+		.index		= 12,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_CUR
+				| UVC_CONTROL_GET_DEF | UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_TEMPERATURE_CONTROL,
+		.index		= 6,
+		.size		= 2,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE | UVC_CONTROL_AUTO_UPDATE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_COMPONENT_AUTO_CONTROL,
+		.index		= 13,
+		.size		= 1,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_CUR
+				| UVC_CONTROL_GET_DEF | UVC_CONTROL_RESTORE,
+	},
+	{
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_COMPONENT_CONTROL,
+		.index		= 7,
+		.size		= 4,
+		.flags		= UVC_CONTROL_SET_CUR | UVC_CONTROL_GET_RANGE
+				| UVC_CONTROL_RESTORE | UVC_CONTROL_AUTO_UPDATE,
+	},
+};
+
+static struct uvc_menu_info power_line_frequency_controls[] = {
+	{ 0, "Disabled" },
+	{ 1, "50 Hz" },
+	{ 2, "60 Hz" },
+};
+
+static struct uvc_menu_info exposure_auto_controls[] = {
+	{ 1, "Manual Mode" },
+	{ 2, "Auto Mode" },
+	{ 4, "Shutter Priority Mode" },
+	{ 8, "Aperture Priority Mode" },
+};
+
+static struct uvc_control_mapping uvc_ctrl_mappings[] = {
+	{
+		.id		= V4L2_CID_BRIGHTNESS,
+		.name		= "Brightness",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_BRIGHTNESS_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
+	},
+	{
+		.id		= V4L2_CID_CONTRAST,
+		.name		= "Contrast",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_CONTRAST_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_HUE,
+		.name		= "Hue",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_HUE_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
+	},
+	{
+		.id		= V4L2_CID_SATURATION,
+		.name		= "Saturation",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_SATURATION_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_SHARPNESS,
+		.name		= "Sharpness",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_SHARPNESS_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_GAMMA,
+		.name		= "Gamma",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_GAMMA_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_BACKLIGHT_COMPENSATION,
+		.name		= "Backlight Compensation",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_BACKLIGHT_COMPENSATION_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_GAIN,
+		.name		= "Gain",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_GAIN_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_POWER_LINE_FREQUENCY,
+		.name		= "Power Line Frequency",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_POWER_LINE_FREQUENCY_CONTROL,
+		.size		= 2,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_MENU,
+		.data_type	= UVC_CTRL_DATA_TYPE_ENUM,
+		.menu_info	= power_line_frequency_controls,
+		.menu_count	= ARRAY_SIZE(power_line_frequency_controls),
+	},
+	{
+		.id		= V4L2_CID_HUE_AUTO,
+		.name		= "Hue, Auto",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_HUE_AUTO_CONTROL,
+		.size		= 1,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_BOOLEAN,
+		.data_type	= UVC_CTRL_DATA_TYPE_BOOLEAN,
+	},
+	{
+		.id		= V4L2_CID_EXPOSURE_AUTO,
+		.name		= "Exposure, Auto",
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_AE_MODE_CONTROL,
+		.size		= 4,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_MENU,
+		.data_type	= UVC_CTRL_DATA_TYPE_BITMASK,
+		.menu_info	= exposure_auto_controls,
+		.menu_count	= ARRAY_SIZE(exposure_auto_controls),
+	},
+	{
+		.id		= V4L2_CID_EXPOSURE_AUTO_PRIORITY,
+		.name		= "Exposure, Auto Priority",
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_AE_PRIORITY_CONTROL,
+		.size		= 1,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_BOOLEAN,
+		.data_type	= UVC_CTRL_DATA_TYPE_BOOLEAN,
+	},
+	{
+		.id		= V4L2_CID_EXPOSURE_ABSOLUTE,
+		.name		= "Exposure (Absolute)",
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_EXPOSURE_TIME_ABSOLUTE_CONTROL,
+		.size		= 32,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_AUTO_WHITE_BALANCE,
+		.name		= "White Balance Temperature, Auto",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_TEMPERATURE_AUTO_CONTROL,
+		.size		= 1,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_BOOLEAN,
+		.data_type	= UVC_CTRL_DATA_TYPE_BOOLEAN,
+	},
+	{
+		.id		= V4L2_CID_WHITE_BALANCE_TEMPERATURE,
+		.name		= "White Balance Temperature",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_TEMPERATURE_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_AUTO_WHITE_BALANCE,
+		.name		= "White Balance Component, Auto",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_COMPONENT_AUTO_CONTROL,
+		.size		= 1,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_BOOLEAN,
+		.data_type	= UVC_CTRL_DATA_TYPE_BOOLEAN,
+	},
+	{
+		.id		= V4L2_CID_BLUE_BALANCE,
+		.name		= "White Balance Blue Component",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_COMPONENT_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
+	},
+	{
+		.id		= V4L2_CID_RED_BALANCE,
+		.name		= "White Balance Red Component",
+		.entity		= UVC_GUID_UVC_PROCESSING,
+		.selector	= PU_WHITE_BALANCE_COMPONENT_CONTROL,
+		.size		= 16,
+		.offset		= 16,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_SIGNED,
+	},
+	{
+		.id		= V4L2_CID_FOCUS_ABSOLUTE,
+		.name		= "Focus (absolute)",
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_FOCUS_ABSOLUTE_CONTROL,
+		.size		= 16,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_INTEGER,
+		.data_type	= UVC_CTRL_DATA_TYPE_UNSIGNED,
+	},
+	{
+		.id		= V4L2_CID_FOCUS_AUTO,
+		.name		= "Focus, Auto",
+		.entity		= UVC_GUID_UVC_CAMERA,
+		.selector	= CT_FOCUS_AUTO_CONTROL,
+		.size		= 1,
+		.offset		= 0,
+		.v4l2_type	= V4L2_CTRL_TYPE_BOOLEAN,
+		.data_type	= UVC_CTRL_DATA_TYPE_BOOLEAN,
+	},
+};
+
+/* ------------------------------------------------------------------------
+ * Utility functions
+ */
+
+static inline __u8 *uvc_ctrl_data(struct uvc_control *ctrl, int id)
+{
+	return ctrl->data + id * ctrl->info->size;
+}
+
+static inline int uvc_get_bit(const __u8 *data, int bit)
+{
+	return (data[bit >> 3] >> (bit & 7)) & 1;
+}
+
+/* Extract the bit string specified by mapping->offset and mapping->size
+ * from the little-endian data stored at 'data' and return the result as
+ * a signed 32bit integer. Sign extension will be performed if the mapping
+ * references a signed data type.
+ */
+static __s32 uvc_get_le_value(const __u8 *data,
+	struct uvc_control_mapping *mapping)
+{
+	int bits = mapping->size;
+	int offset = mapping->offset;
+	__s32 value = 0;
+	__u8 mask;
+
+	data += offset / 8;
+	offset &= 7;
+	mask = ((1LL << bits) - 1) << offset;
+
+	for (; bits > 0; data++) {
+		__u8 byte = *data & mask;
+		value |= offset > 0 ? (byte >> offset) : (byte << (-offset));
+		bits -= 8 - (offset > 0 ? offset : 0);
+		offset -= 8;
+		mask = (1 << bits) - 1;
+	}
+
+	/* Sign-extend the value if needed */
+	if (mapping->data_type == UVC_CTRL_DATA_TYPE_SIGNED)
+		value |= -(value & (1 << (mapping->size - 1)));
+
+	return value;
+}
+
+/* Set the bit string specified by mapping->offset and mapping->size
+ * in the little-endian data stored at 'data' to the value 'value'.
+ */
+static void uvc_set_le_value(__s32 value, __u8 *data,
+	struct uvc_control_mapping *mapping)
+{
+	int bits = mapping->size;
+	int offset = mapping->offset;
+	__u8 mask;
+
+	data += offset / 8;
+	offset &= 7;
+
+	for (; bits > 0; data++) {
+		mask = ((1LL << bits) - 1) << offset;
+		*data = (*data & ~mask) | ((value << offset) & mask);
+		value >>= offset ? offset : 8;
+		bits -= 8 - offset;
+		offset = 0;
+	}
+}
+
+/* ------------------------------------------------------------------------
+ * Terminal and unit management
+ */
+
+static const __u8 uvc_processing_guid[16] = UVC_GUID_UVC_PROCESSING;
+static const __u8 uvc_camera_guid[16] = UVC_GUID_UVC_CAMERA;
+static const __u8 uvc_media_transport_input_guid[16] =
+	UVC_GUID_UVC_MEDIA_TRANSPORT_INPUT;
+
+static int uvc_entity_match_guid(struct uvc_entity *entity, __u8 guid[16])
+{
+	switch (UVC_ENTITY_TYPE(entity)) {
+	case ITT_CAMERA:
+		return memcmp(uvc_camera_guid, guid, 16) == 0;
+
+	case ITT_MEDIA_TRANSPORT_INPUT:
+		return memcmp(uvc_media_transport_input_guid, guid, 16) == 0;
+
+	case VC_PROCESSING_UNIT:
+		return memcmp(uvc_processing_guid, guid, 16) == 0;
+
+	case VC_EXTENSION_UNIT:
+		return memcmp(entity->extension.guidExtensionCode,
+			      guid, 16) == 0;
+
+	default:
+		return 0;
+	}
+}
+
+/* ------------------------------------------------------------------------
+ * UVC Controls
+ */
+
+static void __uvc_find_control(struct uvc_entity *entity, __u32 v4l2_id,
+	struct uvc_control_mapping **mapping, struct uvc_control **control,
+	int next)
+{
+	struct uvc_control *ctrl;
+	struct uvc_control_mapping *map;
+	unsigned int i;
+
+	if (entity == NULL)
+		return;
+
+	for (i = 0; i < entity->ncontrols; ++i) {
+		ctrl = &entity->controls[i];
+		if (ctrl->info == NULL)
+			continue;
+
+		list_for_each_entry(map, &ctrl->info->mappings, list) {
+			if ((map->id == v4l2_id) && !next) {
+				*control = ctrl;
+				*mapping = map;
+				return;
+			}
+
+			if ((*mapping == NULL || (*mapping)->id > map->id) &&
+			    (map->id > v4l2_id) && next) {
+				*control = ctrl;
+				*mapping = map;
+			}
+		}
+	}
+}
+
+struct uvc_control *uvc_find_control(struct uvc_video_device *video,
+	__u32 v4l2_id, struct uvc_control_mapping **mapping)
+{
+	struct uvc_control *ctrl = NULL;
+	struct uvc_entity *entity;
+	int next = v4l2_id & V4L2_CTRL_FLAG_NEXT_CTRL;
+
+	*mapping = NULL;
+
+	/* Mask the query flags. */
+	v4l2_id &= V4L2_CTRL_ID_MASK;
+
+	/* Find the control. */
+	__uvc_find_control(video->processing, v4l2_id, mapping, &ctrl, next);
+	if (ctrl && !next)
+		return ctrl;
+
+	list_for_each_entry(entity, &video->iterms, chain) {
+		__uvc_find_control(entity, v4l2_id, mapping, &ctrl, next);
+		if (ctrl && !next)
+			return ctrl;
+	}
+
+	list_for_each_entry(entity, &video->extensions, chain) {
+		__uvc_find_control(entity, v4l2_id, mapping, &ctrl, next);
+		if (ctrl && !next)
+			return ctrl;
+	}
+
+	if (ctrl == NULL && !next)
+		uvc_trace(UVC_TRACE_CONTROL, "Control 0x%08x not found.\n",
+				v4l2_id);
+
+	return ctrl;
+}
+
+int uvc_query_v4l2_ctrl(struct uvc_video_device *video,
+	struct v4l2_queryctrl *v4l2_ctrl)
+{
+	struct uvc_control *ctrl;
+	struct uvc_control_mapping *mapping;
+	struct uvc_menu_info *menu;
+	unsigned int i;
+	__u8 data[8];
+	int ret;
+
+	ctrl = uvc_find_control(video, v4l2_ctrl->id, &mapping);
+	if (ctrl == NULL)
+		return -EINVAL;
+
+	v4l2_ctrl->id = mapping->id;
+	v4l2_ctrl->type = mapping->v4l2_type;
+	strncpy(v4l2_ctrl->name, mapping->name, sizeof v4l2_ctrl->name);
+	v4l2_ctrl->flags = 0;
+
+	if (!(ctrl->info->flags & UVC_CONTROL_SET_CUR))
+		v4l2_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;
+
+	if (ctrl->info->flags & UVC_CONTROL_GET_DEF) {
+		if ((ret = uvc_query_ctrl(video->dev, GET_DEF, ctrl->entity->id,
+				video->dev->intfnum, ctrl->info->selector,
+				&data, ctrl->info->size)) < 0)
+			return ret;
+		v4l2_ctrl->default_value = uvc_get_le_value(data, mapping);
+	}
+
+	if (mapping->v4l2_type == V4L2_CTRL_TYPE_MENU) {
+		v4l2_ctrl->minimum = 0;
+		v4l2_ctrl->maximum = mapping->menu_count - 1;
+		v4l2_ctrl->step = 1;
+
+		menu = mapping->menu_info;
+		for (i = 0; i < mapping->menu_count; ++i, ++menu) {
+			if (menu->value == v4l2_ctrl->default_value) {
+				v4l2_ctrl->default_value = i;
+				break;
+			}
+		}
+
+		return 0;
+	}
+
+	if (ctrl->info->flags & UVC_CONTROL_GET_MIN) {
+		if ((ret = uvc_query_ctrl(video->dev, GET_MIN, ctrl->entity->id,
+				video->dev->intfnum, ctrl->info->selector,
+				&data, ctrl->info->size)) < 0)
+			return ret;
+		v4l2_ctrl->minimum = uvc_get_le_value(data, mapping);
+	}
+	if (ctrl->info->flags & UVC_CONTROL_GET_MAX) {
+		if ((ret = uvc_query_ctrl(video->dev, GET_MAX, ctrl->entity->id,
+				video->dev->intfnum, ctrl->info->selector,
+				&data, ctrl->info->size)) < 0)
+			return ret;
+		v4l2_ctrl->maximum = uvc_get_le_value(data, mapping);
+	}
+	if (ctrl->info->flags & UVC_CONTROL_GET_RES) {
+		if ((ret = uvc_query_ctrl(video->dev, GET_RES, ctrl->entity->id,
+				video->dev->intfnum, ctrl->info->selector,
+				&data, ctrl->info->size)) < 0)
+			return ret;
+		v4l2_ctrl->step = uvc_get_le_value(data, mapping);
+	}
+
+	return 0;
+}
+
+
+/* --------------------------------------------------------------------------
+ * Control transactions
+ *
+ * To make extended set operations as atomic as the hardware allows, controls
+ * are handled using begin/commit/rollback operations.
+ *
+ * At the beginning of a set request, uvc_ctrl_begin should be called to
+ * initialize the request. This function acquires the control lock.
+ *
+ * When setting a control, the new value is stored in the control data field
+ * at position UVC_CTRL_DATA_CURRENT. The control is then marked as dirty for
+ * later processing. If the UVC and V4L2 control sizes differ, the current
+ * value is loaded from the hardware before storing the new value in the data
+ * field.
+ *
+ * After processing all controls in the transaction, uvc_ctrl_commit or
+ * uvc_ctrl_rollback must be called to apply the pending changes to the
+ * hardware or revert them. When applying changes, all controls marked as
+ * dirty will be modified in the UVC device, and the dirty flag will be
+ * cleared. When reverting controls, the control data field
+ * UVC_CTRL_DATA_CURRENT is reverted to its previous value
+ * (UVC_CTRL_DATA_BACKUP) for all dirty controls. Both functions release the
+ * control lock.
+ */
+int uvc_ctrl_begin(struct uvc_video_device *video)
+{
+	return mutex_lock_interruptible(&video->ctrl_mutex) ? -ERESTARTSYS : 0;
+}
+
+static int uvc_ctrl_commit_entity(struct uvc_device *dev,
+	struct uvc_entity *entity, int rollback)
+{
+	struct uvc_control *ctrl;
+	unsigned int i;
+	int ret;
+
+	if (entity == NULL)
+		return 0;
+
+	for (i = 0; i < entity->ncontrols; ++i) {
+		ctrl = &entity->controls[i];
+		if (ctrl->info == NULL || !ctrl->dirty)
+			continue;
+
+		if (!rollback)
+			ret = uvc_query_ctrl(dev, SET_CUR, ctrl->entity->id,
+				dev->intfnum, ctrl->info->selector,
+				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+				ctrl->info->size);
+		else
+			ret = 0;
+
+		if (rollback || ret < 0)
+			memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+			       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
+			       ctrl->info->size);
+
+		if ((ctrl->info->flags & UVC_CONTROL_GET_CUR) == 0)
+			ctrl->loaded = 0;
+
+		ctrl->dirty = 0;
+
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+int __uvc_ctrl_commit(struct uvc_video_device *video, int rollback)
+{
+	struct uvc_entity *entity;
+	int ret = 0;
+
+	/* Find the control. */
+	ret = uvc_ctrl_commit_entity(video->dev, video->processing, rollback);
+	if (ret < 0)
+		goto done;
+
+	list_for_each_entry(entity, &video->iterms, chain) {
+		ret = uvc_ctrl_commit_entity(video->dev, entity, rollback);
+		if (ret < 0)
+			goto done;
+	}
+
+	list_for_each_entry(entity, &video->extensions, chain) {
+		ret = uvc_ctrl_commit_entity(video->dev, entity, rollback);
+		if (ret < 0)
+			goto done;
+	}
+
+done:
+	mutex_unlock(&video->ctrl_mutex);
+	return ret;
+}
+
+int uvc_ctrl_get(struct uvc_video_device *video,
+	struct v4l2_ext_control *xctrl)
+{
+	struct uvc_control *ctrl;
+	struct uvc_control_mapping *mapping;
+	struct uvc_menu_info *menu;
+	unsigned int i;
+	int ret;
+
+	ctrl = uvc_find_control(video, xctrl->id, &mapping);
+	if (ctrl == NULL || (ctrl->info->flags & UVC_CONTROL_GET_CUR) == 0)
+		return -EINVAL;
+
+	if (!ctrl->loaded) {
+		ret = uvc_query_ctrl(video->dev, GET_CUR, ctrl->entity->id,
+				video->dev->intfnum, ctrl->info->selector,
+				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+				ctrl->info->size);
+		if (ret < 0)
+			return ret;
+
+		if ((ctrl->info->flags & UVC_CONTROL_AUTO_UPDATE) == 0)
+			ctrl->loaded = 1;
+	}
+
+	xctrl->value = uvc_get_le_value(
+		uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT), mapping);
+
+	if (mapping->v4l2_type == V4L2_CTRL_TYPE_MENU) {
+		menu = mapping->menu_info;
+		for (i = 0; i < mapping->menu_count; ++i, ++menu) {
+			if (menu->value == xctrl->value) {
+				xctrl->value = i;
+				break;
+			}
+		}
+	}
+
+	return 0;
+}
+
+int uvc_ctrl_set(struct uvc_video_device *video,
+	struct v4l2_ext_control *xctrl)
+{
+	struct uvc_control *ctrl;
+	struct uvc_control_mapping *mapping;
+	s32 value = xctrl->value;
+	int ret;
+
+	ctrl = uvc_find_control(video, xctrl->id, &mapping);
+	if (ctrl == NULL || (ctrl->info->flags & UVC_CONTROL_SET_CUR) == 0)
+		return -EINVAL;
+
+	if (mapping->v4l2_type == V4L2_CTRL_TYPE_MENU) {
+		if (value < 0 || value >= mapping->menu_count)
+			return -EINVAL;
+		value = mapping->menu_info[value].value;
+	}
+
+	if (!ctrl->loaded && (ctrl->info->size * 8) != mapping->size) {
+		if ((ctrl->info->flags & UVC_CONTROL_GET_CUR) == 0) {
+			memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+				0, ctrl->info->size);
+		} else {
+			ret = uvc_query_ctrl(video->dev, GET_CUR,
+				ctrl->entity->id, video->dev->intfnum,
+				ctrl->info->selector,
+				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+				ctrl->info->size);
+			if (ret < 0)
+				return ret;
+		}
+
+		if ((ctrl->info->flags & UVC_CONTROL_AUTO_UPDATE) == 0)
+			ctrl->loaded = 1;
+	}
+
+	if (!ctrl->dirty) {
+		memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
+		       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+		       ctrl->info->size);
+	}
+
+	uvc_set_le_value(value,
+		uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT), mapping);
+
+	ctrl->dirty = 1;
+	ctrl->modified = 1;
+	return 0;
+}
+
+/* --------------------------------------------------------------------------
+ * Dynamic controls
+ */
+
+int uvc_xu_ctrl_query(struct uvc_video_device *video,
+	struct uvc_xu_control *xctrl, int set)
+{
+	struct uvc_entity *entity;
+	struct uvc_control *ctrl = NULL;
+	unsigned int i, found = 0;
+	__u8 *data;
+	int ret;
+
+	/* Find the extension unit. */
+	list_for_each_entry(entity, &video->extensions, chain) {
+		if (entity->id == xctrl->unit)
+			break;
+	}
+
+	if (entity->id != xctrl->unit) {
+		uvc_trace(UVC_TRACE_CONTROL, "Extension unit %u not found.\n",
+			xctrl->unit);
+		return -EINVAL;
+	}
+
+	/* Find the control. */
+	for (i = 0; i < entity->ncontrols; ++i) {
+		ctrl = &entity->controls[i];
+		if (ctrl->info == NULL)
+			continue;
+
+		if (ctrl->info->selector == xctrl->selector) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (!found) {
+		uvc_trace(UVC_TRACE_CONTROL,
+			"Control " UVC_GUID_FORMAT "/%u not found.\n",
+			UVC_GUID_ARGS(entity->extension.guidExtensionCode),
+			xctrl->selector);
+		return -EINVAL;
+	}
+
+	/* Validate control data size. */
+	if (ctrl->info->size != xctrl->size)
+		return -EINVAL;
+
+	if ((set && !(ctrl->info->flags & UVC_CONTROL_SET_CUR)) ||
+	    (!set && !(ctrl->info->flags & UVC_CONTROL_GET_CUR)))
+		return -EINVAL;
+
+	if (mutex_lock_interruptible(&video->ctrl_mutex))
+		return -ERESTARTSYS;
+
+	memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
+	       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+	       xctrl->size);
+	data = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT);
+
+	if (set && copy_from_user(data, xctrl->data, xctrl->size)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	ret = uvc_query_ctrl(video->dev, set ? SET_CUR : GET_CUR, xctrl->unit,
+			     video->dev->intfnum, xctrl->selector, data,
+			     xctrl->size);
+	if (ret < 0)
+		goto out;
+
+	if (!set && copy_to_user(xctrl->data, data, xctrl->size)) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+out:
+	if (ret)
+		memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
+		       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
+		       xctrl->size);
+
+	mutex_unlock(&video->ctrl_mutex);
+	return ret;
+}
+
+/* --------------------------------------------------------------------------
+ * Suspend/resume
+ */
+
+/*
+ * Restore control values after resume, skipping controls that haven't been
+ * changed.
+ *
+ * TODO
+ * - Don't restore modified controls that are back to their default value.
+ * - Handle restore order (Auto-Exposure Mode should be restored before
+ *   Exposure Time).
+ */
+int uvc_ctrl_resume_device(struct uvc_device *dev)
+{
+	struct uvc_control *ctrl;
+	struct uvc_entity *entity;
+	unsigned int i;
+	int ret;
+
+	/* Walk the entities list and restore controls when possible. */
+	list_for_each_entry(entity, &dev->entities, list) {
+
+		for (i = 0; i < entity->ncontrols; ++i) {
+			ctrl = &entity->controls[i];
+
+			if (ctrl->info == NULL || !ctrl->modified ||
+			    (ctrl->info->flags & UVC_CONTROL_RESTORE) == 0)
+				continue;
+
+			printk(KERN_INFO "restoring control " UVC_GUID_FORMAT
+				"/%u/%u\n", UVC_GUID_ARGS(ctrl->info->entity),
+				ctrl->info->index, ctrl->info->selector);
+			ctrl->dirty = 1;
+		}
+
+		ret = uvc_ctrl_commit_entity(dev, entity, 0);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/* --------------------------------------------------------------------------
+ * Control and mapping handling
+ */
+
+static void uvc_ctrl_add_ctrl(struct uvc_device *dev,
+	struct uvc_control_info *info)
+{
+	struct uvc_entity *entity;
+	struct uvc_control *ctrl = NULL;
+	int ret, found = 0;
+	unsigned int i;
+
+	list_for_each_entry(entity, &dev->entities, list) {
+		if (!uvc_entity_match_guid(entity, info->entity))
+			continue;
+
+		for (i = 0; i < entity->ncontrols; ++i) {
+			ctrl = &entity->controls[i];
+			if (ctrl->index == info->index) {
+				found = 1;
+				break;
+			}
+		}
+
+		if (found)
+			break;
+	}
+
+	if (!found)
+		return;
+
+	if (UVC_ENTITY_TYPE(entity) == VC_EXTENSION_UNIT) {
+		/* Check if the device control information and length match
+		 * the user supplied information.
+		 */
+		__u32 flags;
+		__le16 size;
+		__u8 inf;
+
+		if ((ret = uvc_query_ctrl(dev, GET_LEN, ctrl->entity->id,
+			dev->intfnum, info->selector, (__u8 *)&size, 2)) < 0) {
+			uvc_trace(UVC_TRACE_CONTROL, "GET_LEN failed on "
+				"control " UVC_GUID_FORMAT "/%u (%d).\n",
+				UVC_GUID_ARGS(info->entity), info->selector,
+				ret);
+			return;
+		}
+
+		if (info->size != le16_to_cpu(size)) {
+			uvc_trace(UVC_TRACE_CONTROL, "Control " UVC_GUID_FORMAT
+				"/%u size doesn't match user supplied "
+				"value.\n", UVC_GUID_ARGS(info->entity),
+				info->selector);
+			return;
+		}
+
+		if ((ret = uvc_query_ctrl(dev, GET_INFO, ctrl->entity->id,
+			dev->intfnum, info->selector, &inf, 1)) < 0) {
+			uvc_trace(UVC_TRACE_CONTROL, "GET_INFO failed on "
+				"control " UVC_GUID_FORMAT "/%u (%d).\n",