// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      uvc_ctrl.c  --  USB Video Class driver - Controls
 *
 *      Copyright (C) 2005-2010
 *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
 */

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/atomic.h>
#include <media/v4l2-ctrls.h>

#include "uvcvideo.h"

#define UVC_CTRL_DATA_CURRENT   0
#define UVC_CTRL_DATA_BACKUP    1
#define UVC_CTRL_DATA_MIN       2
#define UVC_CTRL_DATA_MAX       3
#define UVC_CTRL_DATA_RES       4
#define UVC_CTRL_DATA_DEF       5
#define UVC_CTRL_DATA_LAST      6

/* ------------------------------------------------------------------------
 * Controls
 */

static const struct uvc_control_info uvc_ctrls[] = {
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_BRIGHTNESS_CONTROL,
                .index          = 0,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_CONTRAST_CONTROL,
                .index          = 1,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_HUE_CONTROL,
                .index          = 2,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_SATURATION_CONTROL,
                .index          = 3,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_SHARPNESS_CONTROL,
                .index          = 4,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_GAMMA_CONTROL,
                .index          = 5,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_TEMPERATURE_CONTROL,
                .index          = 6,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_COMPONENT_CONTROL,
                .index          = 7,
                .size           = 4,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_BACKLIGHT_COMPENSATION_CONTROL,
                .index          = 8,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_GAIN_CONTROL,
                .index          = 9,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_POWER_LINE_FREQUENCY_CONTROL,
                .index          = 10,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_HUE_AUTO_CONTROL,
                .index          = 11,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_TEMPERATURE_AUTO_CONTROL,
                .index          = 12,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_COMPONENT_AUTO_CONTROL,
                .index          = 13,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_DIGITAL_MULTIPLIER_CONTROL,
                .index          = 14,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_DIGITAL_MULTIPLIER_LIMIT_CONTROL,
                .index          = 15,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_ANALOG_VIDEO_STANDARD_CONTROL,
                .index          = 16,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_GET_CUR,
        },
        {
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_ANALOG_LOCK_STATUS_CONTROL,
                .index          = 17,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_GET_CUR,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_SCANNING_MODE_CONTROL,
                .index          = 0,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_AE_MODE_CONTROL,
                .index          = 1,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_GET_RES
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_AE_PRIORITY_CONTROL,
                .index          = 2,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_EXPOSURE_TIME_ABSOLUTE_CONTROL,
                .index          = 3,
                .size           = 4,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_EXPOSURE_TIME_RELATIVE_CONTROL,
                .index          = 4,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_FOCUS_ABSOLUTE_CONTROL,
                .index          = 5,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_FOCUS_RELATIVE_CONTROL,
                .index          = 6,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_MIN
                                | UVC_CTRL_FLAG_GET_MAX | UVC_CTRL_FLAG_GET_RES
                                | UVC_CTRL_FLAG_GET_DEF
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_IRIS_ABSOLUTE_CONTROL,
                .index          = 7,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_IRIS_RELATIVE_CONTROL,
                .index          = 8,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_ZOOM_ABSOLUTE_CONTROL,
                .index          = 9,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_ZOOM_RELATIVE_CONTROL,
                .index          = 10,
                .size           = 3,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_MIN
                                | UVC_CTRL_FLAG_GET_MAX | UVC_CTRL_FLAG_GET_RES
                                | UVC_CTRL_FLAG_GET_DEF
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PANTILT_ABSOLUTE_CONTROL,
                .index          = 11,
                .size           = 8,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PANTILT_RELATIVE_CONTROL,
                .index          = 12,
                .size           = 4,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_ROLL_ABSOLUTE_CONTROL,
                .index          = 13,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR
                                | UVC_CTRL_FLAG_GET_RANGE
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_ROLL_RELATIVE_CONTROL,
                .index          = 14,
                .size           = 2,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_MIN
                                | UVC_CTRL_FLAG_GET_MAX | UVC_CTRL_FLAG_GET_RES
                                | UVC_CTRL_FLAG_GET_DEF
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_FOCUS_AUTO_CONTROL,
                .index          = 17,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_RESTORE,
        },
        {
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PRIVACY_CONTROL,
                .index          = 18,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_RESTORE
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
        {
                .entity         = UVC_GUID_EXT_GPIO_CONTROLLER,
                .selector       = UVC_CT_PRIVACY_CONTROL,
                .index          = 0,
                .size           = 1,
                .flags          = UVC_CTRL_FLAG_GET_CUR
                                | UVC_CTRL_FLAG_AUTO_UPDATE,
        },
};

static const struct uvc_menu_info power_line_frequency_controls[] = {
        { 0, "Disabled" },
        { 1, "50 Hz" },
        { 2, "60 Hz" },
};

static const struct uvc_menu_info exposure_auto_controls[] = {
        { 2, "Auto Mode" },
        { 1, "Manual Mode" },
        { 4, "Shutter Priority Mode" },
        { 8, "Aperture Priority Mode" },
};

static s32 uvc_ctrl_get_zoom(struct uvc_control_mapping *mapping,
        u8 query, const u8 *data)
{
        s8 zoom = (s8)data[0];

        switch (query) {
        case UVC_GET_CUR:
                return (zoom == 0) ? 0 : (zoom > 0 ? data[2] : -data[2]);

        case UVC_GET_MIN:
        case UVC_GET_MAX:
        case UVC_GET_RES:
        case UVC_GET_DEF:
        default:
                return data[2];
        }
}

static void uvc_ctrl_set_zoom(struct uvc_control_mapping *mapping,
        s32 value, u8 *data)
{
        data[0] = value == 0 ? 0 : (value > 0) ? 1 : 0xff;
        data[2] = min((int)abs(value), 0xff);
}

static s32 uvc_ctrl_get_rel_speed(struct uvc_control_mapping *mapping,
        u8 query, const u8 *data)
{
        unsigned int first = mapping->offset / 8;
        s8 rel = (s8)data[first];

        switch (query) {
        case UVC_GET_CUR:
                return (rel == 0) ? 0 : (rel > 0 ? data[first+1]
                                                 : -data[first+1]);
        case UVC_GET_MIN:
                return -data[first+1];
        case UVC_GET_MAX:
        case UVC_GET_RES:
        case UVC_GET_DEF:
        default:
                return data[first+1];
        }
}

static void uvc_ctrl_set_rel_speed(struct uvc_control_mapping *mapping,
        s32 value, u8 *data)
{
        unsigned int first = mapping->offset / 8;

        data[first] = value == 0 ? 0 : (value > 0) ? 1 : 0xff;
        data[first+1] = min_t(int, abs(value), 0xff);
}

static const struct uvc_control_mapping uvc_ctrl_mappings[] = {
        {
                .id             = V4L2_CID_BRIGHTNESS,
                .name           = "Brightness",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_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       = UVC_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       = UVC_PU_HUE_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
                .master_id      = V4L2_CID_HUE_AUTO,
                .master_manual  = 0,
        },
        {
                .id             = V4L2_CID_SATURATION,
                .name           = "Saturation",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_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       = UVC_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       = UVC_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       = UVC_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       = UVC_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       = UVC_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       = UVC_PU_HUE_AUTO_CONTROL,
                .size           = 1,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_BOOLEAN,
                .data_type      = UVC_CTRL_DATA_TYPE_BOOLEAN,
                .slave_ids      = { V4L2_CID_HUE, },
        },
        {
                .id             = V4L2_CID_EXPOSURE_AUTO,
                .name           = "Exposure, Auto",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_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),
                .slave_ids      = { V4L2_CID_EXPOSURE_ABSOLUTE, },
        },
        {
                .id             = V4L2_CID_EXPOSURE_AUTO_PRIORITY,
                .name           = "Exposure, Auto Priority",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_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       = UVC_CT_EXPOSURE_TIME_ABSOLUTE_CONTROL,
                .size           = 32,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_UNSIGNED,
                .master_id      = V4L2_CID_EXPOSURE_AUTO,
                .master_manual  = V4L2_EXPOSURE_MANUAL,
        },
        {
                .id             = V4L2_CID_AUTO_WHITE_BALANCE,
                .name           = "White Balance Temperature, Auto",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_TEMPERATURE_AUTO_CONTROL,
                .size           = 1,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_BOOLEAN,
                .data_type      = UVC_CTRL_DATA_TYPE_BOOLEAN,
                .slave_ids      = { V4L2_CID_WHITE_BALANCE_TEMPERATURE, },
        },
        {
                .id             = V4L2_CID_WHITE_BALANCE_TEMPERATURE,
                .name           = "White Balance Temperature",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_TEMPERATURE_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_UNSIGNED,
                .master_id      = V4L2_CID_AUTO_WHITE_BALANCE,
                .master_manual  = 0,
        },
        {
                .id             = V4L2_CID_AUTO_WHITE_BALANCE,
                .name           = "White Balance Component, Auto",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_COMPONENT_AUTO_CONTROL,
                .size           = 1,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_BOOLEAN,
                .data_type      = UVC_CTRL_DATA_TYPE_BOOLEAN,
                .slave_ids      = { V4L2_CID_BLUE_BALANCE,
                                    V4L2_CID_RED_BALANCE },
        },
        {
                .id             = V4L2_CID_BLUE_BALANCE,
                .name           = "White Balance Blue Component",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_COMPONENT_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
                .master_id      = V4L2_CID_AUTO_WHITE_BALANCE,
                .master_manual  = 0,
        },
        {
                .id             = V4L2_CID_RED_BALANCE,
                .name           = "White Balance Red Component",
                .entity         = UVC_GUID_UVC_PROCESSING,
                .selector       = UVC_PU_WHITE_BALANCE_COMPONENT_CONTROL,
                .size           = 16,
                .offset         = 16,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
                .master_id      = V4L2_CID_AUTO_WHITE_BALANCE,
                .master_manual  = 0,
        },
        {
                .id             = V4L2_CID_FOCUS_ABSOLUTE,
                .name           = "Focus (absolute)",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_FOCUS_ABSOLUTE_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_UNSIGNED,
                .master_id      = V4L2_CID_FOCUS_AUTO,
                .master_manual  = 0,
        },
        {
                .id             = V4L2_CID_FOCUS_AUTO,
                .name           = "Focus, Auto",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_FOCUS_AUTO_CONTROL,
                .size           = 1,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_BOOLEAN,
                .data_type      = UVC_CTRL_DATA_TYPE_BOOLEAN,
                .slave_ids      = { V4L2_CID_FOCUS_ABSOLUTE, },
        },
        {
                .id             = V4L2_CID_IRIS_ABSOLUTE,
                .name           = "Iris, Absolute",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_IRIS_ABSOLUTE_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_UNSIGNED,
        },
        {
                .id             = V4L2_CID_IRIS_RELATIVE,
                .name           = "Iris, Relative",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_IRIS_RELATIVE_CONTROL,
                .size           = 8,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
        },
        {
                .id             = V4L2_CID_ZOOM_ABSOLUTE,
                .name           = "Zoom, Absolute",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_ZOOM_ABSOLUTE_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_UNSIGNED,
        },
        {
                .id             = V4L2_CID_ZOOM_CONTINUOUS,
                .name           = "Zoom, Continuous",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_ZOOM_RELATIVE_CONTROL,
                .size           = 0,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
                .get            = uvc_ctrl_get_zoom,
                .set            = uvc_ctrl_set_zoom,
        },
        {
                .id             = V4L2_CID_PAN_ABSOLUTE,
                .name           = "Pan (Absolute)",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PANTILT_ABSOLUTE_CONTROL,
                .size           = 32,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
        },
        {
                .id             = V4L2_CID_TILT_ABSOLUTE,
                .name           = "Tilt (Absolute)",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PANTILT_ABSOLUTE_CONTROL,
                .size           = 32,
                .offset         = 32,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
        },
        {
                .id             = V4L2_CID_PAN_SPEED,
                .name           = "Pan (Speed)",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PANTILT_RELATIVE_CONTROL,
                .size           = 16,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
                .get            = uvc_ctrl_get_rel_speed,
                .set            = uvc_ctrl_set_rel_speed,
        },
        {
                .id             = V4L2_CID_TILT_SPEED,
                .name           = "Tilt (Speed)",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PANTILT_RELATIVE_CONTROL,
                .size           = 16,
                .offset         = 16,
                .v4l2_type      = V4L2_CTRL_TYPE_INTEGER,
                .data_type      = UVC_CTRL_DATA_TYPE_SIGNED,
                .get            = uvc_ctrl_get_rel_speed,
                .set            = uvc_ctrl_set_rel_speed,
        },
        {
                .id             = V4L2_CID_PRIVACY,
                .name           = "Privacy",
                .entity         = UVC_GUID_UVC_CAMERA,
                .selector       = UVC_CT_PRIVACY_CONTROL,
                .size           = 1,
                .offset         = 0,
                .v4l2_type      = V4L2_CTRL_TYPE_BOOLEAN,
                .data_type      = UVC_CTRL_DATA_TYPE_BOOLEAN,
        },
        {
                .id             = V4L2_CID_PRIVACY,
                .name           = "Privacy",
                .entity         = UVC_GUID_EXT_GPIO_CONTROLLER,
                .selector       = UVC_CT_PRIVACY_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->uvc_data + id * ctrl->info.size;
}

static inline int uvc_test_bit(const u8 *data, int bit)
{
        return (data[bit >> 3] >> (bit & 7)) & 1;
}

static inline void uvc_clear_bit(u8 *data, int bit)
{
        data[bit >> 3] &= ~(1 << (bit & 7));
}

/* 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(struct uvc_control_mapping *mapping,
        u8 query, const u8 *data)
{
        int bits = mapping->size;
        int offset = mapping->offset;
        s32 value = 0;
        u8 mask;

        data += offset / 8;
        offset &= 7;
        mask = ((1LL << bits) - 1) << offset;

        while (1) {
                u8 byte = *data & mask;
                value |= offset > 0 ? (byte >> offset) : (byte << (-offset));
                bits -= 8 - (offset > 0 ? offset : 0);
                if (bits <= 0)
                        break;

                offset -= 8;
                mask = (1 << bits) - 1;
                data++;
        }

        /* 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(struct uvc_control_mapping *mapping,
        s32 value, u8 *data)
{
        int bits = mapping->size;
        int offset = mapping->offset;
        u8 mask;

        /* According to the v4l2 spec, writing any value to a button control
         * should result in the action belonging to the button control being
         * triggered. UVC devices however want to see a 1 written -> override
         * value.
         */
        if (mapping->v4l2_type == V4L2_CTRL_TYPE_BUTTON)
                value = -1;

        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 int uvc_entity_match_guid(const struct uvc_entity *entity,
                                 const u8 guid[16])
{
        return memcmp(entity->guid, guid, sizeof(entity->guid)) == 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->initialized)
                        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;
                        }
                }
        }
}

static struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
        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. */
        list_for_each_entry(entity, &chain->entities, chain) {
                __uvc_find_control(entity, v4l2_id, mapping, &ctrl, next);
                if (ctrl && !next)
                        return ctrl;
        }

        if (ctrl == NULL && !next)
                uvc_dbg(chain->dev, CONTROL, "Control 0x%08x not found\n",
                        v4l2_id);

        return ctrl;
}

static int uvc_ctrl_populate_cache(struct uvc_video_chain *chain,
        struct uvc_control *ctrl)
{
        int ret;

        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_DEF) {
                ret = uvc_query_ctrl(chain->dev, UVC_GET_DEF, ctrl->entity->id,
                                     chain->dev->intfnum, ctrl->info.selector,
                                     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF),
                                     ctrl->info.size);
                if (ret < 0)
                        return ret;
        }

        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN) {
                ret = uvc_query_ctrl(chain->dev, UVC_GET_MIN, ctrl->entity->id,
                                     chain->dev->intfnum, ctrl->info.selector,
                                     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN),
                                     ctrl->info.size);
                if (ret < 0)
                        return ret;
        }
        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX) {
                ret = uvc_query_ctrl(chain->dev, UVC_GET_MAX, ctrl->entity->id,
                                     chain->dev->intfnum, ctrl->info.selector,
                                     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX),
                                     ctrl->info.size);
                if (ret < 0)
                        return ret;
        }
        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES) {
                ret = uvc_query_ctrl(chain->dev, UVC_GET_RES, ctrl->entity->id,
                                     chain->dev->intfnum, ctrl->info.selector,
                                     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES),
                                     ctrl->info.size);
                if (ret < 0) {
                        if (UVC_ENTITY_TYPE(ctrl->entity) !=
                            UVC_VC_EXTENSION_UNIT)
                                return ret;

                        /* GET_RES is mandatory for XU controls, but some
                         * cameras still choke on it. Ignore errors and set the
                         * resolution value to zero.
                         */
                        uvc_warn_once(chain->dev, UVC_WARN_XU_GET_RES,
                                      "UVC non compliance - GET_RES failed on "
                                      "an XU control. Enabling workaround.\n");
                        memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES), 0,
                               ctrl->info.size);
                }
        }

        ctrl->cached = 1;
        return 0;
}

static s32 __uvc_ctrl_get_value(struct uvc_control_mapping *mapping,
                                const u8 *data)
{
        s32 value = mapping->get(mapping, UVC_GET_CUR, data);

        if (mapping->v4l2_type == V4L2_CTRL_TYPE_MENU) {
                const struct uvc_menu_info *menu = mapping->menu_info;
                unsigned int i;

                for (i = 0; i < mapping->menu_count; ++i, ++menu) {
                        if (menu->value == value) {
                                value = i;
                                break;
                        }
                }
        }

        return value;
}

static int __uvc_ctrl_get(struct uvc_video_chain *chain,
        struct uvc_control *ctrl, struct uvc_control_mapping *mapping,
        s32 *value)
{
        int ret;

        if ((ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) == 0)
                return -EACCES;

        if (!ctrl->loaded) {

                if (ctrl->entity->get_cur) {
                        ret = ctrl->entity->get_cur(chain->dev,
                                ctrl->entity,
                                ctrl->info.selector,
                                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
                                ctrl->info.size);
                } else {
                        ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR,
                                ctrl->entity->id,
                                chain->dev->intfnum,
                                ctrl->info.selector,
                                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
                                ctrl->info.size);
                }
                if (ret < 0)
                        return ret;

                ctrl->loaded = 1;
        }

        *value = __uvc_ctrl_get_value(mapping,
                                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));

        return 0;
}

static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
        struct uvc_control *ctrl,
        struct uvc_control_mapping *mapping,
        struct v4l2_queryctrl *v4l2_ctrl)
{
        struct uvc_control_mapping *master_map = NULL;
        struct uvc_control *master_ctrl = NULL;
        const struct uvc_menu_info *menu;
        unsigned int i;

        memset(v4l2_ctrl, 0, sizeof(*v4l2_ctrl));
        v4l2_ctrl->id = mapping->id;
        v4l2_ctrl->type = mapping->v4l2_type;
        strscpy(v4l2_ctrl->name, mapping->name, sizeof(v4l2_ctrl->name));
        v4l2_ctrl->flags = 0;

        if (!(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
                v4l2_ctrl->flags |= V4L2_CTRL_FLAG_WRITE_ONLY;
        if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
                v4l2_ctrl->flags |= V4L2_CTRL_FLAG_READ_ONLY;

        if (mapping->master_id)
                __uvc_find_control(ctrl->entity, mapping->master_id,
                                   &master_map, &master_ctrl, 0);
        if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
                s32 val;
                int ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
                if (ret < 0)
                        return ret;

                if (val != mapping->master_manual)
                                v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
        }

        if (!ctrl->cached) {
                int ret = uvc_ctrl_populate_cache(chain, ctrl);
                if (ret < 0)
                        return ret;
        }

        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_DEF) {
                v4l2_ctrl->default_value = mapping->get(mapping, UVC_GET_DEF,
                                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF));
        }

        switch (mapping->v4l2_type) {
        case 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;

        case V4L2_CTRL_TYPE_BOOLEAN:
                v4l2_ctrl->minimum = 0;
                v4l2_ctrl->maximum = 1;
                v4l2_ctrl->step = 1;
                return 0;

        case V4L2_CTRL_TYPE_BUTTON:
                v4l2_ctrl->minimum = 0;
                v4l2_ctrl->maximum = 0;
                v4l2_ctrl->step = 0;
                return 0;

        default:
                break;
        }

        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)
                v4l2_ctrl->minimum = mapping->get(mapping, UVC_GET_MIN,
                                     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));

        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
                v4l2_ctrl->maximum = mapping->get(mapping, UVC_GET_MAX,
                                     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));

        if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)
                v4l2_ctrl->step = mapping->get(mapping, UVC_GET_RES,
                                  uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));

        return 0;
}

int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
        struct v4l2_queryctrl *v4l2_ctrl)
{
        struct uvc_control *ctrl;
        struct uvc_control_mapping *mapping;
        int ret;

        ret = mutex_lock_interruptible(&chain->ctrl_mutex);
        if (ret < 0)
                return -ERESTARTSYS;

        ctrl = uvc_find_control(chain, v4l2_ctrl->id, &mapping);
        if (ctrl == NULL) {
                ret = -EINVAL;
                goto done;
        }

        ret = __uvc_query_v4l2_ctrl(chain, ctrl, mapping, v4l2_ctrl);
done:
        mutex_unlock(&chain->ctrl_mutex);
        return ret;
}

/*
 * Mapping V4L2 controls to UVC controls can be straightforward if done well.
 * Most of the UVC controls exist in V4L2, and can be mapped directly. Some
 * must be grouped (for instance the Red Balance, Blue Balance and Do White
 * Balance V4L2 controls use the White Balance Component UVC control) or
 * otherwise translated. The approach we take here is to use a translation
 * table for the controls that can be mapped directly, and handle the others
 * manually.
 */
int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
        struct v4l2_querymenu *query_menu)
{
        const struct uvc_menu_info *menu_info;
        struct uvc_control_mapping *mapping;
        struct uvc_control *ctrl;
        u32 index = query_menu->index;
        u32 id = query_menu->id;
        int ret;

        memset(query_menu, 0, sizeof(*query_menu));
        query_menu->id = id;
        query_menu->index = index;

        ret = mutex_lock_interruptible(&chain->ctrl_mutex);
        if (ret < 0)
                return -ERESTARTSYS;

        ctrl = uvc_find_control(chain, query_menu->id, &mapping);
        if (ctrl == NULL || mapping->v4l2_type != V4L2_CTRL_TYPE_MENU) {
                ret = -EINVAL;
                goto done;
        }

        if (query_menu->index >= mapping->menu_count) {
                ret = -EINVAL;
                goto done;
        }

        menu_info = &mapping->menu_info[query_menu->index];

        if (mapping->data_type == UVC_CTRL_DATA_TYPE_BITMASK &&
            (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)) {
                s32 bitmap;

                if (!ctrl->cached) {
                        ret = uvc_ctrl_populate_cache(chain, ctrl);
                        if (ret < 0)
                                goto done;
                }

                bitmap = mapping->get(mapping, UVC_GET_RES,
                                      uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
                if (!(bitmap & menu_info->value)) {
                        ret = -EINVAL;
                        goto done;
                }
        }

        strscpy(query_menu->name, menu_info->name, sizeof(query_menu->name));

done:
        mutex_unlock(&chain->ctrl_mutex);
        return ret;
}

/* --------------------------------------------------------------------------
 * Ctrl event handling
 */

static void uvc_ctrl_fill_event(struct uvc_video_chain *chain,
        struct v4l2_event *ev,
        struct uvc_control *ctrl,
        struct uvc_control_mapping *mapping,
        s32 value, u32 changes)
{
        struct v4l2_queryctrl v4l2_ctrl;

        __uvc_query_v4l2_ctrl(chain, ctrl, mapping, &v4l2_ctrl);

        memset(ev, 0, sizeof(*ev));
        ev->type = V4L2_EVENT_CTRL;
        ev->id = v4l2_ctrl.id;
        ev->u.ctrl.value = value;
        ev->u.ctrl.changes = changes;
        ev->u.ctrl.type = v4l2_ctrl.type;
        ev->u.ctrl.flags = v4l2_ctrl.flags;
        ev->u.ctrl.minimum = v4l2_ctrl.minimum;
        ev->u.ctrl.maximum = v4l2_ctrl.maximum;
        ev->u.ctrl.step = v4l2_ctrl.step;
        ev->u.ctrl.default_value = v4l2_ctrl.default_value;
}

/*
 * Send control change events to all subscribers for the @ctrl control. By
 * default the subscriber that generated the event, as identified by @handle,
 * is not notified unless it has set the V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK flag.
 * @handle can be NULL for asynchronous events related to auto-update controls,
 * in which case all subscribers are notified.
 */
static void uvc_ctrl_send_event(struct uvc_video_chain *chain,
        struct uvc_fh *handle, struct uvc_control *ctrl,
        struct uvc_control_mapping *mapping, s32 value, u32 changes)
{
        struct v4l2_fh *originator = handle ? &handle->vfh : NULL;
        struct v4l2_subscribed_event *sev;
        struct v4l2_event ev;

        if (list_empty(&mapping->ev_subs))
                return;

        uvc_ctrl_fill_event(chain, &ev, ctrl, mapping, value, changes);

        list_for_each_entry(sev, &mapping->ev_subs, node) {
                if (sev->fh != originator ||
                    (sev->flags & V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK) ||
                    (changes & V4L2_EVENT_CTRL_CH_FLAGS))
                        v4l2_event_queue_fh(sev->fh, &ev);
        }
}

/*
 * Send control change events for the slave of the @master control identified
 * by the V4L2 ID @slave_id. The @handle identifies the event subscriber that
 * generated the event and may be NULL for auto-update events.
 */
static void uvc_ctrl_send_slave_event(struct uvc_video_chain *chain,
        struct uvc_fh *handle, struct uvc_control *master, u32 slave_id)
{
        struct uvc_control_mapping *mapping = NULL;
        struct uvc_control *ctrl = NULL;
        u32 changes = V4L2_EVENT_CTRL_CH_FLAGS;
        s32 val = 0;

        __uvc_find_control(master->entity, slave_id, &mapping, &ctrl, 0);
        if (ctrl == NULL)
                return;

        if (__uvc_ctrl_get(chain, ctrl, mapping, &val) == 0)
                changes |= V4L2_EVENT_CTRL_CH_VALUE;

        uvc_ctrl_send_event(chain, handle, ctrl, mapping, val, changes);
}

void uvc_ctrl_status_event(struct uvc_video_chain *chain,
                           struct uvc_control *ctrl, const u8 *data)
{
        struct uvc_control_mapping *mapping;
        struct uvc_fh *handle;
        unsigned int i;

        mutex_lock(&chain->ctrl_mutex);

        handle = ctrl->handle;
        ctrl->handle = NULL;

        list_for_each_entry(mapping, &ctrl->info.mappings, list) {
                s32 value = __uvc_ctrl_get_value(mapping, data);

                /*
                 * handle may be NULL here if the device sends auto-update
                 * events without a prior related control set from userspace.
                 */
                for (i = 0; i < ARRAY_SIZE(mapping->slave_ids); ++i) {
                        if (!mapping->slave_ids[i])
                                break;

                        uvc_ctrl_send_slave_event(chain, handle, ctrl,
                                                  mapping->slave_ids[i]);
                }

                uvc_ctrl_send_event(chain, handle, ctrl, mapping, value,
                                    V4L2_EVENT_CTRL_CH_VALUE);
        }

        mutex_unlock(&chain->ctrl_mutex);
}

static void uvc_ctrl_status_event_work(struct work_struct *work)
{
        struct uvc_device *dev = container_of(work, struct uvc_device,
                                              async_ctrl.work);
        struct uvc_ctrl_work *w = &dev->async_ctrl;
        int ret;

        uvc_ctrl_status_event(w->chain, w->ctrl, w->data);

        /* Resubmit the URB. */
        w->urb->interval = dev->int_ep->desc.bInterval;
        ret = usb_submit_urb(w->urb, GFP_KERNEL);
        if (ret < 0)
                dev_err(&dev->udev->dev,
                        "Failed to resubmit status URB (%d).\n", ret);
}

bool uvc_ctrl_status_event_async(struct urb *urb, struct uvc_video_chain *chain,
                                 struct uvc_control *ctrl, const u8 *data)
{
        struct uvc_device *dev = chain->dev;
        struct uvc_ctrl_work *w = &dev->async_ctrl;

        if (list_empty(&ctrl->info.mappings)) {
                ctrl->handle = NULL;
                return false;
        }

        w->data = data;
        w->urb = urb;
        w->chain = chain;
        w->ctrl = ctrl;

        schedule_work(&w->work);

        return true;
}

static bool uvc_ctrl_xctrls_has_control(const struct v4l2_ext_control *xctrls,
                                        unsigned int xctrls_count, u32 id)
{
        unsigned int i;

        for (i = 0; i < xctrls_count; ++i) {
                if (xctrls[i].id == id)
                        return true;
        }

        return false;
}

static void uvc_ctrl_send_events(struct uvc_fh *handle,
        const struct v4l2_ext_control *xctrls, unsigned int xctrls_count)
{
        struct uvc_control_mapping *mapping;
        struct uvc_control *ctrl;
        u32 changes = V4L2_EVENT_CTRL_CH_VALUE;
        unsigned int i;
        unsigned int j;

        for (i = 0; i < xctrls_count; ++i) {
                ctrl = uvc_find_control(handle->chain, xctrls[i].id, &mapping);

                if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS)
                        /* Notification will be sent from an Interrupt event. */
                        continue;

                for (j = 0; j < ARRAY_SIZE(mapping->slave_ids); ++j) {
                        u32 slave_id = mapping->slave_ids[j];

                        if (!slave_id)
                                break;

                        /*
                         * We can skip sending an event for the slave if the
                         * slave is being modified in the same transaction.
                         */
                        if (uvc_ctrl_xctrls_has_control(xctrls, xctrls_count,
                                                        slave_id))
                                continue;

                        uvc_ctrl_send_slave_event(handle->chain, handle, ctrl,
                                                  slave_id);
                }

                /*
                 * If the master is being modified in the same transaction
                 * flags may change too.
                 */
                if (mapping->master_id &&
                    uvc_ctrl_xctrls_has_control(xctrls, xctrls_count,
                                                mapping->master_id))
                        changes |= V4L2_EVENT_CTRL_CH_FLAGS;

                uvc_ctrl_send_event(handle->chain, handle, ctrl, mapping,
                                    xctrls[i].value, changes);
        }
}

static int uvc_ctrl_add_event(struct v4l2_subscribed_event *sev, unsigned elems)
{
        struct uvc_fh *handle = container_of(sev->fh, struct uvc_fh, vfh);
        struct uvc_control_mapping *mapping;
        struct uvc_control *ctrl;
        int ret;

        ret = mutex_lock_interruptible(&handle->chain->ctrl_mutex);
        if (ret < 0)
                return -ERESTARTSYS;

        ctrl = uvc_find_control(handle->chain, sev->id, &mapping);
        if (ctrl == NULL) {
                ret = -EINVAL;
                goto done;
        }

        list_add_tail(&sev->node, &mapping->ev_subs);
        if (sev->flags & V4L2_EVENT_SUB_FL_SEND_INITIAL) {
                struct v4l2_event ev;
                u32 changes = V4L2_EVENT_CTRL_CH_FLAGS;
                s32 val = 0;

                if (__uvc_ctrl_get(handle->chain, ctrl, mapping, &val) == 0)
                        changes |= V4L2_EVENT_CTRL_CH_VALUE;

                uvc_ctrl_fill_event(handle->chain, &ev, ctrl, mapping, val,
                                    changes);
                /* Mark the queue as active, allowing this initial
                   event to be accepted. */
                sev->elems = elems;
                v4l2_event_queue_fh(sev->fh, &ev);
        }

done:
        mutex_unlock(&handle->chain->ctrl_mutex);
        return ret;
}

static void uvc_ctrl_del_event(struct v4l2_subscribed_event *sev)
{
        struct uvc_fh *handle = container_of(sev->fh, struct uvc_fh, vfh);

        mutex_lock(&handle->chain->ctrl_mutex);
        list_del(&sev->node);
        mutex_unlock(&handle->chain->ctrl_mutex);
}

const struct v4l2_subscribed_event_ops uvc_ctrl_sub_ev_ops = {
        .add = uvc_ctrl_add_event,
        .del = uvc_ctrl_del_event,
        .replace = v4l2_ctrl_replace,
        .merge = v4l2_ctrl_merge,
};

/* --------------------------------------------------------------------------
 * 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_chain *chain)
{
        return mutex_lock_interruptible(&chain->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->initialized)
                        continue;

                /* Reset the loaded flag for auto-update controls that were
                 * marked as loaded in uvc_ctrl_get/uvc_ctrl_set to prevent
                 * uvc_ctrl_get from using the cached value, and for write-only
                 * controls to prevent uvc_ctrl_set from setting bits not
                 * explicitly set by the user.
                 */
                if (ctrl->info.flags & UVC_CTRL_FLAG_AUTO_UPDATE ||
                    !(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
                        ctrl->loaded = 0;

                if (!ctrl->dirty)
                        continue;

                if (!rollback)
                        ret = uvc_query_ctrl(dev, UVC_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);

                ctrl->dirty = 0;

                if (ret < 0)
                        return ret;
        }

        return 0;
}

int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
                      const struct v4l2_ext_control *xctrls,
                      unsigned int xctrls_count)
{
        struct uvc_video_chain *chain = handle->chain;
        struct uvc_entity *entity;
        int ret = 0;

        /* Find the control. */
        list_for_each_entry(entity, &chain->entities, chain) {
                ret = uvc_ctrl_commit_entity(chain->dev, entity, rollback);
                if (ret < 0)
                        goto done;
        }

        if (!rollback)
                uvc_ctrl_send_events(handle, xctrls, xctrls_count);
done:
        mutex_unlock(&chain->ctrl_mutex);
        return ret;
}

int uvc_ctrl_get(struct uvc_video_chain *chain,
        struct v4l2_ext_control *xctrl)
{
        struct uvc_control *ctrl;
        struct uvc_control_mapping *mapping;

        ctrl = uvc_find_control(chain, xctrl->id, &mapping);
        if (ctrl == NULL)
                return -EINVAL;

        return __uvc_ctrl_get(chain, ctrl, mapping, &xctrl->value);
}

int uvc_ctrl_set(struct uvc_fh *handle,
        struct v4l2_ext_control *xctrl)
{
        struct uvc_video_chain *chain = handle->chain;
        struct uvc_control *ctrl;
        struct uvc_control_mapping *mapping;
        s32 value;
        u32 step;
        s32 min;
        s32 max;
        int ret;

        ctrl = uvc_find_control(chain, xctrl->id, &mapping);
        if (ctrl == NULL)
                return -EINVAL;
        if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
                return -EACCES;

        /* Clamp out of range values. */
        switch (mapping->v4l2_type) {
        case V4L2_CTRL_TYPE_INTEGER:
                if (!ctrl->cached) {
                        ret = uvc_ctrl_populate_cache(chain, ctrl);
                        if (ret < 0)
                                return ret;
                }

                min = mapping->get(mapping, UVC_GET_MIN,
                                   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
                max = mapping->get(mapping, UVC_GET_MAX,
                                   uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
                step = mapping->get(mapping, UVC_GET_RES,
                                    uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
                if (step == 0)
                        step = 1;

                xctrl->value = min + DIV_ROUND_CLOSEST((u32)(xctrl->value - min),
                                                        step) * step;
                if (mapping->data_type == UVC_CTRL_DATA_TYPE_SIGNED)
                        xctrl->value = clamp(xctrl->value, min, max);
                else
                        xctrl->value = clamp_t(u32, xctrl->value, min, max);
                value = xctrl->value;
                break;

        case V4L2_CTRL_TYPE_BOOLEAN:
                xctrl->value = clamp(xctrl->value, 0, 1);
                value = xctrl->value;
                break;

        case V4L2_CTRL_TYPE_MENU:
                if (xctrl->value < 0 || xctrl->value >= mapping->menu_count)
                        return -ERANGE;
                value = mapping->menu_info[xctrl->value].value;

                /* Valid menu indices are reported by the GET_RES request for
                 * UVC controls that support it.
                 */
                if (mapping->data_type == UVC_CTRL_DATA_TYPE_BITMASK &&
                    (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)) {
                        if (!ctrl->cached) {
                                ret = uvc_ctrl_populate_cache(chain, ctrl);
                                if (ret < 0)
                                        return ret;
                        }

                        step = mapping->get(mapping, UVC_GET_RES,
                                        uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
                        if (!(step & value))
                                return -EINVAL;
                }

                break;

        default:
                value = xctrl->value;
                break;
        }

        /* If the mapping doesn't span the whole UVC control, the current value
         * needs to be loaded from the device to perform the read-modify-write
         * operation.
         */
        if (!ctrl->loaded && (ctrl->info.size * 8) != mapping->size) {
                if ((ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) == 0) {
                        memset(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
                                0, ctrl->info.size);
                } else {
                        ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR,
                                ctrl->entity->id, chain->dev->intfnum,
                                ctrl->info.selector,
                                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
                                ctrl->info.size);
                        if (ret < 0)
                                return ret;
                }

                ctrl->loaded = 1;
        }

        /* Backup the current value in case we need to rollback later. */
        if (!ctrl->dirty) {
                memcpy(uvc_ctrl_data(ctrl, UVC_CTRL_DATA_BACKUP),
                       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT),
                       ctrl->info.size);
        }

        mapping->set(mapping, value,
                uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));

        if (ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS)
                ctrl->handle = handle;

        ctrl->dirty = 1;
        ctrl->modified = 1;
        return 0;
}

/* --------------------------------------------------------------------------
 * Dynamic controls
 */

/*
 * Retrieve flags for a given control
 */
static int uvc_ctrl_get_flags(struct uvc_device *dev,
                              const struct uvc_control *ctrl,
                              struct uvc_control_info *info)
{
        u8 *data;
        int ret;

        data = kmalloc(1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (ctrl->entity->get_info)
                ret = ctrl->entity->get_info(dev, ctrl->entity,
                                             ctrl->info.selector, data);
        else
                ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id,
                                     dev->intfnum, info->selector, data, 1);
        if (!ret)
                info->flags |= (data[0] & UVC_CONTROL_CAP_GET ?
                                UVC_CTRL_FLAG_GET_CUR : 0)
                            |  (data[0] & UVC_CONTROL_CAP_SET ?
                                UVC_CTRL_FLAG_SET_CUR : 0)
                            |  (data[0] & UVC_CONTROL_CAP_AUTOUPDATE ?
                                UVC_CTRL_FLAG_AUTO_UPDATE : 0)
                            |  (data[0] & UVC_CONTROL_CAP_ASYNCHRONOUS ?
                                UVC_CTRL_FLAG_ASYNCHRONOUS : 0);

        kfree(data);
        return ret;
}

static void uvc_ctrl_fixup_xu_info(struct uvc_device *dev,
        const struct uvc_control *ctrl, struct uvc_control_info *info)
{
        struct uvc_ctrl_fixup {
                struct usb_device_id id;
                u8 entity;
                u8 selector;
                u8 flags;
        };

        static const struct uvc_ctrl_fixup fixups[] = {
                { { USB_DEVICE(0x046d, 0x08c2) }, 9, 1,
                        UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX |
                        UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_SET_CUR |
                        UVC_CTRL_FLAG_AUTO_UPDATE },
                { { USB_DEVICE(0x046d, 0x08cc) }, 9, 1,
                        UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX |
                        UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_SET_CUR |
                        UVC_CTRL_FLAG_AUTO_UPDATE },
                { { USB_DEVICE(0x046d, 0x0994) }, 9, 1,
                        UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX |
                        UVC_CTRL_FLAG_GET_DEF | UVC_CTRL_FLAG_SET_CUR |
                        UVC_CTRL_FLAG_AUTO_UPDATE },
        };

        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(fixups); ++i) {
                if (!usb_match_one_id(dev->intf, &fixups[i].id))
                        continue;

                if (fixups[i].entity == ctrl->entity->id &&
                    fixups[i].selector == info->selector) {
                        info->flags = fixups[i].flags;
                        return;
                }
        }
}

/*
 * Query control information (size and flags) for XU controls.
 */
static int uvc_ctrl_fill_xu_info(struct uvc_device *dev,
        const struct uvc_control *ctrl, struct uvc_control_info *info)
{
        u8 *data;
        int ret;

        data = kmalloc(2, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        memcpy(info->entity, ctrl->entity->guid, sizeof(info->entity));
        info->index = ctrl->index;
        info->selector = ctrl->index + 1;

        /* Query and verify the control length (GET_LEN) */
        ret = uvc_query_ctrl(dev, UVC_GET_LEN, ctrl->entity->id, dev->intfnum,
                             info->selector, data, 2);
        if (ret < 0) {
                uvc_dbg(dev, CONTROL,
                        "GET_LEN failed on control %pUl/%u (%d)\n",
                        info->entity, info->selector, ret);
                goto done;
        }

        info->size = le16_to_cpup((__le16 *)data);

        info->flags = UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX
                    | UVC_CTRL_FLAG_GET_RES | UVC_CTRL_FLAG_GET_DEF;

        ret = uvc_ctrl_get_flags(dev, ctrl, info);
        if (ret < 0) {
                uvc_dbg(dev, CONTROL,
                        "Failed to get flags for control %pUl/%u (%d)\n",
                        info->entity, info->selector, ret);
                goto done;
        }

        uvc_ctrl_fixup_xu_info(dev, ctrl, info);

        uvc_dbg(dev, CONTROL,
                "XU control %pUl/%u queried: len %u, flags { get %u set %u auto %u }\n",
                info->entity, info->selector, info->size,
                (info->flags & UVC_CTRL_FLAG_GET_CUR) ? 1 : 0,
                (info->flags & UVC_CTRL_FLAG_SET_CUR) ? 1 : 0,
                (info->flags & UVC_CTRL_FLAG_AUTO_UPDATE) ? 1 : 0);

done:
        kfree(data);
        return ret;
}

static int uvc_ctrl_add_info(struct uvc_device *dev, struct uvc_control *ctrl,
        const struct uvc_control_info *info);

static int uvc_ctrl_init_xu_ctrl(struct uvc_device *dev,
        struct uvc_control *ctrl)
{
        struct uvc_control_info info;
        int ret;

        if (ctrl->initialized)
                return 0;

        ret = uvc_ctrl_fill_xu_info(dev, ctrl, &info);
        if (ret < 0)
                return ret;

        ret = uvc_ctrl_add_info(dev, ctrl, &info);
        if (ret < 0)
                uvc_dbg(dev, CONTROL,
                        "Failed to initialize control %pUl/%u on device %s entity %u\n",
                        info.entity, info.selector, dev->udev->devpath,
                        ctrl->entity->id);

        return ret;
}

int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
        struct uvc_xu_control_query *xqry)
{
        struct uvc_entity *entity;
        struct uvc_control *ctrl;
        unsigned int i;
        bool found;
        u32 reqflags;
        u16 size;
        u8 *data = NULL;
        int ret;

        /* Find the extension unit. */
        found = false;
        list_for_each_entry(entity, &chain->entities, chain) {
                if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT &&
                    entity->id == xqry->unit) {
                        found = true;
                        break;
                }
        }

        if (!found) {
                uvc_dbg(chain->dev, CONTROL, "Extension unit %u not found\n",
                        xqry->unit);
                return -ENOENT;
        }

        /* Find the control and perform delayed initialization if needed. */
        found = false;
        for (i = 0; i < entity->ncontrols; ++i) {
                ctrl = &entity->controls[i];
                if (ctrl->index == xqry->selector - 1) {
                        found = true;
                        break;
                }
        }

        if (!found) {
                uvc_dbg(chain->dev, CONTROL, "Control %pUl/%u not found\n",
                        entity->guid, xqry->selector);
                return -ENOENT;
        }

        if (mutex_lock_interruptible(&chain->ctrl_mutex))
                return -ERESTARTSYS;

        ret = uvc_ctrl_init_xu_ctrl(chain->dev, ctrl);
        if (ret < 0) {
                ret = -ENOENT;
                goto done;
        }

        /* Validate the required buffer size and flags for the request */
        reqflags = 0;
        size = ctrl->info.size;

        switch (xqry->query) {
        case UVC_GET_CUR:
                reqflags = UVC_CTRL_FLAG_GET_CUR;
                break;
        case UVC_GET_MIN:
                reqflags = UVC_CTRL_FLAG_GET_MIN;
                break;
        case UVC_GET_MAX:
                reqflags = UVC_CTRL_FLAG_GET_MAX;
                break;
        case UVC_GET_DEF:
                reqflags = UVC_CTRL_FLAG_GET_DEF;
                break;
        case UVC_GET_RES:
                reqflags = UVC_CTRL_FLAG_GET_RES;
                break;
        case UVC_SET_CUR:
                reqflags = UVC_CTRL_FLAG_SET_CUR;
                break;
        case UVC_GET_LEN:
                size = 2;
                break;
        case UVC_GET_INFO:
                size = 1;
                break;
        default:
                ret = -EINVAL;
                goto done;
        }

        if (size != xqry->size) {
                ret = -ENOBUFS;
                goto done;
        }

        if (reqflags && !(ctrl->info.flags & reqflags)) {
                ret = -EBADRQC;
                goto done;
        }

        data = kmalloc(size, GFP_KERNEL);
        if (data == NULL) {
                ret = -ENOMEM;
                goto done;
        }

        if (xqry->query == UVC_SET_CUR &&
            copy_from_user(data, xqry->data, size)) {
                ret = -EFAULT;
                goto done;
        }

        ret = uvc_query_ctrl(chain->dev, xqry->query, xqry->unit,
                             chain->dev->intfnum, xqry->selector, data, size);
        if (ret < 0)
                goto done;

        if (xqry->query != UVC_SET_CUR &&
            copy_to_user(xqry->data, data, size))
                ret = -EFAULT;
done:
        kfree(data);
        mutex_unlock(&chain->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_restore_values(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->initialized || !ctrl->modified ||
                            (ctrl->info.flags & UVC_CTRL_FLAG_RESTORE) == 0)
                                continue;
                        dev_info(&dev->udev->dev,
                                 "restoring control %pUl/%u/%u\n",
                                 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
 */

/*
 * Add control information to a given control.
 */
static int uvc_ctrl_add_info(struct uvc_device *dev, struct uvc_control *ctrl,
        const struct uvc_control_info *info)
{
        ctrl->info = *info;
        INIT_LIST_HEAD(&ctrl->info.mappings);

        /* Allocate an array to save control values (cur, def, max, etc.) */
        ctrl->uvc_data = kzalloc(ctrl->info.size * UVC_CTRL_DATA_LAST + 1,
                                 GFP_KERNEL);
        if (!ctrl->uvc_data)
                return -ENOMEM;

        ctrl->initialized = 1;

        uvc_dbg(dev, CONTROL, "Added control %pUl/%u to device %s entity %u\n",
                ctrl->info.entity, ctrl->info.selector, dev->udev->devpath,
                ctrl->entity->id);

        return 0;
}

/*
 * Add a control mapping to a given control.
 */
static int __uvc_ctrl_add_mapping(struct uvc_device *dev,
        struct uvc_control *ctrl, const struct uvc_control_mapping *mapping)
{
        struct uvc_control_mapping *map;
        unsigned int size;

        /* Most mappings come from static kernel data and need to be duplicated.
         * Mappings that come from userspace will be unnecessarily duplicated,
         * this could be optimized.
         */
        map = kmemdup(mapping, sizeof(*mapping), GFP_KERNEL);
        if (map == NULL)
                return -ENOMEM;

        INIT_LIST_HEAD(&map->ev_subs);

        size = sizeof(*mapping->menu_info) * mapping->menu_count;
        map->menu_info = kmemdup(mapping->menu_info, size, GFP_KERNEL);
        if (map->menu_info == NULL) {
                kfree(map);
                return -ENOMEM;
        }

        if (map->get == NULL)
                map->get = uvc_get_le_value;
        if (map->set == NULL)
                map->set = uvc_set_le_value;

        list_add_tail(&map->list, &ctrl->info.mappings);
        uvc_dbg(dev, CONTROL, "Adding mapping '%s' to control %pUl/%u\n",
                map->name, ctrl->info.entity, ctrl->info.selector);

        return 0;
}

int uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
        const struct uvc_control_mapping *mapping)
{
        struct uvc_device *dev = chain->dev;
        struct uvc_control_mapping *map;
        struct uvc_entity *entity;
        struct uvc_control *ctrl;
        int found = 0;
        int ret;

        if (mapping->id & ~V4L2_CTRL_ID_MASK) {
                uvc_dbg(dev, CONTROL,
                        "Can't add mapping '%s', control id 0x%08x is invalid\n",
                        mapping->name, mapping->id);
                return -EINVAL;
        }

        /* Search for the matching (GUID/CS) control on the current chain */
        list_for_each_entry(entity, &chain->entities, chain) {
                unsigned int i;

                if (UVC_ENTITY_TYPE(entity) != UVC_VC_EXTENSION_UNIT ||
                    !uvc_entity_match_guid(entity, mapping->entity))
                        continue;

                for (i = 0; i < entity->ncontrols; ++i) {
                        ctrl = &entity->controls[i];
                        if (ctrl->index == mapping->selector - 1) {
                                found = 1;
                                break;
                        }
                }

                if (found)
                        break;
        }
        if (!found)
                return -ENOENT;

        if (mutex_lock_interruptible(&chain->ctrl_mutex))
                return -ERESTARTSYS;

        /* Perform delayed initialization of XU controls */
        ret = uvc_ctrl_init_xu_ctrl(dev, ctrl);
        if (ret < 0) {
                ret = -ENOENT;
                goto done;
        }

        /* Validate the user-provided bit-size and offset */
        if (mapping->size > 32 ||
            mapping->offset + mapping->size > ctrl->info.size * 8) {
                ret = -EINVAL;
                goto done;
        }

        list_for_each_entry(map, &ctrl->info.mappings, list) {
                if (mapping->id == map->id) {
                        uvc_dbg(dev, CONTROL,
                                "Can't add mapping '%s', control id 0x%08x already exists\n",
                                mapping->name, mapping->id);
                        ret = -EEXIST;
                        goto done;
                }
        }

        /* Prevent excess memory consumption */
        if (atomic_inc_return(&dev->nmappings) > UVC_MAX_CONTROL_MAPPINGS) {
                atomic_dec(&dev->nmappings);
                uvc_dbg(dev, CONTROL,
                        "Can't add mapping '%s', maximum mappings count (%u) exceeded\n",
                        mapping->name, UVC_MAX_CONTROL_MAPPINGS);
                ret = -ENOMEM;
                goto done;
        }

        ret = __uvc_ctrl_add_mapping(dev, ctrl, mapping);
        if (ret < 0)
                atomic_dec(&dev->nmappings);

done:
        mutex_unlock(&chain->ctrl_mutex);
        return ret;
}

/*
 * Prune an entity of its bogus controls using a blacklist. Bogus controls
 * are currently the ones that crash the camera or unconditionally return an
 * error when queried.
 */
static void uvc_ctrl_prune_entity(struct uvc_device *dev,
        struct uvc_entity *entity)
{
        struct uvc_ctrl_blacklist {
                struct usb_device_id id;
                u8 index;
        };

        static const struct uvc_ctrl_blacklist processing_blacklist[] = {
                { { USB_DEVICE(0x13d3, 0x509b) }, 9 }, /* Gain */
                { { USB_DEVICE(0x1c4f, 0x3000) }, 6 }, /* WB Temperature */
                { { USB_DEVICE(0x5986, 0x0241) }, 2 }, /* Hue */
        };
        static const struct uvc_ctrl_blacklist camera_blacklist[] = {
                { { USB_DEVICE(0x06f8, 0x3005) }, 9 }, /* Zoom, Absolute */
        };

        const struct uvc_ctrl_blacklist *blacklist;
        unsigned int size;
        unsigned int count;
        unsigned int i;
        u8 *controls;

        switch (UVC_ENTITY_TYPE(entity)) {
        case UVC_VC_PROCESSING_UNIT:
                blacklist = processing_blacklist;
                count = ARRAY_SIZE(processing_blacklist);
                controls = entity->processing.bmControls;
                size = entity->processing.bControlSize;
                break;

        case UVC_ITT_CAMERA:
                blacklist = camera_blacklist;
                count = ARRAY_SIZE(camera_blacklist);
                controls = entity->camera.bmControls;
                size = entity->camera.bControlSize;
                break;

        default:
                return;
        }

        for (i = 0; i < count; ++i) {
                if (!usb_match_one_id(dev->intf, &blacklist[i].id))
                        continue;

                if (blacklist[i].index >= 8 * size ||
                    !uvc_test_bit(controls, blacklist[i].index))
                        continue;

                uvc_dbg(dev, CONTROL,
                        "%u/%u control is black listed, removing it\n",
                        entity->id, blacklist[i].index);

                uvc_clear_bit(controls, blacklist[i].index);
        }
}

/*
 * Add control information and hardcoded stock control mappings to the given
 * device.
 */
static void uvc_ctrl_init_ctrl(struct uvc_device *dev, struct uvc_control *ctrl)
{
        const struct uvc_control_info *info = uvc_ctrls;
        const struct uvc_control_info *iend = info + ARRAY_SIZE(uvc_ctrls);
        const struct uvc_control_mapping *mapping = uvc_ctrl_mappings;
        const struct uvc_control_mapping *mend =
                mapping + ARRAY_SIZE(uvc_ctrl_mappings);

        /* XU controls initialization requires querying the device for control
         * information. As some buggy UVC devices will crash when queried
         * repeatedly in a tight loop, delay XU controls initialization until
         * first use.
         */
        if (UVC_ENTITY_TYPE(ctrl->entity) == UVC_VC_EXTENSION_UNIT)
                return;

        for (; info < iend; ++info) {
                if (uvc_entity_match_guid(ctrl->entity, info->entity) &&
                    ctrl->index == info->index) {
                        uvc_ctrl_add_info(dev, ctrl, info);
                        /*
                         * Retrieve control flags from the device. Ignore errors
                         * and work with default flag values from the uvc_ctrl
                         * array when the device doesn't properly implement
                         * GET_INFO on standard controls.
                         */
                        uvc_ctrl_get_flags(dev, ctrl, &ctrl->info);
                        break;
                 }
        }

        if (!ctrl->initialized)
                return;

        for (; mapping < mend; ++mapping) {
                if (uvc_entity_match_guid(ctrl->entity, mapping->entity) &&
                    ctrl->info.selector == mapping->selector)
                        __uvc_ctrl_add_mapping(dev, ctrl, mapping);
        }
}

/*
 * Initialize device controls.
 */
int uvc_ctrl_init_device(struct uvc_device *dev)
{
        struct uvc_entity *entity;
        unsigned int i;

        INIT_WORK(&dev->async_ctrl.work, uvc_ctrl_status_event_work);

        /* Walk the entities list and instantiate controls */
        list_for_each_entry(entity, &dev->entities, list) {
                struct uvc_control *ctrl;
                unsigned int bControlSize = 0, ncontrols;
                u8 *bmControls = NULL;

                if (UVC_ENTITY_TYPE(entity) == UVC_VC_EXTENSION_UNIT) {
                        bmControls = entity->extension.bmControls;
                        bControlSize = entity->extension.bControlSize;
                } else if (UVC_ENTITY_TYPE(entity) == UVC_VC_PROCESSING_UNIT) {
                        bmControls = entity->processing.bmControls;
                        bControlSize = entity->processing.bControlSize;
                } else if (UVC_ENTITY_TYPE(entity) == UVC_ITT_CAMERA) {
                        bmControls = entity->camera.bmControls;
                        bControlSize = entity->camera.bControlSize;
                } else if (UVC_ENTITY_TYPE(entity) == UVC_EXT_GPIO_UNIT) {
                        bmControls = entity->gpio.bmControls;
                        bControlSize = entity->gpio.bControlSize;
                }

                /* Remove bogus/blacklisted controls */
                uvc_ctrl_prune_entity(dev, entity);

                /* Count supported controls and allocate the controls array */
                ncontrols = memweight(bmControls, bControlSize);
                if (ncontrols == 0)
                        continue;

                entity->controls = kcalloc(ncontrols, sizeof(*ctrl),
                                           GFP_KERNEL);
                if (entity->controls == NULL)
                        return -ENOMEM;
                entity->ncontrols = ncontrols;

                /* Initialize all supported controls */
                ctrl = entity->controls;
                for (i = 0; i < bControlSize * 8; ++i) {
                        if (uvc_test_bit(bmControls, i) == 0)
                                continue;

                        ctrl->entity = entity;
                        ctrl->index = i;

                        uvc_ctrl_init_ctrl(dev, ctrl);
                        ctrl++;
                }
        }

        return 0;
}

/*
 * Cleanup device controls.
 */
static void uvc_ctrl_cleanup_mappings(struct uvc_device *dev,
        struct uvc_control *ctrl)
{
        struct uvc_control_mapping *mapping, *nm;

        list_for_each_entry_safe(mapping, nm, &ctrl->info.mappings, list) {
                list_del(&mapping->list);
                kfree(mapping->menu_info);
                kfree(mapping);
        }
}

void uvc_ctrl_cleanup_device(struct uvc_device *dev)
{
        struct uvc_entity *entity;
        unsigned int i;

        /* Can be uninitialized if we are aborting on probe error. */
        if (dev->async_ctrl.work.func)
                cancel_work_sync(&dev->async_ctrl.work);

        /* Free controls and control mappings for all entities. */
        list_for_each_entry(entity, &dev->entities, list) {
                for (i = 0; i < entity->ncontrols; ++i) {
                        struct uvc_control *ctrl = &entity->controls[i];

                        if (!ctrl->initialized)
                                continue;

                        uvc_ctrl_cleanup_mappings(dev, ctrl);
                        kfree(ctrl->uvc_data);
                }

                kfree(entity->controls);
        }
}