Quelle  uvc_ctrl.c   Sprache: C

// 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 <asm/barrier.h>
#include <linux/bitops.h>
#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/usb/uvc.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,
 },
 /*
 * UVC_CTRL_FLAG_AUTO_UPDATE is needed because the RoI may get updated
 * by sensors.
 * "This RoI should be the same as specified in most recent SET_CUR
 * except in the case where the ‘Auto Detect and Track’ and/or
 * ‘Image Stabilization’ bit have been set."
 * 4.2.2.1.20 Digital Region of Interest (ROI) Control
 */
 {
  .entity  = UVC_GUID_UVC_CAMERA,
  .selector = UVC_CT_REGION_OF_INTEREST_CONTROL,
  .index  = 21,
  .size  = 10,
  .flags  = UVC_CTRL_FLAG_SET_CUR | UVC_CTRL_FLAG_GET_CUR
    | UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX
    | UVC_CTRL_FLAG_GET_DEF
    | UVC_CTRL_FLAG_AUTO_UPDATE,
 },
};

static const u32 uvc_control_classes[] = {
 V4L2_CID_CAMERA_CLASS,
 V4L2_CID_USER_CLASS,
};

static const int exposure_auto_mapping[] = { 2, 1, 4, 8 };

static bool uvc_ctrl_mapping_is_compound(struct uvc_control_mapping *mapping)
{
 return mapping->v4l2_type >= V4L2_CTRL_COMPOUND_TYPES;
}

static s32 uvc_mapping_get_s32(struct uvc_control_mapping *mapping,
          u8 query, const void *data_in)
{
 s32 data_out = 0;

 mapping->get(mapping, query, data_in, sizeof(data_out), &data_out);

 return data_out;
}

static void uvc_mapping_set_s32(struct uvc_control_mapping *mapping,
    s32 data_in, void *data_out)
{
 mapping->set(mapping, sizeof(data_in), &data_in, data_out);
}

/*
 * This function translates the V4L2 menu index @idx, as exposed to userspace as
 * the V4L2 control value, to the corresponding UVC control value used by the
 * device. The custom menu_mapping in the control @mapping is used when
 * available, otherwise the function assumes that the V4L2 and UVC values are
 * identical.
 *
 * For controls of type UVC_CTRL_DATA_TYPE_BITMASK, the UVC control value is
 * expressed as a bitmask and is thus guaranteed to have a single bit set.
 *
 * The function returns -EINVAL if the V4L2 menu index @idx isn't valid for the
 * control, which includes all controls whose type isn't UVC_CTRL_DATA_TYPE_ENUM
 * or UVC_CTRL_DATA_TYPE_BITMASK.
 */
static int uvc_mapping_get_menu_value(const struct uvc_control_mapping *mapping,
          u32 idx)
{
 if (!test_bit(idx, &mapping->menu_mask))
  return -EINVAL;

 if (mapping->menu_mapping)
  return mapping->menu_mapping[idx];

 return idx;
}

static const char *
uvc_mapping_get_menu_name(const struct uvc_control_mapping *mapping, u32 idx)
{
 if (!test_bit(idx, &mapping->menu_mask))
  return NULL;

 if (mapping->menu_names)
  return mapping->menu_names[idx];

 return v4l2_ctrl_get_menu(mapping->id)[idx];
}

static int uvc_ctrl_get_zoom(struct uvc_control_mapping *mapping, u8 query,
        const void *uvc_in, size_t v4l2_size,
        void *v4l2_out)
{
 u8 value = ((u8 *)uvc_in)[2];
 s8 sign = ((s8 *)uvc_in)[0];
 s32 *out = v4l2_out;

 if (WARN_ON(v4l2_size != sizeof(s32)))
  return -EINVAL;

 switch (query) {
 case UVC_GET_CUR:
  *out = (sign == 0) ? 0 : (sign > 0 ? value : -value);
  return 0;

 case UVC_GET_MIN:
 case UVC_GET_MAX:
 case UVC_GET_RES:
 case UVC_GET_DEF:
 default:
  *out = value;
  return 0;
 }
}

static int uvc_ctrl_set_zoom(struct uvc_control_mapping *mapping,
        size_t v4l2_size, const void *v4l2_in,
        void *uvc_out)
{
 u8 *out = uvc_out;
 s32 value;

 if (WARN_ON(v4l2_size != sizeof(s32)))
  return -EINVAL;

 value = *(u32 *)v4l2_in;
 out[0] = value == 0 ? 0 : (value > 0) ? 1 : 0xff;
 out[2] = min_t(int, abs(value), 0xff);

 return 0;
}

static int uvc_ctrl_get_rel_speed(struct uvc_control_mapping *mapping,
      u8 query, const void *uvc_in,
      size_t v4l2_size, void *v4l2_out)
{
 unsigned int first = mapping->offset / 8;
 u8 value = ((u8 *)uvc_in)[first + 1];
 s8 sign = ((s8 *)uvc_in)[first];
 s32 *out = v4l2_out;

 if (WARN_ON(v4l2_size != sizeof(s32)))
  return -EINVAL;

 switch (query) {
 case UVC_GET_CUR:
  *out = (sign == 0) ? 0 : (sign > 0 ? value : -value);
  return 0;
 case UVC_GET_MIN:
  *out = -value;
  return 0;
 case UVC_GET_MAX:
 case UVC_GET_RES:
 case UVC_GET_DEF:
 default:
  *out = value;
  return 0;
 }
}

static int uvc_ctrl_set_rel_speed(struct uvc_control_mapping *mapping,
      size_t v4l2_size, const void *v4l2_in,
      void *uvc_out)
{
 unsigned int first = mapping->offset / 8;
 u8 *out = uvc_out;
 s32 value;

 if (WARN_ON(v4l2_size != sizeof(s32)))
  return -EINVAL;

 value = *(u32 *)v4l2_in;
 out[first] = value == 0 ? 0 : (value > 0) ? 1 : 0xff;
 out[first + 1] = min_t(int, abs(value), 0xff);

 return 0;
}

static const struct uvc_control_mapping uvc_ctrl_power_line_mapping_limited = {
 .id  = V4L2_CID_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_mask = GENMASK(V4L2_CID_POWER_LINE_FREQUENCY_60HZ,
      V4L2_CID_POWER_LINE_FREQUENCY_50HZ),
};

static const struct uvc_control_mapping uvc_ctrl_power_line_mapping_uvc11 = {
 .id  = V4L2_CID_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_mask = GENMASK(V4L2_CID_POWER_LINE_FREQUENCY_60HZ,
      V4L2_CID_POWER_LINE_FREQUENCY_DISABLED),
};

static const struct uvc_control_mapping uvc_ctrl_power_line_mapping_uvc15 = {
 .id  = V4L2_CID_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_mask = GENMASK(V4L2_CID_POWER_LINE_FREQUENCY_AUTO,
      V4L2_CID_POWER_LINE_FREQUENCY_DISABLED),
};

static const struct uvc_control_mapping *uvc_ctrl_filter_plf_mapping(
 struct uvc_video_chain *chain, struct uvc_control *ctrl)
{
 const struct uvc_control_mapping *out_mapping =
     &uvc_ctrl_power_line_mapping_uvc11;
 u8 *buf __free(kfree) = NULL;
 u8 init_val;
 int ret;

 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
 if (!buf)
  return NULL;

 /* Save the current PLF value, so we can restore it. */
 ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR, ctrl->entity->id,
        chain->dev->intfnum, ctrl->info.selector,
        buf, sizeof(*buf));
 /* If we cannot read the control skip it. */
 if (ret)
  return NULL;
 init_val = *buf;

 /* If PLF value cannot be set to off, it is limited. */
 *buf = V4L2_CID_POWER_LINE_FREQUENCY_DISABLED;
 ret = uvc_query_ctrl(chain->dev, UVC_SET_CUR, ctrl->entity->id,
        chain->dev->intfnum, ctrl->info.selector,
        buf, sizeof(*buf));
 if (ret)
  return &uvc_ctrl_power_line_mapping_limited;

 /* UVC 1.1 does not define auto, we can exit. */
 if (chain->dev->uvc_version < 0x150)
  goto end;

 /* Check if the device supports auto. */
 *buf = V4L2_CID_POWER_LINE_FREQUENCY_AUTO;
 ret = uvc_query_ctrl(chain->dev, UVC_SET_CUR, ctrl->entity->id,
        chain->dev->intfnum, ctrl->info.selector,
        buf, sizeof(*buf));
 if (!ret)
  out_mapping = &uvc_ctrl_power_line_mapping_uvc15;

end:
 /* Restore initial value and add mapping. */
 *buf = init_val;
 uvc_query_ctrl(chain->dev, UVC_SET_CUR, ctrl->entity->id,
         chain->dev->intfnum, ctrl->info.selector,
         buf, sizeof(*buf));

 return out_mapping;
}

static int uvc_get_rect(struct uvc_control_mapping *mapping, u8 query,
   const void *uvc_in, size_t v4l2_size, void *v4l2_out)
{
 const struct uvc_rect *uvc_rect = uvc_in;
 struct v4l2_rect *v4l2_rect = v4l2_out;

 if (WARN_ON(v4l2_size != sizeof(struct v4l2_rect)))
  return -EINVAL;

 if (uvc_rect->left > uvc_rect->right ||
     uvc_rect->top > uvc_rect->bottom)
  return -EIO;

 v4l2_rect->top = uvc_rect->top;
 v4l2_rect->left = uvc_rect->left;
 v4l2_rect->height = uvc_rect->bottom - uvc_rect->top + 1;
 v4l2_rect->width = uvc_rect->right - uvc_rect->left + 1;

 return 0;
}

static int uvc_set_rect(struct uvc_control_mapping *mapping, size_t v4l2_size,
   const void *v4l2_in, void *uvc_out)
{
 struct uvc_rect *uvc_rect = uvc_out;
 const struct v4l2_rect *v4l2_rect = v4l2_in;

 if (WARN_ON(v4l2_size != sizeof(struct v4l2_rect)))
  return -EINVAL;

 uvc_rect->top = min(0xffff, v4l2_rect->top);
 uvc_rect->left = min(0xffff, v4l2_rect->left);
 uvc_rect->bottom = min(0xffff, v4l2_rect->top + v4l2_rect->height - 1);
 uvc_rect->right = min(0xffff, v4l2_rect->left + v4l2_rect->width - 1);

 return 0;
}

static const struct uvc_control_mapping uvc_ctrl_mappings[] = {
 {
  .id  = V4L2_CID_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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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_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,
  .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_mapping = exposure_auto_mapping,
  .menu_mask = GENMASK(V4L2_EXPOSURE_APERTURE_PRIORITY,
       V4L2_EXPOSURE_AUTO),
  .slave_ids = { V4L2_CID_EXPOSURE_ABSOLUTE, },
 },
 {
  .id  = V4L2_CID_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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
  .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,
 },
 {
  .entity  = UVC_GUID_UVC_PROCESSING,
  .selector = UVC_PU_POWER_LINE_FREQUENCY_CONTROL,
  .filter_mapping = uvc_ctrl_filter_plf_mapping,
 },
 {
  .id  = V4L2_CID_UVC_REGION_OF_INTEREST_RECT,
  .entity  = UVC_GUID_UVC_CAMERA,
  .selector = UVC_CT_REGION_OF_INTEREST_CONTROL,
  .size  = sizeof(struct uvc_rect) * 8,
  .offset  = 0,
  .v4l2_type = V4L2_CTRL_TYPE_RECT,
  .data_type = UVC_CTRL_DATA_TYPE_RECT,
  .get  = uvc_get_rect,
  .set  = uvc_set_rect,
  .name  = "Region of Interest Rectangle",
 },
 {
  .id  = V4L2_CID_UVC_REGION_OF_INTEREST_AUTO,
  .entity  = UVC_GUID_UVC_CAMERA,
  .selector = UVC_CT_REGION_OF_INTEREST_CONTROL,
  .size  = 16,
  .offset  = 64,
  .v4l2_type = V4L2_CTRL_TYPE_BITMASK,
  .data_type = UVC_CTRL_DATA_TYPE_BITMASK,
  .name  = "Region of Interest Auto Ctrls",
 },
};

/* ------------------------------------------------------------------------
 * 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));
}

static s32 uvc_menu_to_v4l2_menu(struct uvc_control_mapping *mapping, s32 val)
{
 unsigned int i;

 for (i = 0; BIT(i) <= mapping->menu_mask; ++i) {
  u32 menu_value;

  if (!test_bit(i, &mapping->menu_mask))
   continue;

  menu_value = uvc_mapping_get_menu_value(mapping, i);

  if (menu_value == val)
   return i;
 }

 return val;
}

/*
 * 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 int uvc_get_le_value(struct uvc_control_mapping *mapping,
       u8 query, const void *uvc_in, size_t v4l2_size,
       void *v4l2_out)
{
 int offset = mapping->offset;
 int bits = mapping->size;
 const u8 *data = uvc_in;
 s32 *out = v4l2_out;
 s32 value = 0;
 u8 mask;

 if (WARN_ON(v4l2_size != sizeof(s32)))
  return -EINVAL;

 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 - max(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)));

 /* If it is a menu, convert from uvc to v4l2. */
 if (mapping->v4l2_type != V4L2_CTRL_TYPE_MENU) {
  *out = value;
  return 0;
 }

 switch (query) {
 case UVC_GET_CUR:
 case UVC_GET_DEF:
  *out = uvc_menu_to_v4l2_menu(mapping, value);
  return 0;
 }

 *out = value;
 return 0;
}

/*
 * Set the bit string specified by mapping->offset and mapping->size
 * in the little-endian data stored at 'data' to the value 'value'.
 */
static int uvc_set_le_value(struct uvc_control_mapping *mapping,
       size_t v4l2_size, const void *v4l2_in,
       void *uvc_out)
{
 int offset = mapping->offset;
 int bits = mapping->size;
 u8 *data = uvc_out;
 s32 value;
 u8 mask;

 if (WARN_ON(v4l2_size != sizeof(s32)))
  return -EINVAL;

 value = *(s32 *)v4l2_in;

 switch (mapping->v4l2_type) {
 case V4L2_CTRL_TYPE_MENU:
  value = uvc_mapping_get_menu_value(mapping, value);
  break;
 case V4L2_CTRL_TYPE_BUTTON:
  /*
 * 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.
 */
  value = -1;
  break;
 default:
  break;
 }

 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;
 }

 return 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, int next_compound)
{
 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 && !next_compound) {
    *control = ctrl;
    *mapping = map;
    return;
   }

   if ((*mapping == NULL || (*mapping)->id > map->id) &&
       (map->id > v4l2_id) &&
       (uvc_ctrl_mapping_is_compound(map) ?
        next_compound : 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;
 int next_compound = v4l2_id & V4L2_CTRL_FLAG_NEXT_COMPOUND;

 *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,
       next_compound);
  if (ctrl && !next && !next_compound)
   return ctrl;
 }

 if (!ctrl && !next && !next_compound)
  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 int __uvc_ctrl_load_cur(struct uvc_video_chain *chain,
          struct uvc_control *ctrl)
{
 u8 *data;
 int ret;

 if (ctrl->loaded)
  return 0;

 data = uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT);

 if ((ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) == 0) {
  memset(data, 0, ctrl->info.size);
  ctrl->loaded = 1;

  return 0;
 }

 if (ctrl->entity->get_cur)
  ret = ctrl->entity->get_cur(chain->dev, ctrl->entity,
         ctrl->info.selector, data,
         ctrl->info.size);
 else
  ret = uvc_query_ctrl(chain->dev, UVC_GET_CUR,
         ctrl->entity->id, chain->dev->intfnum,
         ctrl->info.selector, data,
         ctrl->info.size);

 if (ret < 0)
  return ret;

 ctrl->loaded = 1;

 return ret;
}

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;

 ret = __uvc_ctrl_load_cur(chain, ctrl);
 if (ret < 0)
  return ret;

 *value = uvc_mapping_get_s32(mapping, UVC_GET_CUR,
         uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));

 return 0;
}

static int __uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
      u32 found_id)
{
 bool find_next = req_id &
  (V4L2_CTRL_FLAG_NEXT_CTRL | V4L2_CTRL_FLAG_NEXT_COMPOUND);
 unsigned int i;

 req_id &= V4L2_CTRL_ID_MASK;

 for (i = 0; i < ARRAY_SIZE(uvc_control_classes); i++) {
  if (!(chain->ctrl_class_bitmap & BIT(i)))
   continue;
  if (!find_next) {
   if (uvc_control_classes[i] == req_id)
    return i;
   continue;
  }
  if (uvc_control_classes[i] > req_id &&
      uvc_control_classes[i] < found_id)
   return i;
 }

 return -ENODEV;
}

static int uvc_query_v4l2_class(struct uvc_video_chain *chain, u32 req_id,
    u32 found_id,
    struct v4l2_query_ext_ctrl *v4l2_ctrl)
{
 int idx;

 idx = __uvc_query_v4l2_class(chain, req_id, found_id);
 if (idx < 0)
  return -ENODEV;

 memset(v4l2_ctrl, 0, sizeof(*v4l2_ctrl));
 v4l2_ctrl->id = uvc_control_classes[idx];
 strscpy(v4l2_ctrl->name, v4l2_ctrl_get_name(v4l2_ctrl->id),
  sizeof(v4l2_ctrl->name));
 v4l2_ctrl->type = V4L2_CTRL_TYPE_CTRL_CLASS;
 v4l2_ctrl->flags = V4L2_CTRL_FLAG_WRITE_ONLY
    | V4L2_CTRL_FLAG_READ_ONLY;
 return 0;
}

static bool uvc_ctrl_is_readable(u32 which, struct uvc_control *ctrl,
     struct uvc_control_mapping *mapping)
{
 if (which == V4L2_CTRL_WHICH_CUR_VAL)
  return !!(ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR);

 if (which == V4L2_CTRL_WHICH_DEF_VAL)
  return !!(ctrl->info.flags & UVC_CTRL_FLAG_GET_DEF);

 /* Types with implicit boundaries. */
 switch (mapping->v4l2_type) {
 case V4L2_CTRL_TYPE_MENU:
 case V4L2_CTRL_TYPE_BOOLEAN:
 case V4L2_CTRL_TYPE_BUTTON:
  return true;
 case V4L2_CTRL_TYPE_BITMASK:
  return (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES) ||
   (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX);
 default:
  break;
 }

 if (which == V4L2_CTRL_WHICH_MIN_VAL)
  return !!(ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN);

 if (which == V4L2_CTRL_WHICH_MAX_VAL)
  return !!(ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX);

 return false;
}

/*
 * Check if control @v4l2_id can be accessed by the given control @ioctl
 * (VIDIOC_G_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS or VIDIOC_S_EXT_CTRLS).
 *
 * For set operations on slave controls, check if the master's value is set to
 * manual, either in the others controls set in the same ioctl call, or from
 * the master's current value. This catches VIDIOC_S_EXT_CTRLS calls that set
 * both the master and slave control, such as for instance setting
 * auto_exposure=1, exposure_time_absolute=251.
 */
int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
      const struct v4l2_ext_controls *ctrls,
      unsigned long ioctl)
{
 struct uvc_control_mapping *master_map = NULL;
 struct uvc_control *master_ctrl = NULL;
 struct uvc_control_mapping *mapping;
 struct uvc_control *ctrl;
 s32 val;
 int ret;
 int i;

 if (__uvc_query_v4l2_class(chain, v4l2_id, 0) >= 0)
  return -EACCES;

 ctrl = uvc_find_control(chain, v4l2_id, &mapping);
 if (!ctrl)
  return -EINVAL;

 if (ioctl == VIDIOC_G_EXT_CTRLS)
  return uvc_ctrl_is_readable(ctrls->which, ctrl, mapping);

 if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR))
  return -EACCES;

 if (ioctl != VIDIOC_S_EXT_CTRLS || !mapping->master_id)
  return 0;

 /*
 * Iterate backwards in cases where the master control is accessed
 * multiple times in the same ioctl. We want the last value.
 */
 for (i = ctrls->count - 1; i >= 0; i--) {
  if (ctrls->controls[i].id == mapping->master_id)
   return ctrls->controls[i].value ==
     mapping->master_manual ? 0 : -EACCES;
 }

 __uvc_find_control(ctrl->entity, mapping->master_id, &master_map,
      &master_ctrl, 0, 0);

 if (!master_ctrl || !(master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR))
  return 0;
 if (WARN_ON(uvc_ctrl_mapping_is_compound(master_map)))
  return -EIO;

 ret = __uvc_ctrl_get(chain, master_ctrl, master_map, &val);
 if (ret >= 0 && val != mapping->master_manual)
  return -EACCES;

 return 0;
}

static const char *uvc_map_get_name(const struct uvc_control_mapping *map)
{
 const char *name;

 if (map->name)
  return map->name;

 name = v4l2_ctrl_get_name(map->id);
 if (name)
  return name;

 return "Unknown Control";
}

static u32 uvc_get_ctrl_bitmap(struct uvc_control *ctrl,
          struct uvc_control_mapping *mapping)
{
 /*
 * Some controls, like CT_AE_MODE_CONTROL, use GET_RES to represent
 * the number of bits supported. Those controls do not list GET_MAX
 * as supported.
 */
 if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)
  return uvc_mapping_get_s32(mapping, UVC_GET_RES,
        uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));

 if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
  return uvc_mapping_get_s32(mapping, UVC_GET_MAX,
        uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));

 return ~0;
}

/*
 * Maximum retry count to avoid spurious errors with controls. Increasing this
 * value does no seem to produce better results in the tested hardware.
 */
#define MAX_QUERY_RETRIES 2

static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain,
          struct uvc_control *ctrl,
          struct uvc_control_mapping *mapping,
          struct v4l2_query_ext_ctrl *v4l2_ctrl)
{
 if (!ctrl->cached) {
  unsigned int retries;
  int ret;

  for (retries = 0; retries < MAX_QUERY_RETRIES; retries++) {
   ret = uvc_ctrl_populate_cache(chain, ctrl);
   if (ret != -EIO)
    break;
  }

  if (ret)
   return ret;
 }

 if (ctrl->info.flags & UVC_CTRL_FLAG_GET_DEF) {
  v4l2_ctrl->default_value = uvc_mapping_get_s32(mapping,
    UVC_GET_DEF, uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF));
 }

 switch (mapping->v4l2_type) {
 case V4L2_CTRL_TYPE_MENU:
  v4l2_ctrl->minimum = ffs(mapping->menu_mask) - 1;
  v4l2_ctrl->maximum = fls(mapping->menu_mask) - 1;
  v4l2_ctrl->step = 1;
  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;

 case V4L2_CTRL_TYPE_BITMASK:
  v4l2_ctrl->minimum = 0;
  v4l2_ctrl->maximum = uvc_get_ctrl_bitmap(ctrl, mapping);
  v4l2_ctrl->step = 0;
  return 0;

 default:
  break;
 }

 if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)
  v4l2_ctrl->minimum = uvc_mapping_get_s32(mapping, UVC_GET_MIN,
    uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
 else
  v4l2_ctrl->minimum = 0;

 if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
  v4l2_ctrl->maximum = uvc_mapping_get_s32(mapping, UVC_GET_MAX,
    uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
 else
  v4l2_ctrl->maximum = 0;

 if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)
  v4l2_ctrl->step = uvc_mapping_get_s32(mapping, UVC_GET_RES,
    uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
 else
  v4l2_ctrl->step = 0;

 return 0;
}

static size_t uvc_mapping_v4l2_size(struct uvc_control_mapping *mapping)
{
 if (mapping->v4l2_type == V4L2_CTRL_TYPE_RECT)
  return sizeof(struct v4l2_rect);

 if (uvc_ctrl_mapping_is_compound(mapping))
  return DIV_ROUND_UP(mapping->size, 8);

 return sizeof(s32);
}

static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
     struct uvc_control *ctrl,
     struct uvc_control_mapping *mapping,
     struct v4l2_query_ext_ctrl *v4l2_ctrl)
{
 struct uvc_control_mapping *master_map = NULL;
 struct uvc_control *master_ctrl = NULL;
 int ret;

 memset(v4l2_ctrl, 0, sizeof(*v4l2_ctrl));
 v4l2_ctrl->id = mapping->id;
 v4l2_ctrl->type = mapping->v4l2_type;
 strscpy(v4l2_ctrl->name, uvc_map_get_name(mapping),
  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 ((ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX) &&
     (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN))
  v4l2_ctrl->flags |= V4L2_CTRL_FLAG_HAS_WHICH_MIN_MAX;

 if (mapping->master_id)
  __uvc_find_control(ctrl->entity, mapping->master_id,
       &master_map, &master_ctrl, 0, 0);
 if (master_ctrl && (master_ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR)) {
  unsigned int retries;
  s32 val;
  int ret;

  if (WARN_ON(uvc_ctrl_mapping_is_compound(master_map)))
   return -EIO;

  for (retries = 0; retries < MAX_QUERY_RETRIES; retries++) {
   ret = __uvc_ctrl_get(chain, master_ctrl, master_map,
          &val);
   if (!ret)
    break;
   if (ret < 0 && ret != -EIO)
    return ret;
  }

  if (ret == -EIO) {
   dev_warn_ratelimited(&chain->dev->udev->dev,
          "UVC non compliance: Error %d querying master control %x (%s)\n",
          ret, master_map->id,
          uvc_map_get_name(master_map));
  } else {
   if (val != mapping->master_manual)
    v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
  }
 }

 v4l2_ctrl->elem_size = uvc_mapping_v4l2_size(mapping);
 v4l2_ctrl->elems = 1;

 if (v4l2_ctrl->type >= V4L2_CTRL_COMPOUND_TYPES) {
  v4l2_ctrl->flags |= V4L2_CTRL_FLAG_HAS_PAYLOAD;
  v4l2_ctrl->default_value = 0;
  v4l2_ctrl->minimum = 0;
  v4l2_ctrl->maximum = 0;
  v4l2_ctrl->step = 0;
  return 0;
 }

 ret = __uvc_queryctrl_boundaries(chain, ctrl, mapping, v4l2_ctrl);
 if (ret && !mapping->disabled) {
  dev_warn(&chain->dev->udev->dev,
    "UVC non compliance: permanently disabling control %x (%s), due to error %d\n",
    mapping->id, uvc_map_get_name(mapping), ret);
  mapping->disabled = true;
 }

 if (mapping->disabled)
  v4l2_ctrl->flags |= V4L2_CTRL_FLAG_DISABLED;

 return 0;
}

int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
   struct v4l2_query_ext_ctrl *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;

 /* Check if the ctrl is a know class */
 if (!(v4l2_ctrl->id & V4L2_CTRL_FLAG_NEXT_CTRL)) {
  ret = uvc_query_v4l2_class(chain, v4l2_ctrl->id, 0, v4l2_ctrl);
  if (!ret)
   goto done;
 }

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

 /*
 * If we're enumerating control with V4L2_CTRL_FLAG_NEXT_CTRL, check if
 * a class should be inserted between the previous control and the one
 * we have just found.
 */
 if (v4l2_ctrl->id & V4L2_CTRL_FLAG_NEXT_CTRL) {
  ret = uvc_query_v4l2_class(chain, v4l2_ctrl->id, mapping->id,
        v4l2_ctrl);
  if (!ret)
   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)
{
 struct uvc_control_mapping *mapping;
 struct uvc_control *ctrl;
 u32 index = query_menu->index;
 u32 id = query_menu->id;
 const char *name;
 int ret;

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

 if (index >= BITS_PER_TYPE(mapping->menu_mask))
  return -EINVAL;

 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 (!test_bit(query_menu->index, &mapping->menu_mask)) {
  ret = -EINVAL;
  goto done;
 }

 if (mapping->data_type == UVC_CTRL_DATA_TYPE_BITMASK) {
  int mask;

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

  mask = uvc_mapping_get_menu_value(mapping, query_menu->index);
  if (mask < 0) {
   ret = mask;
   goto done;
  }

  if (!(uvc_get_ctrl_bitmap(ctrl, mapping) & mask)) {
   ret = -EINVAL;
   goto done;
  }
 }

 name = uvc_mapping_get_menu_name(mapping, query_menu->index);
 if (!name) {
  ret = -EINVAL;
  goto done;
 }

 strscpy(query_menu->name, 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_query_ext_ctrl 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, 0);
 if (ctrl == NULL)
  return;

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

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

static int uvc_ctrl_set_handle(struct uvc_control *ctrl, struct uvc_fh *handle)
{
 int ret;

 lockdep_assert_held(&handle->chain->ctrl_mutex);

 if (ctrl->handle) {
  dev_warn_ratelimited(&handle->stream->dev->udev->dev,
         "UVC non compliance: Setting an async control with a pending operation.");

  if (ctrl->handle == handle)
   return 0;

  WARN_ON(!ctrl->handle->pending_async_ctrls);
  if (ctrl->handle->pending_async_ctrls)
   ctrl->handle->pending_async_ctrls--;
  ctrl->handle = handle;
  ctrl->handle->pending_async_ctrls++;
  return 0;
 }

 ret = uvc_pm_get(handle->chain->dev);
 if (ret)
  return ret;

 ctrl->handle = handle;
 ctrl->handle->pending_async_ctrls++;
 return 0;
}

static int uvc_ctrl_clear_handle(struct uvc_control *ctrl)
{
 lockdep_assert_held(&ctrl->handle->chain->ctrl_mutex);

 if (WARN_ON(!ctrl->handle->pending_async_ctrls)) {
  ctrl->handle = NULL;
  return -EINVAL;
 }

 ctrl->handle->pending_async_ctrls--;
 uvc_pm_put(ctrl->handle->chain->dev);
 ctrl->handle = NULL;
 return 0;
}

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);

 /* Flush the control cache, the data might have changed. */
 ctrl->loaded = 0;

 handle = ctrl->handle;
 if (handle)
  uvc_ctrl_clear_handle(ctrl);

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

  if (uvc_ctrl_mapping_is_compound(mapping))
   value = 0;
  else
   value = uvc_mapping_get_s32(mapping, UVC_GET_CUR, 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);

 /* The barrier is needed to synchronize with uvc_status_stop(). */
 if (smp_load_acquire(&dev->flush_status))
  return;

 /* 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))
  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,
     struct uvc_entity *entity,
     const struct v4l2_ext_control *xctrls,
     unsigned int xctrls_count)
{
 struct uvc_control_mapping *mapping;
 struct uvc_control *ctrl;
 unsigned int i;
 unsigned int j;

 for (i = 0; i < xctrls_count; ++i) {
  u32 changes = V4L2_EVENT_CTRL_CH_VALUE;
  s32 value;

  ctrl = uvc_find_control(handle->chain, xctrls[i].id, &mapping);
  if (ctrl->entity != entity)
   continue;

  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 (uvc_ctrl_mapping_is_compound(mapping))
   value = 0;
  else
   value = xctrls[i].value;
  /*
 * 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,
        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;

 if (__uvc_query_v4l2_class(handle->chain, sev->id, 0) >= 0) {
  ret = 0;
  goto done;
 }

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

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

  ret = uvc_pm_get(handle->chain->dev);
  if (ret)
   goto done;

  if (uvc_ctrl_mapping_is_compound(mapping) ||
      __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);

  uvc_pm_put(handle->chain->dev);

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

 list_add_tail(&sev->node, &mapping->ev_subs);

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);
 if (__uvc_query_v4l2_class(handle->chain, sev->id, 0) >= 0)
  goto done;
 list_del(&sev->node);
done:
 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;
}

/*
 * Returns the number of uvc controls that have been correctly set, or a
 * negative number if there has been an error.
 */
static int uvc_ctrl_commit_entity(struct uvc_device *dev,
      struct uvc_fh *handle,
      struct uvc_entity *entity,
      int rollback,
      struct uvc_control **err_ctrl)
{
 unsigned int processed_ctrls = 0;
 struct uvc_control *ctrl;
 unsigned int i;
 int ret = 0;

 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);

  if (!ret)
   processed_ctrls++;

  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 (!rollback && handle && !ret &&
      ctrl->info.flags & UVC_CTRL_FLAG_ASYNCHRONOUS)
   ret = uvc_ctrl_set_handle(ctrl, handle);

  if (ret < 0 && !rollback) {
   if (err_ctrl)
    *err_ctrl = ctrl;
   /*
 * If we fail to set a control, we need to rollback
 * the next ones.
 */
   rollback = 1;
  }
 }

 if (ret)
  return ret;

 return processed_ctrls;
}

static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
      struct v4l2_ext_controls *ctrls,
      struct uvc_control *uvc_control)
{
 struct uvc_control_mapping *mapping = NULL;
 struct uvc_control *ctrl_found = NULL;
 unsigned int i;

 if (!entity)
  return ctrls->count;

 for (i = 0; i < ctrls->count; i++) {
  __uvc_find_control(entity, ctrls->controls[i].id, &mapping,
       &ctrl_found, 0, 0);
  if (uvc_control == ctrl_found)
   return i;
 }

 return ctrls->count;
}

int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
        struct v4l2_ext_controls *ctrls)
{
 struct uvc_video_chain *chain = handle->chain;
 struct uvc_control *err_ctrl;
 struct uvc_entity *entity;
 int ret_out = 0;
 int ret;

 /* Find the control. */
 list_for_each_entry(entity, &chain->entities, chain) {
  ret = uvc_ctrl_commit_entity(chain->dev, handle, entity,
          rollback, &err_ctrl);
  if (ret < 0) {
   if (ctrls)
    ctrls->error_idx =
     uvc_ctrl_find_ctrl_idx(entity, ctrls,
              err_ctrl);
   /*
 * When we fail to commit an entity, we need to
 * restore the UVC_CTRL_DATA_BACKUP for all the
 * controls in the other entities, otherwise our cache
 * and the hardware will be out of sync.
 */
   rollback = 1;

   ret_out = ret;
  } else if (ret > 0 && !rollback) {
   uvc_ctrl_send_events(handle, entity,
          ctrls->controls, ctrls->count);
  }
 }

 mutex_unlock(&chain->ctrl_mutex);
 return ret_out;
}

static int uvc_mapping_get_xctrl_compound(struct uvc_video_chain *chain,
       struct uvc_control *ctrl,
       struct uvc_control_mapping *mapping,
       u32 which,
       struct v4l2_ext_control *xctrl)
{
 u8 *data __free(kfree) = NULL;
 size_t size;
 u8 query;
 int ret;
 int id;

 switch (which) {
 case V4L2_CTRL_WHICH_CUR_VAL:
  id = UVC_CTRL_DATA_CURRENT;
  query = UVC_GET_CUR;
  break;
 case V4L2_CTRL_WHICH_MIN_VAL:
  id = UVC_CTRL_DATA_MIN;
  query = UVC_GET_MIN;
  break;
 case V4L2_CTRL_WHICH_MAX_VAL:
  id = UVC_CTRL_DATA_MAX;
  query = UVC_GET_MAX;
  break;
 case V4L2_CTRL_WHICH_DEF_VAL:
  id = UVC_CTRL_DATA_DEF;
  query = UVC_GET_DEF;
  break;
 default:
  return -EINVAL;
 }

 size = uvc_mapping_v4l2_size(mapping);
 if (xctrl->size < size) {
  xctrl->size = size;
  return -ENOSPC;
 }

 data = kmalloc(size, GFP_KERNEL);
 if (!data)
  return -ENOMEM;

 if (which == V4L2_CTRL_WHICH_CUR_VAL)
  ret = __uvc_ctrl_load_cur(chain, ctrl);
 else
  ret = uvc_ctrl_populate_cache(chain, ctrl);

 if (ret < 0)
  return ret;

 ret = mapping->get(mapping, query, uvc_ctrl_data(ctrl, id), size, data);
 if (ret < 0)
  return ret;

 /*
 * v4l2_ext_control does not have enough room to fit a compound control.
 * Instead, the value is in the user memory at xctrl->ptr. The v4l2
 * ioctl helper does not copy it for us.
 */
 return copy_to_user(xctrl->ptr, data, size) ? -EFAULT : 0;
}

static int uvc_mapping_get_xctrl_std(struct uvc_video_chain *chain,
         struct uvc_control *ctrl,
         struct uvc_control_mapping *mapping,
         u32 which, struct v4l2_ext_control *xctrl)
{
 struct v4l2_query_ext_ctrl qec;
 int ret;

 switch (which) {
 case V4L2_CTRL_WHICH_CUR_VAL:
  return __uvc_ctrl_get(chain, ctrl, mapping, &xctrl->value);
 case V4L2_CTRL_WHICH_DEF_VAL:
 case V4L2_CTRL_WHICH_MIN_VAL:
 case V4L2_CTRL_WHICH_MAX_VAL:
  break;
 default:
  return -EINVAL;
 }

 ret = __uvc_queryctrl_boundaries(chain, ctrl, mapping, &qec);
 if (ret < 0)
  return ret;

 switch (which) {
 case V4L2_CTRL_WHICH_DEF_VAL:
  xctrl->value = qec.default_value;
  break;
 case V4L2_CTRL_WHICH_MIN_VAL:
  xctrl->value = qec.minimum;
  break;
 case V4L2_CTRL_WHICH_MAX_VAL:
  xctrl->value = qec.maximum;
  break;
 }

 return 0;
}

static int uvc_mapping_get_xctrl(struct uvc_video_chain *chain,
     struct uvc_control *ctrl,
     struct uvc_control_mapping *mapping,
     u32 which, struct v4l2_ext_control *xctrl)
{
 if (uvc_ctrl_mapping_is_compound(mapping))
  return uvc_mapping_get_xctrl_compound(chain, ctrl, mapping,
            which, xctrl);
 return uvc_mapping_get_xctrl_std(chain, ctrl, mapping, which, xctrl);
}

int uvc_ctrl_get(struct uvc_video_chain *chain, u32 which,
   struct v4l2_ext_control *xctrl)
{
 struct uvc_control *ctrl;
 struct uvc_control_mapping *mapping;

 if (__uvc_query_v4l2_class(chain, xctrl->id, 0) >= 0)
  return -EACCES;

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

 return uvc_mapping_get_xctrl(chain, ctrl, mapping, which, xctrl);
}

static int uvc_ctrl_clamp(struct uvc_video_chain *chain,
     struct uvc_control *ctrl,
     struct uvc_control_mapping *mapping,
     s32 *value_in_out)
{
 s32 value = *value_in_out;
 u32 step;
 s32 min;
 s32 max;
 int ret;

 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 = uvc_mapping_get_s32(mapping, UVC_GET_MIN,
       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
  max = uvc_mapping_get_s32(mapping, UVC_GET_MAX,
       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
  step = uvc_mapping_get_s32(mapping, UVC_GET_RES,
        uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
  if (step == 0)
   step = 1;

  value = min + DIV_ROUND_CLOSEST((u32)(value - min), step) * step;
  if (mapping->data_type == UVC_CTRL_DATA_TYPE_SIGNED)
   value = clamp(value, min, max);
  else
   value = clamp_t(u32, value, min, max);
  *value_in_out = value;
  return 0;

 case V4L2_CTRL_TYPE_BITMASK:
  if (!ctrl->cached) {
   ret = uvc_ctrl_populate_cache(chain, ctrl);
   if (ret < 0)
    return ret;
  }

  value &= uvc_get_ctrl_bitmap(ctrl, mapping);
  *value_in_out = value;
  return 0;

 case V4L2_CTRL_TYPE_BOOLEAN:
  *value_in_out = clamp(value, 0, 1);
  return 0;

 case V4L2_CTRL_TYPE_MENU:
  if (value < (ffs(mapping->menu_mask) - 1) ||
      value > (fls(mapping->menu_mask) - 1))
   return -ERANGE;

  if (!test_bit(value, &mapping->menu_mask))
   return -EINVAL;

  /*
 * 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) {
   int val = uvc_mapping_get_menu_value(mapping, value);
   if (!ctrl->cached) {
    ret = uvc_ctrl_populate_cache(chain, ctrl);
    if (ret < 0)
     return ret;
   }

   if (!(uvc_get_ctrl_bitmap(ctrl, mapping) & val))
    return -EINVAL;
  }
  return 0;

 default:
  return 0;
 }

 return 0;
}

static int uvc_mapping_set_xctrl_compound(struct uvc_control *ctrl,
       struct uvc_control_mapping *mapping,
       struct v4l2_ext_control *xctrl)
{
 u8 *data __free(kfree) = NULL;
 size_t size = uvc_mapping_v4l2_size(mapping);

 if (xctrl->size != size)
  return -EINVAL;

 /*
 * v4l2_ext_control does not have enough room to fit a compound control.
 * Instead, the value is in the user memory at xctrl->ptr. The v4l2
 * ioctl helper does not copy it for us.
 */
 data = memdup_user(xctrl->ptr, size);
 if (IS_ERR(data))
  return PTR_ERR(data);

 return mapping->set(mapping, size, data,
       uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
}

static int uvc_mapping_set_xctrl(struct uvc_control *ctrl,
     struct uvc_control_mapping *mapping,
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