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Josuah Demangeon
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uvc: device: move helper functions to a common directory
Move UVC helper functions to a file shared between UVC host and device. The arrays are not visible anymore from either USB host or device, but instead accessed through a front-end funciton. Signed-off-by: Josuah Demangeon <[email protected]>
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‎subsys/usb/CMakeLists.txt‎

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add_subdirectory_ifdef(CONFIG_USB_DEVICE_STACK device)
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add_subdirectory_ifdef(CONFIG_USB_DEVICE_STACK_NEXT device_next)
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add_subdirectory_ifdef(CONFIG_USB_DEVICE_STACK_NEXT common)
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add_subdirectory_ifdef(CONFIG_USB_HOST_STACK host)
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add_subdirectory_ifdef(CONFIG_USB_HOST_STACK common)
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add_subdirectory_ifdef(CONFIG_USBC_STACK usb_c)

‎subsys/usb/common/CMakeLists.txt‎

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# Copyright (c) 2025 Nordic Semiconductor ASA
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# SPDX-License-Identifier: Apache-2.0
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zephyr_library()
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zephyr_library_include_directories(${CMAKE_CURRENT_SOURCE_DIR})
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zephyr_library_sources_ifdef(CONFIG_USBD_VIDEO_CLASS usb_common_uvc.c)
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zephyr_library_sources_ifdef(CONFIG_USBH_VIDEO_CLASS usb_common_uvc.c)

‎subsys/usb/common/usb_common_uvc.c‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <stdint.h>
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#include <zephyr/drivers/video.h>
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#include <zephyr/drivers/video-controls.h>
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#include <zephyr/usb/class/usb_uvc.h>
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#include <zephyr/sys/byteorder.h>
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#include "usb_common_uvc.h"
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static const struct uvc_guid_quirk uvc_guid_quirks[] = {
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{
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.fourcc = VIDEO_PIX_FMT_YUYV,
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.guid = UVC_FORMAT_GUID("YUY2"),
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},
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{
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.fourcc = VIDEO_PIX_FMT_GREY,
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.guid = UVC_FORMAT_GUID("Y800"),
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},
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};
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static const struct uvc_control_map uvc_control_map_ct[] = {
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{
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.size = 1,
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.bit = 1,
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.selector = UVC_CT_AE_MODE_CONTROL,
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.cid = VIDEO_CID_EXPOSURE_AUTO,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 1,
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.bit = 2,
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.selector = UVC_CT_AE_PRIORITY_CONTROL,
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.cid = VIDEO_CID_EXPOSURE_AUTO_PRIORITY,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 4,
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.bit = 3,
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.selector = UVC_CT_EXPOSURE_TIME_ABS_CONTROL,
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.cid = VIDEO_CID_EXPOSURE,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 2,
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.bit = 5,
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.selector = UVC_CT_FOCUS_ABS_CONTROL,
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.cid = VIDEO_CID_FOCUS_ABSOLUTE,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 2,
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.bit = 6,
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.selector = UVC_CT_FOCUS_REL_CONTROL,
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.cid = VIDEO_CID_FOCUS_RELATIVE,
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.type = UVC_CONTROL_SIGNED,
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},
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{
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.size = 2,
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.bit = 7,
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.selector = UVC_CT_IRIS_ABS_CONTROL,
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.cid = VIDEO_CID_IRIS_ABSOLUTE,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 1,
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.bit = 8,
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.selector = UVC_CT_IRIS_REL_CONTROL,
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.cid = VIDEO_CID_IRIS_RELATIVE,
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.type = UVC_CONTROL_SIGNED,
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},
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{
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.size = 2,
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.bit = 9,
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.selector = UVC_CT_ZOOM_ABS_CONTROL,
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.cid = VIDEO_CID_ZOOM_ABSOLUTE,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 3,
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.bit = 10,
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.selector = UVC_CT_ZOOM_REL_CONTROL,
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.cid = VIDEO_CID_ZOOM_RELATIVE,
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.type = UVC_CONTROL_SIGNED,
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},
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};
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static const struct uvc_control_map uvc_control_map_pu[] = {
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{
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.size = 2,
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.bit = 0,
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.selector = UVC_PU_BRIGHTNESS_CONTROL,
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.cid = VIDEO_CID_BRIGHTNESS,
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.type = UVC_CONTROL_SIGNED,
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},
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{
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.size = 1,
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.bit = 1,
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.selector = UVC_PU_CONTRAST_CONTROL,
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.cid = VIDEO_CID_CONTRAST,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 2,
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.bit = 9,
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.selector = UVC_PU_GAIN_CONTROL,
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.cid = VIDEO_CID_GAIN,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 2,
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.bit = 3,
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.selector = UVC_PU_SATURATION_CONTROL,
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.cid = VIDEO_CID_SATURATION,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 2,
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.bit = 6,
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.selector = UVC_PU_WHITE_BALANCE_TEMP_CONTROL,
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.cid = VIDEO_CID_WHITE_BALANCE_TEMPERATURE,
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.type = UVC_CONTROL_UNSIGNED,
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},
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};
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static const struct uvc_control_map uvc_control_map_su[] = {
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{
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.size = 1,
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.bit = 0,
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.selector = UVC_SU_INPUT_SELECT_CONTROL,
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.cid = VIDEO_CID_TEST_PATTERN,
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.type = UVC_CONTROL_UNSIGNED,
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},
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};
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static const struct uvc_control_map uvc_control_map_xu[] = {
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{
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.size = 4,
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.bit = 0,
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.selector = UVC_XU_BASE_CONTROL + 0,
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.cid = VIDEO_CID_PRIVATE_BASE + 0,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 4,
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.bit = 1,
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.selector = UVC_XU_BASE_CONTROL + 1,
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.cid = VIDEO_CID_PRIVATE_BASE + 1,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 4,
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.bit = 2,
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.selector = UVC_XU_BASE_CONTROL + 2,
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.cid = VIDEO_CID_PRIVATE_BASE + 2,
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.type = UVC_CONTROL_UNSIGNED,
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},
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{
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.size = 4,
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.bit = 3,
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.selector = UVC_XU_BASE_CONTROL + 3,
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.cid = VIDEO_CID_PRIVATE_BASE + 3,
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.type = UVC_CONTROL_UNSIGNED,
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},
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};
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int uvc_get_control_map(uint8_t subtype, const struct uvc_control_map **map, size_t *length)
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{
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switch (subtype) {
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case UVC_VC_INPUT_TERMINAL:
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*map = uvc_control_map_ct;
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*length = ARRAY_SIZE(uvc_control_map_ct);
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break;
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case UVC_VC_SELECTOR_UNIT:
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*map = uvc_control_map_su;
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*length = ARRAY_SIZE(uvc_control_map_su);
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break;
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case UVC_VC_PROCESSING_UNIT:
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*map = uvc_control_map_pu;
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*length = ARRAY_SIZE(uvc_control_map_pu);
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break;
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case UVC_VC_EXTENSION_UNIT:
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*map = uvc_control_map_xu;
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*length = ARRAY_SIZE(uvc_control_map_xu);
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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void uvc_fourcc_to_guid(uint8_t guid[16], const uint32_t fourcc)
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{
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uint32_t fourcc_le;
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/* Lookup in the "quirk table" if the UVC format GUID is custom */
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for (int i = 0; i < ARRAY_SIZE(uvc_guid_quirks); i++) {
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if (uvc_guid_quirks[i].fourcc == fourcc) {
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memcpy(guid, uvc_guid_quirks[i].guid, 16);
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return;
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}
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}
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/* By default, UVC GUIDs are the four character code followed by a common suffix */
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fourcc_le = sys_cpu_to_le32(fourcc);
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/* Copy the common suffix with the GUID set to 'XXXX' */
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memcpy(guid, UVC_FORMAT_GUID("XXXX"), 16);
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/* Replace the 'XXXX' by the actual GUID of the format */
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memcpy(guid, &fourcc_le, 4);
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}
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uint32_t uvc_guid_to_fourcc(const uint8_t guid[16])
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{
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uint32_t fourcc;
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/* Lookup in the "quirk table" if the UVC format GUID is custom */
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for (int i = 0; i < ARRAY_SIZE(uvc_guid_quirks); i++) {
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if (memcmp(guid, uvc_guid_quirks[i].guid, 16) == 0) {
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return uvc_guid_quirks[i].fourcc;
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}
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}
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/* Extract the four character code out of the leading 4 bytes of the GUID */
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memcpy(&fourcc, guid, 4);
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fourcc = sys_le32_to_cpu(fourcc);
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return fourcc;
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}

‎subsys/usb/common/usb_common_uvc.h‎

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/*
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* Copyright (c) 2025 Nordic Semiconductor ASA
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_USB_COMMON_UVC_H
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#define ZEPHYR_INCLUDE_USB_COMMON_UVC_H
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#include <stdint.h>
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/**
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* @brief Type of value used by the USB protocol for this control.
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*/
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enum uvc_control_type {
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/** Signed integer control type */
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UVC_CONTROL_SIGNED,
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/** Unsigned integer control type */
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UVC_CONTROL_UNSIGNED,
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};
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/**
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* @brief Mapping between UVC controls and Video controls
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*/
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struct uvc_control_map {
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/* Video CID to use for this control */
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uint32_t cid;
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/* Size to write out */
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uint8_t size;
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/* Bit position in the UVC control */
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uint8_t bit;
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/* UVC selector identifying this control */
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uint8_t selector;
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/* Whether the UVC value is signed, always false for bitmaps and boolean */
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enum uvc_control_type type;
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};
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/**
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* @brief Mapping between UVC GUIDs and standard FourCC.
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*/
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struct uvc_guid_quirk {
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/* A Video API format identifier, for which the UVC format GUID is not standard. */
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uint32_t fourcc;
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/* GUIDs are 16-bytes long, with the first four bytes being the Four Character Code of the
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* format and the rest constant, except for some exceptions listed in this table.
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*/
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uint8_t guid[16];
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};
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/**
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* @brief Get a conversion table for a given control unit type
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*
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* The mappings contains information about how UVC control structures are related to
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* video control structures.
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*
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* @param subtype The field bDescriptorSubType of a descriptor of type USB_DESC_CS_INTERFACE.
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* @param map Filled with a pointer to the conversion table
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* @param length Filled with the number of elements in that conversion table.
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*
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* @return 0 on success, negative code on error.
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*/
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int uvc_get_control_map(uint8_t subtype, const struct uvc_control_map **map, size_t *length);
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/**
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* @brief Convert a standard FourCC to an equivalent UVC GUID.
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*
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* @param guid Array to a GUID, filled in binary format
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* @param fourcc Four character code
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*/
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void uvc_fourcc_to_guid(uint8_t guid[16], const uint32_t fourcc);
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/**
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* @brief Convert an UVC GUID to a standard FourCC
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*
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* @param guid GUID, to convert
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*
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* @return Four Character Code
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*/
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uint32_t uvc_guid_to_fourcc(const uint8_t guid[16]);
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#endif /* ZEPHYR_INCLUDE_USB_COMMON_UVC_H */

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