tests: usb: uvc: connect USB device and host via UVB

Add a test to run the USB Video Class host support by using
the existing Zephyr USB Video Class device support.
This allows running implementing the host side from the device side.
A draft implementation of UVC is added leveraging this test.

Signed-off-by: Josuah Demangeon <[email protected]>

Author: Josuah Demangeon

dts/bindings/usb/zephyr,uvc-host.yaml

@@ -0,0 +1,15 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  USB Video Class (UVC) host instance.
+
+  Each UVC instance added to the USB Host Controller (UHC) node will be visible
+  as a new camera from Zephyr point of view.
+
+  as soon as a camera is connected to USB this device will be usable by the application as a
+  video device, following the video API.
+
+compatible: "zephyr,uvc-host"
+
+include: base.yaml

include/zephyr/usb/usbh.h

@@ -22,7 +22,7 @@
 #include <zephyr/drivers/usb/uhc.h>
 #include <zephyr/sys/iterable_sections.h>
 
-#ifdef __cplusplus
+_data#ifdef __cplusplus
 extern "C" {
 #endif
 

subsys/usb/host/CMakeLists.txt

@@ -16,6 +16,11 @@ zephyr_library_sources_ifdef(
 	usbh_shell.c
 )
 
+zephyr_library_sources_ifdef(
+	CONFIG_USBH_VIDEO_CLASS
+	class/usbh_uvc.c
+)
+
 zephyr_library_sources_ifdef(
   CONFIG_USBIP
   usbip.c

subsys/usb/host/Kconfig

@@ -54,5 +54,6 @@ config USBH_MAX_UHC_MSG
 	  Maximum number of USB host controller events that can be queued.
 
 rsource "Kconfig.usbip"
+rsource "class/Kconfig"
 
 endif # USB_HOST_STACK

subsys/usb/host/class/Kconfig

@@ -0,0 +1,5 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+rsource "Kconfig.uvc"

subsys/usb/host/class/Kconfig.uvc

@@ -0,0 +1,19 @@
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config USBH_VIDEO_CLASS
+	bool "USB Video Class implementation [EXPERIMENTAL]"
+	depends on DT_HAS_ZEPHYR_UVC_HOST_ENABLED
+	select EXPERIMENTAL
+	help
+	  USB Host Video Class (UVC) implementation.
+
+if USBH_VIDEO_CLASS
+
+module = USBH_VIDEO
+module-str = usbh uvc
+default-count = 1
+source "subsys/logging/Kconfig.template.log_config"
+
+endif # USBH_VIDEO_CLASS

subsys/usb/host/class/usbh_uvc.c

@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2025 tinyVision.ai Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT zephyr_uvc_host
+
+#include <stdlib.h>
+
+#include <zephyr/init.h>
+#include <zephyr/devicetree.h>
+#include <zephyr/kernel.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/sys/atomic.h>
+#include <zephyr/usb/usbh.h>
+#include <zephyr/usb/usb_ch9.h>
+#include <zephyr/drivers/usb/udc.h>
+#include <zephyr/drivers/video.h>
+#include <zephyr/drivers/video-controls.h>
+#include <zephyr/logging/log.h>
+
+#include <zephyr/devicetree.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/usb/usb_ch9.h>
+#include <zephyr/usb/class/usb_uvc.h>
+
+#include "usbh_device.h"
+#include "usbh_ch9.h"
+
+#include "../../../drivers/video/video_ctrls.h"
+#include "../../../drivers/video/video_device.h"
+
+LOG_MODULE_REGISTER(usbh_uvc, CONFIG_USBH_VIDEO_LOG_LEVEL);
+
+struct usbh_uvc_config {
+	struct usbh_contex *uhs_ctx;
+};
+
+static int usbh_uvc_request(struct usbh_contex *const uhs_ctx, struct uhc_transfer *const xfer,
+			    int err)
+{
+	LOG_INF("%p %p %d", uhs_ctx, xfer, err);
+
+	return 0;
+}
+
+static int usbh_uvc_connected(struct usbh_contex *const uhs_ctx)
+{
+	struct usb_device *const udev = uhs_ctx->root;
+	const size_t len = 512;
+	struct net_buf *buf;
+	int ret;
+
+	LOG_INF("%p", uhs_ctx);
+
+	buf = usbh_xfer_buf_alloc(udev, len);
+	if (buf == NULL) {
+		LOG_ERR("Failed to allocate a host transfer buffer");
+		return -ENOMEM;
+	}
+
+	ret = usbh_req_desc(udev, USB_DESC_DEVICE, 0, 0, len, buf);
+	if (ret != 0) {
+		LOG_ERR("Failed to request descriptor");
+		return ret;
+	}
+
+	LOG_HEXDUMP_INF(buf->data, buf->len, "buf");
+
+	return 0;
+}
+
+static int usbh_uvc_removed(struct usbh_contex *const uhs_ctx)
+{
+	LOG_INF("%p", uhs_ctx);
+
+	return 0;
+}
+
+static int usbh_uvc_rwup(struct usbh_contex *const uhs_ctx)
+{
+	LOG_INF("%p", uhs_ctx);
+
+	return 0;
+}
+
+static int usbh_uvc_suspended(struct usbh_contex *const uhs_ctx)
+{
+	LOG_INF("%p", uhs_ctx);
+
+	return 0;
+}
+
+static int usbh_uvc_resumed(struct usbh_contex *const uhs_ctx)
+{
+	LOG_INF("%p", uhs_ctx);
+
+	return 0;
+}
+
+static int usbh_uvc_preinit(const struct device *dev)
+{
+	LOG_INF("%s", dev->name);
+
+	return 0;
+}
+
+static const struct usbh_class_data usbh_uvc_class = {
+	.code = {0, 0, 0},
+	.request = usbh_uvc_request,
+	.connected = usbh_uvc_connected,
+	.removed = usbh_uvc_removed,
+	.rwup = usbh_uvc_rwup,
+	.suspended = usbh_uvc_suspended,
+	.resumed = usbh_uvc_resumed,
+};
+
+/* TODO this hardcodes a single class instance as only class of the system */
+const struct usbh_class_data *usbh_class = &usbh_uvc_class;
+
+int usbh_uvc_get_caps(const struct device *const dev, struct video_caps *const caps)
+{
+	return 0;
+}
+
+int usbh_uvc_get_format(const struct device *const dev, struct video_format *const fmt)
+{
+	return 0;
+}
+
+int usbh_uvc_set_stream(const struct device *const dev, bool enable, enum video_buf_type type)
+{
+	return 0;
+}
+
+int usbh_uvc_enqueue(const struct device *const dev, struct video_buffer *const vbuf)
+{
+	return 0;
+}
+
+int usbh_uvc_dequeue(const struct device *const dev, struct video_buffer **const vbuf,
+		     k_timeout_t timeout)
+{
+	return 0;
+}
+
+static DEVICE_API(video, uvc_video_api) = {
+	.get_caps = usbh_uvc_get_caps,
+	.get_format = usbh_uvc_get_format,
+	.set_stream = usbh_uvc_set_stream,
+	.enqueue = usbh_uvc_enqueue,
+	.dequeue = usbh_uvc_dequeue,
+};
+
+#define USBH_VIDEO_DT_DEVICE_DEFINE(n)						\
+										\
+	DEVICE_DT_INST_DEFINE(n, usbh_uvc_preinit, NULL,			\
+			      NULL, &usbh_uvc_class,				\
+			      POST_KERNEL, CONFIG_VIDEO_INIT_PRIORITY,		\
+			      &uvc_video_api);					\
+										\
+	VIDEO_DEVICE_DEFINE(uvc_host_##n, DEVICE_DT_INST_GET(n), NULL);
+
+DT_INST_FOREACH_STATUS_OKAY(USBH_VIDEO_DT_DEVICE_DEFINE)

subsys/usb/host/usbh_core.c

@@ -29,7 +29,7 @@ K_MSGQ_DEFINE(usbh_msgq, sizeof(struct uhc_event),
 K_MSGQ_DEFINE(usbh_bus_msgq, sizeof(struct uhc_event),
 	      CONFIG_USBH_MAX_UHC_MSG, sizeof(uint32_t));
 
-extern const struct usbh_class_data *usbh_class_data;
+extern const struct usbh_class_data *usbh_class;
 
 static int usbh_event_carrier(const struct device *dev,
 			      const struct uhc_event *const event)
@@ -75,7 +75,7 @@ static void dev_connected_handler(struct usbh_contex *const ctx,
 		return;
 	}
 
-	if (usbh_class_data->connected(ctx)) {
+	if (usbh_class->connected(ctx)) {
 		LOG_ERR("The class failed to handle the connection");
 		return;
 	}

tests/subsys/usb/uvc/CMakeLists.txt

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(uvc_uvb)
+
+# This sample cannot use the common USB sample infrastructure as we do not want
+# to initialize the board default `zephyr_udc0` but instead an unrelated `virtual_udc0`.
+#include(${ZEPHYR_BASE}/samples/subsys/usb/common/common.cmake)
+
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})
+zephyr_include_directories(${ZEPHYR_BASE}/subsys/usb/host)

tests/subsys/usb/uvc/app.overlay

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	virtual_uhc0: uhc-virtual {
+		compatible = "zephyr,uhc-virtual";
+		maximum-speed = "full-speed";
+
+		virtual_udc0: udc-virtual {
+			compatible = "zephyr,udc-virtual";
+			num-bidir-endpoints = <4>;
+			maximum-speed = "full-speed";
+		};
+	};
+
+	uvc_device: uvc-device {
+		compatible = "zephyr,uvc-device";
+	};
+
+	uvc_host: uvc-host {
+		compatible = "zephyr,uvc-host";
+	};
+};