USB Host: integrate class API [3: UVC]

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/class/usbd_uvc.h

@@ -13,6 +13,7 @@
 #define ZEPHYR_INCLUDE_USB_CLASS_USBD_UVC_H
 
 #include <zephyr/device.h>
+#include <zephyr/drivers/video.h>
 
 /**
  * @brief USB Video Class (UVC) device API

include/zephyr/usb/usbh.h

@@ -1,5 +1,6 @@
 /*
- * Copyright (c) 2022 Nordic Semiconductor ASA
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ * Copyright 2025 NXP
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -33,6 +34,16 @@ extern "C" {
  * @{
  */
 
+/**
+ * USB host support status
+ */
+struct usbh_status {
+	/** USB host support is initialized */
+	unsigned int initialized : 1;
+	/** USB host support is enabled */
+	unsigned int enabled : 1;
+};
+
 /**
  * USB host support runtime context
  */
@@ -43,6 +54,8 @@ struct usbh_context {
 	struct k_mutex mutex;
 	/** Pointer to UHC device struct */
 	const struct device *dev;
+	/** Status of the USB host support */
+	struct usbh_status status;
 	/** USB device list */
 	sys_dlist_t udevs;
 	/** USB root device */
@@ -60,47 +73,123 @@ struct usbh_context {
 		.addr_ba = &ba_##device_name,				\
 	}
 
+struct usbh_class_data;
+
 /**
- * @brief USB Class Code triple
+ * @brief Information about a device, which is relevant for matching a particular class.
  */
-struct usbh_code_triple {
-	/** Device Class Code */
-	uint8_t dclass;
-	/** Class Subclass Code */
+struct usbh_class_filter {
+	/** Vendor ID */
+	uint16_t vid;
+	/** Product ID */
+	uint16_t pid;
+	/** Class Code */
+	uint8_t class;
+	/** Subclass Code */
 	uint8_t sub;
-	/** Class Protocol Code */
+	/** Protocol Code */
 	uint8_t proto;
+	/** Flags that tell which field to match */
+	uint8_t flags;
 };
 
 /**
- * @brief USB host class data and class instance API
+ * @brief USB host class instance API
+ */
+struct usbh_class_api {
+	/** Host init handler, before any device is connected */
+	int (*init)(struct usbh_class_data *const c_data,
+		    struct usbh_context *const uhs_ctx);
+	/** Request completion event handler */
+	int (*completion_cb)(struct usbh_class_data *const c_data,
+			     struct uhc_transfer *const xfer);
+	/** Device connection handler */
+	int (*probe)(struct usbh_class_data *const c_data,
+		     struct usb_device *const udev,
+		     const uint8_t iface);
+	/** Device removal handler */
+	int (*removed)(struct usbh_class_data *const c_data);
+	/** Bus suspended handler */
+	int (*suspended)(struct usbh_class_data *const c_data);
+	/** Bus resumed handler */
+	int (*resumed)(struct usbh_class_data *const c_data);
+};
+
+/**
+ * @brief USB host class instance data
  */
 struct usbh_class_data {
-	/** Class code supported by this instance */
-	struct usbh_code_triple code;
+	/** Name of the USB host class instance */
+	const char *name;
+	/** Pointer to USB host stack context structure */
+	struct usbh_context *uhs_ctx;
+	/** Pointer to USB device this class is used for */
+	struct usb_device *udev;
+	/** Interface number for which this class matched */
+	uint8_t iface;
+	/** Pointer to host support class API */
+	struct usbh_class_api *api;
+	/** Pointer to private data */
+	void *priv;
+};
 
-	/** Initialization of the class implementation */
-	/* int (*init)(struct usbh_context *const uhs_ctx); */
-	/** Request completion event handler */
-	int (*request)(struct usbh_context *const uhs_ctx,
-			struct uhc_transfer *const xfer, int err);
-	/** Device connected handler  */
-	int (*connected)(struct usbh_context *const uhs_ctx);
-	/** Device removed handler  */
-	int (*removed)(struct usbh_context *const uhs_ctx);
-	/** Bus remote wakeup handler  */
-	int (*rwup)(struct usbh_context *const uhs_ctx);
-	/** Bus suspended handler  */
-	int (*suspended)(struct usbh_context *const uhs_ctx);
-	/** Bus resumed handler  */
-	int (*resumed)(struct usbh_context *const uhs_ctx);
+/**
+ * @cond INTERNAL_HIDDEN
+ *
+ * Internal state of an USB class. Not corresponding to an USB protocol state,
+ * but instead software life cycle.
+ */
+enum usbh_class_state {
+	/** The class is available to be associated to an USB device function. */
+	USBH_CLASS_STATE_IDLE,
+	/** The class got bound to an USB function of a particular device on the bus. */
+	USBH_CLASS_STATE_BOUND,
+	/** The class failed to initialize and cannot be used. */
+	USBH_CLASS_STATE_ERROR,
 };
+/* @endcond */
 
 /**
+ * @cond INTERNAL_HIDDEN
+ *
+ * Variables used by the USB host stack but not exposed to the class
+ * through the class API.
  */
-#define USBH_DEFINE_CLASS(name) \
-	static STRUCT_SECTION_ITERABLE(usbh_class_data, name)
+struct usbh_class_node {
+	/** Class information exposed to host class implementations (drivers). */
+	struct usbh_class_data *const c_data;
+	/** Filter rules to match this USB host class instance against a device class **/
+	struct usbh_class_filter *filters;
+	/** Number of filters in the array */
+	size_t num_filters;
+	/** State of the USB class instance */
+	enum usbh_class_state state;
+};
+/* @endcond */
 
+/**
+ * @brief Define USB host support class data
+ *
+ * Macro defines class (function) data, as well as corresponding node
+ * structures used internally by the stack.
+ *
+ * @param[in] class_name Class name
+ * @param[in] class_api  Pointer to struct usbh_class_api
+ * @param[in] class_priv Class private data
+ * @param[in] filt Array of @ref usbh_class_filter to match this class or NULL to match everything
+ * @param[in] num_filt Number of filters in the array
+ */
+#define USBH_DEFINE_CLASS(class_name, class_api, class_priv, filt, num_filt)	\
+	static struct usbh_class_data class_data_##class_name = {		\
+		.name = STRINGIFY(class_name),					\
+		.api = class_api,						\
+		.priv = class_priv,						\
+	};									\
+	static STRUCT_SECTION_ITERABLE(usbh_class_node, class_name) = {		\
+		.c_data = &class_data_##class_name,				\
+		.filters = filt,						\
+		.num_filters = num_filt,					\
+	};
 
 /**
  * @brief Initialize the USB host support;

subsys/usb/CMakeLists.txt

@@ -5,3 +5,4 @@ add_subdirectory_ifdef(CONFIG_USB_DEVICE_STACK device)
 add_subdirectory_ifdef(CONFIG_USB_DEVICE_STACK_NEXT device_next)
 add_subdirectory_ifdef(CONFIG_USB_HOST_STACK host)
 add_subdirectory_ifdef(CONFIG_USBC_STACK usb_c)
+add_subdirectory(common)

subsys/usb/common/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (c) 2025 Nordic Semiconductor
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_include_directories(include)

subsys/usb/device_next/class/usbd_uvc.c

@@ -25,7 +25,8 @@
 #include <zephyr/usb/usb_ch9.h>
 #include <zephyr/usb/class/usbd_uvc.h>
 
-#include "usbd_uvc.h"
+#include "usb_uvc.h"
+
 #include "../../../drivers/video/video_ctrls.h"
 #include "../../../drivers/video/video_device.h"
 

subsys/usb/host/CMakeLists.txt

@@ -5,9 +5,11 @@ zephyr_library()
 zephyr_library_include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 
 zephyr_library_sources(
+  usbh_api.c
   usbh_ch9.c
+  usbh_class.c
   usbh_core.c
-  usbh_api.c
+  usbh_desc.c
   usbh_device.c
 )
 
@@ -16,6 +18,11 @@ 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