usb: host: uvc: placeholder implementation

Loop through each of the VideoStreaming and VideoControl descriptor
to parse them. This is meant as a stub for the purpose of testing the
class API.

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

Author: Josuah Demangeon

subsys/usb/host/class/usbh_uvc.c

@@ -0,0 +1,222 @@
+/*
+ * 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 "usbh_ch9.h"
+#include "usbh_class.h"
+#include "usbh_desc.h"
+#include "usbh_device.h"
+#include "usb_uvc.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_data {
+	int todo;
+};
+
+/*
+ * Descriptor parsing utilities
+ * Validate and parse the video streaming and video control descriptors.
+ */
+
+static bool usbh_uvc_desc_is_valid_vs_header(const void *const desc,
+						 const void *const desc_end)
+{
+	const struct uvc_stream_header_descriptor *const header_desc = desc;
+
+	return usbh_desc_is_valid(desc, desc_end, sizeof(struct uvc_stream_header_descriptor)) &&
+	       header_desc->bDescriptorType == USB_DESC_CS_INTERFACE &&
+	       (header_desc->bDescriptorSubtype == UVC_VS_OUTPUT_HEADER ||
+		header_desc->bDescriptorSubtype == UVC_VS_INPUT_HEADER);
+}
+
+static bool usbh_uvc_desc_is_valid_vc_header(const void *const desc,
+					     const void *const desc_end)
+{
+	const struct uvc_control_header_descriptor *const header_desc = desc;
+
+	return usbh_desc_is_valid(desc, desc_end, sizeof(struct uvc_control_header_descriptor)) &&
+	       header_desc->bDescriptorType == USB_DESC_CS_INTERFACE &&
+	       header_desc->bDescriptorSubtype == UVC_VC_HEADER;
+}
+
+const void *usbh_uvc_desc_get_vs_end(const struct usb_if_descriptor *if_desc,
+				     const void *const desc_end)
+{
+	const struct uvc_stream_header_descriptor *const header_desc =
+		usbh_desc_get_next(if_desc, desc_end);
+	const void *vs_end;
+
+	if (!usbh_uvc_desc_is_valid_vs_header(header_desc, desc_end)) {
+		return NULL;
+	}
+
+	vs_end = (uint8_t *)header_desc + header_desc->wTotalLength;
+	if (vs_end > desc_end) {
+		return NULL;
+	}
+
+	return vs_end;
+}
+
+const void *usbh_uvc_desc_get_vc_end(const struct usb_if_descriptor *if_desc,
+					  const void *const desc_end)
+{
+	const struct uvc_control_header_descriptor *const header_desc =
+		usbh_desc_get_next(if_desc, desc_end);
+	const void *vc_end;
+
+	if (!usbh_uvc_desc_is_valid_vc_header(header_desc, desc_end)) {
+		return NULL;
+	}
+
+	vc_end = (uint8_t *)header_desc + header_desc->wTotalLength;
+	if (vc_end > desc_end) {
+		LOG_WRN("vc_end %p > desc_end %p", vc_end, desc_end);
+		return NULL;
+	}
+
+	return vc_end;
+}
+
+static int usbh_uvc_parse_vc_desc(struct usbh_class_data *const c_data,
+				  const void *const desc_ptr, const void *const desc_end)
+{
+	return 0;
+}
+
+static int usbh_uvc_parse_vs_desc(struct usbh_class_data *const c_data,
+				  const void *const desc_ptr, const void *const desc_end)
+{
+	return 0;
+}
+
+static int usbh_uvc_probe(struct usbh_class_data *const c_data,
+			  struct usb_device *const udev, const uint8_t iface)
+{
+	return 0;
+}
+
+static int usbh_uvc_removed(struct usbh_class_data *const c_data)
+{
+	return 0;
+}
+
+static int usbh_uvc_init(struct usbh_class_data *const c_data,
+			 struct usbh_context *const uhs_ctx)
+{
+	return 0;
+}
+
+static int usbh_uvc_completion_cb(struct usbh_class_data *const c_data,
+				  struct uhc_transfer *const xfer)
+{
+	return 0;
+}
+
+static int usbh_uvc_suspended(struct usbh_class_data *const c_data)
+{
+	return 0;
+}
+
+static int usbh_uvc_resumed(struct usbh_class_data *const c_data)
+{
+	return 0;
+}
+
+static int usbh_uvc_preinit(const struct device *dev)
+{
+	return 0;
+}
+
+static struct usbh_class_api uvc_class_api = {
+	.init = usbh_uvc_init,
+	.completion_cb = usbh_uvc_completion_cb,
+	.probe = usbh_uvc_probe,
+	.removed = usbh_uvc_removed,
+	.suspended = usbh_uvc_suspended,
+	.resumed = usbh_uvc_resumed,
+};
+
+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,
+};
+
+static struct usbh_class_filter usbh_uvc_filters[] = {
+	{
+		.flags = USBH_CLASS_MATCH_CLASS | USBH_CLASS_MATCH_SUB,
+		.class = USB_BCC_VIDEO,
+		.sub = UVC_SC_VIDEO_INTERFACE_COLLECTION,
+	},
+};
+
+#define USBH_VIDEO_DT_DEVICE_DEFINE(n)						\
+	struct usbh_uvc_data usbh_uvc_data_##n = {				\
+	};									\
+										\
+	USBH_DEFINE_CLASS(uvc_c_data_##n, &uvc_class_api,			\
+			  (void *)DEVICE_DT_INST_GET(n),			\
+			  usbh_uvc_filters, ARRAY_SIZE(usbh_uvc_filters));	\
+										\
+	DEVICE_DT_INST_DEFINE(n, usbh_uvc_preinit, NULL,			\
+			      &usbh_uvc_data_##n, NULL,				\
+			      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)