usb: host: uvc: loop through every descriptor

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 +1,390 @@
+/*
+ * 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 "../../../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;
+};
+
+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_desc_size_is_valid(header_desc, sizeof(*header_desc), desc_end) ||
+	    header_desc->bDescriptorType != USB_DESC_CS_INTERFACE ||
+	    (header_desc->bDescriptorSubtype != UVC_VS_OUTPUT_HEADER &&
+	     header_desc->bDescriptorSubtype != UVC_VS_INPUT_HEADER)) {
+		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_desc_size_is_valid(header_desc, sizeof(*header_desc), desc_end) ||
+	    header_desc->bDescriptorType != USB_DESC_CS_INTERFACE ||
+	    header_desc->bDescriptorSubtype != UVC_VC_HEADER) {
+		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_beg,
+				  const void *const desc_end)
+{
+	/* Skip the interface descriptor itself */
+	const struct usb_desc_header *desc = usbh_desc_get_next(desc_beg, desc_end);
+
+	for (; desc != NULL; desc = usbh_desc_get_next(desc, desc_end)) {
+		if (desc->bDescriptorType == USB_DESC_INTERFACE ||
+		    desc->bDescriptorType == USB_DESC_INTERFACE_ASSOC ||
+		    desc->bDescriptorType == 0) {
+			break;
+		} else if (desc->bDescriptorType == USB_DESC_CS_INTERFACE) {
+			const struct uvc_if_descriptor *const if_desc = (void *)desc;
+
+			switch (if_desc->bDescriptorSubtype) {
+			case UVC_VC_HEADER:
+				LOG_DBG("VideoControl interface: Header");
+				break;
+			case UVC_VC_OUTPUT_TERMINAL:
+				LOG_DBG("VideoControl interface: Output Terminal");
+				break;
+			case UVC_VC_INPUT_TERMINAL:
+				LOG_DBG("VideoControl interface: Input/Camera Terminal");
+				break;
+			case UVC_VC_SELECTOR_UNIT:
+				LOG_DBG("VideoControl interface: Selector Unit");
+				break;
+			case UVC_VC_PROCESSING_UNIT:
+				LOG_DBG("VideoControl interface: Processing Unit");
+				break;
+			case UVC_VC_EXTENSION_UNIT:
+				LOG_DBG("VideoControl interface: Extension Unit");
+				break;
+			case UVC_VC_ENCODING_UNIT:
+				LOG_DBG("VideoControl interface: Encoding Unit");
+				break;
+			default:
+				LOG_WRN("VideoControl interface: unknown subtype %u, skipping",
+					if_desc->bDescriptorSubtype);
+			}
+		} else {
+			LOG_WRN("VideoControl descriptor: unknown type %u, skipping",
+				desc->bDescriptorType);
+		}
+	}
+
+	return 0;
+}
+
+static int usbh_uvc_parse_vs_desc(struct usbh_class_data *const c_data,
+				  const void *const desc_beg,
+				  const void *const desc_end)
+{
+	/* Skip the interface descriptor itself */
+	const struct usb_desc_header *desc = usbh_desc_get_next(desc_beg, desc_end);
+
+	for (; desc != NULL; desc = usbh_desc_get_next(desc, desc_end)) {
+		if (desc->bDescriptorType == USB_DESC_INTERFACE ||
+		    desc->bDescriptorType == USB_DESC_INTERFACE_ASSOC ||
+		    desc->bDescriptorType == 0) {
+			break;
+		} else if (desc->bDescriptorType == USB_DESC_CS_INTERFACE) {
+			const struct uvc_if_descriptor *const if_desc = (void *)desc;
+
+			switch (if_desc->bDescriptorSubtype) {
+			case UVC_VS_INPUT_HEADER:
+				LOG_DBG("VideoStreaming interface: Input header");
+				break;
+			case UVC_VS_OUTPUT_HEADER:
+				LOG_DBG("VideoStreaming interface: Output header");
+				break;
+			case UVC_VS_FORMAT_UNCOMPRESSED:
+				LOG_DBG("VideoStreaming interface: Uncompressed format");
+				break;
+			case UVC_VS_FORMAT_MJPEG:
+				LOG_DBG("VideoStreaming interface: MJPEG format");
+				break;
+			case UVC_VS_FRAME_UNCOMPRESSED:
+				LOG_DBG("VideoStreaming interface: Uncompressed Frame");
+				break;
+			case UVC_VS_FRAME_MJPEG:
+				LOG_DBG("VideoStreaming interface: MJPEG Frame");
+				break;
+			case UVC_VS_COLORFORMAT:
+				LOG_DBG("VideoStreaming interface: Color");
+				break;
+			default:
+				LOG_DBG("VideoStreaming descriptor: unknown subtype %u, skipping",
+					if_desc->bDescriptorSubtype);
+			}
+		} else if (desc->bDescriptorType == USB_DESC_ENDPOINT) {
+			const struct usb_ep_descriptor *const ep_desc = (void *)desc;
+
+			LOG_DBG("VideoStreaming Endpoint", ep_desc->bEndpointAddress);
+		} else {
+			LOG_WRN("VideoStreaming descriptor: unknown type %u, skipping",
+				desc->bDescriptorType);
+		}
+	}
+
+	return 0;
+}
+
+static int usbh_uvc_probe(struct usbh_class_data *const c_data,
+			  struct usb_device *const udev, uint8_t iface)
+{
+	const void *const desc_beg = usbh_desc_get_cfg_beg(udev);
+	const void *const desc_end = usbh_desc_get_cfg_end(udev);
+	const struct usb_association_descriptor *const iad_desc =
+		usbh_desc_get_by_ifnum(desc_beg, desc_end, iface);
+	const struct usb_desc_header *desc;
+	bool has_vc_if = false;
+	bool has_vs_if = false;
+	int ret;
+
+	/* Filter the interface */
+
+	if (iad_desc == NULL) {
+		LOG_ERR("failed to find interface or interface association number %u", iface);
+		return -ENOSYS;
+	}
+
+	if (iad_desc->bDescriptorType != USB_DESC_INTERFACE_ASSOC) {
+		LOG_WRN("Interface %u is not a valid %s, skipping", iface, "interface assoc");
+		return -ENOTSUP;
+	}
+
+	/* Turn the descriptors into Video Interface structures */
+
+	desc = (struct usb_desc_header *)iad_desc;
+	for (int i = 0; i < iad_desc->bInterfaceCount; i++) {
+		const struct usb_if_descriptor *if_desc;
+
+		desc = usbh_desc_get_next(desc, desc_end);
+
+		if_desc = (void *)usbh_desc_get_by_type(desc, desc_end, BIT(USB_DESC_INTERFACE));
+		if (if_desc == NULL) {
+			LOG_ERR("Not as many interfaces (%u) as announced (%u)",
+				i, iad_desc->bInterfaceCount);
+			return -EBADMSG;
+		}
+
+		if (if_desc->bInterfaceClass == USB_BCC_VIDEO &&
+		    if_desc->bInterfaceSubClass == UVC_SC_VIDEOCONTROL) {
+			const void *vc_end;
+
+			if (has_vc_if) {
+				LOG_WRN("Skipping extra VideoControl interface");
+				continue;
+			}
+
+			vc_end = usbh_uvc_desc_get_vc_end(if_desc, desc_end);
+			if (vc_end == NULL) {
+				LOG_ERR("Invalid VideoControl interface descriptor");
+				return -EBADMSG;
+			}
+
+			ret = usbh_uvc_parse_vc_desc(c_data, if_desc, vc_end);
+			if (ret != 0) {
+				LOG_ERR("Failed to parse VC descriptor");
+				return ret;
+			}
+
+			has_vc_if = true;
+		}
+
+		if (if_desc->bInterfaceClass == USB_BCC_VIDEO &&
+		    if_desc->bInterfaceSubClass == UVC_SC_VIDEOSTREAMING) {
+			const void *vs_end;
+
+			if (has_vs_if) {
+				LOG_WRN("Skipping extra VideoStreaming interface");
+				continue;
+			}
+
+			vs_end = usbh_uvc_desc_get_vs_end(if_desc, desc_end);
+			if (vs_end == NULL) {
+				LOG_ERR("Invalid VideoStreaming interface descriptor");
+				return -EBADMSG;
+			}
+
+			ret = usbh_uvc_parse_vs_desc(c_data, if_desc, vs_end);
+			if (ret != 0) {
+				return ret;
+			}
+
+			has_vs_if = true;
+		}
+	}
+
+	if (!has_vs_if) {
+		LOG_ERR("No VideoStreaming interface found");
+		return -EINVAL;
+	}
+
+	if (!has_vc_if) {
+		LOG_DBG("No VideoControl interface found");
+		return -EINVAL;
+	}
+
+	LOG_INF("Interface %u associated with UVC class", 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)
+{
+	LOG_DBG("%s", dev->name);
+
+	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_filter[] = {
+	{
+		.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));			\
+										\
+	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)