usb: device_next: implement blocklist for classes

In the usbd_register_all_classes(), we may need to skip some instances
as they may have very specific function like USB DFU "DFU mode" which
should not be available by default.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>

Author: jfischer-no

include/zephyr/usb/usbd.h

@@ -841,14 +841,30 @@ int usbd_register_class(struct usbd_context *uds_ctx,
  * usbd_register_class for any device, configuration number, or instance,
  * either usbd_register_class or this function will fail.
  *
+ * There may be situations where a particular function should not be
+ * registered, for example, when using the USB DFU implementation, the DFU mode
+ * function must be excluded during normal device operation. To do this, the
+ * device can pass a blocklist in the form shown below as an optional argument.
+ * If the blocklist is not needed, the argument should be NULL.
+ *
+ * @code{.c}
+ * static const char *const blocklist[] = {
+ *         "dfu_dfu",
+ *         NULL,
+ * };
+ * @endcode
+ *
  * @param[in] uds_ctx Pointer to USB device support context
  * @param[in] speed   Configuration speed
  * @param[in] cfg     Configuration value (bConfigurationValue)
+ * @param[in] blocklist Null pointer terminated array of pointers to string
+ *                      literals to be used as a block list
  *
  * @return 0 on success, other values on fail.
  */
 int usbd_register_all_classes(struct usbd_context *uds_ctx,
-			      const enum usbd_speed speed, uint8_t cfg);
+			      const enum usbd_speed speed, uint8_t cfg,
+			      const char *const blocklist[]);
 
 /**
  * @brief Unregister an USB class instance

samples/subsys/usb/common/sample_usbd_init.c

@@ -124,7 +124,8 @@ struct usbd_context *sample_usbd_setup_device(usbd_msg_cb_t msg_cb)
 			return NULL;
 		}
 
-		err = usbd_register_all_classes(&sample_usbd, USBD_SPEED_HS, 1);
+		err = usbd_register_all_classes(&sample_usbd, USBD_SPEED_HS, 1,
+						NULL);
 		if (err) {
 			LOG_ERR("Failed to add register classes");
 			return NULL;
@@ -143,7 +144,7 @@ struct usbd_context *sample_usbd_setup_device(usbd_msg_cb_t msg_cb)
 	/* doc configuration register end */
 
 	/* doc functions register start */
-	err = usbd_register_all_classes(&sample_usbd, USBD_SPEED_FS, 1);
+	err = usbd_register_all_classes(&sample_usbd, USBD_SPEED_FS, 1, NULL);
 	if (err) {
 		LOG_ERR("Failed to add register classes");
 		return NULL;

subsys/usb/device_next/usbd_class.c

@@ -340,13 +340,30 @@ int usbd_register_class(struct usbd_context *const uds_ctx,
 	return ret;
 }
 
+static bool is_blocklisted(const struct usbd_class_node *const c_nd,
+			   const char *const list[])
+{
+	for (int i = 0; list[i] != NULL; i++) {
+		if (strcmp(c_nd->c_data->name, list[i]) == 0) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 int usbd_register_all_classes(struct usbd_context *const uds_ctx,
-			      const enum usbd_speed speed, const uint8_t cfg)
+			      const enum usbd_speed speed, const uint8_t cfg,
+			      const char *const blocklist[])
 {
 	int ret;
 
 	if (speed == USBD_SPEED_HS) {
 		STRUCT_SECTION_FOREACH_ALTERNATE(usbd_class_hs, usbd_class_node, c_nd) {
+			if (blocklist != NULL && is_blocklisted(c_nd, blocklist)) {
+				continue;
+			}
+
 			ret = usbd_register_class(uds_ctx, c_nd->c_data->name,
 						  speed, cfg);
 			if (ret) {
@@ -361,6 +378,10 @@ int usbd_register_all_classes(struct usbd_context *const uds_ctx,
 
 	if (speed == USBD_SPEED_FS) {
 		STRUCT_SECTION_FOREACH_ALTERNATE(usbd_class_fs, usbd_class_node, c_nd) {
+			if (blocklist != NULL && is_blocklisted(c_nd, blocklist)) {
+				continue;
+			}
+
 			ret = usbd_register_class(uds_ctx, c_nd->c_data->name,
 						  speed, cfg);
 			if (ret) {

tests/subsys/usb/device_next/src/main.c

@@ -134,7 +134,7 @@ static void *usb_test_enable(void)
 	zassert_equal(err, 0, "Failed to add configuration (%d)");
 
 	if (usbd_caps_speed(&test_usbd) == USBD_SPEED_HS) {
-		err = usbd_register_all_classes(&test_usbd, USBD_SPEED_HS, 1);
+		err = usbd_register_all_classes(&test_usbd, USBD_SPEED_HS, 1, NULL);
 		zassert_equal(err, 0, "Failed to unregister all instances(%d)");
 
 		err = usbd_unregister_all_classes(&test_usbd, USBD_SPEED_HS, 1);
@@ -144,7 +144,7 @@ static void *usb_test_enable(void)
 		zassert_equal(err, 0, "Failed to register loopback_0 class (%d)");
 	}
 
-	err = usbd_register_all_classes(&test_usbd, USBD_SPEED_FS, 1);
+	err = usbd_register_all_classes(&test_usbd, USBD_SPEED_FS, 1, NULL);
 	zassert_equal(err, 0, "Failed to unregister all instances(%d)");
 
 	err = usbd_unregister_all_classes(&test_usbd, USBD_SPEED_FS, 1);