cpu/gd32v: add periph_usbdev support

cpu/gd32v/Kconfig

@@ -30,6 +30,7 @@ config CPU_FAM_GD32V
 
     select MODULE_PERIPH_CLIC if TEST_KCONFIG
     select MODULE_PERIPH_WDT if MODULE_PERIPH_PM && HAS_PERIPH_WDT
+    select MODULE_USBDEV_SYNOPSYS_DWC2 if MODULE_PERIPH_USBDEV
     select ZTIMER_USEC if MODULE_PERIPH_I2C
     select PACKAGE_NMSIS_SDK
 

cpu/gd32v/Makefile.dep

@@ -11,4 +11,8 @@ ifneq (,$(filter periph_i2c,$(USEMODULE)))
   USEMODULE += ztimer_usec
 endif
 
+ifneq (,$(filter periph_usbdev,$(USEMODULE)))
+  USEMODULE += usbdev_synopsys_dwc2
+endif
+
 include $(RIOTCPU)/riscv_common/Makefile.dep

cpu/gd32v/include/periph_cpu.h

@@ -462,6 +462,7 @@ typedef struct {
  * @name    USB device definitions
  * @{
  */
+#define USBDEV_SET_ADDR_AFTER_STATUS    0   /**< Set device address after SETUP stage */
 #define USBDEV_NUM_ENDPOINTS            4   /**< Number of USB OTG FS endpoints including EP0 */
 /** @} */
 

cpu/gd32v/include/vendor/usbdev_gd32v.h

@@ -70,7 +70,7 @@
 #endif
 
 /**
- * @brief   Total size of the FIFO
+ * @brief   Total size of the FIFO in bytes
  */
 #define DWC2_USB_OTG_FS_TOTAL_FIFO_SIZE (1280)