usbdev: Add callback for CONFIG_USBDEV_SOFINTERRUPT

Previously CONFIG_USBDEV_SOFINTERRUPT existed in many platform
drivers but did nothing. This commit adds a callback function
usbdev_sof_irq() that can be used to take action on this interrupt.

drivers/usbdev/Kconfig

@@ -50,6 +50,14 @@ config USBDEV_MAXPOWER
 		the device is bus powered (USBDEV_BUSPOWERED).  It is, however, used
 		unconditionally in several USB device drivers.
 
+config USBDEV_SOFINTERRUPT
+	bool "Enable USB device SOF interrupts"
+	default n
+	---help---
+		Enable USB start-of-frame interrupts.
+		Can be used for synchronizing to host clock rate.
+		Board logic must provide usbdev_sof_irq() function.
+
 config USBDEV_DMA
 	bool "Enable DMA methods"
 	default n

include/nuttx/usb/usbdev.h

@@ -480,6 +480,19 @@ FAR void *usbdev_dma_alloc(size_t size);
 void usbdev_dma_free(FAR void *memory);
 #endif
 
+/****************************************************************************
+ * Name: up_usbdev_sof_irq
+ *
+ * Description:
+ *   If CONFIG_USBDEV_SOFINTERRUPT is enabled, board logic must provide
+ *   this function. It gets called in interrupt mode by USB device code
+ *   every time start-of-frame USB packet is received from host.
+ *
+ ****************************************************************************/
+#ifdef CONFIG_USBDEV_SOFINTERRUPT
+void usbdev_sof_irq(FAR struct usbdev_s *dev, uint16_t frameno);
+#endif
+
 #undef EXTERN
 #if defined(__cplusplus)
 }