fix(nrf52840): add missing flow control functions

Author: mikesmitty

src/machine/machine_nrf52840_usb.go

@@ -258,16 +258,9 @@ func initEndpoint(ep, config uint32) {
 func (dev *USBDevice) SendUSBInPacket(ep uint32, data []byte) bool {
 	sendUSBPacket(ep, data, 0)
 
-	// clear transfer complete flag
-	nrf.USBD.INTENCLR.Set(nrf.USBD_INTENCLR_ENDEPOUT0 << 4)
-
 	return true
 }
 
-func SendUSBInPacket(ep uint32, data []byte) bool {
-	return USBDev.SendUSBInPacket(ep, data)
-}
-
 // Prevent file size increases: https://github.com/tinygo-org/tinygo/pull/998
 //
 //go:noinline
@@ -313,16 +306,27 @@ func (dev *USBDevice) AckUsbOutTransfer(ep uint32) {
 	nrf.USBD.SIZE.EPOUT[ep].Set(0)
 }
 
-func AckUsbOutTransfer(ep uint32) {
-	USBDev.AckUsbOutTransfer(ep)
-}
-
 func (dev *USBDevice) SendZlp() {
 	nrf.USBD.TASKS_EP0STATUS.Set(1)
 }
 
-func SendZlp() {
-	USBDev.SendZlp()
+// Set the USB endpoint Packet ID to DATA0 or DATA1.
+// In endpoints must have bit 7 (0x80) set.
+func setEPDataPID(ep uint32, dataOne bool) {
+	// nrf52840 DTOGGLE requires a "Select" write first (Value=Nop=0),
+	// then a "Set" write (Value=Data0/Data1).
+
+	// Select Endpoint (Value=Nop=0)
+	nrf.USBD.DTOGGLE.Set(ep)
+
+	// Now write the value
+	val := ep
+	if dataOne {
+		val |= nrf.USBD_DTOGGLE_VALUE_Data1 << nrf.USBD_DTOGGLE_VALUE_Pos
+	} else {
+		val |= nrf.USBD_DTOGGLE_VALUE_Data0 << nrf.USBD_DTOGGLE_VALUE_Pos
+	}
+	nrf.USBD.DTOGGLE.Set(val)
 }
 
 // Set ENDPOINT_HALT/stall status on a USB IN endpoint.
@@ -339,12 +343,23 @@ func (dev *USBDevice) SetStallEPOut(ep uint32) {
 
 // Clear the ENDPOINT_HALT/stall on a USB IN endpoint.
 func (dev *USBDevice) ClearStallEPIn(ep uint32) {
+	// Disable Endpoint
+	nrf.USBD.EPINEN.ClearBits(1 << ep)
+
 	// Bit 8 is STALL (0 for UnStall), Bit 7 is IO (1 for IN), Bits 0-2 are EP number.
 	nrf.USBD.EPSTALL.Set((0 << 8) | (1 << 7) | (ep & 0x7))
+
+	// Reset Data Toggle to DATA0 *after* unstalling.
+	setEPDataPID(ep|usb.EndpointIn, false)
+
+	// Re-enable Endpoint
+	nrf.USBD.EPINEN.SetBits(1 << ep)
 }
 
 // Clear the ENDPOINT_HALT/stall on a USB OUT endpoint.
 func (dev *USBDevice) ClearStallEPOut(ep uint32) {
+	// Reset Data Toggle to DATA0.
+	setEPDataPID(ep, false)
 	// Bit 8 is STALL (0 for UnStall), Bit 7 is IO (0 for OUT), Bits 0-2 are EP number.
 	nrf.USBD.EPSTALL.Set((0 << 8) | (0 << 7) | (ep & 0x7))
 }