rp2040: add support for EnterBootloader()

src/machine/machine_rp2040_usb.go

@@ -4,7 +4,6 @@
 package machine
 
 import (
-	"device/arm"
 	"device/rp"
 	"machine/usb"
 	"runtime/interrupt"
@@ -153,7 +152,8 @@ func initEndpoint(ep, config uint32) {
 
 	case usb.ENDPOINT_TYPE_CONTROL:
 		val |= usbEpControlEndpointTypeControl
-		usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBuf0CtrlAvail)
+		usbDPSRAM.EPxBufferControl[ep].Out.Set(usbBuf0CtrlData1Pid)
+		usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
 
 	}
 }
@@ -207,6 +207,21 @@ func sendUSBPacket(ep uint32, data []byte, maxsize uint16) {
 
 func ReceiveUSBControlPacket() ([cdcLineInfoSize]byte, error) {
 	var b [cdcLineInfoSize]byte
+	ep := 0
+
+	for !usbDPSRAM.EPxBufferControl[ep].Out.HasBits(usbBuf0CtrlFull) {
+		// TODO: timeout
+	}
+
+	ctrl := usbDPSRAM.EPxBufferControl[ep].Out.Get()
+	usbDPSRAM.EPxBufferControl[ep].Out.Set(USBBufferLen & usbBuf0CtrlLenMask)
+	sz := ctrl & usbBuf0CtrlLenMask
+
+	copy(b[:], usbDPSRAM.EPxBuffer[ep].Buffer0[:sz])
+
+	usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlData1Pid)
+	usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlAvail)
+
 	return b, nil
 }
 
@@ -218,7 +233,7 @@ func handleEndpointRx(ep uint32) []byte {
 	copy(buf, usbDPSRAM.EPxBuffer[ep].Buffer0[:sz])
 
 	epXdata0[ep] = !epXdata0[ep]
-	if epXdata0[ep] {
+	if epXdata0[ep] || ep == 0 {
 		usbDPSRAM.EPxBufferControl[ep].Out.SetBits(usbBuf0CtrlData1Pid)
 	}
 
@@ -259,16 +274,6 @@ func sendStallViaEPIn(ep uint32) {
 	usbDPSRAM.EPxBufferControl[ep&0x7F].In.Set(val)
 }
 
-// EnterBootloader should perform a system reset in preparation
-// to switch to the bootloader to flash new firmware.
-func EnterBootloader() {
-	arm.DisableInterrupts()
-
-	// TODO: Perform magic reset into bootloader
-
-	arm.SystemReset()
-}
-
 type USBDPSRAM struct {
 	// Note that EPxControl[0] is not EP0Control but 8-byte setup data.
 	EPxControl [16]USBEndpointControlRegister