samd21,samd51,nrf52840: unify bootloader entry process

src/machine/machine_atsamd21.go

@@ -1734,9 +1734,9 @@ func (tcc *TCC) Set(channel uint8, value uint32) {
 	}
 }
 
-// ResetProcessor should perform a system reset in preperation
+// EnterBootloader should perform a system reset in preperation
 // to switch to the bootloader to flash new firmware.
-func ResetProcessor() {
+func EnterBootloader() {
 	arm.DisableInterrupts()
 
 	// Perform magic reset into bootloader, as mentioned in

src/machine/machine_atsamd21_usb.go

@@ -583,7 +583,7 @@ func cdcSetup(setup usbSetup) bool {
 		if setup.bRequest == usb_CDC_SET_LINE_CODING || setup.bRequest == usb_CDC_SET_CONTROL_LINE_STATE {
 			// auto-reset into the bootloader
 			if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
-				ResetProcessor()
+				EnterBootloader()
 			} else {
 				// TODO: cancel any reset
 			}

src/machine/machine_atsamd51.go

@@ -1974,9 +1974,9 @@ func (tcc *TCC) Set(channel uint8, value uint32) {
 	}
 }
 
-// ResetProcessor should perform a system reset in preparation
+// EnterBootloader should perform a system reset in preparation
 // to switch to the bootloader to flash new firmware.
-func ResetProcessor() {
+func EnterBootloader() {
 	arm.DisableInterrupts()
 
 	// Perform magic reset into bootloader, as mentioned in

src/machine/machine_atsamd51_usb.go

@@ -586,7 +586,7 @@ func cdcSetup(setup usbSetup) bool {
 		if setup.bRequest == usb_CDC_SET_LINE_CODING || setup.bRequest == usb_CDC_SET_CONTROL_LINE_STATE {
 			// auto-reset into the bootloader
 			if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
-				ResetProcessor()
+				EnterBootloader()
 			} else {
 				// TODO: cancel any reset
 			}

src/machine/machine_nrf52840_enter_bootloader.go

@@ -0,0 +1,39 @@
+//go:build nrf52840
+// +build nrf52840
+
+package machine
+
+import (
+	"device/arm"
+	"device/nrf"
+)
+
+const (
+	DFU_MAGIC_SERIAL_ONLY_RESET = 0x4e
+	DFU_MAGIC_UF2_RESET         = 0x57
+	DFU_MAGIC_OTA_RESET         = 0xA8
+)
+
+// EnterSerialBootloader resets the chip into the serial bootloader. After
+// reset, it can be flashed using serial/nrfutil.
+func EnterSerialBootloader() {
+	arm.DisableInterrupts()
+	nrf.POWER.GPREGRET.Set(DFU_MAGIC_SERIAL_ONLY_RESET)
+	arm.SystemReset()
+}
+
+// EnterUF2Bootloader resets the chip into the UF2 bootloader. After reset, it
+// can be flashed via nrfutil or by copying a UF2 file to the mass storage device
+func EnterUF2Bootloader() {
+	arm.DisableInterrupts()
+	nrf.POWER.GPREGRET.Set(DFU_MAGIC_UF2_RESET)
+	arm.SystemReset()
+}
+
+// EnterOTABootloader resets the chip into the bootloader so that it can be
+// flashed via an OTA update
+func EnterOTABootloader() {
+	arm.DisableInterrupts()
+	nrf.POWER.GPREGRET.Set(DFU_MAGIC_OTA_RESET)
+	arm.SystemReset()
+}

src/machine/machine_nrf52840_usb.go

@@ -320,7 +320,9 @@ func (usbcdc *USBCDC) handleInterrupt(interrupt.Interrupt) {
 				count := int(nrf.USBD.SIZE.EPOUT[0].Get())
 				if count >= 7 {
 					parseUSBLineInfo(udd_ep_out_cache_buffer[0][:count])
-					checkShouldReset()
+					if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
+						EnterBootloader()
+					}
 				}
 				nrf.USBD.TASKS_EP0STATUS.Set(1)
 			}
@@ -484,7 +486,9 @@ func cdcSetup(setup usbSetup) bool {
 
 		if setup.bRequest == usb_CDC_SET_CONTROL_LINE_STATE {
 			usbLineInfo.lineState = setup.wValueL
-			checkShouldReset()
+			if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
+				EnterBootloader()
+			}
 			nrf.USBD.TASKS_EP0STATUS.Set(1)
 		}
 

src/machine/machine_nrf52840_usb_reset_bossa.go

@@ -3,25 +3,8 @@
 
 package machine
 
-import (
+// EnterBootloader resets the chip into the serial bootloader. After
-	"device/arm"
+// reset, it can be flashed using serial/nrfutil.
-	"device/nrf"
+func EnterBootloader() {
-)
-
-const DFU_MAGIC_SERIAL_ONLY_RESET = 0xb0
-
-// checkShouldReset is called by the USB-CDC implementation to check whether to
-// reset into the bootloader/OTA and if so, resets the chip appropriately.
-func checkShouldReset() {
-	if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
 	EnterSerialBootloader()
 }
-}
-
-// EnterSerialBootloader resets the chip into the serial bootloader. After
-// reset, it can be flashed using serial/nrfutil.
-func EnterSerialBootloader() {
-	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_SERIAL_ONLY_RESET)
-	arm.SystemReset()
-}

src/machine/machine_nrf52840_usb_reset_none.go

@@ -3,5 +3,7 @@
 
 package machine
 
-func checkShouldReset() {
+// EnterBootloader resets the chip into the serial bootloader.
+func EnterBootloader() {
+	// skip
 }

src/machine/machine_nrf52840_usb_reset_uf2.go

@@ -3,45 +3,8 @@
 
 package machine
 
-import (
+// EnterBootloader resets the chip into the UF2 bootloader. After reset, it
-	"device/arm"
+// can be flashed via nrfutil or by copying a UF2 file to the mass storage device
-	"device/nrf"
+func EnterBootloader() {
-)
-
-const (
-	DFU_MAGIC_SERIAL_ONLY_RESET = 0x4e
-	DFU_MAGIC_UF2_RESET         = 0x57
-	DFU_MAGIC_OTA_RESET         = 0xA8
-)
-
-// checkShouldReset is called by the USB-CDC implementation to check whether to
-// reset into the bootloader/OTA and if so, resets the chip appropriately.
-func checkShouldReset() {
-	if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
 	EnterUF2Bootloader()
 }
-}
-
-// EnterSerialBootloader resets the chip into the serial bootloader. After
-// reset, it can be flashed using serial/nrfutil.
-func EnterSerialBootloader() {
-	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_SERIAL_ONLY_RESET)
-	arm.SystemReset()
-}
-
-// EnterUF2Bootloader resets the chip into the UF2 bootloader. After reset, it
-// can be flashed via nrfutil or by copying a UF2 file to the mass storage device
-func EnterUF2Bootloader() {
-	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_UF2_RESET)
-	arm.SystemReset()
-}
-
-// EnterOTABootloader resets the chip into the bootloader so that it can be
-// flashed via an OTA update
-func EnterOTABootloader() {
-	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_OTA_RESET)
-	arm.SystemReset()
-}