// +build nrf52840,nrf52840_reset_uf2

package machine

import (
	"device/arm"
	"device/nrf"
)

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()
}
