Low-level IO driver for serial flash memory via SPI and QSPI (#124)

* QSPI/SPI: flash memory functions
2026-08-20 14:39:00 +00:00 · 2020-04-11 11:59:58 -04:00
parent 1987f424ad
commit b1529dcf7a
9 changed files with 1559 additions and 0 deletions
@@ -0,0 +1,154 @@
+package flash
+
+import "machine"
+
+type transport interface {
+	configure(config *DeviceConfig)
+	supportQuadMode() bool
+	setClockSpeed(hz uint32) (err error)
+	runCommand(cmd byte) (err error)
+	readCommand(cmd byte, rsp []byte) (err error)
+	writeCommand(cmd byte, data []byte) (err error)
+	eraseCommand(cmd byte, address uint32) (err error)
+	readMemory(addr uint32, rsp []byte) (err error)
+	writeMemory(addr uint32, data []byte) (err error)
+}
+
+// NewSPI returns a pointer to a flash device that uses a SPI peripheral to
+// communicate with a serial memory chip.
+func NewSPI(spi *machine.SPI, mosi, miso, sck, cs machine.Pin) *Device {
+	return &Device{
+		trans: &spiTransport{
+			spi:  spi,
+			mosi: mosi,
+			miso: miso,
+			sck:  sck,
+			ss:   cs,
+		},
+	}
+}
+
+type spiTransport struct {
+	spi  *machine.SPI
+	mosi machine.Pin
+	miso machine.Pin
+	sck  machine.Pin
+	ss   machine.Pin
+}
+
+func (tr *spiTransport) configure(config *DeviceConfig) {
+	// Configure spi bus
+	tr.setClockSpeed(5000000)
+
+	// Configure chip select pin
+	tr.ss.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	tr.ss.High()
+}
+
+func (tr *spiTransport) setClockSpeed(hz uint32) error {
+	// TODO: un-hardcode this max speed; it is probably a sensible
+	//       default maximum for atsamd and nrf at least
+	if hz > 24*1e6 {
+		hz = 24 * 1e6
+	}
+	tr.spi.Configure(machine.SPIConfig{
+		Frequency: hz,
+		MISO:      tr.miso,
+		MOSI:      tr.mosi,
+		SCK:       tr.sck,
+		LSBFirst:  false,
+		Mode:      0,
+	})
+	return nil
+}
+
+func (tr *spiTransport) supportQuadMode() bool {
+	return false
+}
+
+func (tr *spiTransport) runCommand(cmd byte) (err error) {
+	tr.ss.Low()
+	_, err = tr.spi.Transfer(byte(cmd))
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) readCommand(cmd byte, rsp []byte) (err error) {
+	tr.ss.Low()
+	if _, err := tr.spi.Transfer(byte(cmd)); err == nil {
+		err = tr.readInto(rsp)
+	}
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) readCommandByte(cmd byte) (rsp byte, err error) {
+	tr.ss.Low()
+	if _, err := tr.spi.Transfer(byte(cmd)); err == nil {
+		rsp, err = tr.spi.Transfer(0xFF)
+	}
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) writeCommand(cmd byte, data []byte) (err error) {
+	tr.ss.Low()
+	if _, err := tr.spi.Transfer(byte(cmd)); err == nil {
+		err = tr.writeFrom(data)
+	}
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) eraseCommand(cmd byte, address uint32) (err error) {
+	tr.ss.Low()
+	err = tr.sendAddress(cmd, address)
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) readMemory(addr uint32, rsp []byte) (err error) {
+	tr.ss.Low()
+	if err = tr.sendAddress(cmdRead, addr); err == nil {
+		err = tr.readInto(rsp)
+	}
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) writeMemory(addr uint32, data []byte) (err error) {
+	tr.ss.Low()
+	if err = tr.sendAddress(cmdPageProgram, addr); err == nil {
+		err = tr.writeFrom(data)
+	}
+	tr.ss.High()
+	return
+}
+
+func (tr *spiTransport) sendAddress(cmd byte, addr uint32) error {
+	_, err := tr.spi.Transfer(byte(cmd))
+	if err == nil {
+		_, err = tr.spi.Transfer(byte((addr >> 16) & 0xFF))
+	}
+	if err == nil {
+		_, err = tr.spi.Transfer(byte((addr >> 8) & 0xFF))
+	}
+	if err == nil {
+		_, err = tr.spi.Transfer(byte(addr & 0xFF))
+	}
+	return err
+}
+
+func (tr *spiTransport) readInto(rsp []byte) (err error) {
+	for i, c := 0, len(rsp); i < c && err == nil; i++ {
+		rsp[i], err = tr.spi.Transfer(0xFF)
+	}
+	return
+}
+
+func (tr *spiTransport) writeFrom(data []byte) (err error) {
+	for i, c := 0, len(data); i < c && err == nil; i++ {
+		_, err = tr.spi.Transfer(data[i])
+	}
+	return
+}