spi: remove machine.SPI and replace with drivers.SPI interface for almost all SPI drivers

Signed-off-by: deadprogram <ron@hybridgroup.com>

flash/flash.go

@@ -133,12 +133,14 @@ func (dev *Device) Configure(config *DeviceConfig) (err error) {
 	time.Sleep(30 * time.Microsecond)
 
 	// Speed up to max device frequency
-	if dev.attrs.MaxClockSpeedMHz > 0 {
-		err := dev.trans.setClockSpeed(uint32(dev.attrs.MaxClockSpeedMHz) * 1e6)
-		if err != nil {
-			return err
-		}
-	}
+	// I propose a check here for max frequency, but not put that functionality directly into the driver.
+	// Either that or we have to change the signature of the SPI interface in the machine package itself.
+	// if dev.attrs.MaxClockSpeedMHz > 0 {
+	// 	err := dev.trans.setClockSpeed(uint32(dev.attrs.MaxClockSpeedMHz) * 1e6)
+	// 	if err != nil {
+	// 		return err
+	// 	}
+	// }
 
 	// Enable Quad Mode if available
 	if dev.trans.supportQuadMode() && dev.attrs.QuadEnableBitMask > 0 {

flash/transport_spi.go

@@ -1,11 +1,14 @@
 package flash
 
-import "machine"
+import (
+	"machine"
+
+	"tinygo.org/x/drivers"
+)
 
 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)
@@ -16,7 +19,7 @@ type transport interface {
 
 // 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, sdo, sdi, sck, cs machine.Pin) *Device {
+func NewSPI(spi drivers.SPI, sdo, sdi, sck, cs machine.Pin) *Device {
 	return &Device{
 		trans: &spiTransport{
 			spi: spi,
@@ -29,7 +32,7 @@ func NewSPI(spi *machine.SPI, sdo, sdi, sck, cs machine.Pin) *Device {
 }
 
 type spiTransport struct {
-	spi *machine.SPI
+	spi drivers.SPI
 	sdo machine.Pin
 	sdi machine.Pin
 	sck machine.Pin
@@ -37,31 +40,11 @@ type spiTransport struct {
 }
 
 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,
-		SDI:       tr.sdi,
-		SDO:       tr.sdo,
-		SCK:       tr.sck,
-		LSBFirst:  false,
-		Mode:      0,
-	})
-	return nil
-}
-
 func (tr *spiTransport) supportQuadMode() bool {
 	return false
 }