Pin HAL to break dependency of drivers from TinyGo's machine package

rpio/spi.go

@@ -0,0 +1,30 @@
+package rpio // import "tinygo.org/x/drivers/rpio"
+
+import go_rpio "github.com/stianeikeland/go-rpio/v4"
+
+type SPI struct {
+}
+
+func NewSPI() (s *SPI) {
+	if err := go_rpio.SpiBegin(go_rpio.Spi0); err != nil {
+		panic(err)
+	}
+	go_rpio.SpiSpeed(25_000_000) // 25 MHz
+	go_rpio.SpiChipSelect(0)
+	return &SPI{}
+}
+
+func (s *SPI) Tx(w, r []byte) error {
+	data := make([]byte, len(w))
+	copy(data, w)
+	go_rpio.SpiExchange(data)
+	copy(r, data)
+	return nil
+}
+
+func (s *SPI) Transfer(b byte) (byte, error) {
+	w := []byte{b}
+	r := make([]byte, len(w))
+	err := s.Tx(w, r)
+	return r[0], err
+}