add regmap package to facilitate heapless driver development (#768)

Author: soypat

internal/regmap/devices.go

@@ -0,0 +1,121 @@
+package regmap
+
+import (
+	"encoding/binary"
+	"io"
+
+	"tinygo.org/x/drivers"
+)
+
+// Device8 implements common logic to most 8-bit peripherals with an I2C or SPI bus.
+type Device8 struct {
+	buf [10]byte
+}
+
+// clear zeroes Device8's buffers.
+func (d *Device8) clear() {
+	d.buf = [10]byte{}
+}
+
+// I2C methods.
+
+func (d *Device8) Read8I2C(bus drivers.I2C, i2cAddr uint16, addr uint8) (byte, error) {
+	d.buf[0] = addr
+	err := bus.Tx(i2cAddr, d.buf[0:1], d.buf[1:2])
+	return d.buf[1], err
+}
+
+func (d *Device8) Read16I2C(bus drivers.I2C, i2cAddr uint16, addr uint8, order binary.ByteOrder) (uint16, error) {
+	d.buf[0] = addr
+	err := bus.Tx(i2cAddr, d.buf[0:1], d.buf[1:3])
+	return order.Uint16(d.buf[1:3]), err
+}
+
+func (d *Device8) Read32I2C(bus drivers.I2C, i2cAddr uint16, addr uint8, order binary.ByteOrder) (uint32, error) {
+	d.buf[0] = addr
+	err := bus.Tx(i2cAddr, d.buf[0:1], d.buf[1:5])
+	return order.Uint32(d.buf[1:5]), err
+}
+
+func (d *Device8) ReadDataI2C(bus drivers.I2C, i2cAddr uint16, addr uint8, dataDestination []byte) error {
+	d.buf[0] = addr
+	return bus.Tx(i2cAddr, d.buf[:1], dataDestination)
+}
+
+func (d *Device8) Write8I2C(bus drivers.I2C, i2cAddr uint16, addr, value uint8) error {
+	d.buf[0] = addr
+	d.buf[1] = value
+	return bus.Tx(i2cAddr, d.buf[:2], nil)
+}
+
+func (d *Device8) Write16I2C(bus drivers.I2C, i2cAddr uint16, addr uint8, value uint16, order binary.ByteOrder) error {
+	d.buf[0] = addr
+	order.PutUint16(d.buf[1:3], value)
+	return bus.Tx(i2cAddr, d.buf[0:3], nil)
+}
+
+func (d *Device8) Write32I2C(bus drivers.I2C, i2cAddr uint16, addr uint8, value uint32, order binary.ByteOrder) error {
+	d.buf[0] = addr
+	order.PutUint32(d.buf[1:5], value)
+	return bus.Tx(i2cAddr, d.buf[0:5], nil)
+}
+
+// SPI methods.
+
+func (d *Device8) Read8SPI(bus drivers.SPI, addr uint8) (byte, error) {
+	d.clear()
+	d.buf[0] = addr
+	err := bus.Tx(d.buf[0:1], d.buf[1:2]) // We suppose data is returned after first byte in SPI.
+	return d.buf[1], err
+}
+
+func (d *Device8) Read16SPI(bus drivers.SPI, addr uint8, order binary.ByteOrder) (uint16, error) {
+	d.clear()
+	d.buf[0] = addr
+	err := bus.Tx(d.buf[0:3], d.buf[3:6]) // We suppose data is returned after first byte in SPI.
+	return order.Uint16(d.buf[4:6]), err
+}
+
+func (d *Device8) Read32SPI(bus drivers.SPI, addr uint8, order binary.ByteOrder) (uint32, error) {
+	d.clear()
+	d.buf[0] = addr
+	err := bus.Tx(d.buf[0:5], d.buf[5:10]) // We suppose data is returned after first byte in SPI.
+	return order.Uint32(d.buf[6:10]), err
+}
+
+// ReadDataSPI reads data from a 8bit device address. It assumes data at register address is sent back
+// from device after first byte is written as address.
+// It needs the auxiliary buffer length to be large enough to contain both the write and read portions of buffer,
+// so 2*(dataLength+1) < len(auxiliaryBuf) must hold.
+func (d *Device8) ReadDataSPI(bus drivers.SPI, addr uint8, dataLength int, auxiliaryBuf []byte) ([]byte, error) {
+	split := len(auxiliaryBuf) / 2
+	if split < dataLength+1 {
+		return nil, io.ErrShortBuffer
+	}
+
+	wbuf, rbuf := auxiliaryBuf[:split], auxiliaryBuf[split:]
+	wbuf[0] = addr
+	err := bus.Tx(wbuf, rbuf)
+	return rbuf[1:], err
+}
+
+func (d *Device8) Write8SPI(bus drivers.SPI, addr, value uint8) error {
+	d.clear()
+	d.buf[0] = addr
+	d.buf[1] = value
+	return bus.Tx(d.buf[:2], nil)
+}
+
+func (d *Device8) Write16SPI(bus drivers.SPI, addr uint8, value uint16, order binary.ByteOrder) error {
+	d.clear()
+	d.buf[0] = addr
+	order.PutUint16(d.buf[1:3], value)
+	return bus.Tx(d.buf[:3], nil)
+}
+
+func (d *Device8) Write32SPI(bus drivers.SPI, addr uint8, value uint32, order binary.ByteOrder) error {
+	d.clear()
+	d.buf[0] = addr
+	order.PutUint32(d.buf[1:5], value)
+	return bus.Tx(d.buf[:5], nil)
+}