OneWire bus impl

host/rpi/onewirebus.go

@@ -0,0 +1,192 @@
+// I²C support.
+
+package rpi
+
+import (
+	"fmt"
+	"os"
+	"sync"
+
+	"github.com/golang/glog"
+	"github.com/zlowred/embd"
+	"io/ioutil"
+)
+
+type w1Bus struct {
+	l    byte
+	busMap     map[string]embd.W1Device
+	mu   sync.Mutex
+
+	initialized bool
+}
+
+type w1Device struct {
+	file *os.File
+	addr string
+	mu   sync.Mutex
+
+	initialized bool
+}
+
+func NewW1Bus(l byte) embd.W1Bus {
+	fmt.Println("new w1 bus")
+	return &w1Bus{l: l, busMap: make(map[string]embd.W1Device)}
+}
+
+func (b *w1Bus) init() error {
+	if b.initialized {
+		return nil
+	}
+
+	var err error
+	if  _, err = os.Stat("/sys/bus/w1"); os.IsNotExist(err) {
+		return err
+	}
+
+	glog.V(2).Infof("onewire: bus %v initialized", b.l)
+
+	b.initialized = true
+
+	return nil
+}
+
+func (d *w1Device) init() error {
+	if d.initialized {
+		return nil
+	}
+
+	var err error
+	if d.file, err = os.OpenFile(fmt.Sprintf("/sys/bus/w1/devices/%s/rw", d.addr), os.O_RDWR, os.ModeExclusive); err != nil {
+		return err
+	}
+
+	glog.V(2).Infof("onewire: device %s initialized", d.addr)
+
+	d.initialized = true
+
+	return nil
+}
+
+func (d *w1Device) ReadByte() (byte, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if err := d.init(); err != nil {
+		return 0, err
+	}
+
+	bytes := make([]byte, 1)
+	n, _ := d.file.Read(bytes)
+
+	if n != 1 {
+		return 0, fmt.Errorf("onewire: Unexpected number (%v) of bytes read in ReadByte", n)
+	}
+
+	return bytes[0], nil
+}
+
+func (d *w1Device) WriteByte(value byte) error {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if err := d.init(); err != nil {
+		return err
+	}
+
+	n, err := d.file.Write([]byte{value})
+
+	if n != 1 {
+		err = fmt.Errorf("onewire: Unexpected number (%v) of bytes written in WriteByte", n)
+	}
+
+	return err
+}
+
+func (d *w1Device) WriteBytes(value []byte) error {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if err := d.init(); err != nil {
+		return err
+	}
+
+	for i := range value {
+		n, err := d.file.Write([]byte{value[i]})
+
+		if n != 1 {
+			return fmt.Errorf("onewire: Unexpected number (%v) of bytes written in WriteBytes", n)
+		}
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (d *w1Device) ReadBytes(number int) (value []byte, err error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if err := d.init(); err != nil {
+		return nil, err
+	}
+
+	bytes := make([]byte, number)
+	n, _ := d.file.Read(bytes)
+
+	if n != number {
+		return nil, fmt.Errorf("onewire: Unexpected number (%v) of bytes read in ReadBytes", n)
+	}
+
+	return bytes, nil
+}
+
+func (b *w1Bus) ListDevices() (devices []string, err error) {
+	dir, err := ioutil.ReadDir("/sys/bus/w1/devices/")
+	if err != nil {
+		return nil, err
+	}
+	devs := make([]string, len(dir))
+
+	for index, element := range dir {
+		devs[index] = element.Name()
+	}
+
+	return devs, nil
+}
+
+func (b *w1Bus) Open(address string) (device embd.W1Device, err error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if d, ok := b.busMap[address]; ok {
+		return d, nil
+	}
+
+	d := &w1Device{addr: address}
+	b.busMap[address] = d
+	return d, nil
+}
+
+func (b *w1Bus) Close() error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	for _, b := range b.busMap {
+		b.Close()
+	}
+
+	return nil
+}
+
+func (b *w1Device) Close() error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if !b.initialized {
+		return nil
+	}
+
+	return b.file.Close()
+}