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embd/host/generic/led.go
Karan Misra c35deeb17c host specific drivers can now be loaded separately
this ensures cleaner abstractions/code and will ensure that the produced
binary is as small as possible. a convenience package is provided to
easily load all hosts easily: "github.com/kidoman/embd/host/all"
2014-04-06 06:50:09 +05:30

114 lines
1.6 KiB
Go

// LED control support.
package generic
import (
"fmt"
"io/ioutil"
"os"
"strings"
"github.com/kidoman/embd"
)
type led struct {
id string
brightness *os.File
initialized bool
}
func NewLED(id string) embd.LED {
return &led{id: id}
}
func (l *led) init() error {
if l.initialized {
return nil
}
var err error
if l.brightness, err = l.brightnessFile(); err != nil {
return err
}
l.initialized = true
return nil
}
func (l *led) brightnessFilePath() string {
return fmt.Sprintf("/sys/class/leds/%v/brightness", l.id)
}
func (l *led) openFile(path string) (*os.File, error) {
return os.OpenFile(path, os.O_RDWR, os.ModeExclusive)
}
func (l *led) brightnessFile() (*os.File, error) {
return l.openFile(l.brightnessFilePath())
}
func (l *led) On() error {
if err := l.init(); err != nil {
return err
}
_, err := l.brightness.WriteString("1")
return err
}
func (l *led) Off() error {
if err := l.init(); err != nil {
return err
}
_, err := l.brightness.WriteString("0")
return err
}
func (l *led) isOn() (bool, error) {
l.brightness.Seek(0, 0)
bytes, err := ioutil.ReadAll(l.brightness)
if err != nil {
return false, err
}
str := string(bytes)
str = strings.TrimSpace(str)
if str == "1" {
return true, nil
}
return false, nil
}
func (l *led) Toggle() error {
if err := l.init(); err != nil {
return err
}
state, err := l.isOn()
if err != nil {
return err
}
if state {
return l.Off()
}
return l.On()
}
func (l *led) Close() error {
if !l.initialized {
return nil
}
if err := l.brightness.Close(); err != nil {
return err
}
l.initialized = false
return nil
}