mirror of https://github.com/kidoman/embd
155 lines
2.5 KiB
Go
155 lines
2.5 KiB
Go
package gpio
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import (
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"fmt"
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"os"
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"strconv"
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"github.com/golang/glog"
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"github.com/kidoman/embd/gpio"
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)
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const (
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Normal int = 1 << iota
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I2C
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UART
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SPI
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GPMC
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LCD
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PWM
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)
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type PinDesc struct {
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N int
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IDs []string
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Caps int
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}
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type PinMap []*PinDesc
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func (m PinMap) Lookup(k interface{}) (*PinDesc, bool) {
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switch key := k.(type) {
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case int:
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for i := range m {
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if m[i].N == key {
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return m[i], true
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}
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}
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case string:
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for i := range m {
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for j := range m[i].IDs {
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if m[i].IDs[j] == key {
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return m[i], true
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}
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}
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}
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}
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return nil, false
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}
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type GPIO struct {
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exporter, unexporter *os.File
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initialized bool
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pinMap PinMap
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initializedPins map[int]*digitalPin
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}
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func New(pinMap PinMap) *GPIO {
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return &GPIO{
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pinMap: pinMap,
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initializedPins: map[int]*digitalPin{},
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}
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}
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func (io *GPIO) init() error {
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if io.initialized {
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return nil
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}
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var err error
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if io.exporter, err = os.OpenFile("/sys/class/gpio/export", os.O_WRONLY, os.ModeExclusive); err != nil {
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return err
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}
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if io.unexporter, err = os.OpenFile("/sys/class/gpio/unexport", os.O_WRONLY, os.ModeExclusive); err != nil {
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return err
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}
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io.initialized = true
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return nil
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}
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func (io *GPIO) lookupKey(key interface{}) (*PinDesc, bool) {
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return io.pinMap.Lookup(key)
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}
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func (io *GPIO) export(n int) error {
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_, err := io.exporter.WriteString(strconv.Itoa(n))
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return err
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}
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func (io *GPIO) unexport(n int) error {
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_, err := io.unexporter.WriteString(strconv.Itoa(n))
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return err
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}
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func (io *GPIO) digitalPin(key interface{}) (*digitalPin, error) {
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pd, found := io.lookupKey(key)
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if !found {
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err := fmt.Errorf("gpio: could not find pin matching %q", key)
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return nil, err
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}
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n := pd.N
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p, ok := io.initializedPins[n]
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if ok {
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return p, nil
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}
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if pd.Caps&Normal == 0 {
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err := fmt.Errorf("gpio: sorry, pin %q cannot be used for GPIO", key)
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return nil, err
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}
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if pd.Caps != Normal {
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glog.Infof("gpio: pin %q is not a dedicated GPIO pin. please refer to the system reference manual for more details", key)
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}
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if err := io.export(n); err != nil {
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return nil, err
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}
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p, err := newDigitalPin(n)
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if err != nil {
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io.unexport(n)
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return nil, err
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}
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io.initializedPins[n] = p
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return p, nil
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}
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func (io *GPIO) DigitalPin(key interface{}) (gpio.DigitalPin, error) {
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if err := io.init(); err != nil {
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return nil, err
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}
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return io.digitalPin(key)
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}
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func (io *GPIO) Close() error {
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for n := range io.initializedPins {
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io.unexport(n)
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}
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io.exporter.Close()
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io.unexporter.Close()
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return nil
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}
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