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embd/gpiogeneric.go

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Go
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package embd
import (
"fmt"
"github.com/golang/glog"
)
const (
CapNormal int = 1 << iota
CapI2C
CapUART
CapSPI
CapGPMC
CapLCD
CapPWM
)
type PinDesc struct {
N int
IDs []string
Caps int
}
type PinMap []*PinDesc
func (m PinMap) Lookup(k interface{}) (*PinDesc, bool) {
switch key := k.(type) {
case int:
for i := range m {
if m[i].N == key {
return m[i], true
}
}
case string:
for i := range m {
for j := range m[i].IDs {
if m[i].IDs[j] == key {
return m[i], true
}
}
}
}
return nil, false
}
type pin interface {
Close() error
}
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type gpioDriver struct {
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pinMap PinMap
initializedPins map[int]pin
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}
func newGPIODriver(pinMap PinMap) *gpioDriver {
return &gpioDriver{
pinMap: pinMap,
initializedPins: map[int]pin{},
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}
}
func (io *gpioDriver) lookupKey(key interface{}) (*PinDesc, bool) {
return io.pinMap.Lookup(key)
}
func (io *gpioDriver) digitalPin(key interface{}) (*digitalPin, error) {
pd, found := io.lookupKey(key)
if !found {
return nil, fmt.Errorf("gpio: could not find pin matching %q", key)
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}
n := pd.N
p, ok := io.initializedPins[n]
if ok {
dp, ok := p.(*digitalPin)
if !ok {
return nil, fmt.Errorf("gpio: sorry, pin %q is already initialized for a different mode", key)
}
return dp, nil
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}
if pd.Caps&CapNormal == 0 {
return nil, fmt.Errorf("gpio: sorry, pin %q cannot be used for digital io", key)
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}
if pd.Caps != CapNormal {
glog.Infof("gpio: pin %q is not a dedicated digital io pin. please refer to the system reference manual for more details", key)
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}
dp := newDigitalPin(n)
io.initializedPins[n] = dp
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return dp, nil
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}
func (io *gpioDriver) DigitalPin(key interface{}) (DigitalPin, error) {
return io.digitalPin(key)
}
func (io *gpioDriver) Close() error {
for _, p := range io.initializedPins {
if err := p.Close(); err != nil {
return err
}
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}
return nil
}