mirror of https://github.com/kidoman/embd
105 lines
1.7 KiB
Go
105 lines
1.7 KiB
Go
// Analog I/O support on the BBB.
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package bbb
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import (
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"fmt"
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"io/ioutil"
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"os"
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"strconv"
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"strings"
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"github.com/kidoman/embd"
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)
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type analogPin struct {
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id string
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n int
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drv embd.GPIODriver
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val *os.File
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initialized bool
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}
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func newAnalogPin(pd *embd.PinDesc, drv embd.GPIODriver) embd.AnalogPin {
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return &analogPin{id: pd.ID, n: pd.AnalogLogical, drv: drv}
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}
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func (p *analogPin) N() int {
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return p.n
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}
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func (p *analogPin) init() error {
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if p.initialized {
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return nil
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}
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var err error
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if err = p.ensureEnabled(); err != nil {
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return err
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}
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if p.val, err = p.valueFile(); err != nil {
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return err
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}
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p.initialized = true
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return nil
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}
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func (p *analogPin) ensureEnabled() error {
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return ensureFeatureEnabled("cape-bone-iio")
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}
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func (p *analogPin) valueFilePath() (string, error) {
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pattern := fmt.Sprintf("/sys/devices/ocp.*/helper.*/AIN%v", p.n)
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return embd.FindFirstMatchingFile(pattern)
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}
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func (p *analogPin) openFile(path string) (*os.File, error) {
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return os.OpenFile(path, os.O_RDONLY, os.ModeExclusive)
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}
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func (p *analogPin) valueFile() (*os.File, error) {
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path, err := p.valueFilePath()
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if err != nil {
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return nil, err
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}
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return p.openFile(path)
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}
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func (p *analogPin) Read() (int, error) {
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if err := p.init(); err != nil {
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return 0, err
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}
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p.val.Seek(0, 0)
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bytes, err := ioutil.ReadAll(p.val)
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if err != nil {
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return 0, err
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}
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str := string(bytes)
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str = strings.TrimSpace(str)
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return strconv.Atoi(str)
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}
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func (p *analogPin) Close() error {
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if err := p.drv.Unregister(p.id); err != nil {
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return err
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}
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if !p.initialized {
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return nil
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}
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if err := p.val.Close(); err != nil {
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return err
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}
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p.initialized = false
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return nil
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}
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