mirror of https://github.com/kidoman/embd
124 lines
2.7 KiB
Go
124 lines
2.7 KiB
Go
/*
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* Copyright (c) Karan Misra 2014
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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* associated documentation files (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge, publish, distribute,
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* sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all copies or
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* substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
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* NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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// 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/cfreeman/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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