func ensureFeatureEnabled(id string) error {
glog.V(3).Infof("bbb: enabling feature %v", id)
pattern := "/sys/devices/bone_capemgr.*/slots"
file, err := embd.FindFirstMatchingFile(pattern)
if err != nil {
return err
}
bytes, err := ioutil.ReadFile(file)
if err != nil {
return err
}
str := string(bytes)
if strings.Contains(str, id) {
glog.V(3).Infof("bbb: feature %v already enabled", id)
return nil
}
slots, err := os.OpenFile(file, os.O_WRONLY, os.ModeExclusive)
if err != nil {
return err
}
defer slots.Close()
glog.V(3).Infof("bbb: writing %v to slots file", id)
_, err = slots.WriteString(id)
return err
}
// This cannot be currently used to disable things like the
// analog and pwm modules. Removing them from slots file can
// potentially cause a kernel panic and unsettle things. So the
// recommended thing to do is to simply reboot.
func ensureFeatureDisabled(id string) error {
pattern := "/sys/devices/bone_capemgr.*/slots"
file, err := embd.FindFirstMatchingFile(pattern)
if err != nil {
return err
}
slots, err := os.OpenFile(file, os.O_RDWR, os.ModeExclusive)
if err != nil {
return err
}
defer slots.Close()
scanner := bufio.NewScanner(slots)
for scanner.Scan() {
text := scanner.Text()
if !strings.Contains(text, id) {
continue
}
// Extract the id from the line
idx := strings.Index(text, ":")
if idx < 0 {
// Something is off, bail
continue
}
dis := strings.TrimSpace(text[:idx])
slots.Seek(0, 0)
_, err = slots.WriteString("-" + dis)
return err
}
// Could not disable the feature
return fmt.Errorf("embd: could not disable feature %q", id)
}
func (p *analogPin) valueFilePath() (string, error) {
pattern := fmt.Sprintf("/sys/devices/ocp.*/helper.*/AIN%v", p.n)
return embd.FindFirstMatchingFile(pattern)
}
func (p *pwmPin) basePath() (string, error) {
pattern := "/sys/devices/ocp.*/pwm_test_" + p.n + ".*"
return embd.FindFirstMatchingFile(pattern)
}