mokhtar
e4c34784c8
the oneshot+timer produced 8367 journal lines a day of systemd start/stop noise. now Type=notify with an internal ticker, logging transitions only. hardware sits behind sensor.Sensor; internal/monitor is pure, so the shutdown state machine is tested without a pi. four guards, each tested, because a false poweroff of a box with no physical access is worse than a missed one: - a failed read resets the arming window rather than pausing it - voltage must actually fall across the window, else it is a stuck sensor. this is the only defence against the ac line reading 0 while mains is connected, so it is load-bearing - a settle period stops a restart loop acting on early readings - flapping ac cannot accumulate verified on hardware 2026-08-09: after poweroff on battery the x1208 starts the pi again when mains returns, with no button press. that was the risk that could have made this feature unsafe. a failed tick rewrites the previous sample with sensor_healthy 0 and the failure counter, so last_update still freezes for the staleness alert while the failure stays visible. module path moved to git.mial.net. debian units and the compose overlay deleted; deployment lives in the infra repo.
87 lines
2.0 KiB
Go
87 lines
2.0 KiB
Go
// Package pld reads the X1208 power-loss-detect line.
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//
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// The HAT drives GPIO 6 high while mains power is present and low while the
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// Pi runs on cells.
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package pld
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import (
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"fmt"
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"github.com/warthog618/go-gpiocdev"
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)
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const (
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// DefaultChip is addressed by name, not by /dev path, so this does not
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// depend on any distribution-specific symlink.
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DefaultChip = "gpiochip0"
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// DefaultLine is the power-loss-detect line on the X1208.
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DefaultLine = 6
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consumer = "x1208-exporter"
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)
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// Line holds the GPIO request open across reads. The kernel grants the request
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// exclusively, so reacquiring it per read risks EBUSY against our own
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// not-yet-released handle.
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type Line struct {
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chip string
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offset int
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line *gpiocdev.Line
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}
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// New returns a Line that has not yet been requested. The first Read requests it.
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func New(chip string, offset int) *Line {
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if chip == "" {
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chip = DefaultChip
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}
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return &Line{chip: chip, offset: offset}
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}
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func (l *Line) ensureOpen() error {
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if l.line != nil {
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return nil
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}
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line, err := gpiocdev.RequestLine(l.chip, l.offset,
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gpiocdev.AsInput,
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gpiocdev.WithConsumer(consumer))
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if err != nil {
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return fmt.Errorf("request %s line %d: %w", l.chip, l.offset, err)
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}
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l.line = line
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return nil
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}
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// Close releases the line. It is safe to call more than once.
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func (l *Line) Close() error {
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if l.line == nil {
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return nil
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}
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line := l.line
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l.line = nil
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return line.Close()
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}
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// Read reports whether mains power is present.
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//
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// On error the line is released so the next Read requests a fresh one.
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//
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// A read that succeeds is not proof that the value is meaningful: a floating
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// or misconfigured line returns 0 with no error. Callers that act on "no AC"
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// must corroborate it, not trust this alone.
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func (l *Line) Read() (acPresent bool, err error) {
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if err := l.ensureOpen(); err != nil {
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return false, err
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}
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defer func() {
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if err != nil {
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_ = l.Close()
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}
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}()
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v, err := l.line.Value()
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if err != nil {
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return false, fmt.Errorf("read %s line %d: %w", l.chip, l.offset, err)
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}
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return v != 0, nil
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}
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