initial commit: geekworm x1208 ups prometheus exporter

2026-04-17 20:30:34 +02:00
commit aae6cee886
11 changed files with 389 additions and 0 deletions
@@ -0,0 +1,181 @@
+package main
+
+import (
+	"encoding/binary"
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/warthog618/go-gpiocdev"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	i2cDev      = "/dev/i2c-1"
+	gpioChip    = "gpiochip0"
+	gpioPLDPin  = 6
+	maxAddr     = 0x36
+	regVoltage  = 0x02
+	regCapacity = 0x04
+	i2cSlave    = 0x0703 // I2C_SLAVE
+	maxRetries  = 3
+)
+
+func readI2CWord(fd int, reg byte) (uint16, error) {
+	if _, err := unix.Write(fd, []byte{reg}); err != nil {
+		return 0, fmt.Errorf("write reg: %w", err)
+	}
+	buf := make([]byte, 2)
+	n, err := unix.Read(fd, buf)
+	if err != nil {
+		return 0, fmt.Errorf("read: %w", err)
+	}
+	if n != 2 {
+		return 0, fmt.Errorf("short read: %d bytes", n)
+	}
+	return binary.BigEndian.Uint16(buf), nil
+}
+
+func readI2CWordRetry(fd int, reg byte, validate func(uint16) bool) (uint16, error) {
+	var lastErr error
+	for i := 0; i < maxRetries; i++ {
+		v, err := readI2CWord(fd, reg)
+		if err == nil && validate(v) {
+			return v, nil
+		}
+		if err != nil {
+			lastErr = err
+		} else {
+			lastErr = fmt.Errorf("read out of range: 0x%04x", v)
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	return 0, lastErr
+}
+
+func readBattery() (voltage float64, percent float64, err error) {
+	fd, err := unix.Open(i2cDev, unix.O_RDWR, 0)
+	if err != nil {
+		return 0, 0, fmt.Errorf("open %s: %w", i2cDev, err)
+	}
+	defer unix.Close(fd)
+
+	if err := unix.IoctlSetInt(fd, i2cSlave, maxAddr); err != nil {
+		return 0, 0, fmt.Errorf("ioctl I2C_SLAVE: %w", err)
+	}
+
+	rawV, err := readI2CWordRetry(fd, regVoltage, func(v uint16) bool {
+		f := float64(v) * 1.25 / 1000 / 16
+		return f > 2.0 && f < 5.0
+	})
+	if err != nil {
+		return 0, 0, fmt.Errorf("voltage: %w", err)
+	}
+	voltage = float64(rawV) * 1.25 / 1000 / 16
+
+	rawC, err := readI2CWordRetry(fd, regCapacity, func(v uint16) bool {
+		return float64(v)/256 <= 110
+	})
+	if err != nil {
+		return 0, 0, fmt.Errorf("capacity: %w", err)
+	}
+	percent = float64(rawC) / 256
+	return voltage, percent, nil
+}
+
+func readACPower() (int, error) {
+	line, err := gpiocdev.RequestLine(gpioChip, gpioPLDPin,
+		gpiocdev.AsInput,
+		gpiocdev.WithConsumer("x1208-exporter"))
+	if err != nil {
+		return 0, fmt.Errorf("request gpio: %w", err)
+	}
+	defer line.Close()
+
+	v, err := line.Value()
+	if err != nil {
+		return 0, fmt.Errorf("read gpio: %w", err)
+	}
+	return v, nil
+}
+
+func writeAtomic(path string, content string) error {
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return err
+	}
+	tmp, err := os.CreateTemp(dir, ".x1208.*.tmp")
+	if err != nil {
+		return err
+	}
+	tmpPath := tmp.Name()
+	defer os.Remove(tmpPath)
+	if _, err := tmp.WriteString(content); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Chmod(0o644); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	return os.Rename(tmpPath, path)
+}
+
+func main() {
+	out := flag.String("out", "/var/lib/node-exporter/textfiles/x1208.prom", "output prom file")
+	flag.Parse()
+
+	var (
+		ac           int
+		voltage      float64
+		percent      float64
+		acErr, batErr error
+	)
+
+	ac, acErr = readACPower()
+	voltage, percent, batErr = readBattery()
+
+	if acErr != nil && batErr != nil {
+		fmt.Fprintf(os.Stderr, "all reads failed: ac=%v bat=%v\n", acErr, batErr)
+		os.Exit(1)
+	}
+
+	now := time.Now().Unix()
+	var content string
+	content += "# HELP rpi_ups_last_update_seconds Unix timestamp of last successful exporter run.\n"
+	content += "# TYPE rpi_ups_last_update_seconds gauge\n"
+	content += fmt.Sprintf("rpi_ups_last_update_seconds %d\n", now)
+
+	if acErr == nil {
+		content += "# HELP rpi_ups_ac_power AC adapter present (1=plugged in, 0=on battery).\n"
+		content += "# TYPE rpi_ups_ac_power gauge\n"
+		content += fmt.Sprintf("rpi_ups_ac_power %d\n", ac)
+	} else {
+		fmt.Fprintf(os.Stderr, "ac read failed: %v\n", acErr)
+	}
+
+	if batErr == nil {
+		content += "# HELP rpi_ups_voltage_volts Battery cell voltage from MAX17040 fuel gauge.\n"
+		content += "# TYPE rpi_ups_voltage_volts gauge\n"
+		content += fmt.Sprintf("rpi_ups_voltage_volts %.3f\n", voltage)
+		content += "# HELP rpi_ups_battery_percent Battery state of charge from MAX17040 fuel gauge.\n"
+		content += "# TYPE rpi_ups_battery_percent gauge\n"
+		content += fmt.Sprintf("rpi_ups_battery_percent %.2f\n", percent)
+	} else {
+		fmt.Fprintf(os.Stderr, "battery read failed: %v\n", batErr)
+	}
+
+	if err := writeAtomic(*out, content); err != nil {
+		fmt.Fprintf(os.Stderr, "write %s: %v\n", *out, err)
+		os.Exit(1)
+	}
+
+	if acErr != nil || batErr != nil {
+		os.Exit(1)
+	}
+}