Add debug log ring buffer with timestamps, log CLI subcommand

cmd/picomap/main.go

@@ -29,10 +29,12 @@ func main() {
 		err = cmdInfo()
 	case "load":
 		err = cmdLoad(args)
+	case "log":
+		err = cmdLog(args)
 	case "test":
 		err = cmdTest(args)
 	default:
-		slog.Error("unknown command", "cmd", cmd)
+		slog.Error("usage: picomap <info|load|log|test> [args...]")
 		os.Exit(1)
 	}
 	if err != nil {
@@ -128,6 +130,38 @@ func buildFirmware(buildDir string) error {
 	return nil
 }
 
+func cmdLog(_ []string) error {
+	devs, err := client.ListSerial()
+	if err != nil {
+		return err
+	}
+	if len(devs) == 0 {
+		return fmt.Errorf("no devices found")
+	}
+	for _, dev := range devs {
+		log := slog.With("dev", dev)
+		c, err := client.NewSerial(dev, 2*time.Second)
+		if err != nil {
+			log.Error("connect error", "err", err)
+			continue
+		}
+		resp, err := c.Log()
+		c.Close()
+		if err != nil {
+			log.Error("log error", "err", err)
+			continue
+		}
+		if len(resp.Entries) == 0 {
+			log.Info("no debug messages")
+			continue
+		}
+		for _, e := range resp.Entries {
+			log.Info("dlog", "t_us", e.TimestampUS, "msg", e.Message)
+		}
+	}
+	return nil
+}
+
 func cmdLoad(args []string) error {
 	target := "all"
 	if len(args) > 0 {