OCPBUGS-77750: Auto-detect GNSS serial port by NIC

addons/intel/e810.go

@@ -67,6 +67,9 @@ var DpllPins = []*dpll_netlink.PinInfo{}
 
 func OnPTPConfigChangeE810(data *interface{}, nodeProfile *ptpv1.PtpProfile) error {
 	glog.Info("calling onPTPConfigChange for e810 plugin")
+
+	autoDetectGNSSSerialPort(nodeProfile)
+
 	var e810Opts E810Opts
 	var err error
 	var optsByteArray []byte

addons/intel/gnss_detect.go

@@ -0,0 +1,120 @@
+package intel
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/bigkevmcd/go-configparser"
+	"github.com/golang/glog"
+	ptpv1 "github.com/k8snetworkplumbingwg/ptp-operator/api/v1"
+)
+
+const (
+	nmeaSerialPortKey       = "ts2phc.nmea_serialport"
+	ts2phcMasterKey         = "ts2phc.master"
+	gnssDeviceSysfsTemplate = "/sys/class/net/%s/device/gnss"
+)
+
+var knownNonInterfaceSections = map[string]bool{
+	"global": true,
+	"nmea":   true,
+}
+
+// findLeadingInterface parses a ts2phcConf string to determine if auto-detection
+// of the GNSS serial port is needed, and if so, returns the leading interface name.
+//
+// Returns the interface name and true if auto-detection should proceed:
+//   - [nmea] section must be present (T-GM profile)
+//   - ts2phc.nmea_serialport must NOT be already set in [global]
+//   - At least one interface section must exist
+//
+// The leading interface is the one that does NOT have "ts2phc.master 0".
+func findLeadingInterface(ts2phcConf string) (string, bool) {
+	conf, err := configparser.ParseReaderWithOptions(
+		strings.NewReader(ts2phcConf),
+		configparser.Delimiters(" "),
+	)
+	if err != nil {
+		glog.Warningf("failed to parse ts2phcConf: %v", err)
+		return "", false
+	}
+
+	if !conf.HasSection("nmea") {
+		return "", false
+	}
+
+	if serialPort, _ := conf.Get("global", nmeaSerialPortKey); serialPort != "" {
+		glog.Infof("ts2phc.nmea_serialport already set to %q, skipping auto-detection", serialPort)
+		return "", false
+	}
+
+	var candidates []string
+	for _, section := range conf.Sections() {
+		if knownNonInterfaceSections[section] {
+			continue
+		}
+		val, _ := conf.Get(section, ts2phcMasterKey)
+		if val != "0" {
+			candidates = append(candidates, section)
+		}
+	}
+
+	if len(candidates) == 0 {
+		glog.Warning("T-GM profile detected but no leading interface found (all interfaces have ts2phc.master 0)")
+		return "", false
+	}
+	if len(candidates) > 1 {
+		glog.Warningf("multiple interfaces without ts2phc.master 0: %v; using %s", candidates, candidates[0])
+	}
+	return candidates[0], true
+}
+
+// gnssDeviceFromInterface resolves the GNSS device path for a given network interface
+// by reading the sysfs directory /sys/class/net/<iface>/device/gnss/.
+func gnssDeviceFromInterface(iface string) (string, error) {
+	gnssDir := fmt.Sprintf(gnssDeviceSysfsTemplate, iface)
+	entries, err := filesystem.ReadDir(gnssDir)
+	if err != nil {
+		return "", fmt.Errorf("no GNSS device found for interface %s: %w", iface, err)
+	}
+	if len(entries) == 0 {
+		return "", fmt.Errorf("GNSS sysfs directory %s is empty", gnssDir)
+	}
+	if len(entries) > 1 {
+		glog.Warningf("multiple GNSS devices found for %s, using %s", iface, entries[0].Name())
+	}
+	return fmt.Sprintf("/dev/%s", entries[0].Name()), nil
+}
+
+// autoDetectGNSSSerialPort attempts to auto-detect the GNSS serial port
+// from the ts2phcConf and patch it into the node profile if needed.
+func autoDetectGNSSSerialPort(nodeProfile *ptpv1.PtpProfile) {
+	if nodeProfile.Ts2PhcConf == nil {
+		return
+	}
+	leadingIface, found := findLeadingInterface(*nodeProfile.Ts2PhcConf)
+	if !found {
+		return
+	}
+	gnssPath, err := gnssDeviceFromInterface(leadingIface)
+	if err != nil {
+		glog.Warningf("could not auto-detect GNSS device for %s: %v", leadingIface, err)
+		return
+	}
+	glog.Infof("auto-detected GNSS serial port %s from interface %s", gnssPath, leadingIface)
+
+	// Insert into the raw config string to preserve original formatting.
+	// This mirrors how ExtendGlobalSection in config.go modifies the parsed config.
+	setting := fmt.Sprintf("%s %s", nmeaSerialPortKey, gnssPath)
+	lines := strings.Split(*nodeProfile.Ts2PhcConf, "\n")
+	for i, line := range lines {
+		if strings.TrimSpace(line) == "[global]" {
+			result := make([]string, 0, len(lines)+1)
+			result = append(result, lines[:i+1]...)
+			result = append(result, setting)
+			result = append(result, lines[i+1:]...)
+			*nodeProfile.Ts2PhcConf = strings.Join(result, "\n")
+			return
+		}
+	}
+}