net: gptp: Allow user to tweak priority1 and priority2 values

Instead of hardcoding the priority1 and priority2 values used
in BMCA, let the user tweak the values via Kconfig.

Fixes zephyrproject-rtos#28151

Signed-off-by: Jukka Rissanen <[email protected]>

Author: jukkar

include/net/gptp.h

@@ -34,7 +34,12 @@ extern "C" {
 
 #define GPTP_PRIORITY1_NON_GM_CAPABLE      255
 #define GPTP_PRIORITY1_GM_CAPABLE          248
+
+#if defined(CONFIG_NET_GPTP_BMCA_PRIORITY2)
+#define GPTP_PRIORITY2_DEFAULT             CONFIG_NET_GPTP_BMCA_PRIORITY2
+#else
 #define GPTP_PRIORITY2_DEFAULT             248
+#endif
 
 /** @endcond */
 

subsys/net/l2/ethernet/gptp/Kconfig

@@ -195,6 +195,31 @@ config NET_GPTP_PATH_TRACE_ELEMENTS
 	  Announce message. Each array element takes 8 bytes. If this value
 	  is set to 8, then 8 * 8 = 64 bytes of memory is used.
 
+config NET_GPTP_BMCA_PRIORITY1
+	int "BMCA priority1 value"
+	default 248 if NET_GPTP_GM_CAPABLE
+	default 255
+	range 0 255
+	help
+	  The priority1 attribute of the local clock. It is used in the
+	  Best Master Clock selection Algorithm (BMCA), lower values take
+	  precedence. The default value is 255 if the device is non grand
+	  master capable, and 248 if it is GM capable.
+	  See Chapter 8.6.2.1 of IEEE 802.1AS for a more detailed description
+	  of priority1. Note that if the system	is non GM capable, then the
+	  value 255 is used always and this setting is ignored.
+
+config NET_GPTP_BMCA_PRIORITY2
+	int "BMCA priority2 value"
+	default 248
+	range 0 255
+	help
+	  The priority2 attribute of the local clock. It is used in the BMCA
+	  (Best Master Clock selection Algorithm), lower values take
+	  precedence. The default value is 248.
+	  See Chapter 8.6.2.5 of IEEE 802.1AS for a more detailed description
+	  of priority2.
+
 config NET_GPTP_STATISTICS
 	bool "Collect gPTP statistics"
 	help

subsys/net/l2/ethernet/gptp/gptp.c

@@ -382,7 +382,15 @@ static void gptp_init_clock_ds(void)
 		GPTP_OFFSET_SCALED_LOG_VAR_UNKNOWN;
 
 	if (default_ds->gm_capable) {
-		default_ds->priority1 = GPTP_PRIORITY1_GM_CAPABLE;
+		/* The priority1 value cannot be 255 for GM capable
+		 * system.
+		 */
+		if (CONFIG_NET_GPTP_BMCA_PRIORITY1 ==
+		    GPTP_PRIORITY1_NON_GM_CAPABLE) {
+			default_ds->priority1 = GPTP_PRIORITY1_GM_CAPABLE;
+		} else {
+			default_ds->priority1 = CONFIG_NET_GPTP_BMCA_PRIORITY1;
+		}
 	} else {
 		default_ds->priority1 = GPTP_PRIORITY1_NON_GM_CAPABLE;
 	}