igc: Fix PPS delta between two synchronized end-points

This patch fix the pulse per second output delta between
two synchronized end-points.

Based on Intel Discrete I225 Software User Manual Section
4.2.15 TimeSync Auxiliary Control Register, ST0[Bit 4] and
ST1[Bit 7] must be set to ensure that clock output will be
toggles based on frequency value defined. This is to ensure
that output of the PPS is aligned with the clock.

How to test:

1) Running time synchronization on both end points.
Ex: ptp4l --step_threshold=1 -m -f gPTP.cfg -i <interface name>

2) Configure PPS output using below command for both end-points
Ex: SDP0 on I225 REV4 SKU variant

./testptp -d /dev/ptp0 -L 0,2
./testptp -d /dev/ptp0 -p 1000000000

3) Measure the output using analyzer for both end-points

Fixes: 87938851 ("igc: enable auxiliary PHC functions for the i225")
Signed-off-by: Christopher S Hall <christopher.s.hall@intel.com>
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igc/igc_defines.h

@@ -475,7 +475,9 @@
 #define IGC_TSAUXC_EN_TT0	BIT(0)  /* Enable target time 0. */
 #define IGC_TSAUXC_EN_TT1	BIT(1)  /* Enable target time 1. */
 #define IGC_TSAUXC_EN_CLK0	BIT(2)  /* Enable Configurable Frequency Clock 0. */
+#define IGC_TSAUXC_ST0		BIT(4)  /* Start Clock 0 Toggle on Target Time 0. */
 #define IGC_TSAUXC_EN_CLK1	BIT(5)  /* Enable Configurable Frequency Clock 1. */
+#define IGC_TSAUXC_ST1		BIT(7)  /* Start Clock 1 Toggle on Target Time 1. */
 #define IGC_TSAUXC_EN_TS0	BIT(8)  /* Enable hardware timestamp 0. */
 #define IGC_TSAUXC_AUTT0	BIT(9)  /* Auxiliary Timestamp Taken. */
 #define IGC_TSAUXC_EN_TS1	BIT(10) /* Enable hardware timestamp 0. */

drivers/net/ethernet/intel/igc/igc_ptp.c

@@ -322,7 +322,7 @@ static int igc_ptp_feature_enable_i225(struct ptp_clock_info *ptp,
 		ts = ns_to_timespec64(ns);
 		if (rq->perout.index == 1) {
 			if (use_freq) {
-				tsauxc_mask = IGC_TSAUXC_EN_CLK1;
+				tsauxc_mask = IGC_TSAUXC_EN_CLK1 | IGC_TSAUXC_ST1;
 				tsim_mask = 0;
 			} else {
 				tsauxc_mask = IGC_TSAUXC_EN_TT1;
@@ -333,7 +333,7 @@ static int igc_ptp_feature_enable_i225(struct ptp_clock_info *ptp,
 			freqout = IGC_FREQOUT1;
 		} else {
 			if (use_freq) {
-				tsauxc_mask = IGC_TSAUXC_EN_CLK0;
+				tsauxc_mask = IGC_TSAUXC_EN_CLK0 | IGC_TSAUXC_ST0;
 				tsim_mask = 0;
 			} else {
 				tsauxc_mask = IGC_TSAUXC_EN_TT0;
@@ -347,10 +347,12 @@ static int igc_ptp_feature_enable_i225(struct ptp_clock_info *ptp,
 		tsauxc = rd32(IGC_TSAUXC);
 		tsim = rd32(IGC_TSIM);
 		if (rq->perout.index == 1) {
-			tsauxc &= ~(IGC_TSAUXC_EN_TT1 | IGC_TSAUXC_EN_CLK1);
+			tsauxc &= ~(IGC_TSAUXC_EN_TT1 | IGC_TSAUXC_EN_CLK1 |
+				    IGC_TSAUXC_ST1);
 			tsim &= ~IGC_TSICR_TT1;
 		} else {
-			tsauxc &= ~(IGC_TSAUXC_EN_TT0 | IGC_TSAUXC_EN_CLK0);
+			tsauxc &= ~(IGC_TSAUXC_EN_TT0 | IGC_TSAUXC_EN_CLK0 |
+				    IGC_TSAUXC_ST0);
 			tsim &= ~IGC_TSICR_TT0;
 		}
 		if (on) {