igc: Enable internal i225 PPS

The i225 device can produce one interrupt on the full second, much
like i210 - from where this patch is inspired.

This patch sets up the full second interruption on the i225 and when
receiving it, it sends a PPS event to PTP (Precision Time Protocol)
kernel subsystem.

The PTP subsystem exposes the PPS events via ioctl and sysfs, and one
can use the `testptp` tool (tools/testing/selftests/ptp) to check that
the events are being generated.

Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

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

@@ -223,6 +223,8 @@ struct igc_adapter {
 	char fw_version[32];
 
 	struct bpf_prog *xdp_prog;
+
+	bool pps_sys_wrap_on;
 };
 
 void igc_up(struct igc_adapter *adapter);

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

@@ -4251,9 +4251,17 @@ igc_features_check(struct sk_buff *skb, struct net_device *dev,
 static void igc_tsync_interrupt(struct igc_adapter *adapter)
 {
 	struct igc_hw *hw = &adapter->hw;
+	struct ptp_clock_event event;
 	u32 tsicr = rd32(IGC_TSICR);
 	u32 ack = 0;
 
+	if (tsicr & IGC_TSICR_SYS_WRAP) {
+		event.type = PTP_CLOCK_PPS;
+		if (adapter->ptp_caps.pps)
+			ptp_clock_event(adapter->ptp_clock, &event);
+		ack |= IGC_TSICR_SYS_WRAP;
+	}
+
 	if (tsicr & IGC_TSICR_TXTS) {
 		/* retrieve hardware timestamp */
 		schedule_work(&adapter->ptp_tx_work);

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

@@ -123,6 +123,29 @@ static int igc_ptp_settime_i225(struct ptp_clock_info *ptp,
 static int igc_ptp_feature_enable_i225(struct ptp_clock_info *ptp,
 				       struct ptp_clock_request *rq, int on)
 {
+	struct igc_adapter *igc =
+		container_of(ptp, struct igc_adapter, ptp_caps);
+	struct igc_hw *hw = &igc->hw;
+	unsigned long flags;
+	u32 tsim;
+
+	switch (rq->type) {
+	case PTP_CLK_REQ_PPS:
+		spin_lock_irqsave(&igc->tmreg_lock, flags);
+		tsim = rd32(IGC_TSIM);
+		if (on)
+			tsim |= IGC_TSICR_SYS_WRAP;
+		else
+			tsim &= ~IGC_TSICR_SYS_WRAP;
+		igc->pps_sys_wrap_on = on;
+		wr32(IGC_TSIM, tsim);
+		spin_unlock_irqrestore(&igc->tmreg_lock, flags);
+		return 0;
+
+	default:
+		break;
+	}
+
 	return -EOPNOTSUPP;
 }
 
@@ -497,6 +520,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
 		adapter->ptp_caps.gettimex64 = igc_ptp_gettimex64_i225;
 		adapter->ptp_caps.settime64 = igc_ptp_settime_i225;
 		adapter->ptp_caps.enable = igc_ptp_feature_enable_i225;
+		adapter->ptp_caps.pps = 1;
 		break;
 	default:
 		adapter->ptp_clock = NULL;
@@ -598,7 +622,9 @@ void igc_ptp_reset(struct igc_adapter *adapter)
 	case igc_i225:
 		wr32(IGC_TSAUXC, 0x0);
 		wr32(IGC_TSSDP, 0x0);
-		wr32(IGC_TSIM, IGC_TSICR_INTERRUPTS);
+		wr32(IGC_TSIM,
+		     IGC_TSICR_INTERRUPTS |
+		     (adapter->pps_sys_wrap_on ? IGC_TSICR_SYS_WRAP : 0));
 		wr32(IGC_IMS, IGC_IMS_TS);
 		break;
 	default: