net: fec: Restart PPS after link state change

On link state change, the controller gets reset,
causing PPS to drop out. Re-enable PPS if it was
enabled before the controller reset.

Fixes: 6605b73 ("FEC: Add time stamping code and a PTP hardware clock")
Signed-off-by: Csókás, Bence <csokas.bence@prolan.hu>
Link: https://patch.msgid.link/20240924093705.2897329-1-csokas.bence@prolan.hu
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/freescale/fec.h

@@ -691,10 +691,16 @@ struct fec_enet_private {
 	/* XDP BPF Program */
 	struct bpf_prog *xdp_prog;
 
+	struct {
+		int pps_enable;
+	} ptp_saved_state;
+
 	u64 ethtool_stats[];
 };
 
 void fec_ptp_init(struct platform_device *pdev, int irq_idx);
+void fec_ptp_restore_state(struct fec_enet_private *fep);
+void fec_ptp_save_state(struct fec_enet_private *fep);
 void fec_ptp_stop(struct platform_device *pdev);
 void fec_ptp_start_cyclecounter(struct net_device *ndev);
 int fec_ptp_set(struct net_device *ndev, struct kernel_hwtstamp_config *config,

drivers/net/ethernet/freescale/fec_main.c

@@ -1077,6 +1077,8 @@ fec_restart(struct net_device *ndev)
 	u32 rcntl = OPT_FRAME_SIZE | 0x04;
 	u32 ecntl = FEC_ECR_ETHEREN;
 
+	fec_ptp_save_state(fep);
+
 	/* Whack a reset.  We should wait for this.
 	 * For i.MX6SX SOC, enet use AXI bus, we use disable MAC
 	 * instead of reset MAC itself.
@@ -1244,8 +1246,10 @@ fec_restart(struct net_device *ndev)
 	writel(ecntl, fep->hwp + FEC_ECNTRL);
 	fec_enet_active_rxring(ndev);
 
-	if (fep->bufdesc_ex)
+	if (fep->bufdesc_ex) {
 		fec_ptp_start_cyclecounter(ndev);
+		fec_ptp_restore_state(fep);
+	}
 
 	/* Enable interrupts we wish to service */
 	if (fep->link)
@@ -1336,6 +1340,8 @@ fec_stop(struct net_device *ndev)
 			netdev_err(ndev, "Graceful transmit stop did not complete!\n");
 	}
 
+	fec_ptp_save_state(fep);
+
 	/* Whack a reset.  We should wait for this.
 	 * For i.MX6SX SOC, enet use AXI bus, we use disable MAC
 	 * instead of reset MAC itself.
@@ -1366,6 +1372,9 @@ fec_stop(struct net_device *ndev)
 		val = readl(fep->hwp + FEC_ECNTRL);
 		val |= FEC_ECR_EN1588;
 		writel(val, fep->hwp + FEC_ECNTRL);
+
+		fec_ptp_start_cyclecounter(ndev);
+		fec_ptp_restore_state(fep);
 	}
 }
 

drivers/net/ethernet/freescale/fec_ptp.c

@@ -764,6 +764,36 @@ void fec_ptp_init(struct platform_device *pdev, int irq_idx)
 	schedule_delayed_work(&fep->time_keep, HZ);
 }
 
+void fec_ptp_save_state(struct fec_enet_private *fep)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&fep->tmreg_lock, flags);
+
+	fep->ptp_saved_state.pps_enable = fep->pps_enable;
+
+	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
+}
+
+/* Restore PTP functionality after a reset */
+void fec_ptp_restore_state(struct fec_enet_private *fep)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&fep->tmreg_lock, flags);
+
+	/* Reset turned it off, so adjust our status flag */
+	fep->pps_enable = 0;
+
+	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
+
+	/* Restart PPS if needed */
+	if (fep->ptp_saved_state.pps_enable) {
+		/* Re-enable PPS */
+		fec_ptp_enable_pps(fep, 1);
+	}
+}
+
 void fec_ptp_stop(struct platform_device *pdev)
 {
 	struct net_device *ndev = platform_get_drvdata(pdev);