[PATCH 2/2] net: fec: Reload PTP registers after link-state change

["Csókás, Bence" <csokas.bence@prolan.hu>]

On link-state change, the controller gets reset,
which clears all PTP registers, including PHC time,
calibrated clock correction values etc. For correct
IEEE 1588 operation we need to restore these after
the reset.

Signed-off-by: Csókás, Bence <csokas.bence@prolan.hu>
---
 drivers/net/ethernet/freescale/fec.h      |  7 +++++
 drivers/net/ethernet/freescale/fec_main.c |  4 +++
 drivers/net/ethernet/freescale/fec_ptp.c  | 35 +++++++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/drivers/net/ethernet/freescale/fec.h b/drivers/net/ethernet/freescale/fec.h
index afa0bfb974e6..efe770fe337d 100644
--- a/drivers/net/ethernet/freescale/fec.h
+++ b/drivers/net/ethernet/freescale/fec.h
@@ -691,11 +691,18 @@ struct fec_enet_private {
 	/* XDP BPF Program */
 	struct bpf_prog *xdp_prog;
 
+	struct {
+		u64 ns_sys, ns_phc;
+		u32 at_corr;
+		u8 at_inc_corr;
+	} 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,
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 531b51091e7d..570f8a14d975 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/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.
@@ -1338,6 +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.
diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
index c5b89352373a..8011a6f3c4be 100644
--- a/drivers/net/ethernet/freescale/fec_ptp.c
+++ b/drivers/net/ethernet/freescale/fec_ptp.c
@@ -770,9 +770,44 @@ 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;
+	u32 atime_inc_corr;
+
+	spin_lock_irqsave(&fep->tmreg_lock, flags);
+
+	fep->ptp_saved_state.ns_phc = timecounter_read(&fep->tc);
+	fep->ptp_saved_state.ns_sys = ktime_get_ns();
+
+	fep->ptp_saved_state.at_corr = readl(fep->hwp + FEC_ATIME_CORR);
+	atime_inc_corr = readl(fep->hwp + FEC_ATIME_INC) & FEC_T_INC_CORR_MASK;
+	fep->ptp_saved_state.at_inc_corr = (u8)(atime_inc_corr >> FEC_T_INC_CORR_OFFSET);
+
+	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
+}
+
 /* Restore PTP functionality after a reset */
 void fec_ptp_restore_state(struct fec_enet_private *fep)
 {
+	u32 atime_inc = readl(fep->hwp + FEC_ATIME_INC) & FEC_T_INC_MASK;
+	unsigned long flags;
+	u32 counter;
+	u64 ns;
+
+	spin_lock_irqsave(&fep->tmreg_lock, flags);
+
+	writel(fep->ptp_saved_state.at_corr, fep->hwp + FEC_ATIME_CORR);
+	atime_inc |= ((u32)fep->ptp_saved_state.at_inc_corr) << FEC_T_INC_CORR_OFFSET;
+	writel(atime_inc, fep->hwp + FEC_ATIME_INC);
+
+	ns = ktime_get_ns() - fep->ptp_saved_state.ns_sys + fep->ptp_saved_state.ns_phc;
+	counter = ns & fep->cc.mask;
+	writel(counter, fep->hwp + FEC_ATIME);
+	timecounter_init(&fep->tc, &fep->cc, ns);
+
+	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
+
 	/* Restart PPS if needed */
 	if (fep->pps_enable) {
 		/* Reset turned it off, so adjust our status flag */
-- 
2.34.1