3 files changed, 29 insertions, 3 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 2d566f3c827b..2e5720d34a16 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -215,6 +215,8 @@ struct igc_adapter {
 	spinlock_t tmreg_lock;
 	struct cyclecounter cc;
 	struct timecounter tc;
+	struct timespec64 prev_ptp_time; /* Pre-reset PTP clock */
+	ktime_t ptp_reset_start; /* Reset time in clock mono */
 };
 
 void igc_up(struct igc_adapter *adapter);
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 7576dbfdac99..1c16cd35c81c 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -3778,6 +3778,8 @@ void igc_down(struct igc_adapter *adapter)
 
 	set_bit(__IGC_DOWN, &adapter->state);
 
+	igc_ptp_suspend(adapter);
+
 	/* disable receives in the hardware */
 	rctl = rd32(IGC_RCTL);
 	wr32(IGC_RCTL, rctl & ~IGC_RCTL_EN);
diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 0300b45b36e2..49abefdab26c 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -8,6 +8,7 @@
 #include <linux/pci.h>
 #include <linux/ptp_classify.h>
 #include <linux/clocksource.h>
+#include <linux/ktime.h>
 
 #define INCVALUE_MASK		0x7fffffff
 #define ISGN			0x80000000
@@ -500,6 +501,9 @@ void igc_ptp_init(struct igc_adapter *adapter)
 	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
 	adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;
 
+	adapter->prev_ptp_time = ktime_to_timespec64(ktime_get_real());
+	adapter->ptp_reset_start = ktime_get();
+
 	adapter->ptp_clock = ptp_clock_register(&adapter->ptp_caps,
 						&adapter->pdev->dev);
 	if (IS_ERR(adapter->ptp_clock)) {
@@ -511,6 +515,24 @@ void igc_ptp_init(struct igc_adapter *adapter)
 	}
 }
 
+static void igc_ptp_time_save(struct igc_adapter *adapter)
+{
+	igc_ptp_read_i225(adapter, &adapter->prev_ptp_time);
+	adapter->ptp_reset_start = ktime_get();
+}
+
+static void igc_ptp_time_restore(struct igc_adapter *adapter)
+{
+	struct timespec64 ts = adapter->prev_ptp_time;
+	ktime_t delta;
+
+	delta = ktime_sub(ktime_get(), adapter->ptp_reset_start);
+
+	timespec64_add_ns(&ts, ktime_to_ns(delta));
+
+	igc_ptp_write_i225(adapter, &ts);
+}
+
 /**
  * igc_ptp_suspend - Disable PTP work items and prepare for suspend
  * @adapter: Board private structure
@@ -527,6 +549,8 @@ void igc_ptp_suspend(struct igc_adapter *adapter)
 	dev_kfree_skb_any(adapter->ptp_tx_skb);
 	adapter->ptp_tx_skb = NULL;
 	clear_bit_unlock(__IGC_PTP_TX_IN_PROGRESS, &adapter->state);
+
+	igc_ptp_time_save(adapter);
 }
 
 /**
@@ -576,9 +600,7 @@ void igc_ptp_reset(struct igc_adapter *adapter)
 
 	/* Re-initialize the timer. */
 	if (hw->mac.type == igc_i225) {
-		struct timespec64 ts64 = ktime_to_timespec64(ktime_get_real());
-
-		igc_ptp_write_i225(adapter, &ts64);
+		igc_ptp_time_restore(adapter);
 	} else {
 		timecounter_init(&adapter->tc, &adapter->cc,
 				 ktime_to_ns(ktime_get_real()));