igc: Add support for PTP .getcyclesx64()

Add support for using Timer 1 (i225/i226 have 4 timer registers) as a
free-running clock (the "cycles" clock) in addition to Timer 0 (the
default, "adjustable clock"). The objective is to allow taprio/etf
offloading to coexist with PTP vclocks.

Besides the implementation of .getcyclesx64() for i225/i226, to keep
timestamping working when vclocks are in use, we also need to add
support for TX and RX timestamping using the free running timer, when
the requesting socket is bound to a vclock.

On the RX side, i225/i226 can be configured to store the values of two
timers in the received packet metadata area, so it's a matter of
configuring the right registers and retrieving the right timestamp.

The TX is a bit more involved because the hardware stores a single
timestamp (with the selected timer in the TX descriptor) into one of
the timestamp registers.

Note some changes at how the timestamps are done for RX, the
conversion and adjustment of timestamps are now done closer to the
consumption of the timestamp instead of near the reception.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 31 insertions, 19 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_ptp.c b/drivers/net/ethernet/intel/igc/igc_ptp.c
index 928f38792203..885faaa7b9de 100644
--- a/drivers/net/ethernet/intel/igc/igc_ptp.c
+++ b/drivers/net/ethernet/intel/igc/igc_ptp.c
@@ -459,12 +459,10 @@ static int igc_ptp_systim_to_hwtstamp(struct igc_adapter *adapter,
 /**
  * igc_ptp_rx_pktstamp - Retrieve timestamp from Rx packet buffer
  * @adapter: Pointer to adapter the packet buffer belongs to
- * @buf: Pointer to packet buffer
+ * @buf: Pointer to start of timestamp in HW format (2 32-bit words)
  *
- * This function retrieves the timestamp saved in the beginning of packet
- * buffer. While two timestamps are available, one in timer0 reference and the
- * other in timer1 reference, this function considers only the timestamp in
- * timer0 reference.
+ * This function retrieves and converts the timestamp stored at @buf
+ * to ktime_t, adjusting for hardware latencies.
  *
  * Returns timestamp value.
  */
@@ -474,17 +472,8 @@ ktime_t igc_ptp_rx_pktstamp(struct igc_adapter *adapter, __le32 *buf)
 	u32 secs, nsecs;
 	int adjust;
 
-	/* Timestamps are saved in little endian at the beginning of the packet
-	 * buffer following the layout:
-	 *
-	 * DWORD: | 0              | 1              | 2              | 3              |
-	 * Field: | Timer1 SYSTIML | Timer1 SYSTIMH | Timer0 SYSTIML | Timer0 SYSTIMH |
-	 *
-	 * SYSTIML holds the nanoseconds part while SYSTIMH holds the seconds
-	 * part of the timestamp.
-	 */
-	nsecs = le32_to_cpu(buf[2]);
-	secs = le32_to_cpu(buf[3]);
+	nsecs = le32_to_cpu(buf[0]);
+	secs = le32_to_cpu(buf[1]);
 
 	timestamp = ktime_set(secs, nsecs);
 
@@ -542,10 +531,11 @@ static void igc_ptp_enable_rx_timestamp(struct igc_adapter *adapter)
 
 	for (i = 0; i < adapter->num_rx_queues; i++) {
 		val = rd32(IGC_SRRCTL(i));
-		/* FIXME: For now, only support retrieving RX timestamps from
-		 * timer 0.
+		/* Enable retrieving timestamps from timer 0, the
+		 * "adjustable clock" and timer 1 the "free running
+		 * clock".
 		 */
-		val |= IGC_SRRCTL_TIMER1SEL(0) | IGC_SRRCTL_TIMER0SEL(0) |
+		val |= IGC_SRRCTL_TIMER1SEL(1) | IGC_SRRCTL_TIMER0SEL(0) |
 		       IGC_SRRCTL_TIMESTAMP;
 		wr32(IGC_SRRCTL(i), val);
 	}
@@ -1035,6 +1025,26 @@ static int igc_ptp_getcrosststamp(struct ptp_clock_info *ptp,
 					     adapter, &adapter->snapshot, cts);
 }
 
+static int igc_ptp_getcyclesx64(struct ptp_clock_info *ptp,
+				struct timespec64 *ts,
+				struct ptp_system_timestamp *sts)
+{
+	struct igc_adapter *igc = container_of(ptp, struct igc_adapter, ptp_caps);
+	struct igc_hw *hw = &igc->hw;
+	unsigned long flags;
+
+	spin_lock_irqsave(&igc->free_timer_lock, flags);
+
+	ptp_read_system_prets(sts);
+	ts->tv_nsec = rd32(IGC_SYSTIML_1);
+	ts->tv_sec = rd32(IGC_SYSTIMH_1);
+	ptp_read_system_postts(sts);
+
+	spin_unlock_irqrestore(&igc->free_timer_lock, flags);
+
+	return 0;
+}
+
 /**
  * igc_ptp_init - Initialize PTP functionality
  * @adapter: Board private structure
@@ -1088,6 +1098,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
 		adapter->ptp_caps.adjfine = igc_ptp_adjfine_i225;
 		adapter->ptp_caps.adjtime = igc_ptp_adjtime_i225;
 		adapter->ptp_caps.gettimex64 = igc_ptp_gettimex64_i225;
+		adapter->ptp_caps.getcyclesx64 = igc_ptp_getcyclesx64;
 		adapter->ptp_caps.settime64 = igc_ptp_settime_i225;
 		adapter->ptp_caps.enable = igc_ptp_feature_enable_i225;
 		adapter->ptp_caps.pps = 1;
@@ -1108,6 +1119,7 @@ void igc_ptp_init(struct igc_adapter *adapter)
 	}
 
 	spin_lock_init(&adapter->ptp_tx_lock);
+	spin_lock_init(&adapter->free_timer_lock);
 	spin_lock_init(&adapter->tmreg_lock);
 
 	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;