ixgbe: Hardware Timestamping + PTP Hardware Clock (PHC)

This patch enables hardware timestamping for use with PTP software by
extracting a ns counter from an arbitrary fixed point cycles counter.
The hardware generates SYSTIME registers using the DMA tick which
changes based on the current link speed. These SYSTIME registers are
converted to ns using the cyclecounter and timecounter structures
provided by the kernel. Using the SO_TIMESTAMPING api, software can
enable and access timestamps for PTP packets.

The SO_TIMESTAMPING API has space for 3 different kinds of timestamps,
SYS, RAW, and SOF. SYS hardware timestamps are hardware ns values that
are then scaled to the software clock. RAW hardware timestamps are the
direct raw value of the ns counter. SOF software timestamps are the
software timestamp calculated as close as possible to the software
transmit, but are not offloaded to the hardware. This patch only
supports the RAW hardware timestamps due to inefficiency of the SYS
design.

This patch also enables the PHC subsystem features for atomically
adjusting the cycle register, and adjusting the clock frequency in
parts per billion. This frequency adjustment works by slightly
adjusting the value added to the cycle registers each DMA tick. This
causes the hardware registers to overflow rapidly (approximately once
every 34 seconds, when at 10gig link). To solve this, the timecounter
structure is used, along with a timer set for every 25 seconds. This
allows for detecting register overflow and converting the cycle
counter registers into ns values needed for providing useful
timestamps to the network stack.

Only the basic required clock functions are supported at this time,
although the hardware supports some ancillary features and these could
easily be enabled in the future.

Note that use of this hardware timestamping requires modifying daemon
software to use the SO_TIMESTAMPING API for timestamps, and the
ptp_clock PHC framework for accessing the clock. The timestamps have
no relation to the system time at all, so software must use the posix
clock generated by the PHC framework instead.

Signed-off-by: Jacob E Keller <jacob.e.keller@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 52 insertions, 1 deletions

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 1693ec3d4046..9a83c4055c5f 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -789,6 +789,13 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
 		total_bytes += tx_buffer->bytecount;
 		total_packets += tx_buffer->gso_segs;
 
+#ifdef CONFIG_IXGBE_PTP
+		if (unlikely(tx_buffer->tx_flags &
+			     IXGBE_TX_FLAGS_TSTAMP))
+			ixgbe_ptp_tx_hwtstamp(q_vector,
+					      tx_buffer->skb);
+
+#endif
 		/* free the skb */
 		dev_kfree_skb_any(tx_buffer->skb);
 
@@ -1389,6 +1396,11 @@ static void ixgbe_process_skb_fields(struct ixgbe_ring *rx_ring,
 
 	ixgbe_rx_checksum(rx_ring, rx_desc, skb);
 
+#ifdef CONFIG_IXGBE_PTP
+	if (ixgbe_test_staterr(rx_desc, IXGBE_RXDADV_STAT_TS))
+		ixgbe_ptp_rx_hwtstamp(rx_ring->q_vector, skb);
+#endif
+
 	if (ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_VP)) {
 		u16 vid = le16_to_cpu(rx_desc->wb.upper.vlan);
 		__vlan_hwaccel_put_tag(skb, vid);
@@ -5387,6 +5399,11 @@ static void ixgbe_watchdog_link_is_up(struct ixgbe_adapter *adapter)
 		flow_rx = false;
 		break;
 	}
+
+#ifdef CONFIG_IXGBE_PTP
+	ixgbe_ptp_start_cyclecounter(adapter);
+#endif
+
 	e_info(drv, "NIC Link is Up %s, Flow Control: %s\n",
 	       (link_speed == IXGBE_LINK_SPEED_10GB_FULL ?
 	       "10 Gbps" :
@@ -5424,6 +5441,10 @@ static void ixgbe_watchdog_link_is_down(struct ixgbe_adapter *adapter)
 	if (ixgbe_is_sfp(hw) && hw->mac.type == ixgbe_mac_82598EB)
 		adapter->flags2 |= IXGBE_FLAG2_SEARCH_FOR_SFP;
 
+#ifdef CONFIG_IXGBE_PTP
+	ixgbe_ptp_start_cyclecounter(adapter);
+#endif
+
 	e_info(drv, "NIC Link is Down\n");
 	netif_carrier_off(netdev);
 }
@@ -5723,6 +5744,9 @@ static void ixgbe_service_task(struct work_struct *work)
 	ixgbe_watchdog_subtask(adapter);
 	ixgbe_fdir_reinit_subtask(adapter);
 	ixgbe_check_hang_subtask(adapter);
+#ifdef CONFIG_IXGBE_PTP
+	ixgbe_ptp_overflow_check(adapter);
+#endif
 
 	ixgbe_service_event_complete(adapter);
 }
@@ -5873,6 +5897,11 @@ static __le32 ixgbe_tx_cmd_type(u32 tx_flags)
 	if (tx_flags & IXGBE_TX_FLAGS_HW_VLAN)
 		cmd_type |= cpu_to_le32(IXGBE_ADVTXD_DCMD_VLE);
 
+#ifdef CONFIG_IXGBE_PTP
+	if (tx_flags & IXGBE_TX_FLAGS_TSTAMP)
+		cmd_type |= cpu_to_le32(IXGBE_ADVTXD_MAC_TSTAMP);
+#endif
+
 	/* set segmentation enable bits for TSO/FSO */
 #ifdef IXGBE_FCOE
 	if (tx_flags & (IXGBE_TX_FLAGS_TSO | IXGBE_TX_FLAGS_FSO))
@@ -6263,6 +6292,13 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
 		tx_flags |= IXGBE_TX_FLAGS_SW_VLAN;
 	}
 
+#ifdef CONFIG_IXGBE_PTP
+	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
+		skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
+		tx_flags |= IXGBE_TX_FLAGS_TSTAMP;
+	}
+#endif
+
 #ifdef CONFIG_PCI_IOV
 	/*
 	 * Use the l2switch_enable flag - would be false if the DMA
@@ -6415,7 +6451,14 @@ static int ixgbe_ioctl(struct net_device *netdev, struct ifreq *req, int cmd)
 {
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
 
-	return mdio_mii_ioctl(&adapter->hw.phy.mdio, if_mii(req), cmd);
+	switch (cmd) {
+#ifdef CONFIG_IXGBE_PTP
+	case SIOCSHWTSTAMP:
+		return ixgbe_ptp_hwtstamp_ioctl(adapter, req, cmd);
+#endif
+	default:
+		return mdio_mii_ioctl(&adapter->hw.phy.mdio, if_mii(req), cmd);
+	}
 }
 
 /**
@@ -7202,6 +7245,10 @@ static int __devinit ixgbe_probe(struct pci_dev *pdev,
 
 	device_set_wakeup_enable(&adapter->pdev->dev, adapter->wol);
 
+#ifdef CONFIG_IXGBE_PTP
+	ixgbe_ptp_init(adapter);
+#endif /* CONFIG_IXGBE_PTP*/
+
 	/* save off EEPROM version number */
 	hw->eeprom.ops.read(hw, 0x2e, &adapter->eeprom_verh);
 	hw->eeprom.ops.read(hw, 0x2d, &adapter->eeprom_verl);
@@ -7330,6 +7377,10 @@ static void __devexit ixgbe_remove(struct pci_dev *pdev)
 	set_bit(__IXGBE_DOWN, &adapter->state);
 	cancel_work_sync(&adapter->service_task);
 
+#ifdef CONFIG_IXGBE_PTP
+	ixgbe_ptp_stop(adapter);
+#endif
+
 #ifdef CONFIG_IXGBE_DCA
 	if (adapter->flags & IXGBE_FLAG_DCA_ENABLED) {
 		adapter->flags &= ~IXGBE_FLAG_DCA_ENABLED;