net/mlx5e: Add PTP Hardware Clock (PHC) support

Add a PHC support to the mlx5_en driver. Use reader/writer spinlocks to
protect the timecounter since every packet received needs to call
timecounter_cycle2time() when timestamping is enabled.  This can become
a performance bottleneck with RSS and multiple receive queues if normal
spinlocks are used.

The driver has been tested with both Documentation/ptp/testptp and the
linuxptp project (http://linuxptp.sourceforge.net/) on a Mellanox
ConnectX-4 card.
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/Kconfig

@@ -13,6 +13,7 @@ config MLX5_CORE
 config MLX5_CORE_EN
 	bool "Mellanox Technologies ConnectX-4 Ethernet support"
 	depends on NETDEVICES && ETHERNET && PCI && MLX5_CORE
+	select PTP_1588_CLOCK
 	default n
 	---help---
 	  Ethernet support in Mellanox Technologies ConnectX-4 NIC.

drivers/net/ethernet/mellanox/mlx5/core/en.h

@@ -34,6 +34,7 @@
 #include <linux/etherdevice.h>
 #include <linux/timecounter.h>
 #include <linux/net_tstamp.h>
+#include <linux/ptp_clock_kernel.h>
 #include <linux/mlx5/driver.h>
 #include <linux/mlx5/qp.h>
 #include <linux/mlx5/cq.h>
@@ -295,6 +296,8 @@ struct mlx5e_tstamp {
 	unsigned long              overflow_period;
 	struct delayed_work        overflow_work;
 	struct mlx5_core_dev      *mdev;
+	struct ptp_clock          *ptp;
+	struct ptp_clock_info      ptp_info;
 };
 
 enum {

drivers/net/ethernet/mellanox/mlx5/core/en_clock.c

@@ -130,6 +130,89 @@ int mlx5e_hwstamp_get(struct net_device *dev, struct ifreq *ifr)
 	return copy_to_user(ifr->ifr_data, cfg, sizeof(*cfg)) ? -EFAULT : 0;
 }
 
+static int mlx5e_ptp_settime(struct ptp_clock_info *ptp,
+			     const struct timespec64 *ts)
+{
+	struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
+						   ptp_info);
+	u64 ns = timespec64_to_ns(ts);
+
+	write_lock(&tstamp->lock);
+	timecounter_init(&tstamp->clock, &tstamp->cycles, ns);
+	write_unlock(&tstamp->lock);
+
+	return 0;
+}
+
+static int mlx5e_ptp_gettime(struct ptp_clock_info *ptp,
+			     struct timespec64 *ts)
+{
+	struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
+						   ptp_info);
+	u64 ns;
+
+	write_lock(&tstamp->lock);
+	ns = timecounter_read(&tstamp->clock);
+	write_unlock(&tstamp->lock);
+
+	*ts = ns_to_timespec64(ns);
+
+	return 0;
+}
+
+static int mlx5e_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
+						   ptp_info);
+
+	write_lock(&tstamp->lock);
+	timecounter_adjtime(&tstamp->clock, delta);
+	write_unlock(&tstamp->lock);
+
+	return 0;
+}
+
+static int mlx5e_ptp_adjfreq(struct ptp_clock_info *ptp, s32 delta)
+{
+	u64 adj;
+	u32 diff;
+	int neg_adj = 0;
+	struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
+						  ptp_info);
+
+	if (delta < 0) {
+		neg_adj = 1;
+		delta = -delta;
+	}
+
+	adj = tstamp->nominal_c_mult;
+	adj *= delta;
+	diff = div_u64(adj, 1000000000ULL);
+
+	write_lock(&tstamp->lock);
+	timecounter_read(&tstamp->clock);
+	tstamp->cycles.mult = neg_adj ? tstamp->nominal_c_mult - diff :
+					tstamp->nominal_c_mult + diff;
+	write_unlock(&tstamp->lock);
+
+	return 0;
+}
+
+static const struct ptp_clock_info mlx5e_ptp_clock_info = {
+	.owner		= THIS_MODULE,
+	.max_adj	= 100000000,
+	.n_alarm	= 0,
+	.n_ext_ts	= 0,
+	.n_per_out	= 0,
+	.n_pins		= 0,
+	.pps		= 0,
+	.adjfreq	= mlx5e_ptp_adjfreq,
+	.adjtime	= mlx5e_ptp_adjtime,
+	.gettime64	= mlx5e_ptp_gettime,
+	.settime64	= mlx5e_ptp_settime,
+	.enable		= NULL,
+};
+
 static void mlx5e_timestamp_init_config(struct mlx5e_tstamp *tstamp)
 {
 	tstamp->hwtstamp_config.tx_type = HWTSTAMP_TX_OFF;
@@ -174,6 +257,18 @@ void mlx5e_timestamp_init(struct mlx5e_priv *priv)
 		schedule_delayed_work(&tstamp->overflow_work, 0);
 	else
 		mlx5_core_warn(priv->mdev, "invalid overflow period, overflow_work is not scheduled\n");
+
+	/* Configure the PHC */
+	tstamp->ptp_info = mlx5e_ptp_clock_info;
+	snprintf(tstamp->ptp_info.name, 16, "mlx5 ptp");
+
+	tstamp->ptp = ptp_clock_register(&tstamp->ptp_info,
+					 &priv->mdev->pdev->dev);
+	if (IS_ERR_OR_NULL(tstamp->ptp)) {
+		mlx5_core_warn(priv->mdev, "ptp_clock_register failed %ld\n",
+			       PTR_ERR(tstamp->ptp));
+		tstamp->ptp = NULL;
+	}
 }
 
 void mlx5e_timestamp_cleanup(struct mlx5e_priv *priv)
@@ -183,5 +278,10 @@ void mlx5e_timestamp_cleanup(struct mlx5e_priv *priv)
 	if (!MLX5_CAP_GEN(priv->mdev, device_frequency_khz))
 		return;
 
+	if (priv->tstamp.ptp) {
+		ptp_clock_unregister(priv->tstamp.ptp);
+		priv->tstamp.ptp = NULL;
+	}
+
 	cancel_delayed_work_sync(&tstamp->overflow_work);
 }

drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c

@@ -865,7 +865,8 @@ static int mlx5e_get_ts_info(struct net_device *dev,
 	if (ret)
 		return ret;
 
-	info->phc_index = -1;
+	info->phc_index = priv->tstamp.ptp ?
+			  ptp_clock_index(priv->tstamp.ptp) : -1;
 
 	if (!MLX5_CAP_GEN(priv->mdev, device_frequency_khz))
 		return 0;