ixgbe: Enable timesync clock-out feature for PPS support on X540

This patch enables the PPS system in the PHC framework, by enabling
the clock-out feature on the X540 device. Causes the SDP0 to be set as
a 1Hz clock. Also configures the timesync interrupt cause in order to
report each pulse to the PPS via the PHC framework, which can be used
for general system clock synchronization. (This allows a stable method
for tuning the general system time via the on-board SYSTIM register
based clock.)

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, 169 insertions, 1 deletions

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
index 0b6553ee18af..ddc6a4d19302 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
@@ -96,6 +96,10 @@
 
 #define IXGBE_OVERFLOW_PERIOD    (HZ * 30)
 
+#ifndef NSECS_PER_SEC
+#define NSECS_PER_SEC 1000000000ULL
+#endif
+
 /**
  * ixgbe_ptp_read - read raw cycle counter (to be used by time counter)
  * @cc - the cyclecounter structure
@@ -252,15 +256,154 @@ static int ixgbe_ptp_settime(struct ptp_clock_info *ptp,
  * @on - whether to enable or disable the feature
  *
  * enable (or disable) ancillary features of the phc subsystem.
- * our driver does not support any of these features
+ * our driver only supports the PPS feature on the X540
  */
 static int ixgbe_ptp_enable(struct ptp_clock_info *ptp,
 			    struct ptp_clock_request *rq, int on)
 {
+	struct ixgbe_adapter *adapter =
+		container_of(ptp, struct ixgbe_adapter, ptp_caps);
+
+	/**
+	 * When PPS is enabled, unmask the interrupt for the ClockOut
+	 * feature, so that the interrupt handler can send the PPS
+	 * event when the clock SDP triggers. Clear mask when PPS is
+	 * disabled
+	 */
+	if (rq->type == PTP_CLK_REQ_PPS) {
+		switch (adapter->hw.mac.type) {
+		case ixgbe_mac_X540:
+			if (on)
+				adapter->flags2 |= IXGBE_FLAG2_PTP_PPS_ENABLED;
+			else
+				adapter->flags2 &=
+					~IXGBE_FLAG2_PTP_PPS_ENABLED;
+			return 0;
+		default:
+			break;
+		}
+	}
+
 	return -ENOTSUPP;
 }
 
 /**
+ * ixgbe_ptp_check_pps_event
+ * @adapter - the private adapter structure
+ * @eicr - the interrupt cause register value
+ *
+ * This function is called by the interrupt routine when checking for
+ * interrupts. It will check and handle a pps event.
+ */
+void ixgbe_ptp_check_pps_event(struct ixgbe_adapter *adapter, u32 eicr)
+{
+	struct ixgbe_hw *hw = &adapter->hw;
+	struct ptp_clock_event event;
+
+	event.type = PTP_CLOCK_PPS;
+
+	/* Make sure ptp clock is valid, and PPS event enabled */
+	if (!adapter->ptp_clock ||
+	    !(adapter->flags2 & IXGBE_FLAG2_PTP_PPS_ENABLED))
+		return;
+
+	switch (hw->mac.type) {
+	case ixgbe_mac_X540:
+		if (eicr & IXGBE_EICR_TIMESYNC)
+			ptp_clock_event(adapter->ptp_clock, &event);
+		break;
+	default:
+		break;
+	}
+}
+
+/**
+ * ixgbe_ptp_enable_sdp
+ * @hw - the hardware private structure
+ * @shift - the clock shift for calculating nanoseconds
+ *
+ * this function enables the clock out feature on the sdp0 for the
+ * X540 device. It will create a 1second periodic output that can be
+ * used as the PPS (via an interrupt).
+ *
+ * It calculates when the systime will be on an exact second, and then
+ * aligns the start of the PPS signal to that value. The shift is
+ * necessary because it can change based on the link speed.
+ */
+static void ixgbe_ptp_enable_sdp(struct ixgbe_hw *hw, int shift)
+{
+	u32 esdp, tsauxc, clktiml, clktimh, trgttiml, trgttimh;
+	u64 clock_edge = 0;
+	u32 rem;
+
+	switch (hw->mac.type) {
+	case ixgbe_mac_X540:
+		esdp = IXGBE_READ_REG(hw, IXGBE_ESDP);
+
+		/*
+		 * enable the SDP0 pin as output, and connected to the native
+		 * function for Timesync (ClockOut)
+		 */
+		esdp |= (IXGBE_ESDP_SDP0_DIR |
+			 IXGBE_ESDP_SDP0_NATIVE);
+
+		/*
+		 * enable the Clock Out feature on SDP0, and allow interrupts
+		 * to occur when the pin changes
+		 */
+		tsauxc = (IXGBE_TSAUXC_EN_CLK |
+			  IXGBE_TSAUXC_SYNCLK |
+			  IXGBE_TSAUXC_SDP0_INT);
+
+		/* clock period (or pulse length) */
+		clktiml = (u32)(NSECS_PER_SEC << shift);
+		clktimh = (u32)((NSECS_PER_SEC << shift) >> 32);
+
+		clock_edge |= (u64)IXGBE_READ_REG(hw, IXGBE_SYSTIML);
+		clock_edge |= (u64)IXGBE_READ_REG(hw, IXGBE_SYSTIMH) << 32;
+
+		/*
+		 * account for the fact that we can't do u64 division
+		 * with remainder, by converting the clock values into
+		 * nanoseconds first
+		 */
+		clock_edge >>= shift;
+		div_u64_rem(clock_edge, NSECS_PER_SEC, &rem);
+		clock_edge += (NSECS_PER_SEC - rem);
+		clock_edge <<= shift;
+
+		/* specify the initial clock start time */
+		trgttiml = (u32)clock_edge;
+		trgttimh = (u32)(clock_edge >> 32);
+
+		IXGBE_WRITE_REG(hw, IXGBE_CLKTIML, clktiml);
+		IXGBE_WRITE_REG(hw, IXGBE_CLKTIMH, clktimh);
+		IXGBE_WRITE_REG(hw, IXGBE_TRGTTIML0, trgttiml);
+		IXGBE_WRITE_REG(hw, IXGBE_TRGTTIMH0, trgttimh);
+
+		IXGBE_WRITE_REG(hw, IXGBE_ESDP, esdp);
+		IXGBE_WRITE_REG(hw, IXGBE_TSAUXC, tsauxc);
+
+		IXGBE_WRITE_REG(hw, IXGBE_EIMS, IXGBE_EICR_TIMESYNC);
+		break;
+	default:
+		break;
+	}
+}
+
+/**
+ * ixgbe_ptp_disable_sdp
+ * @hw - the private hardware structure
+ *
+ * this function disables the auxiliary SDP clock out feature
+ */
+static void ixgbe_ptp_disable_sdp(struct ixgbe_hw *hw)
+{
+	IXGBE_WRITE_REG(hw, IXGBE_EIMC, IXGBE_EICR_TIMESYNC);
+	IXGBE_WRITE_REG(hw, IXGBE_TSAUXC, 0);
+}
+
+/**
  * ixgbe_ptp_overflow_check - delayed work to detect SYSTIME overflow
  * @work: structure containing information about this work task
  *
@@ -557,6 +700,9 @@ int ixgbe_ptp_hwtstamp_ioctl(struct ixgbe_adapter *adapter,
  * the device, which is used to generate the cycle counter
  * registers. Therefor this function is called whenever the link speed
  * changes.
+ *
+ * This function also turns on the SDP pin for clock out feature (X540
+ * only), because this is where the shift is first calculated.
  */
 void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter)
 {
@@ -588,6 +734,9 @@ void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter)
 	if (adapter->cycle_speed == cycle_speed)
 		return;
 
+	/* disable the SDP clock out */
+	ixgbe_ptp_disable_sdp(hw);
+
 	/**
 	 * Scale the NIC cycle counter by a large factor so that
 	 * relatively small corrections to the frequency can be added
@@ -640,6 +789,10 @@ void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter)
 	IXGBE_WRITE_REG(hw, IXGBE_SYSTIMH, 0x00000000);
 	IXGBE_WRITE_FLUSH(hw);
 
+	/* now that the shift has been calculated and the systime
+	 * registers reset, (re-)enable the Clock out feature*/
+	ixgbe_ptp_enable_sdp(hw, shift);
+
 	/* store the new cycle speed */
 	adapter->cycle_speed = cycle_speed;
 
@@ -676,6 +829,19 @@ void ixgbe_ptp_init(struct ixgbe_adapter *adapter)
 
 	switch (adapter->hw.mac.type) {
 	case ixgbe_mac_X540:
+		snprintf(adapter->ptp_caps.name, 16, "%pm", netdev->dev_addr);
+		adapter->ptp_caps.owner = THIS_MODULE;
+		adapter->ptp_caps.max_adj = 250000000;
+		adapter->ptp_caps.n_alarm = 0;
+		adapter->ptp_caps.n_ext_ts = 0;
+		adapter->ptp_caps.n_per_out = 0;
+		adapter->ptp_caps.pps = 1;
+		adapter->ptp_caps.adjfreq = ixgbe_ptp_adjfreq;
+		adapter->ptp_caps.adjtime = ixgbe_ptp_adjtime;
+		adapter->ptp_caps.gettime = ixgbe_ptp_gettime;
+		adapter->ptp_caps.settime = ixgbe_ptp_settime;
+		adapter->ptp_caps.enable = ixgbe_ptp_enable;
+		break;
 	case ixgbe_mac_82599EB:
 		snprintf(adapter->ptp_caps.name, 16, "%pm", netdev->dev_addr);
 		adapter->ptp_caps.owner = THIS_MODULE;
@@ -720,6 +886,8 @@ void ixgbe_ptp_init(struct ixgbe_adapter *adapter)
  */
 void ixgbe_ptp_stop(struct ixgbe_adapter *adapter)
 {
+	ixgbe_ptp_disable_sdp(&adapter->hw);
+
 	/* stop the overflow check task */
 	adapter->flags2 &= ~IXGBE_FLAG2_OVERFLOW_CHECK_ENABLED;