e1000e: Adds hardware supported cross timestamp on e1000e nic

Modern Intel systems supports cross timestamping of the network device
clock and Always Running Timer (ART) in hardware.  This allows the
device time and system time to be precisely correlated. The timestamp
pair is returned through e1000e_phc_get_syncdevicetime() used by
get_system_device_crosststamp().  The hardware cross-timestamp result
is made available to applications through the PTP_SYS_OFFSET_PRECISE
ioctl which calls e1000e_phc_getcrosststamp().

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
[jstultz: Reworked to use new interface, commit message tweaks]
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 85 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/e1000e/ptp.c b/drivers/net/ethernet/intel/e1000e/ptp.c
index 25a0ad5102d6..e2ff3ef75d5d 100644
--- a/drivers/net/ethernet/intel/e1000e/ptp.c
+++ b/drivers/net/ethernet/intel/e1000e/ptp.c
@@ -26,6 +26,12 @@
 
 #include "e1000.h"
 
+#ifdef CONFIG_E1000E_HWTS
+#include <linux/clocksource.h>
+#include <linux/ktime.h>
+#include <asm/tsc.h>
+#endif
+
 /**
  * e1000e_phc_adjfreq - adjust the frequency of the hardware clock
  * @ptp: ptp clock structure
@@ -98,6 +104,78 @@ static int e1000e_phc_adjtime(struct ptp_clock_info *ptp, s64 delta)
 	return 0;
 }
 
+#ifdef CONFIG_E1000E_HWTS
+#define MAX_HW_WAIT_COUNT (3)
+
+/**
+ * e1000e_phc_get_syncdevicetime - Callback given to timekeeping code reads system/device registers
+ * @device: current device time
+ * @system: system counter value read synchronously with device time
+ * @ctx: context provided by timekeeping code
+ *
+ * Read device and system (ART) clock simultaneously and return the corrected
+ * clock values in ns.
+ **/
+static int e1000e_phc_get_syncdevicetime(ktime_t *device,
+					 struct system_counterval_t *system,
+					 void *ctx)
+{
+	struct e1000_adapter *adapter = (struct e1000_adapter *)ctx;
+	struct e1000_hw *hw = &adapter->hw;
+	unsigned long flags;
+	int i;
+	u32 tsync_ctrl;
+	cycle_t dev_cycles;
+	cycle_t sys_cycles;
+
+	tsync_ctrl = er32(TSYNCTXCTL);
+	tsync_ctrl |= E1000_TSYNCTXCTL_START_SYNC |
+		E1000_TSYNCTXCTL_MAX_ALLOWED_DLY_MASK;
+	ew32(TSYNCTXCTL, tsync_ctrl);
+	for (i = 0; i < MAX_HW_WAIT_COUNT; ++i) {
+		udelay(1);
+		tsync_ctrl = er32(TSYNCTXCTL);
+		if (tsync_ctrl & E1000_TSYNCTXCTL_SYNC_COMP)
+			break;
+	}
+
+	if (i == MAX_HW_WAIT_COUNT)
+		return -ETIMEDOUT;
+
+	dev_cycles = er32(SYSSTMPH);
+	dev_cycles <<= 32;
+	dev_cycles |= er32(SYSSTMPL);
+	spin_lock_irqsave(&adapter->systim_lock, flags);
+	*device = ns_to_ktime(timecounter_cyc2time(&adapter->tc, dev_cycles));
+	spin_unlock_irqrestore(&adapter->systim_lock, flags);
+
+	sys_cycles = er32(PLTSTMPH);
+	sys_cycles <<= 32;
+	sys_cycles |= er32(PLTSTMPL);
+	*system = convert_art_to_tsc(sys_cycles);
+
+	return 0;
+}
+
+/**
+ * e1000e_phc_getsynctime - Reads the current system/device cross timestamp
+ * @ptp: ptp clock structure
+ * @cts: structure containing timestamp
+ *
+ * Read device and system (ART) clock simultaneously and return the scaled
+ * clock values in ns.
+ **/
+static int e1000e_phc_getcrosststamp(struct ptp_clock_info *ptp,
+				     struct system_device_crosststamp *xtstamp)
+{
+	struct e1000_adapter *adapter = container_of(ptp, struct e1000_adapter,
+						     ptp_clock_info);
+
+	return get_device_system_crosststamp(e1000e_phc_get_syncdevicetime,
+						adapter, NULL, xtstamp);
+}
+#endif/*CONFIG_E1000E_HWTS*/
+
 /**
  * e1000e_phc_gettime - Reads the current time from the hardware clock
  * @ptp: ptp clock structure
@@ -236,6 +314,13 @@ void e1000e_ptp_init(struct e1000_adapter *adapter)
 		break;
 	}
 
+#ifdef CONFIG_E1000E_HWTS
+	/* CPU must have ART and GBe must be from Sunrise Point or greater */
+	if (hw->mac.type >= e1000_pch_spt && boot_cpu_has(X86_FEATURE_ART))
+		adapter->ptp_clock_info.getcrosststamp =
+			e1000e_phc_getcrosststamp;
+#endif/*CONFIG_E1000E_HWTS*/
+
 	INIT_DELAYED_WORK(&adapter->systim_overflow_work,
 			  e1000e_systim_overflow_work);