igb: add PTP Hardware Clock code

This patch adds a source file implementing a PHC. Only the basic
clock operations have been implemented, although the hardware
would offer some ancillary functions. The code is fairly self
contained and is not yet used in the main igb driver.

Every timestamp and clock read operation must consult the overflow
counter to form a correct time value. Access to the counter is
protected by a spin lock, and the counter is implemented using the
standard cyclecounter/timecounter code.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/igb.h

@@ -37,6 +37,7 @@
 #include <linux/clocksource.h>
 #include <linux/timecompare.h>
 #include <linux/net_tstamp.h>
+#include <linux/ptp_clock_kernel.h>
 #include <linux/bitops.h>
 #include <linux/if_vlan.h>
 
@@ -364,6 +365,13 @@ struct igb_adapter {
 	u32 wvbr;
 	int node;
 	u32 *shadow_vfta;
+
+	struct ptp_clock *ptp_clock;
+	struct ptp_clock_info caps;
+	struct delayed_work overflow_work;
+	spinlock_t tmreg_lock;
+	struct cyclecounter cc;
+	struct timecounter tc;
 };
 
 #define IGB_FLAG_HAS_MSI           (1 << 0)

drivers/net/ethernet/intel/igb/igb_ptp.c

@@ -0,0 +1,322 @@
+/*
+ * PTP Hardware Clock (PHC) driver for the Intel 82576 and 82580
+ *
+ * Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/pci.h>
+
+#include "igb.h"
+
+#define INCVALUE_MASK		0x7fffffff
+#define ISGN			0x80000000
+
+/*
+ * Neither the 82576 nor the 82580 offer registers wide enough to hold
+ * nanoseconds time values for very long. For the 82580, SYSTIM always
+ * counts nanoseconds, but the upper 24 bits are not availible. The
+ * frequency is adjusted by changing the 32 bit fractional nanoseconds
+ * register, TIMINCA.
+ *
+ * For the 82576, the SYSTIM register time unit is affect by the
+ * choice of the 24 bit TININCA:IV (incvalue) field. Five bits of this
+ * field are needed to provide the nominal 16 nanosecond period,
+ * leaving 19 bits for fractional nanoseconds.
+ *
+ *
+ *             SYSTIMH            SYSTIML
+ *        +--------------+   +---+---+------+
+ *  82576 |      32      |   | 8 | 5 |  19  |
+ *        +--------------+   +---+---+------+
+ *         \________ 45 bits _______/  fract
+ *
+ *        +----------+---+   +--------------+
+ *  82580 |    24    | 8 |   |      32      |
+ *        +----------+---+   +--------------+
+ *          reserved  \______ 40 bits _____/
+ *
+ *
+ * The 45 bit 82576 SYSTIM overflows every
+ *   2^45 * 10^-9 / 3600 = 9.77 hours.
+ *
+ * The 40 bit 82580 SYSTIM overflows every
+ *   2^40 * 10^-9 /  60  = 18.3 minutes.
+ */
+
+#define IGB_OVERFLOW_PERIOD	(HZ * 60 * 9)
+#define INCPERIOD_82576		(1 << E1000_TIMINCA_16NS_SHIFT)
+#define INCVALUE_82576_MASK	((1 << E1000_TIMINCA_16NS_SHIFT) - 1)
+#define INCVALUE_82576		(16 << IGB_82576_TSYNC_SHIFT)
+#define IGB_NBITS_82580		40
+
+/*
+ * SYSTIM read access for the 82576
+ */
+
+static cycle_t igb_82576_systim_read(const struct cyclecounter *cc)
+{
+	u64 val;
+	u32 lo, hi;
+	struct igb_adapter *igb = container_of(cc, struct igb_adapter, cc);
+	struct e1000_hw *hw = &igb->hw;
+
+	lo = rd32(E1000_SYSTIML);
+	hi = rd32(E1000_SYSTIMH);
+
+	val = ((u64) hi) << 32;
+	val |= lo;
+
+	return val;
+}
+
+/*
+ * SYSTIM read access for the 82580
+ */
+
+static cycle_t igb_82580_systim_read(const struct cyclecounter *cc)
+{
+	u64 val;
+	u32 lo, hi, jk;
+	struct igb_adapter *igb = container_of(cc, struct igb_adapter, cc);
+	struct e1000_hw *hw = &igb->hw;
+
+	jk = rd32(E1000_SYSTIMR);
+	lo = rd32(E1000_SYSTIML);
+	hi = rd32(E1000_SYSTIMH);
+
+	val = ((u64) hi) << 32;
+	val |= lo;
+
+	return val;
+}
+
+/*
+ * PTP clock operations
+ */
+
+static int ptp_82576_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
+{
+	u64 rate;
+	u32 incvalue;
+	int neg_adj = 0;
+	struct igb_adapter *igb = container_of(ptp, struct igb_adapter, caps);
+	struct e1000_hw *hw = &igb->hw;
+
+	if (ppb < 0) {
+		neg_adj = 1;
+		ppb = -ppb;
+	}
+	rate = ppb;
+	rate <<= 14;
+	rate = div_u64(rate, 1953125);
+
+	incvalue = 16 << IGB_82576_TSYNC_SHIFT;
+
+	if (neg_adj)
+		incvalue -= rate;
+	else
+		incvalue += rate;
+
+	wr32(E1000_TIMINCA, INCPERIOD_82576 | (incvalue & INCVALUE_82576_MASK));
+
+	return 0;
+}
+
+static int ptp_82580_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
+{
+	u64 rate;
+	u32 inca;
+	int neg_adj = 0;
+	struct igb_adapter *igb = container_of(ptp, struct igb_adapter, caps);
+	struct e1000_hw *hw = &igb->hw;
+
+	if (ppb < 0) {
+		neg_adj = 1;
+		ppb = -ppb;
+	}
+	rate = ppb;
+	rate <<= 26;
+	rate = div_u64(rate, 1953125);
+
+	inca = rate & INCVALUE_MASK;
+	if (neg_adj)
+		inca |= ISGN;
+
+	wr32(E1000_TIMINCA, inca);
+
+	return 0;
+}
+
+static int igb_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	s64 now;
+	unsigned long flags;
+	struct igb_adapter *igb = container_of(ptp, struct igb_adapter, caps);
+
+	spin_lock_irqsave(&igb->tmreg_lock, flags);
+
+	now = timecounter_read(&igb->tc);
+	now += delta;
+	timecounter_init(&igb->tc, &igb->cc, now);
+
+	spin_unlock_irqrestore(&igb->tmreg_lock, flags);
+
+	return 0;
+}
+
+static int igb_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
+{
+	u64 ns;
+	u32 remainder;
+	unsigned long flags;
+	struct igb_adapter *igb = container_of(ptp, struct igb_adapter, caps);
+
+	spin_lock_irqsave(&igb->tmreg_lock, flags);
+
+	ns = timecounter_read(&igb->tc);
+
+	spin_unlock_irqrestore(&igb->tmreg_lock, flags);
+
+	ts->tv_sec = div_u64_rem(ns, 1000000000, &remainder);
+	ts->tv_nsec = remainder;
+
+	return 0;
+}
+
+static int igb_settime(struct ptp_clock_info *ptp, const struct timespec *ts)
+{
+	u64 ns;
+	unsigned long flags;
+	struct igb_adapter *igb = container_of(ptp, struct igb_adapter, caps);
+
+	ns = ts->tv_sec * 1000000000ULL;
+	ns += ts->tv_nsec;
+
+	spin_lock_irqsave(&igb->tmreg_lock, flags);
+
+	timecounter_init(&igb->tc, &igb->cc, ns);
+
+	spin_unlock_irqrestore(&igb->tmreg_lock, flags);
+
+	return 0;
+}
+
+static int ptp_82576_enable(struct ptp_clock_info *ptp,
+			    struct ptp_clock_request *rq, int on)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ptp_82580_enable(struct ptp_clock_info *ptp,
+			    struct ptp_clock_request *rq, int on)
+{
+	return -EOPNOTSUPP;
+}
+
+static void igb_overflow_check(struct work_struct *work)
+{
+	struct timespec ts;
+	struct igb_adapter *igb =
+		container_of(work, struct igb_adapter, overflow_work.work);
+
+	igb_gettime(&igb->caps, &ts);
+
+	pr_debug("igb overflow check at %ld.%09lu\n", ts.tv_sec, ts.tv_nsec);
+
+	schedule_delayed_work(&igb->overflow_work, IGB_OVERFLOW_PERIOD);
+}
+
+void igb_ptp_init(struct igb_adapter *adapter)
+{
+	struct e1000_hw *hw = &adapter->hw;
+
+	switch (hw->mac.type) {
+	case e1000_i350:
+	case e1000_82580:
+		adapter->caps.owner	= THIS_MODULE;
+		strcpy(adapter->caps.name, "igb-82580");
+		adapter->caps.max_adj	= 62499999;
+		adapter->caps.n_ext_ts	= 0;
+		adapter->caps.pps	= 0;
+		adapter->caps.adjfreq	= ptp_82580_adjfreq;
+		adapter->caps.adjtime	= igb_adjtime;
+		adapter->caps.gettime	= igb_gettime;
+		adapter->caps.settime	= igb_settime;
+		adapter->caps.enable	= ptp_82580_enable;
+		adapter->cc.read	= igb_82580_systim_read;
+		adapter->cc.mask	= CLOCKSOURCE_MASK(IGB_NBITS_82580);
+		adapter->cc.mult	= 1;
+		adapter->cc.shift	= 0;
+		/* Enable the timer functions by clearing bit 31. */
+		wr32(E1000_TSAUXC, 0x0);
+		break;
+
+	case e1000_82576:
+		adapter->caps.owner	= THIS_MODULE;
+		strcpy(adapter->caps.name, "igb-82576");
+		adapter->caps.max_adj	= 1000000000;
+		adapter->caps.n_ext_ts	= 0;
+		adapter->caps.pps	= 0;
+		adapter->caps.adjfreq	= ptp_82576_adjfreq;
+		adapter->caps.adjtime	= igb_adjtime;
+		adapter->caps.gettime	= igb_gettime;
+		adapter->caps.settime	= igb_settime;
+		adapter->caps.enable	= ptp_82576_enable;
+		adapter->cc.read	= igb_82576_systim_read;
+		adapter->cc.mask	= CLOCKSOURCE_MASK(64);
+		adapter->cc.mult	= 1;
+		adapter->cc.shift	= IGB_82576_TSYNC_SHIFT;
+		/* Dial the nominal frequency. */
+		wr32(E1000_TIMINCA, INCPERIOD_82576 | INCVALUE_82576);
+		break;
+
+	default:
+		adapter->ptp_clock = NULL;
+		return;
+	}
+
+	wrfl();
+
+	timecounter_init(&adapter->tc, &adapter->cc,
+			 ktime_to_ns(ktime_get_real()));
+
+	INIT_DELAYED_WORK(&adapter->overflow_work, igb_overflow_check);
+
+	spin_lock_init(&adapter->tmreg_lock);
+
+	schedule_delayed_work(&adapter->overflow_work, IGB_OVERFLOW_PERIOD);
+
+	adapter->ptp_clock = ptp_clock_register(&adapter->caps);
+	if (IS_ERR(adapter->ptp_clock)) {
+		adapter->ptp_clock = NULL;
+		dev_err(&adapter->pdev->dev, "ptp_clock_register failed\n");
+	} else
+		dev_info(&adapter->pdev->dev, "added PHC on %s\n",
+			 adapter->netdev->name);
+}
+
+void igb_ptp_remove(struct igb_adapter *adapter)
+{
+	cancel_delayed_work_sync(&adapter->overflow_work);
+
+	if (adapter->ptp_clock) {
+		ptp_clock_unregister(adapter->ptp_clock);
+		dev_info(&adapter->pdev->dev, "removed PHC on %s\n",
+			 adapter->netdev->name);
+	}
+}