path: root/drivers/net/ethernet/intel/igb/igb_ptp.c

// SPDX-License-Identifier: GPL-2.0+
/* Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com> */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/pci.h>
#include <linux/ptp_classify.h>

#include "igb.h"

#define INCVALUE_MASK		0x7fffffff
#define ISGN			0x80000000

/* The 82580 timesync updates the system timer every 8ns by 8ns,
 * and this update value cannot be reprogrammed.
 *
 * 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 available. 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.
 *
 * We scale the NIC clock cycle by a large factor so that relatively
 * small clock corrections can be added or subtracted at each clock
 * tick. The drawbacks of a large factor are a) that the clock
 * register overflows more quickly (not such a big deal) and b) that
 * the increment per tick has to fit into 24 bits.  As a result we
 * need to use a shift of 19 so we can fit a value of 16 into the
 * TIMINCA register.
 *
 *
 *             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.
 *
 * SYSTIM is converted to real time using a timecounter. As
 * timecounter_cyc2time() allows old timestamps, the timecounter needs
 * to be updated at least once per half of the SYSTIM interval.
 * Scheduling of delayed work is not very accurate, and also the NIC
 * clock can be adjusted to run up to 6% faster and the system clock
 * up to 10% slower, so we aim for 6 minutes to be sure the actual
 * interval in the NIC time is shorter than 9.16 minutes.
 */

#define IGB_SYSTIM_OVERFLOW_PERIOD	(HZ * 60 * 6)
#define IGB_PTP_TX_TIMEOUT		(HZ * 15)
#define INCPERIOD_82576			BIT(E1000_TIMINCA_16NS_SHIFT)
#define INCVALUE_82576_MASK		GENMASK(E1000_TIMINCA_16NS_SHIFT - 1, 0)
#define INCVALUE_82576			(16u << IGB_82576_TSYNC_SHIFT)
#define IGB_NBITS_82580			40

static void igb_ptp_tx_hwtstamp(struct igb_adapter *adapter);
static void igb_ptp_sdp_init(struct igb_adapter *adapter);

/* SYSTIM read access for the 82576 */
static u64 igb_ptp_read_82576(const struct cyclecounter *cc)
{
	struct igb_adapter *igb = container_of(cc, struct igb_adapter, cc);
	struct e1000_hw *hw = &igb->hw;
	u64 val;
	u32 lo, hi;

	lo = rd32(E1000_SYSTIML);
	hi = rd32(E1000_SYSTIMH);

	val = ((u64) hi) << 32;
	val |= lo;

	return val;
}

/* SYSTIM read access for the 82580 */
static u64 igb_ptp_read_82580(const struct cyclecounter *cc)
{
	struct igb_adapter *igb = container_of(cc, struct igb_adapter, cc);
	struct e1000_hw *hw = &igb->hw;
	u32 lo, hi;
	u64 val;

	/* The timestamp latches on lowest register read. For the 82580
	 * the lowest register is SYSTIMR instead of SYSTIML.  However we only
	 * need to provide nanosecond resolution, so we just ignore it.
	 */
	rd32(E1000_SYSTIMR);
	lo = rd32(E1000_SYSTIML);
	hi = rd32(E1000_SYSTIMH);

	val = ((u64) hi) << 32;
	val |= lo;

	return val;
}

/* SYSTIM read access for I210/I211 */
static void igb_ptp_read_i210(struct igb_adapter *adapter,
			      struct timespec64 *ts)
{
	struct e1000_hw *hw = &adapter->hw;
	u32 sec, nsec;

	/* The timestamp latches on lowest register read. For I210/I211, the
	 * lowest register is SYSTIMR. Since we only need to provide nanosecond
	 * resolution, we can ignore it.
	 */
	rd32(E1000_SYSTIMR);
	nsec = rd32(E1000_SYSTIML);
	sec = rd32(E1000_SYSTIMH);

	ts->tv_sec = sec;
	ts->tv_nsec = nsec;
}

static void igb_ptp_write_i210(struct igb_adapter *adapter,
			       const struct timespec64 *ts)
{
	struct e1000_hw *hw = &adapter->hw;

	/* Writing the SYSTIMR register is not necessary as it only provides
	 * sub-nanosecond resolution.
	 */
	wr32(E1000_SYSTIML, ts->tv_nsec);
	wr32(E1000_SYSTIMH, (u32)ts->tv_sec);
}

/**
 * igb_ptp_systim_to_hwtstamp - convert system time value to hw timestamp
 * @adapter: board private structure
 * @hwtstamps: timestamp structure to update
 * @systim: unsigned 64bit system time value.
 *
 * We need to convert the system time value stored in the RX/TXSTMP registers
 * into a hwtstamp which can be used by the upper level timestamping functions.
 *
 * The 'tmreg_lock' spinlock is used to protect the consistency of the
 * system time value. This is needed because reading the 64 bit time
 * value involves reading two (or three) 32 bit registers. The first
 * read latches the value. Ditto for writing.
 *
 * In addition, here have extended the system time with an overflow
 * counter in software.
 **/
static void igb_ptp_systim_to_hwtstamp(struct igb_adapter *adapter,
				       struct skb_shared_hwtstamps *hwtstamps,
				       u64 systim)
{
	unsigned long flags;
	u64 ns;

	memset(hwtstamps, 0, sizeof(*hwtstamps));

	switch (adapter->hw.mac.type) {
	case e1000_82576:
	case e1000_82580:
	case e1000_i354:
	case e1000_i350:
		spin_lock_irqsave(&adapter->tmreg_lock, flags);
		ns = timecounter_cyc2time(&adapter->tc, systim);
		spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

		hwtstamps->hwtstamp = ns_to_ktime(ns);
		break;
	case e1000_i210:
	case e1000_i211:
		/* Upper 32 bits contain s, lower 32 bits contain ns. */
		hwtstamps->hwtstamp = ktime_set(systim >> 32,
						systim & 0xFFFFFFFF);
		break;
	default:
		break;
	}
}

/* PTP clock operations */
static int igb_ptp_adjfine_82576(struct ptp_clock_info *ptp, long scaled_ppm)
{
	struct igb_adapter *igb = container_of(ptp, struct igb_adapter,
					       ptp_caps);
	struct e1000_hw *hw = &igb->hw;
	int neg_adj = 0;
	u64 rate;
	u32 incvalue;

	if (scaled_ppm < 0) {
		neg_adj = 1;
		scaled_ppm = -scaled_ppm;
	}

	incvalue = INCVALUE_82576;
	rate = mul_u64_u6