// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 1999 - 2018 Intel Corporation. */

#include "ixgbe.h"
#include <linux/ptp_classify.h>
#include <linux/clocksource.h>

/*
 * The 82599 and the X540 do not have true 64bit nanosecond scale
 * counter registers. Instead, SYSTIME is defined by a fixed point
 * system which allows the user to define the scale counter increment
 * value at every level change of the oscillator driving the SYSTIME
 * value. For both devices the TIMINCA:IV field defines this
 * increment. On the X540 device, 31 bits are provided. However on the
 * 82599 only provides 24 bits. The time unit is determined by the
 * clock frequency of the oscillator in combination with the TIMINCA
 * register. When these devices link at 10Gb the oscillator has a
 * period of 6.4ns. In order to convert the scale counter into
 * nanoseconds the cyclecounter and timecounter structures are
 * used. The SYSTIME registers need to be converted to ns values by use
 * of only a right shift (division by power of 2). The following math
 * determines the largest incvalue that will fit into the available
 * bits in the TIMINCA register.
 *
 * PeriodWidth: Number of bits to store the clock period
 * MaxWidth: The maximum width value of the TIMINCA register
 * Period: The clock period for the oscillator
 * round(): discard the fractional portion of the calculation
 *
 * Period * [ 2 ^ ( MaxWidth - PeriodWidth ) ]
 *
 * For the X540, MaxWidth is 31 bits, and the base period is 6.4 ns
 * For the 82599, MaxWidth is 24 bits, and the base period is 6.4 ns
 *
 * The period also changes based on the link speed:
 * At 10Gb link or no link, the period remains the same.
 * At 1Gb link, the period is multiplied by 10. (64ns)
 * At 100Mb link, the period is multiplied by 100. (640ns)
 *
 * The calculated value allows us to right shift the SYSTIME register
 * value in order to quickly convert it into a nanosecond clock,
 * while allowing for the maximum possible adjustment value.
 *
 * These diagrams are only for the 10Gb link period
 *
 *           SYSTIMEH            SYSTIMEL
 *       +--------------+  +--------------+
 * X540  |      32      |  | 1 | 3 |  28  |
 *       *--------------+  +--------------+
 *        \________ 36 bits ______/  fract
 *
 *       +--------------+  +--------------+
 * 82599 |      32      |  | 8 | 3 |  21  |
 *       *--------------+  +--------------+
 *        \________ 43 bits ______/  fract
 *
 * The 36 bit X540 SYSTIME overflows every
 *   2^36 * 10^-9 / 60 = 1.14 minutes or 69 seconds
 *
 * The 43 bit 82599 SYSTIME overflows every
 *   2^43 * 10^-9 / 3600 = 2.4 hours
 */
#define IXGBE_INCVAL_10GB 0x66666666
#define IXGBE_INCVAL_1GB  0x40000000
#define IXGBE_INCVAL_100  0x50000000

#define IXGBE_INCVAL_SHIFT_10GB  28
#define IXGBE_INCVAL_SHIFT_1GB   24
#define IXGBE_INCVAL_SHIFT_100   21

#define IXGBE_INCVAL_SHIFT_82599 7
#define IXGBE_INCPER_SHIFT_82599 24

#define IXGBE_OVERFLOW_PERIOD    (HZ * 30)
#define IXGBE_PTP_TX_TIMEOUT     (HZ)

/* We use our own definitions instead of NSEC_PER_SEC because we want to mark
 * the value as a ULL to force precision when bit shifting.
 */
#define NS_PER_SEC      1000000000ULL
#define NS_PER_HALF_SEC  500000000ULL

/* In contrast, the X550 controller has two registers, SYSTIMEH and SYSTIMEL
 * which contain measurements of seconds and nanoseconds respectively. This
 * matches the standard linux representation of time in the kernel. In addition,
 * the X550 also has a SYSTIMER register which represents residue, or
 * subnanosecond overflow adjustments. To control clock adjustment, the TIMINCA
 * register is used, but it is unlike the X540 and 82599 devices. TIMINCA
 * represents units of 2^-32 nanoseconds, and uses 31 bits for this, with the
 * high bit representing whether the adjustent is positive or negative. Every
 * clock cycle, the X550 will add 12.5 ns + TIMINCA which can result in a range
 * of 12 to 13 nanoseconds adjustment. Unlike the 82599 and X540 devices, the
 * X550's clock for purposes of SYSTIME generation is constant and not dependent
 * on the link speed.
 *
 *           SYSTIMEH           SYSTIMEL        SYSTIMER
 *       +--------------+  +--------------+  +-------------+
 * X550  |      32      |  |      32      |  |     32      |
 *       *--------------+  +--------------+  +-------------+
 *       \____seconds___/   \_nanoseconds_/  \__2^-32 ns__/
 *
 * This results in a full 96 bits to represent the clock, with 32 bits for
 * seconds, 32 bits for nanoseconds (largest value is 0d999999999 or just under
 * 1 second) and an additional 32 bits to measure sub nanosecond adjustments for
 * underflow of adjustments.
 *
 * The 32 bits of seconds for the X550 overflows every
 *   2^32 / ( 365.25 * 24 * 60 * 60 ) = ~136 years.
 *
 * In order to adjust the clock frequency for the X550, the TIMINCA register is
 * provided. This register represents a + or minus nearly 0.5 ns adjustment to
 * the base frequency. It is measured in 2^-32 ns units, with the high bit being
 * the sign bit. This register enables software to calculate frequency
 * adjustments and apply them directly to the clock rate.
 *
 * The math for converting scaled_ppm into TIMINCA values is fairly
 * straightforward.
 *
 *   TIMINCA value = ( Base_Frequency * scaled_ppm ) / 1000000ULL << 16
 *
 * To avoid overflow, we simply use mul_u64_u64_div_u64.
 *
 * This assumes that scaled_ppm is never high enough to create a value bigger
 * than TIMINCA's 31 bits can store. This is ensured by the stack, and is
 * measured in parts per billion. Calculating this value is also simple.
 *   Max ppb = ( Max Adjustment / Base Frequency ) / 1000000000ULL
 *
 * For the X550, the Max adjustment is +/- 0.5 ns, and the base frequency is
 * 12.5 nanoseconds. This means that the Max ppb is 39999999
 *   Note: We subtract one in order to ensure no overflow, because the TIMINCA
 *         register can only hold slightly under 0.5 nanoseconds.
 *
 * Because TIMINCA is measured in 2^-32 ns units, we have to convert 12.5 ns
 * into 2^-32 units, which is
 *
 *  12.5 * 2^32 = C80000000
 *
 * Some revisions of hardware have a faster base frequency than the registers
 * were defined for. To fix this, we use a timecounter structure with the
 * proper mult and shift to convert the cycles into nanoseconds of time.
 */
#define IXGBE_X550_BASE_PERIOD 0xC80000000ULL
#define INCVALUE_MASK	0x7FFFFFFF
#define ISGN		0x80000000

/**
 * ixgbe_ptp_setup_sdp_X540
 * @adapter: private adapter structure
 *
 * this function enables or disables the clock out feature on SDP0 for
 * the X540 device. It will create a 1 second periodic output that can
 * be used as the PPS (via an interrupt).
 *
 * It calculates when the system time will be on an exact second, and then
 * aligns the start of the PPS signal to that value.
 *
 * This works by using the cycle counter shift and mult values in reverse, and
 * assumes that the values we're shifting will not overflow.
 */
static void ixgbe_ptp_setup_sdp_X540(struct ixgbe_adapter *adapter)
{
	struct cyclecounter *cc = &adapter->hw_cc;
	struct ixgbe_hw *hw = &adapter->hw;
	u32 esdp, tsauxc, clktiml, clktimh, trgttiml, trgttimh, rem;
	u64 ns = 0, clock_edge = 0, clock_period;
	unsigned long flags;

	/* disable the pin first */
	IXGBE_WRITE_REG(hw, IXGBE_TSAUXC, 0x0);
	IXGBE_WRITE_FLUSH(hw);

	if (!(adapter->flags2 & IXGBE_FLAG2_PTP_PPS_ENABLED))
		return;

	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);

	/* Determine the clock time period to use. This assumes that the
	 * cycle counter shift is small enough to avoid overflow.
	 */
	clock_period = div_u64((NS_PER_HALF_SEC << cc->shift), cc->mult);
	clktiml = (u32)(clock_period);
	clktimh = (u32)(clock_period >> 32);

	/* Read the current clock time, and save the cycle counter value */
	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	ns = timecounter_read(&adapter->hw_tc);
	clock_edge = adapter->hw_tc.cycle_last;
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	/* Figure out how many seconds to add in order to round up */
	div_u64_rem(ns, NS_PER_SEC, &rem);

	/* Figure out how many nanoseconds to add to round the clock edge up
	 * to the next full second
	 */
	rem = (NS_PER_SEC - rem);

	/* Adjust the clock edge to align with the next full second. */
	clock_edge += div_u64(((u64)rem << cc->shift), cc->mult);
	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_FLUSH(hw);
}

/**
 * ixgbe_ptp_setup_sdp_X550
 * @adapter: private adapter structure
 *
 * Enable or disable a clock output signal on SDP 0 for X550 hardware.
 *
 * Use the target time feature to align the output signal on the next full
 * second.
 *
 * This works by using the cycle counter shift and mult values in reverse, and
 * assumes that the values we're shifting will not overflow.
 */
static void ixgbe_ptp_setup_sdp_X550(struct ixgbe_adapter *adapter)
{
	u32 esdp, tsauxc, freqout, trgttiml, trgttimh, rem, tssdp;
	struct cyclecounter *cc = &adapter->hw_cc;
	struct ixgbe_hw *hw = &adapter->hw;
	u64 ns = 0, clock_edge = 0;
	struct timespec64 ts;
	unsigned long flags;

	/* disable the pin first */
	IXGBE_WRITE_REG(hw, IXGBE_TSAUXC, 0x0);
	IXGBE_WRITE_FLUSH(hw);

	if (!(adapter->flags2 & IXGBE_FLAG2_PTP_PPS_ENABLED))
		return;

	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 use Target Time 0 to
	 * enable generation of interrupts on the clock change.
	 */
#define IXGBE_TSAUXC_DIS_TS_CLEAR 0x40000000
	tsauxc = (IXGBE_TSAUXC_EN_CLK | IXGBE_TSAUXC_ST0 |
		  IXGBE_TSAUXC_EN_TT0 | IXGBE_TSAUXC_SDP0_INT |
		  IXGBE_TSAUXC_DIS_TS_CLEAR);

	tssdp = (IXGBE_TSSDP_TS_SDP0_EN |
		 IXGBE_TSSDP_TS_SDP0_CLK0);

	/* Determine the clock time period to use. This assumes that the
	 * cycle counter shift is small enough to avoid overflowing a 32bit
	 * value.
	 */
	freqout = div_u64(NS_PER_HALF_SEC << cc->shift,  cc->mult);

	/* Read the current clock time, and save the cycle counter value */
	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	ns = timecounter_read(&adapter->hw_tc);
	clock_edge = adapter->hw_tc.cycle_last;
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	/* Figure out how far past the next second we are */
	div_u64_rem(ns, NS_PER_SEC, &rem);

	/* Figure out how many nanoseconds to add to round the clock edge up
	 * to the next full second
	 */
	rem = (NS_PER_SEC - rem);

	/* Adjust the clock edge to align with the next full second. */
	clock_edge += div_u64(((u64)rem << cc->shift), cc->mult);

	/* X550 hardware stores the time in 32bits of 'billions of cycles' and
	 * 32bits of 'cycles'. There's no guarantee that cycles represents
	 * nanoseconds. However, we can use the math from a timespec64 to
	 * convert into the hardware representation.
	 *
	 * See ixgbe_ptp_read_X550() for more details.
	 */
	ts = ns_to_timespec64(clock_edge);
	trgttiml = (u32)ts.tv_nsec;
	trgttimh = (u32)ts.tv_sec;

	IXGBE_WRITE_REG(hw, IXGBE_FREQOUT0, freqout);
	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_TSSDP, tssdp);
	IXGBE_WRITE_REG(hw, IXGBE_TSAUXC, tsauxc);

	IXGBE_WRITE_FLUSH(hw);
}

/**
 * ixgbe_ptp_read_X550 - read cycle counter value
 * @cc: cyclecounter structure
 *
 * This function reads SYSTIME registers. It is called by the cyclecounter
 * structure to convert from internal representation into nanoseconds. We need
 * this for X550 since some skews do not have expected clock frequency and
 * result of SYSTIME is 32bits of "billions of cycles" and 32 bits of
 * "cycles", rather than seconds and nanoseconds.
 */
static u64 ixgbe_ptp_read_X550(const struct cyclecounter *cc)
{
	struct ixgbe_adapter *adapter =
		container_of(cc, struct ixgbe_adapter, hw_cc);
	struct ixgbe_hw *hw = &adapter->hw;
	struct timespec64 ts;

	/* storage is 32 bits of 'billions of cycles' and 32 bits of 'cycles'.
	 * Some revisions of hardware run at a higher frequency and so the
	 * cycles are not guaranteed to be nanoseconds. The timespec64 created
	 * here is used for its math/conversions but does not necessarily
	 * represent nominal time.
	 *
	 * It should be noted that this cyclecounter will overflow at a
	 * non-bitmask field since we have to convert our billions of cycles
	 * into an actual cycles count. This results in some possible weird
	 * situations at high cycle counter stamps. However given that 32 bits
	 * of "seconds" is ~138 years this isn't a problem. Even at the
	 * increased frequency of some revisions, this is still ~103 years.
	 * Since the SYSTIME values start at 0 and we never write them, it is
	 * highly unlikely for the cyclecounter to overflow in practice.
	 */
	IXGBE_READ_REG(hw, IXGBE_SYSTIMR);
	ts.tv_nsec = IXGBE_READ_REG(hw, IXGBE_SYSTIML);
	ts.tv_sec = IXGBE_READ_REG(hw, IXGBE_SYSTIMH);

	return (u64)timespec64_to_ns(&ts);
}

/**
 * ixgbe_ptp_read_82599 - read raw cycle counter (to be used by time counter)
 * @cc: the cyclecounter structure
 *
 * this function reads the cyclecounter registers and is called by the
 * cyclecounter structure used to construct a ns counter from the
 * arbitrary fixed point registers
 */
static u64 ixgbe_ptp_read_82599(const struct cyclecounter *cc)
{
	struct ixgbe_adapter *adapter =
		container_of(cc, struct ixgbe_adapter, hw_cc);
	struct ixgbe_hw *hw = &adapter->hw;
	u64 stamp = 0;

	stamp |= (u64)IXGBE_READ_REG(hw, IXGBE_SYSTIML);
	stamp |= (u64)IXGBE_READ_REG(hw, IXGBE_SYSTIMH) << 32;

	return stamp;
}

/**
 * ixgbe_ptp_convert_to_hwtstamp - convert register value to hw timestamp
 * @adapter: private adapter structure
 * @hwtstamp: stack timestamp structure
 * @timestamp: unsigned 64bit system time value
 *
 * We need to convert the adapter's RX/TXSTMP registers into a hwtstamp value
 * which can be used by the stack's ptp functions.
 *
 * The lock is used to protect consistency of the cyclecounter and the SYSTIME
 * registers. However, it does not need to protect against the Rx or Tx
 * timestamp registers, as there can't be a new timestamp until the old one is
 * unlatched by reading.
 *
 * In addition to the timestamp in hardware, some controllers need a software
 * overflow cyclecounter, and this function takes this into account as well.
 **/
static void ixgbe_ptp_convert_to_hwtstamp(struct ixgbe_adapter *adapter,
					  struct skb_shared_hwtstamps *hwtstamp,
					  u64 timestamp)
{
	unsigned long flags;
	struct timespec64 systime;
	u64 ns;

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

	switch (adapter->hw.mac.type) {
	/* X550 and later hardware supposedly represent time using a seconds
	 * and nanoseconds counter, instead of raw 64bits nanoseconds. We need
	 * to convert the timestamp into cycles before it can be fed to the
	 * cyclecounter. We need an actual cyclecounter because some revisions
	 * of hardware run at a higher frequency and thus the counter does
	 * not represent seconds/nanoseconds. Instead it can be thought of as
	 * cycles and billions of cycles.
	 */
	case ixgbe_mac_X550:
	case ixgbe_mac_X550EM_x:
	case ixgbe_mac_x550em_a:
		/* Upper 32 bits represent billions of cycles, lower 32 bits
		 * represent cycles. However, we use timespec64_to_ns for the
		 * correct math even though the units haven't been corrected
		 * yet.
		 */
		systime.tv_sec = timestamp >> 32;
		systime.tv_nsec = timestamp & 0xFFFFFFFF;

		timestamp = timespec64_to_ns(&systime);
		break;
	default:
		break;
	}

	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	ns = timecounter_cyc2time(&adapter->hw_tc, timestamp);
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	hwtstamp->hwtstamp = ns_to_ktime(ns);
}

/**
 * ixgbe_ptp_adjfine_82599
 * @ptp: the ptp clock structure
 * @scaled_ppm: scaled parts per million adjustment from base
 *
 * Adjust the frequency of the ptp cycle counter by the
 * indicated scaled_ppm from the base frequency.
 *
 * Scaled parts per million is ppm with a 16-bit binary fractional field.
 */
static int ixgbe_ptp_adjfine_82599(struct ptp_clock_info *ptp, long scaled_ppm)
{
	struct ixgbe_adapter *adapter =
		container_of(ptp, struct ixgbe_adapter, ptp_caps);
	struct ixgbe_hw *hw = &adapter->hw;
	u64 incval;

	smp_mb();
	incval = READ_ONCE(adapter->base_incval);
	incval = adjust_by_scaled_ppm(incval, scaled_ppm);

	switch (hw->mac.type) {
	case ixgbe_mac_X540:
		if (incval > 0xFFFFFFFFULL)
			e_dev_warn("PTP scaled_ppm adjusted SYSTIME rate overflowed!\n");
		IXGBE_WRITE_REG(hw, IXGBE_TIMINCA, (u32)incval);
		break;
	case ixgbe_mac_82599EB:
		if (incval > 0x00FFFFFFULL)
			e_dev_warn("PTP scaled_ppm adjusted SYSTIME rate overflowed!\n");
		IXGBE_WRITE_REG(hw, IXGBE_TIMINCA,
				BIT(IXGBE_INCPER_SHIFT_82599) |
				((u32)incval & 0x00FFFFFFUL));
		break;
	default:
		break;
	}

	return 0;
}

/**
 * ixgbe_ptp_adjfine_X550
 * @ptp: the ptp clock structure
 * @scaled_ppm: scaled parts per million adjustment from base
 *
 * Adjust the frequency of the SYSTIME registers by the indicated scaled_ppm
 * from base frequency.
 *
 * Scaled parts per million is ppm with a 16-bit binary fractional field.
 */
static int ixgbe_ptp_adjfine_X550(struct ptp_clock_info *ptp, long scaled_ppm)
{
	struct ixgbe_adapter *adapter =
			container_of(ptp, struct ixgbe_adapter, ptp_caps);
	struct ixgbe_hw *hw = &adapter->hw;
	bool neg_adj;
	u64 rate;
	u32 inca;

	neg_adj = diff_by_scaled_ppm(IXGBE_X550_BASE_PERIOD, scaled_ppm, &rate);

	/* warn if rate is too large */
	if (rate >= INCVALUE_MASK)
		e_dev_warn("PTP scaled_ppm adjusted SYSTIME rate overflowed!\n");

	inca = rate & INCVALUE_MASK;
	if (neg_adj)
		inca |= ISGN;

	IXGBE_WRITE_REG(hw, IXGBE_TIMINCA, inca);

	return 0;
}

/**
 * ixgbe_ptp_adjtime
 * @ptp: the ptp clock structure
 * @delta: offset to adjust the cycle counter by
 *
 * adjust the timer by resetting the timecounter structure.
 */
static int ixgbe_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
	struct ixgbe_adapter *adapter =
		container_of(ptp, struct ixgbe_adapter, ptp_caps);
	unsigned long flags;

	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	timecounter_adjtime(&adapter->hw_tc, delta);
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	if (adapter->ptp_setup_sdp)
		adapter->ptp_setup_sdp(adapter);

	return 0;
}

/**
 * ixgbe_ptp_gettimex
 * @ptp: the ptp clock structure
 * @ts: timespec to hold the PHC timestamp
 * @sts: structure to hold the system time before and after reading the PHC
 *
 * read the timecounter and return the correct value on ns,
 * after converting it into a struct timespec.
 */
static int ixgbe_ptp_gettimex(struct ptp_clock_info *ptp,
			      struct timespec64 *ts,
			      struct ptp_system_timestamp *sts)
{
	struct ixgbe_adapter *adapter =
		container_of(ptp, struct ixgbe_adapter, ptp_caps);
	struct ixgbe_hw *hw = &adapter->hw;
	unsigned long flags;
	u64 ns, stamp;

	spin_lock_irqsave(&adapter->tmreg_lock, flags);

	switch (adapter->hw.mac.type) {
	case ixgbe_mac_X550:
	case ixgbe_mac_X550EM_x:
	case ixgbe_mac_x550em_a:
		/* Upper 32 bits represent billions of cycles, lower 32 bits
		 * represent cycles. However, we use timespec64_to_ns for the
		 * correct math even though the units haven't been corrected
		 * yet.
		 */
		ptp_read_system_prets(sts);
		IXGBE_READ_REG(hw, IXGBE_SYSTIMR);
		ptp_read_system_postts(sts);
		ts->tv_nsec = IXGBE_READ_REG(hw, IXGBE_SYSTIML);
		ts->tv_sec = IXGBE_READ_REG(hw, IXGBE_SYSTIMH);
		stamp = timespec64_to_ns(ts);
		break;
	default:
		ptp_read_system_prets(sts);
		stamp = IXGBE_READ_REG(hw, IXGBE_SYSTIML);
		ptp_read_system_postts(sts);
		stamp |= (u64)IXGBE_READ_REG(hw, IXGBE_SYSTIMH) << 32;
		break;
	}

	ns = timecounter_cyc2time(&adapter->hw_tc, stamp);

	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	*ts = ns_to_timespec64(ns);

	return 0;
}

/**
 * ixgbe_ptp_settime
 * @ptp: the ptp clock structure
 * @ts: the timespec containing the new time for the cycle counter
 *
 * reset the timecounter to use a new base value instead of the kernel
 * wall timer value.
 */
static int ixgbe_ptp_settime(struct ptp_clock_info *ptp,
			     const struct timespec64 *ts)
{
	struct ixgbe_adapter *adapter =
		container_of(ptp, struct ixgbe_adapter, ptp_caps);
	unsigned long flags;
	u64 ns = timespec64_to_ns(ts);

	/* reset the timecounter */
	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	timecounter_init(&adapter->hw_tc, &adapter->hw_cc, ns);
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	if (adapter->ptp_setup_sdp)
		adapter->ptp_setup_sdp(adapter);
	return 0;
}

/**
 * ixgbe_ptp_feature_enable
 * @ptp: the ptp clock structure
 * @rq: the requested feature to change
 * @on: whether to enable or disable the feature
 *
 * enable (or disable) ancillary features of the phc subsystem.
 * our driver only supports the PPS feature on the X540
 */
static int ixgbe_ptp_feature_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 || !adapter->ptp_setup_sdp)
		return -ENOTSUPP;

	if (on)
		adapter->flags2 |= IXGBE_FLAG2_PTP_PPS_ENABLED;
	else
		adapter->flags2 &= ~IXGBE_FLAG2_PTP_PPS_ENABLED;

	adapter->ptp_setup_sdp(adapter);
	return 0;
}

/**
 * ixgbe_ptp_check_pps_event
 * @adapter: the private adapter structure
 *
 * 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)
{
	struct ixgbe_hw *hw = &adapter->hw;
	struct ptp_clock_event event;

	event.type = PTP_CLOCK_PPS;

	/* this check is necessary in case the interrupt was enabled via some
	 * alternative means (ex. debug_fs). Better to check here than
	 * everywhere that calls this function.
	 */
	if (!adapter->ptp_clock)
		return;

	switch (hw->mac.type) {
	case ixgbe_mac_X540:
		ptp_clock_event(adapter->ptp_clock, &event);
		break;
	default:
		break;
	}
}

/**
 * ixgbe_ptp_overflow_check - watchdog task to detect SYSTIME overflow
 * @adapter: private adapter struct
 *
 * this watchdog task periodically reads the timecounter
 * in order to prevent missing when the system time registers wrap
 * around. This needs to be run approximately twice a minute.
 */
void ixgbe_ptp_overflow_check(struct ixgbe_adapter *adapter)
{
	bool timeout = time_is_before_jiffies(adapter->last_overflow_check +
					     IXGBE_OVERFLOW_PERIOD);
	unsigned long flags;

	if (timeout) {
		/* Update the timecounter */
		spin_lock_irqsave(&adapter->tmreg_lock, flags);
		timecounter_read(&adapter->hw_tc);
		spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

		adapter->last_overflow_check = jiffies;
	}
}

/**
 * ixgbe_ptp_rx_hang - detect error case when Rx timestamp registers latched
 * @adapter: private network adapter structure
 *
 * this watchdog task is scheduled to detect error case where hardware has
 * dropped an Rx packet that was timestamped when the ring is full. The
 * particular error is rare but leaves the device in a state unable to timestamp
 * any future packets.
 */
void ixgbe_ptp_rx_hang(struct ixgbe_adapter *adapter)
{
	struct ixgbe_hw *hw = &adapter->hw;
	u32 tsyncrxctl = IXGBE_READ_REG(hw, IXGBE_TSYNCRXCTL);
	struct ixgbe_ring *rx_ring;
	unsigned long rx_event;
	int n;

	/* if we don't have a valid timestamp in the registers, just update the
	 * timeout counter and exit
	 */
	if (!(tsyncrxctl & IXGBE_TSYNCRXCTL_VALID)) {
		adapter->last_rx_ptp_check = jiffies;
		return;
	}

	/* determine the most recent watchdog or rx_timestamp event */
	rx_event = adapter->last_rx_ptp_check;
	for (n = 0; n < adapter->num_rx_queues; n++) {
		rx_ring = adapter->rx_ring[n];
		if (time_after(rx_ring->last_rx_timestamp, rx_event))
			rx_event = rx_ring->last_rx_timestamp;
	}

	/* only need to read the high RXSTMP register to clear the lock */
	if (time_is_before_jiffies(rx_event + 5 * HZ)) {
		IXGBE_READ_REG(hw, IXGBE_RXSTMPH);
		adapter->last_rx_ptp_check = jiffies;

		adapter->rx_hwtstamp_cleared++;
		e_warn(drv, "clearing RX Timestamp hang\n");
	}
}

/**
 * ixgbe_ptp_clear_tx_timestamp - utility function to clear Tx timestamp state
 * @adapter: the private adapter structure
 *
 * This function should be called whenever the state related to a Tx timestamp
 * needs to be cleared. This helps ensure that all related bits are reset for
 * the next Tx timestamp event.
 */
static void ixgbe_ptp_clear_tx_timestamp(struct ixgbe_adapter *adapter)
{
	struct ixgbe_hw *hw = &adapter->hw;

	IXGBE_READ_REG(hw, IXGBE_TXSTMPH);
	if (adapter->ptp_tx_skb) {
		dev_kfree_skb_any(adapter->ptp_tx_skb);
		adapter->ptp_tx_skb = NULL;
	}
	clear_bit_unlock(__IXGBE_PTP_TX_IN_PROGRESS, &adapter->state);
}

/**
 * ixgbe_ptp_tx_hang - detect error case where Tx timestamp never finishes
 * @adapter: private network adapter structure
 */
void ixgbe_ptp_tx_hang(struct ixgbe_adapter *adapter)
{
	bool timeout = time_is_before_jiffies(adapter->ptp_tx_start +
					      IXGBE_PTP_TX_TIMEOUT);

	if (!adapter->ptp_tx_skb)
		return;

	if (!test_bit(__IXGBE_PTP_TX_IN_PROGRESS, &adapter->state))
		return;

	/* If we haven't received a timestamp within the timeout, it is
	 * reasonable to assume that it will never occur, so we can unlock the
	 * timestamp bit when this occurs.
	 */
	if (timeout) {
		cancel_work_sync(&adapter->ptp_tx_work);
		ixgbe_ptp_clear_tx_timestamp(adapter);
		adapter->tx_hwtstamp_timeouts++;
		e_warn(drv, "clearing Tx timestamp hang\n");
	}
}

/**
 * ixgbe_ptp_tx_hwtstamp - utility function which checks for TX time stamp
 * @adapter: the private adapter struct
 *
 * if the timestamp is valid, we convert it into the timecounter ns
 * value, then store that result into the shhwtstamps structure which
 * is passed up the network stack
 */
static void ixgbe_ptp_tx_hwtstamp(struct ixgbe_adapter *adapter)
{
	struct sk_buff *skb = adapter->ptp_tx_skb;
	struct ixgbe_hw *hw = &adapter->hw;
	struct skb_shared_hwtstamps shhwtstamps;
	u64 regval = 0;

	regval |= (u64)IXGBE_READ_REG(hw, IXGBE_TXSTMPL);
	regval |= (u64)IXGBE_READ_REG(hw, IXGBE_TXSTMPH) << 32;
	ixgbe_ptp_convert_to_hwtstamp(adapter, &shhwtstamps, regval);

	/* Handle cleanup of the ptp_tx_skb ourselves, and unlock the state
	 * bit prior to notifying the stack via skb_tstamp_tx(). This prevents
	 * well behaved applications from attempting to timestamp again prior
	 * to the lock bit being clear.
	 */
	adapter->ptp_tx_skb = NULL;
	clear_bit_unlock(__IXGBE_PTP_TX_IN_PROGRESS, &adapter->state);

	/* Notify the stack and then free the skb after we've unlocked */
	skb_tstamp_tx(skb, &shhwtstamps);
	dev_kfree_skb_any(skb);
}

/**
 * ixgbe_ptp_tx_hwtstamp_work
 * @work: pointer to the work struct
 *
 * This work item polls TSYNCTXCTL valid bit to determine when a Tx hardware
 * timestamp has been taken for the current skb. It is necessary, because the
 * descriptor's "done" bit does not correlate with the timestamp event.
 */
static void ixgbe_ptp_tx_hwtstamp_work(struct work_struct *work)
{
	struct ixgbe_adapter *adapter = container_of(work, struct ixgbe_adapter,
						     ptp_tx_work);
	struct ixgbe_hw *hw = &adapter->hw;
	bool timeout = time_is_before_jiffies(adapter->ptp_tx_start +
					      IXGBE_PTP_TX_TIMEOUT);
	u32 tsynctxctl;

	/* we have to have a valid skb to poll for a timestamp */
	if (!adapter->ptp_tx_skb) {
		ixgbe_ptp_clear_tx_timestamp(adapter);
		return;
	}

	/* stop polling once we have a valid timestamp */
	tsynctxctl = IXGBE_READ_REG(hw, IXGBE_TSYNCTXCTL);
	if (tsynctxctl & IXGBE_TSYNCTXCTL_VALID) {
		ixgbe_ptp_tx_hwtstamp(adapter);
		return;
	}

	if (timeout) {
		ixgbe_ptp_clear_tx_timestamp(adapter);
		adapter->tx_hwtstamp_timeouts++;
		e_warn(drv, "clearing Tx Timestamp hang\n");
	} else {
		/* reschedule to keep checking if it's not available yet */
		schedule_work(&adapter->ptp_tx_work);
	}
}

/**
 * ixgbe_ptp_rx_pktstamp - utility function to get RX time stamp from buffer
 * @q_vector: structure containing interrupt and ring information
 * @skb: the packet
 *
 * This function will be called by the Rx routine of the timestamp for this
 * packet is stored in the buffer. The value is stored in little endian format
 * starting at the end of the packet data.
 */
void ixgbe_ptp_rx_pktstamp(struct ixgbe_q_vector *q_vector,
			   struct sk_buff *skb)
{
	__le64 regval;

	/* copy the bits out of the skb, and then trim the skb length */
	skb_copy_bits(skb, skb->len - IXGBE_TS_HDR_LEN, &regval,
		      IXGBE_TS_HDR_LEN);
	__pskb_trim(skb, skb->len - IXGBE_TS_HDR_LEN);

	/* The timestamp is recorded in little endian format, and is stored at
	 * the end of the packet.
	 *
	 * DWORD: N              N + 1      N + 2
	 * Field: End of Packet  SYSTIMH    SYSTIML
	 */
	ixgbe_ptp_convert_to_hwtstamp(q_vector->adapter, skb_hwtstamps(skb),
				      le64_to_cpu(regval));
}

/**
 * ixgbe_ptp_rx_rgtstamp - utility function which checks for RX time stamp
 * @q_vector: structure containing interrupt and ring information
 * @skb: particular skb to send timestamp with
 *
 * if the timestamp is valid, we convert it into the timecounter ns
 * value, then store that result into the shhwtstamps structure which
 * is passed up the network stack
 */
void ixgbe_ptp_rx_rgtstamp(struct ixgbe_q_vector *q_vector,
			   struct sk_buff *skb)
{
	struct ixgbe_adapter *adapter;
	struct ixgbe_hw *hw;
	u64 regval = 0;
	u32 tsyncrxctl;

	/* we cannot process timestamps on a ring without a q_vector */
	if (!q_vector || !q_vector->adapter)
		return;

	adapter = q_vector->adapter;
	hw = &adapter->hw;

	/* Read the tsyncrxctl register afterwards in order to prevent taking an
	 * I/O hit on every packet.
	 */

	tsyncrxctl = IXGBE_READ_REG(hw, IXGBE_TSYNCRXCTL);
	if (!(tsyncrxctl & IXGBE_TSYNCRXCTL_VALID))
		return;

	regval |= (u64)IXGBE_READ_REG(hw, IXGBE_RXSTMPL);
	regval |= (u64)IXGBE_READ_REG(hw, IXGBE_RXSTMPH) << 32;

	ixgbe_ptp_convert_to_hwtstamp(adapter, skb_hwtstamps(skb), regval);
}

/**
 * ixgbe_ptp_get_ts_config - get current hardware timestamping configuration
 * @adapter: pointer to adapter structure
 * @ifr: ioctl data
 *
 * This function returns the current timestamping settings. Rather than
 * attempt to deconstruct registers to fill in the values, simply keep a copy
 * of the old settings around, and return a copy when requested.
 */
int ixgbe_ptp_get_ts_config(struct ixgbe_adapter *adapter, struct ifreq *ifr)
{
	struct hwtstamp_config *config = &adapter->tstamp_config;

	return copy_to_user(ifr->ifr_data, config,
			    sizeof(*config)) ? -EFAULT : 0;
}

/**
 * ixgbe_ptp_set_timestamp_mode - setup the hardware for the requested mode
 * @adapter: the private ixgbe adapter structure
 * @config: the hwtstamp configuration requested
 *
 * Outgoing time stamping can be enabled and disabled. Play nice and
 * disable it when requested, although it shouldn't cause any overhead
 * when no packet needs it. At most one packet in the queue may be
 * marked for time stamping, otherwise it would be impossible to tell
 * for sure to which packet the hardware time stamp belongs.
 *
 * Incoming time stamping has to be configured via the hardware
 * filters. Not all combinations are supported, in particular event
 * type has to be specified. Matching the kind of event packet is
 * not supported, with the exception of "all V2 events regardless of
 * level 2 or 4".
 *
 * Since hardware always timestamps Path delay packets when timestamping V2
 * packets, regardless of the type specified in the register, only use V2
 * Event mode. This more accurately tells the user what the hardware is going
 * to do anyways.
 *
 * Note: this may modify the hwtstamp configuration towards a more general
 * mode, if required to support the specifically requested mode.
 */
static int ixgbe_ptp_set_timestamp_mode(struct ixgbe_adapter *adapter,
				 struct hwtstamp_config *config)
{
	struct ixgbe_hw *hw = &adapter->hw;
	u32 tsync_tx_ctl = IXGBE_TSYNCTXCTL_ENABLED;
	u32 tsync_rx_ctl = IXGBE_TSYNCRXCTL_ENABLED;
	u32 tsync_rx_mtrl = PTP_EV_PORT << 16;
	u32 aflags = adapter->flags;
	bool is_l2 = false;
	u32 regval;

	switch (config->tx_type) {
	case HWTSTAMP_TX_OFF:
		tsync_tx_ctl = 0;
		break;
	case HWTSTAMP_TX_ON:
		break;
	default:
		return -ERANGE;
	}

	switch (config->rx_filter) {
	case HWTSTAMP_FILTER_NONE:
		tsync_rx_ctl = 0;
		tsync_rx_mtrl = 0;
		aflags &= ~(IXGBE_FLAG_RX_HWTSTAMP_ENABLED |
			    IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER);
		break;
	case HWTSTAMP_FILTER_PTP_V1_L4_SYNC:
		tsync_rx_ctl |= IXGBE_TSYNCRXCTL_TYPE_L4_V1;
		tsync_rx_mtrl |= IXGBE_RXMTRL_V1_SYNC_MSG;
		aflags |= (IXGBE_FLAG_RX_HWTSTAMP_ENABLED |
			   IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER);
		break;
	case HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ:
		tsync_rx_ctl |= IXGBE_TSYNCRXCTL_TYPE_L4_V1;
		tsync_rx_mtrl |= IXGBE_RXMTRL_V1_DELAY_REQ_MSG;
		aflags |= (IXGBE_FLAG_RX_HWTSTAMP_ENABLED |
			   IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER);
		break;
	case HWTSTAMP_FILTER_PTP_V2_EVENT:
	case HWTSTAMP_FILTER_PTP_V2_L2_EVENT:
	case HWTSTAMP_FILTER_PTP_V2_L4_EVENT:
	case HWTSTAMP_FILTER_PTP_V2_SYNC:
	case HWTSTAMP_FILTER_PTP_V2_L2_SYNC:
	case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
	case HWTSTAMP_FILTER_PTP_V2_DELAY_REQ:
	case HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ:
	case HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ:
		tsync_rx_ctl |= IXGBE_TSYNCRXCTL_TYPE_EVENT_V2;
		is_l2 = true;
		config->rx_filter = HWTSTAMP_FILTER_PTP_V2_EVENT;
		aflags |= (IXGBE_FLAG_RX_HWTSTAMP_ENABLED |
			   IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER);
		break;
	case HWTSTAMP_FILTER_PTP_V1_L4_EVENT:
	case HWTSTAMP_FILTER_NTP_ALL:
	case HWTSTAMP_FILTER_ALL:
		/* The X550 controller is capable of timestamping all packets,
		 * which allows it to accept any filter.
		 */
		if (hw->mac.type >= ixgbe_mac_X550) {
			tsync_rx_ctl |= IXGBE_TSYNCRXCTL_TYPE_ALL;
			config->rx_filter = HWTSTAMP_FILTER_ALL;
			aflags |= IXGBE_FLAG_RX_HWTSTAMP_ENABLED;
			break;
		}
		fallthrough;
	default:
		/*
		 * register RXMTRL must be set in order to do V1 packets,
		 * therefore it is not possible to time stamp both V1 Sync and
		 * Delay_Req messages and hardware does not support
		 * timestamping all packets => return error
		 */
		config->rx_filter = HWTSTAMP_FILTER_NONE;
		return -ERANGE;
	}

	if (hw->mac.type == ixgbe_mac_82598EB) {
		adapter->flags &= ~(IXGBE_FLAG_RX_HWTSTAMP_ENABLED |
				    IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER);
		if (tsync_rx_ctl | tsync_tx_ctl)
			return -ERANGE;
		return 0;
	}

	/* Per-packet timestamping only works if the filter is set to all
	 * packets. Since this is desired, always timestamp all packets as long
	 * as any Rx filter was configured.
	 */
	switch (hw->mac.type) {
	case ixgbe_mac_X550:
	case ixgbe_mac_X550EM_x:
	case ixgbe_mac_x550em_a:
		/* enable timestamping all packets only if at least some
		 * packets were requested. Otherwise, play nice and disable
		 * timestamping
		 */
		if (config->rx_filter == HWTSTAMP_FILTER_NONE)
			break;

		tsync_rx_ctl = IXGBE_TSYNCRXCTL_ENABLED |
			       IXGBE_TSYNCRXCTL_TYPE_ALL |
			       IXGBE_TSYNCRXCTL_TSIP_UT_EN;
		config->rx_filter = HWTSTAMP_FILTER_ALL;
		aflags |= IXGBE_FLAG_RX_HWTSTAMP_ENABLED;
		aflags &= ~IXGBE_FLAG_RX_HWTSTAMP_IN_REGISTER;
		is_l2 = true;
		break;
	default:
		break;
	}

	/* define ethertype filter for timestamping L2 packets */
	if (is_l2)
		IXGBE_WRITE_REG(hw, IXGBE_ETQF(IXGBE_ETQF_FILTER_1588),
				(IXGBE_ETQF_FILTER_EN | /* enable filter */
				 IXGBE_ETQF_1588 | /* enable timestamping */
				 ETH_P_1588));     /* 1588 eth protocol type */
	else
		IXGBE_WRITE_REG(hw, IXGBE_ETQF(IXGBE_ETQF_FILTER_1588), 0);

	/* enable/disable TX */
	regval = IXGBE_READ_REG(hw, IXGBE_TSYNCTXCTL);
	regval &= ~IXGBE_TSYNCTXCTL_ENABLED;
	regval |= tsync_tx_ctl;
	IXGBE_WRITE_REG(hw, IXGBE_TSYNCTXCTL, regval);

	/* enable/disable RX */
	regval = IXGBE_READ_REG(hw, IXGBE_TSYNCRXCTL);
	regval &= ~(IXGBE_TSYNCRXCTL_ENABLED | IXGBE_TSYNCRXCTL_TYPE_MASK);
	regval |= tsync_rx_ctl;
	IXGBE_WRITE_REG(hw, IXGBE_TSYNCRXCTL, regval);

	/* define which PTP packets are time stamped */
	IXGBE_WRITE_REG(hw, IXGBE_RXMTRL, tsync_rx_mtrl);

	IXGBE_WRITE_FLUSH(hw);

	/* configure adapter flags only when HW is actually configured */
	adapter->flags = aflags;

	/* clear TX/RX time stamp registers, just to be sure */
	ixgbe_ptp_clear_tx_timestamp(adapter);
	IXGBE_READ_REG(hw, IXGBE_RXSTMPH);

	return 0;
}

/**
 * ixgbe_ptp_set_ts_config - user entry point for timestamp mode
 * @adapter: pointer to adapter struct
 * @ifr: ioctl data
 *
 * Set hardware to requested mode. If unsupported, return an error with no
 * changes. Otherwise, store the mode for future reference.
 */
int ixgbe_ptp_set_ts_config(struct ixgbe_adapter *adapter, struct ifreq *ifr)
{
	struct hwtstamp_config config;
	int err;

	if (copy_from_user(&config, ifr->ifr_data, sizeof(config)))
		return -EFAULT;

	err = ixgbe_ptp_set_timestamp_mode(adapter, &config);
	if (err)
		return err;

	/* save these settings for future reference */
	memcpy(&adapter->tstamp_config, &config,
	       sizeof(adapter->tstamp_config));

	return copy_to_user(ifr->ifr_data, &config, sizeof(config)) ?
		-EFAULT : 0;
}

static void ixgbe_ptp_link_speed_adjust(struct ixgbe_adapter *adapter,
					u32 *shift, u32 *incval)
{
	/**
	 * Scale the NIC cycle counter by a large factor so that
	 * relatively small corrections to the frequency can be added
	 * or subtracted. The drawbacks of a large factor include
	 * (a) the clock register overflows more quickly, (b) the cycle
	 * counter structure must be able to convert the systime value
	 * to nanoseconds using only a multiplier and a right-shift,
	 * and (c) the value must fit within the timinca register space
	 * => math based on internal DMA clock rate and available bits
	 *
	 * Note that when there is no link, internal DMA clock is same as when
	 * link speed is 10Gb. Set the registers correctly even when link is
	 * down to preserve the clock setting
	 */
	switch (adapter->link_speed) {
	case IXGBE_LINK_SPEED_100_FULL:
		*shift = IXGBE_INCVAL_SHIFT_100;
		*incval = IXGBE_INCVAL_100;
		break;
	case IXGBE_LINK_SPEED_1GB_FULL:
		*shift = IXGBE_INCVAL_SHIFT_1GB;
		*incval = IXGBE_INCVAL_1GB;
		break;
	case IXGBE_LINK_SPEED_10GB_FULL:
	default:
		*shift = IXGBE_INCVAL_SHIFT_10GB;
		*incval = IXGBE_INCVAL_10GB;
		break;
	}
}

/**
 * ixgbe_ptp_start_cyclecounter - create the cycle counter from hw
 * @adapter: pointer to the adapter structure
 *
 * This function should be called to set the proper values for the TIMINCA
 * register and tell the cyclecounter structure what the tick rate of SYSTIME
 * is. It does not directly modify SYSTIME registers or the timecounter
 * structure. It should be called whenever a new TIMINCA value is necessary,
 * such as during initialization or when the link speed changes.
 */
void ixgbe_ptp_start_cyclecounter(struct ixgbe_adapter *adapter)
{
	struct ixgbe_hw *hw = &adapter->hw;
	struct cyclecounter cc;
	unsigned long flags;
	u32 incval = 0;
	u32 fuse0 = 0;

	/* For some of the boards below this mask is technically incorrect.
	 * The timestamp mask overflows at approximately 61bits. However the
	 * particular hardware does not overflow on an even bitmask value.
	 * Instead, it overflows due to conversion of upper 32bits billions of
	 * cycles. Timecounters are not really intended for this purpose so
	 * they do not properly function if the overflow point isn't 2^N-1.
	 * However, the actual SYSTIME values in question take ~138 years to
	 * overflow. In practice this means they won't actually overflow. A
	 * proper fix to this problem would require modification of the
	 * timecounter delta calculations.
	 */
	cc.mask = CLOCKSOURCE_MASK(64);
	cc.mult = 1;
	cc.shift = 0;

	switch (hw->mac.type) {
	case ixgbe_mac_X550EM_x:
		/* SYSTIME assumes X550EM_x board frequency is 300Mhz, and is
		 * designed to represent seconds and nanoseconds when this is
		 * the case. However, some revisions of hardware have a 400Mhz
		 * clock and we have to compensate for this frequency
		 * variation using corrected mult and shift values.
		 */
		fuse0 = IXGBE_READ_REG(hw, IXGBE_FUSES0_GROUP(0));
		if (!(fuse0 & IXGBE_FUSES0_300MHZ)) {
			cc.mult = 3;
			cc.shift = 2;
		}
		fallthrough;
	case ixgbe_mac_x550em_a:
	case ixgbe_mac_X550:
		cc.read = ixgbe_ptp_read_X550;
		break;
	case ixgbe_mac_X540:
		cc.read = ixgbe_ptp_read_82599;

		ixgbe_ptp_link_speed_adjust(adapter, &cc.shift, &incval);
		IXGBE_WRITE_REG(hw, IXGBE_TIMINCA, incval);
		break;
	case ixgbe_mac_82599EB:
		cc.read = ixgbe_ptp_read_82599;

		ixgbe_ptp_link_speed_adjust(adapter, &cc.shift, &incval);
		incval >>= IXGBE_INCVAL_SHIFT_82599;
		cc.shift -= IXGBE_INCVAL_SHIFT_82599;
		IXGBE_WRITE_REG(hw, IXGBE_TIMINCA,
				BIT(IXGBE_INCPER_SHIFT_82599) | incval);
		break;
	default:
		/* other devices aren't supported */
		return;
	}

	/* update the base incval used to calculate frequency adjustment */
	WRITE_ONCE(adapter->base_incval, incval);
	smp_mb();

	/* need lock to prevent incorrect read while modifying cyclecounter */
	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	memcpy(&adapter->hw_cc, &cc, sizeof(adapter->hw_cc));
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
}

/**
 * ixgbe_ptp_init_systime - Initialize SYSTIME registers
 * @adapter: the ixgbe private board structure
 *
 * Initialize and start the SYSTIME registers.
 */
static void ixgbe_ptp_init_systime(struct ixgbe_adapter *adapter)
{
	struct ixgbe_hw *hw = &adapter->hw;
	u32 tsauxc;

	switch (hw->mac.type) {
	case ixgbe_mac_X550EM_x:
	case ixgbe_mac_x550em_a:
	case ixgbe_mac_X550:
		tsauxc = IXGBE_READ_REG(hw, IXGBE_TSAUXC);

		/* Reset SYSTIME registers to 0 */
		IXGBE_WRITE_REG(hw, IXGBE_SYSTIMR, 0);
		IXGBE_WRITE_REG(hw, IXGBE_SYSTIML, 0);
		IXGBE_WRITE_REG(hw, IXGBE_SYSTIMH, 0);

		/* Reset interrupt settings */
		IXGBE_WRITE_REG(hw, IXGBE_TSIM, IXGBE_TSIM_TXTS);
		IXGBE_WRITE_REG(hw, IXGBE_EIMS, IXGBE_EIMS_TIMESYNC);

		/* Activate the SYSTIME counter */
		IXGBE_WRITE_REG(hw, IXGBE_TSAUXC,
				tsauxc & ~IXGBE_TSAUXC_DISABLE_SYSTIME);
		break;
	case ixgbe_mac_X540:
	case ixgbe_mac_82599EB:
		/* Reset SYSTIME registers to 0 */
		IXGBE_WRITE_REG(hw, IXGBE_SYSTIML, 0);
		IXGBE_WRITE_REG(hw, IXGBE_SYSTIMH, 0);
		break;
	default:
		/* Other devices aren't supported */
		return;
	}

	IXGBE_WRITE_FLUSH(hw);
}

/**
 * ixgbe_ptp_reset
 * @adapter: the ixgbe private board structure
 *
 * When the MAC resets, all the hardware bits for timesync are reset. This
 * function is used to re-enable the device for PTP based on current settings.
 * We do lose the current clock time, so just reset the cyclecounter to the
 * system real clock time.
 *
 * This function will maintain hwtstamp_config settings, and resets the SDP
 * output if it was enabled.
 */
void ixgbe_ptp_reset(struct ixgbe_adapter *adapter)
{
	struct ixgbe_hw *hw = &adapter->hw;
	unsigned long flags;

	/* reset the hardware timestamping mode */
	ixgbe_ptp_set_timestamp_mode(adapter, &adapter->tstamp_config);

	/* 82598 does not support PTP */
	if (hw->mac.type == ixgbe_mac_82598EB)
		return;

	ixgbe_ptp_start_cyclecounter(adapter);

	ixgbe_ptp_init_systime(adapter);

	spin_lock_irqsave(&adapter->tmreg_lock, flags);
	timecounter_init(&adapter->hw_tc, &adapter->hw_cc,
			 ktime_to_ns(ktime_get_real()));
	spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

	adapter->last_overflow_check = jiffies;

	/* Now that the shift has been calculated and the systime
	 * registers reset, (re-)enable the Clock out feature
	 */
	if (adapter->ptp_setup_sdp)
		adapter->ptp_setup_sdp(adapter);
}

/**
 * ixgbe_ptp_create_clock
 * @adapter: the ixgbe private adapter structure
 *
 * This function performs setup of the user entry point function table and
 * initializes the PTP clock device, which is used to access the clock-like
 * features of the PTP core. It will be called by ixgbe_ptp_init, and may
 * reuse a previously initialized clock (such as during a suspend/resume
 * cycle).
 */
static long ixgbe_ptp_create_clock(struct ixgbe_adapter *adapter)
{
	struct net_device *netdev = adapter->netdev;
	long err;

	/* do nothing if we already have a clock device */
	if (!IS_ERR_OR_NULL(adapter->ptp_clock))
		return 0;

	switch (adapter->hw.mac.type) {
	case ixgbe_mac_X540:
		snprintf(adapter->ptp_caps.name,
			 sizeof(adapter->ptp_caps.name),
			 "%s", netdev->name);
		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.adjfine = ixgbe_ptp_adjfine_82599;
		adapter->ptp_caps.adjtime = ixgbe_ptp_adjtime;
		adapter->ptp_caps.gettimex64 = ixgbe_ptp_gettimex;
		adapter->ptp_caps.settime64 = ixgbe_ptp_settime;
		adapter->ptp_caps.enable = ixgbe_ptp_feature_enable;
		adapter->ptp_setup_sdp = ixgbe_ptp_setup_sdp_X540;
		break;
	case ixgbe_mac_82599EB:
		snprintf(adapter->ptp_caps.name,
			 sizeof(adapter->ptp_caps.name),
			 "%s", netdev->name);
		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 = 0;
		adapter->ptp_caps.adjfine = ixgbe_ptp_adjfine_82599;
		adapter->ptp_caps.adjtime = ixgbe_ptp_adjtime;
		adapter->ptp_caps.gettimex64 = ixgbe_ptp_gettimex;
		adapter->ptp_caps.settime64 = ixgbe_ptp_settime;
		adapter->ptp_caps.enable = ixgbe_ptp_feature_enable;
		break;
	case ixgbe_mac_X550:
	case ixgbe_mac_X550EM_x:
	case ixgbe_mac_x550em_a:
		snprintf(adapter->ptp_caps.name, 16, "%s", netdev->name);
		adapter->ptp_caps.owner = THIS_MODULE;
		adapter->ptp_caps.max_adj = 30000000;
		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.adjfine = ixgbe_ptp_adjfine_X550;
		adapter->ptp_caps.adjtime = ixgbe_ptp_adjtime;
		adapter->ptp_caps.gettimex64 = ixgbe_ptp_gettimex;
		adapter->ptp_caps.settime64 = ixgbe_ptp_settime;
		adapter->ptp_caps.enable = ixgbe_ptp_feature_enable;
		adapter->ptp_setup_sdp = ixgbe_ptp_setup_sdp_X550;
		break;
	default:
		adapter->ptp_clock = NULL;
		adapter->ptp_setup_sdp = NULL;
		return -EOPNOTSUPP;
	}

	adapter->ptp_clock = ptp_clock_register(&adapter->ptp_caps,
						&adapter->pdev->dev);
	if (IS_ERR(adapter->ptp_clock)) {
		err = PTR_ERR(adapter->ptp_clock);
		adapter->ptp_clock = NULL;
		e_dev_err("ptp_clock_register failed\n");
		return err;
	} else if (adapter->ptp_clock)
		e_dev_info("registered PHC device on %s\n", netdev->name);

	/* set default timestamp mode to disabled here. We do this in
	 * create_clock instead of init, because we don't want to override the
	 * previous settings during a resume cycle.
	 */
	adapter->tstamp_config.rx_filter = HWTSTAMP_FILTER_NONE;
	adapter->tstamp_config.tx_type = HWTSTAMP_TX_OFF;

	return 0;
}

/**
 * ixgbe_ptp_init
 * @adapter: the ixgbe private adapter structure
 *
 * This function performs the required steps for enabling PTP
 * support. If PTP support has already been loaded it simply calls the
 * cyclecounter init routine and exits.
 */
void ixgbe_ptp_init(struct ixgbe_adapter *adapter)
{
	/* initialize the spin lock first since we can't control when a user
	 * will call the entry functions once we have initialized the clock
	 * device
	 */
	spin_lock_init(&adapter->tmreg_lock);

	/* obtain a PTP device, or re-use an existing device */
	if (ixgbe_ptp_create_clock(adapter))
		return;

	/* we have a clock so we can initialize work now */
	INIT_WORK(&adapter->ptp_tx_work, ixgbe_ptp_tx_hwtstamp_work);

	/* reset the PTP related hardware bits */
	ixgbe_ptp_reset(adapter);

	/* enter the IXGBE_PTP_RUNNING state */
	set_bit(__IXGBE_PTP_RUNNING, &adapter->state);

	return;
}

/**
 * ixgbe_ptp_suspend - stop PTP work items
 * @adapter: pointer to adapter struct
 *
 * this function suspends PTP activity, and prevents more PTP work from being
 * generated, but does not destroy the PTP clock device.
 */
void ixgbe_ptp_suspend(struct ixgbe_adapter *adapter)
{
	/* Leave the IXGBE_PTP_RUNNING state. */
	if (!test_and_clear_bit(__IXGBE_PTP_RUNNING, &adapter->state))
		return;

	adapter->flags2 &= ~IXGBE_FLAG2_PTP_PPS_ENABLED;
	if (adapter->ptp_setup_sdp)
		adapter->ptp_setup_sdp(adapter);

	/* ensure that we cancel any pending PTP Tx work item in progress */
	cancel_work_sync(&adapter->ptp_tx_work);
	ixgbe_ptp_clear_tx_timestamp(adapter);
}

/**
 * ixgbe_ptp_stop - close the PTP device
 * @adapter: pointer to adapter struct
 *
 * completely destroy the PTP device, should only be called when the device is
 * being fully closed.
 */
void ixgbe_ptp_stop(struct ixgbe_adapter *adapter)
{
	/* first, suspend PTP activity */
	ixgbe_ptp_suspend(adapter);

	/* disable the PTP clock device */
	if (adapter->ptp_clock) {
		ptp_clock_unregister(adapter->ptp_clock);
		adapter->ptp_clock = NULL;
		e_dev_info("removed PHC on %s\n",
			   adapter->netdev->name);
	}
}