/****************************************************************************
 * Driver for Solarflare network controllers and boards
 * Copyright 2011-2013 Solarflare Communications Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation, incorporated herein by reference.
 */

/* Theory of operation:
 *
 * PTP support is assisted by firmware running on the MC, which provides
 * the hardware timestamping capabilities.  Both transmitted and received
 * PTP event packets are queued onto internal queues for subsequent processing;
 * this is because the MC operations are relatively long and would block
 * block NAPI/interrupt operation.
 *
 * Receive event processing:
 *      The event contains the packet's UUID and sequence number, together
 *      with the hardware timestamp.  The PTP receive packet queue is searched
 *      for this UUID/sequence number and, if found, put on a pending queue.
 *      Packets not matching are delivered without timestamps (MCDI events will
 *      always arrive after the actual packet).
 *      It is important for the operation of the PTP protocol that the ordering
 *      of packets between the event and general port is maintained.
 *
 * Work queue processing:
 *      If work waiting, synchronise host/hardware time
 *
 *      Transmit: send packet through MC, which returns the transmission time
 *      that is converted to an appropriate timestamp.
 *
 *      Receive: the packet's reception time is converted to an appropriate
 *      timestamp.
 */
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/time.h>
#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/net_tstamp.h>
#include <linux/pps_kernel.h>
#include <linux/ptp_clock_kernel.h>
#include "net_driver.h"
#include "efx.h"
#include "mcdi.h"
#include "mcdi_pcol.h"
#include "io.h"
#include "farch_regs.h"
#include "nic.h"

/* Maximum number of events expected to make up a PTP event */
#define MAX_EVENT_FRAGS                 3

/* Maximum delay, ms, to begin synchronisation */
#define MAX_SYNCHRONISE_WAIT_MS         2

/* How long, at most, to spend synchronising */
#define SYNCHRONISE_PERIOD_NS           250000

/* How often to update the shared memory time */
#define SYNCHRONISATION_GRANULARITY_NS  200

/* Minimum permitted length of a (corrected) synchronisation time */
#define DEFAULT_MIN_SYNCHRONISATION_NS  120

/* Maximum permitted length of a (corrected) synchronisation time */
#define MAX_SYNCHRONISATION_NS          1000

/* How many (MC) receive events that can be queued */
#define MAX_RECEIVE_EVENTS              8

/* Length of (modified) moving average. */
#define AVERAGE_LENGTH                  16

/* How long an unmatched event or packet can be held */
#define PKT_EVENT_LIFETIME_MS           10

/* Offsets into PTP packet for identification.  These offsets are from the
 * start of the IP header, not the MAC header.  Note that neither PTP V1 nor
 * PTP V2 permit the use of IPV4 options.
 */
#define PTP_DPORT_OFFSET        22

#define PTP_V1_VERSION_LENGTH   2
#define PTP_V1_VERSION_OFFSET   28

#define PTP_V1_UUID_LENGTH      6
#define PTP_V1_UUID_OFFSET      50

#define PTP_V1_SEQUENCE_LENGTH  2
#define PTP_V1_SEQUENCE_OFFSET  58

/* The minimum length of a PTP V1 packet for offsets, etc. to be valid:
 * includes IP header.
 */
#define PTP_V1_MIN_LENGTH       64

#define PTP_V2_VERSION_LENGTH   1
#define PTP_V2_VERSION_OFFSET   29

#define PTP_V2_UUID_LENGTH      8
#define PTP_V2_UUID_OFFSET      48

/* Although PTP V2 UUIDs are comprised a ClockIdentity (8) and PortNumber (2),
 * the MC only captures the last six bytes of the clock identity. These values
 * reflect those, not the ones used in the standard.  The standard permits
 * mapping of V1 UUIDs to V2 UUIDs with these same values.
 */
#define PTP_V2_MC_UUID_LENGTH   6
#define PTP_V2_MC_UUID_OFFSET   50

#define PTP_V2_SEQUENCE_LENGTH  2
#define PTP_V2_SEQUENCE_OFFSET  58

/* The minimum length of a PTP V2 packet for offsets, etc. to be valid:
 * includes IP header.
 */
#define PTP_V2_MIN_LENGTH       63

#define PTP_MIN_LENGTH          63

#define PTP_ADDRESS             0xe0000181      /* 224.0.1.129 */
#define PTP_EVENT_PORT          319
#define PTP_GENERAL_PORT        320

/* Annoyingly the format of the version numbers are different between
 * versions 1 and 2 so it isn't possible to simply look for 1 or 2.
 */
#define PTP_VERSION_V1          1

#define PTP_VERSION_V2          2
#define PTP_VERSION_V2_MASK     0x0f

enum ptp_packet_state {
        PTP_PACKET_STATE_UNMATCHED = 0,
        PTP_PACKET_STATE_MATCHED,
        PTP_PACKET_STATE_TIMED_OUT,
        PTP_PACKET_STATE_MATCH_UNWANTED
};

/* NIC synchronised with single word of time only comprising
 * partial seconds and full nanoseconds: 10^9 ~ 2^30 so 2 bits for seconds.
 */
#define MC_NANOSECOND_BITS      30
#define MC_NANOSECOND_MASK      ((1 << MC_NANOSECOND_BITS) - 1)
#define MC_SECOND_MASK          ((1 << (32 - MC_NANOSECOND_BITS)) - 1)

/* Maximum parts-per-billion adjustment that is acceptable */
#define MAX_PPB                 1000000

/* Number of bits required to hold the above */
#define MAX_PPB_BITS            20

/* Number of extra bits allowed when calculating fractional ns.
 * EXTRA_BITS + MC_CMD_PTP_IN_ADJUST_BITS + MAX_PPB_BITS should
 * be less than 63.
 */
#define PPB_EXTRA_BITS          2

/* Precalculate scale word to avoid long long division at runtime */
#define PPB_SCALE_WORD  ((1LL << (PPB_EXTRA_BITS + MC_CMD_PTP_IN_ADJUST_BITS +\
                        MAX_PPB_BITS)) / 1000000000LL)

#define PTP_SYNC_ATTEMPTS       4

/**
 * struct efx_ptp_match - Matching structure, stored in sk_buff's cb area.
 * @words: UUID and (partial) sequence number
 * @expiry: Time after which the packet should be delivered irrespective of
 *            event arrival.
 * @state: The state of the packet - whether it is ready for processing or
 *         whether that is of no interest.
 */
struct efx_ptp_match {
        u32 words[DIV_ROUND_UP(PTP_V1_UUID_LENGTH, 4)];
        unsigned long expiry;
        enum ptp_packet_state state;
};

/**
 * struct efx_ptp_event_rx - A PTP receive event (from MC)
 * @seq0: First part of (PTP) UUID
 * @seq1: Second part of (PTP) UUID and sequence number
 * @hwtimestamp: Event timestamp
 */
struct efx_ptp_event_rx {
        struct list_head link;
        u32 seq0;
        u32 seq1;
        ktime_t hwtimestamp;
        unsigned long expiry;
};

/**
 * struct efx_ptp_timeset - Synchronisation between host and MC
 * @host_start: Host time immediately before hardware timestamp taken
 * @major: Hardware timestamp, major
 * @minor: Hardware timestamp, minor
 * @host_end: Host time immediately after hardware timestamp taken
 * @wait: Number of NIC clock ticks between hardware timestamp being read and
 *          host end time being seen
 * @window: Difference of host_end and host_start
 * @valid: Whether this timeset is valid
 */
struct efx_ptp_timeset {
        u32 host_start;
        u32 major;
        u32 minor;
        u32 host_end;
        u32 wait;
        u32 window;     /* Derived: end - start, allowing for wrap */
};

/**
 * struct efx_ptp_data - Precision Time Protocol (PTP) state
 * @efx: The NIC context
 * @channel: The PTP channel (Siena only)
 * @rx_ts_inline: Flag for whether RX timestamps are inline (else they are
 *      separate events)
 * @rxq: Receive queue (awaiting timestamps)
 * @txq: Transmit queue
 * @evt_list: List of MC receive events awaiting packets
 * @evt_free_list: List of free events
 * @evt_lock: Lock for manipulating evt_list and evt_free_list
 * @evt_overflow: Boolean indicating that event list has overflowed
 * @rx_evts: Instantiated events (on evt_list and evt_free_list)
 * @workwq: Work queue for processing pending PTP operations
 * @work: Work task
 * @reset_required: A serious error has occurred and the PTP task needs to be
 *                  reset (disable, enable).
 * @rxfilter_event: Receive filter when operating
 * @rxfilter_general: Receive filter when operating
 * @config: Current timestamp configuration
 * @enabled: PTP operation enabled
 * @mode: Mode in which PTP operating (PTP version)
 * @time_format: Time format supported by this NIC
 * @ns_to_nic_time: Function to convert from scalar nanoseconds to NIC time
 * @nic_to_kernel_time: Function to convert from NIC to kernel time
 * @min_synchronisation_ns: Minimum acceptable corrected sync window
 * @ts_corrections.tx: Required driver correction of transmit timestamps
 * @ts_corrections.rx: Required driver correction of receive timestamps
 * @ts_corrections.pps_out: PPS output error (information only)
 * @ts_corrections.pps_in: Required driver correction of PPS input timestamps
 * @evt_frags: Partly assembled PTP events
 * @evt_frag_idx: Current fragment number
 * @evt_code: Last event code
 * @start: Address at which MC indicates ready for synchronisation
 * @host_time_pps: Host time at last PPS
 * @current_adjfreq: Current ppb adjustment.
 * @phc_clock: Pointer to registered phc device (if primary function)
 * @phc_clock_info: Registration structure for phc device
 * @pps_work: pps work task for handling pps events
 * @pps_workwq: pps work queue
 * @nic_ts_enabled: Flag indicating if NIC generated TS events are handled
 * @txbuf: Buffer for use when transmitting (PTP) packets to MC (avoids
 *         allocations in main data path).
 * @good_syncs: Number of successful synchronisations.
 * @fast_syncs: Number of synchronisations requiring short delay
 * @bad_syncs: Number of failed synchronisations.
 * @sync_timeouts: Number of synchronisation timeouts
 * @no_time_syncs: Number of synchronisations with no good times.
 * @invalid_sync_windows: Number of sync windows with bad durations.
 * @undersize_sync_windows: Number of corrected sync windows that are too small
 * @oversize_sync_windows: Number of corrected sync windows that are too large
 * @rx_no_timestamp: Number of packets received without a timestamp.
 * @timeset: Last set of synchronisation statistics.
 */
struct efx_ptp_data {
        struct efx_nic *efx;
        struct efx_channel *channel;
        bool rx_ts_inline;
        struct sk_buff_head rxq;
        struct sk_buff_head txq;
        struct list_head evt_list;
        struct list_head evt_free_list;
        spinlock_t evt_lock;
        bool evt_overflow;
        struct efx_ptp_event_rx rx_evts[MAX_RECEIVE_EVENTS];
        struct workqueue_struct *workwq;
        struct work_struct work;
        bool reset_required;
        u32 rxfilter_event;
        u32 rxfilter_general;
        bool rxfilter_installed;
        struct hwtstamp_config config;
        bool enabled;
        unsigned int mode;
        unsigned int time_format;
        void (*ns_to_nic_time)(s64 ns, u32 *nic_major, u32 *nic_minor);
        ktime_t (*nic_to_kernel_time)(u32 nic_major, u32 nic_minor,
                                      s32 correction);
        unsigned int min_synchronisation_ns;
        struct {
                s32 tx;
                s32 rx;
                s32 pps_out;
                s32 pps_in;
        } ts_corrections;
        efx_qword_t evt_frags[MAX_EVENT_FRAGS];
        int evt_frag_idx;
        int evt_code;
        struct efx_buffer start;
        struct pps_event_time host_time_pps;
        s64 current_adjfreq;
        struct ptp_clock *phc_clock;
        struct ptp_clock_info phc_clock_info;
        struct work_struct pps_work;
        struct workqueue_struct *pps_workwq;
        bool nic_ts_enabled;
        MCDI_DECLARE_BUF(txbuf, MC_CMD_PTP_IN_TRANSMIT_LENMAX);

        unsigned int good_syncs;
        unsigned int fast_syncs;
        unsigned int bad_syncs;
        unsigned int sync_timeouts;
        unsigned int no_time_syncs;
        unsigned int invalid_sync_windows;
        unsigned int undersize_sync_windows;
        unsigned int oversize_sync_windows;
        unsigned int rx_no_timestamp;
        struct efx_ptp_timeset
        timeset[MC_CMD_PTP_OUT_SYNCHRONIZE_TIMESET_MAXNUM];
};

static int efx_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta);
static int efx_phc_adjtime(struct ptp_clock_info *ptp, s64 delta);
static int efx_phc_gettime(struct ptp_clock_info *ptp, struct timespec *ts);
static int efx_phc_settime(struct ptp_clock_info *ptp,
                           const struct timespec *e_ts);
static int efx_phc_enable(struct ptp_clock_info *ptp,
                          struct ptp_clock_request *request, int on);

#define PTP_SW_STAT(ext_name, field_name)                               \
        { #ext_name, 0, offsetof(struct efx_ptp_data, field_name) }
#define PTP_MC_STAT(ext_name, mcdi_name)                                \
        { #ext_name, 32, MC_CMD_PTP_OUT_STATUS_STATS_ ## mcdi_name ## _OFST }
static const struct efx_hw_stat_desc efx_ptp_stat_desc[] = {
        PTP_SW_STAT(ptp_good_syncs, good_syncs),
        PTP_SW_STAT(ptp_fast_syncs, fast_syncs),
        PTP_SW_STAT(ptp_bad_syncs, bad_syncs),
        PTP_SW_STAT(ptp_sync_timeouts, sync_timeouts),
        PTP_SW_STAT(ptp_no_time_syncs, no_time_syncs),
        PTP_SW_STAT(ptp_invalid_sync_windows, invalid_sync_windows),
        PTP_SW_STAT(ptp_undersize_sync_windows, undersize_sync_windows),
        PTP_SW_STAT(ptp_oversize_sync_windows, oversize_sync_windows),
        PTP_SW_STAT(ptp_rx_no_timestamp, rx_no_timestamp),
        PTP_MC_STAT(ptp_tx_timestamp_packets, TX),
        PTP_MC_STAT(ptp_rx_timestamp_packets, RX),
        PTP_MC_STAT(ptp_timestamp_packets, TS),
        PTP_MC_STAT(ptp_filter_matches, FM),
        PTP_MC_STAT(ptp_non_filter_matches, NFM),
};
#define PTP_STAT_COUNT ARRAY_SIZE(efx_ptp_stat_desc)
static const unsigned long efx_ptp_stat_mask[] = {
        [0 ... BITS_TO_LONGS(PTP_STAT_COUNT) - 1] = ~0UL,
};

size_t efx_ptp_describe_stats(struct efx_nic *efx, u8 *strings)
{
        if (!efx->ptp_data)
                return 0;

        return efx_nic_describe_stats(efx_ptp_stat_desc, PTP_STAT_COUNT,
                                      efx_ptp_stat_mask, strings);
}

size_t efx_ptp_update_stats(struct efx_nic *efx, u64 *stats)
{
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_STATUS_LEN);
        MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_STATUS_LEN);
        size_t i;
        int rc;

        if (!efx->ptp_data)
                return 0;

        /* Copy software statistics */
        for (i = 0; i < PTP_STAT_COUNT; i++) {
                if (efx_ptp_stat_desc[i].dma_width)
                        continue;
                stats[i] = *(unsigned int *)((char *)efx->ptp_data +
                                             efx_ptp_stat_desc[i].offset);
        }

        /* Fetch MC statistics.  We *must* fill in all statistics or
         * risk leaking kernel memory to userland, so if the MCDI
         * request fails we pretend we got zeroes.
         */
        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_STATUS);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
        rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                          outbuf, sizeof(outbuf), NULL);
        if (rc) {
                netif_err(efx, hw, efx->net_dev,
                          "MC_CMD_PTP_OP_STATUS failed (%d)\n", rc);
                memset(outbuf, 0, sizeof(outbuf));
        }
        efx_nic_update_stats(efx_ptp_stat_desc, PTP_STAT_COUNT,
                             efx_ptp_stat_mask,
                             stats, _MCDI_PTR(outbuf, 0), false);

        return PTP_STAT_COUNT;
}

/* For Siena platforms NIC time is s and ns */
static void efx_ptp_ns_to_s_ns(s64 ns, u32 *nic_major, u32 *nic_minor)
{
        struct timespec ts = ns_to_timespec(ns);
        *nic_major = ts.tv_sec;
        *nic_minor = ts.tv_nsec;
}

static ktime_t efx_ptp_s_ns_to_ktime_correction(u32 nic_major, u32 nic_minor,
                                                s32 correction)
{
        ktime_t kt = ktime_set(nic_major, nic_minor);
        if (correction >= 0)
                kt = ktime_add_ns(kt, (u64)correction);
        else
                kt = ktime_sub_ns(kt, (u64)-correction);
        return kt;
}

/* To convert from s27 format to ns we multiply then divide by a power of 2.
 * For the conversion from ns to s27, the operation is also converted to a
 * multiply and shift.
 */
#define S27_TO_NS_SHIFT (27)
#define NS_TO_S27_MULT  (((1ULL << 63) + NSEC_PER_SEC / 2) / NSEC_PER_SEC)
#define NS_TO_S27_SHIFT (63 - S27_TO_NS_SHIFT)
#define S27_MINOR_MAX   (1 << S27_TO_NS_SHIFT)

/* For Huntington platforms NIC time is in seconds and fractions of a second
 * where the minor register only uses 27 bits in units of 2^-27s.
 */
static void efx_ptp_ns_to_s27(s64 ns, u32 *nic_major, u32 *nic_minor)
{
        struct timespec ts = ns_to_timespec(ns);
        u32 maj = ts.tv_sec;
        u32 min = (u32)(((u64)ts.tv_nsec * NS_TO_S27_MULT +
                         (1ULL << (NS_TO_S27_SHIFT - 1))) >> NS_TO_S27_SHIFT);

        /* The conversion can result in the minor value exceeding the maximum.
         * In this case, round up to the next second.
         */
        if (min >= S27_MINOR_MAX) {
                min -= S27_MINOR_MAX;
                maj++;
        }

        *nic_major = maj;
        *nic_minor = min;
}

static inline ktime_t efx_ptp_s27_to_ktime(u32 nic_major, u32 nic_minor)
{
        u32 ns = (u32)(((u64)nic_minor * NSEC_PER_SEC +
                        (1ULL << (S27_TO_NS_SHIFT - 1))) >> S27_TO_NS_SHIFT);
        return ktime_set(nic_major, ns);
}

static ktime_t efx_ptp_s27_to_ktime_correction(u32 nic_major, u32 nic_minor,
                                               s32 correction)
{
        /* Apply the correction and deal with carry */
        nic_minor += correction;
        if ((s32)nic_minor < 0) {
                nic_minor += S27_MINOR_MAX;
                nic_major--;
        } else if (nic_minor >= S27_MINOR_MAX) {
                nic_minor -= S27_MINOR_MAX;
                nic_major++;
        }

        return efx_ptp_s27_to_ktime(nic_major, nic_minor);
}

/* Get PTP attributes and set up time conversions */
static int efx_ptp_get_attributes(struct efx_nic *efx)
{
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_GET_ATTRIBUTES_LEN);
        MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_GET_ATTRIBUTES_LEN);
        struct efx_ptp_data *ptp = efx->ptp_data;
        int rc;
        u32 fmt;
        size_t out_len;

        /* Get the PTP attributes. If the NIC doesn't support the operation we
         * use the default format for compatibility with older NICs i.e.
         * seconds and nanoseconds.
         */
        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_GET_ATTRIBUTES);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
        rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                          outbuf, sizeof(outbuf), &out_len);
        if (rc == 0)
                fmt = MCDI_DWORD(outbuf, PTP_OUT_GET_ATTRIBUTES_TIME_FORMAT);
        else if (rc == -EINVAL)
                fmt = MC_CMD_PTP_OUT_GET_ATTRIBUTES_SECONDS_NANOSECONDS;
        else
                return rc;

        if (fmt == MC_CMD_PTP_OUT_GET_ATTRIBUTES_SECONDS_27FRACTION) {
                ptp->ns_to_nic_time = efx_ptp_ns_to_s27;
                ptp->nic_to_kernel_time = efx_ptp_s27_to_ktime_correction;
        } else if (fmt == MC_CMD_PTP_OUT_GET_ATTRIBUTES_SECONDS_NANOSECONDS) {
                ptp->ns_to_nic_time = efx_ptp_ns_to_s_ns;
                ptp->nic_to_kernel_time = efx_ptp_s_ns_to_ktime_correction;
        } else {
                return -ERANGE;
        }

        ptp->time_format = fmt;

        /* MC_CMD_PTP_OP_GET_ATTRIBUTES is an extended version of an older
         * operation MC_CMD_PTP_OP_GET_TIME_FORMAT that also returns a value
         * to use for the minimum acceptable corrected synchronization window.
         * If we have the extra information store it. For older firmware that
         * does not implement the extended command use the default value.
         */
        if (rc == 0 && out_len >= MC_CMD_PTP_OUT_GET_ATTRIBUTES_LEN)
                ptp->min_synchronisation_ns =
                        MCDI_DWORD(outbuf,
                                   PTP_OUT_GET_ATTRIBUTES_SYNC_WINDOW_MIN);
        else
                ptp->min_synchronisation_ns = DEFAULT_MIN_SYNCHRONISATION_NS;

        return 0;
}

/* Get PTP timestamp corrections */
static int efx_ptp_get_timestamp_corrections(struct efx_nic *efx)
{
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_GET_TIMESTAMP_CORRECTIONS_LEN);
        MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_GET_TIMESTAMP_CORRECTIONS_LEN);
        int rc;

        /* Get the timestamp corrections from the NIC. If this operation is
         * not supported (older NICs) then no correction is required.
         */
        MCDI_SET_DWORD(inbuf, PTP_IN_OP,
                       MC_CMD_PTP_OP_GET_TIMESTAMP_CORRECTIONS);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);

        rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                          outbuf, sizeof(outbuf), NULL);
        if (rc == 0) {
                efx->ptp_data->ts_corrections.tx = MCDI_DWORD(outbuf,
                        PTP_OUT_GET_TIMESTAMP_CORRECTIONS_TRANSMIT);
                efx->ptp_data->ts_corrections.rx = MCDI_DWORD(outbuf,
                        PTP_OUT_GET_TIMESTAMP_CORRECTIONS_RECEIVE);
                efx->ptp_data->ts_corrections.pps_out = MCDI_DWORD(outbuf,
                        PTP_OUT_GET_TIMESTAMP_CORRECTIONS_PPS_OUT);
                efx->ptp_data->ts_corrections.pps_in = MCDI_DWORD(outbuf,
                        PTP_OUT_GET_TIMESTAMP_CORRECTIONS_PPS_IN);
        } else if (rc == -EINVAL) {
                efx->ptp_data->ts_corrections.tx = 0;
                efx->ptp_data->ts_corrections.rx = 0;
                efx->ptp_data->ts_corrections.pps_out = 0;
                efx->ptp_data->ts_corrections.pps_in = 0;
        } else {
                return rc;
        }

        return 0;
}

/* Enable MCDI PTP support. */
static int efx_ptp_enable(struct efx_nic *efx)
{
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_ENABLE_LEN);
        MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, 0);
        int rc;

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_ENABLE);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
        MCDI_SET_DWORD(inbuf, PTP_IN_ENABLE_QUEUE,
                       efx->ptp_data->channel ?
                       efx->ptp_data->channel->channel : 0);
        MCDI_SET_DWORD(inbuf, PTP_IN_ENABLE_MODE, efx->ptp_data->mode);

        rc = efx_mcdi_rpc_quiet(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                                outbuf, sizeof(outbuf), NULL);
        rc = (rc == -EALREADY) ? 0 : rc;
        if (rc)
                efx_mcdi_display_error(efx, MC_CMD_PTP,
                                       MC_CMD_PTP_IN_ENABLE_LEN,
                                       outbuf, sizeof(outbuf), rc);
        return rc;
}

/* Disable MCDI PTP support.
 *
 * Note that this function should never rely on the presence of ptp_data -
 * may be called before that exists.
 */
static int efx_ptp_disable(struct efx_nic *efx)
{
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_DISABLE_LEN);
        MCDI_DECLARE_BUF_OUT_OR_ERR(outbuf, 0);
        int rc;

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_DISABLE);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
        rc = efx_mcdi_rpc_quiet(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                                outbuf, sizeof(outbuf), NULL);
        rc = (rc == -EALREADY) ? 0 : rc;
        if (rc)
                efx_mcdi_display_error(efx, MC_CMD_PTP,
                                       MC_CMD_PTP_IN_DISABLE_LEN,
                                       outbuf, sizeof(outbuf), rc);
        return rc;
}

static void efx_ptp_deliver_rx_queue(struct sk_buff_head *q)
{
        struct sk_buff *skb;

        while ((skb = skb_dequeue(q))) {
                local_bh_disable();
                netif_receive_skb(skb);
                local_bh_enable();
        }
}

static void efx_ptp_handle_no_channel(struct efx_nic *efx)
{
        netif_err(efx, drv, efx->net_dev,
                  "ERROR: PTP requires MSI-X and 1 additional interrupt"
                  "vector. PTP disabled\n");
}

/* Repeatedly send the host time to the MC which will capture the hardware
 * time.
 */
static void efx_ptp_send_times(struct efx_nic *efx,
                               struct pps_event_time *last_time)
{
        struct pps_event_time now;
        struct timespec limit;
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct timespec start;
        int *mc_running = ptp->start.addr;

        pps_get_ts(&now);
        start = now.ts_real;
        limit = now.ts_real;
        timespec_add_ns(&limit, SYNCHRONISE_PERIOD_NS);

        /* Write host time for specified period or until MC is done */
        while ((timespec_compare(&now.ts_real, &limit) < 0) &&
               ACCESS_ONCE(*mc_running)) {
                struct timespec update_time;
                unsigned int host_time;

                /* Don't update continuously to avoid saturating the PCIe bus */
                update_time = now.ts_real;
                timespec_add_ns(&update_time, SYNCHRONISATION_GRANULARITY_NS);
                do {
                        pps_get_ts(&now);
                } while ((timespec_compare(&now.ts_real, &update_time) < 0) &&
                         ACCESS_ONCE(*mc_running));

                /* Synchronise NIC with single word of time only */
                host_time = (now.ts_real.tv_sec << MC_NANOSECOND_BITS |
                             now.ts_real.tv_nsec);
                /* Update host time in NIC memory */
                efx->type->ptp_write_host_time(efx, host_time);
        }
        *last_time = now;
}

/* Read a timeset from the MC's results and partial process. */
static void efx_ptp_read_timeset(MCDI_DECLARE_STRUCT_PTR(data),
                                 struct efx_ptp_timeset *timeset)
{
        unsigned start_ns, end_ns;

        timeset->host_start = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_HOSTSTART);
        timeset->major = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_MAJOR);
        timeset->minor = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_MINOR);
        timeset->host_end = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_HOSTEND),
        timeset->wait = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_WAITNS);

        /* Ignore seconds */
        start_ns = timeset->host_start & MC_NANOSECOND_MASK;
        end_ns = timeset->host_end & MC_NANOSECOND_MASK;
        /* Allow for rollover */
        if (end_ns < start_ns)
                end_ns += NSEC_PER_SEC;
        /* Determine duration of operation */
        timeset->window = end_ns - start_ns;
}

/* Process times received from MC.
 *
 * Extract times from returned results, and establish the minimum value
 * seen.  The minimum value represents the "best" possible time and events
 * too much greater than this are rejected - the machine is, perhaps, too
 * busy. A number of readings are taken so that, hopefully, at least one good
 * synchronisation will be seen in the results.
 */
static int
efx_ptp_process_times(struct efx_nic *efx, MCDI_DECLARE_STRUCT_PTR(synch_buf),
                      size_t response_length,
                      const struct pps_event_time *last_time)
{
        unsigned number_readings =
                MCDI_VAR_ARRAY_LEN(response_length,
                                   PTP_OUT_SYNCHRONIZE_TIMESET);
        unsigned i;
        unsigned ngood = 0;
        unsigned last_good = 0;
        struct efx_ptp_data *ptp = efx->ptp_data;
        u32 last_sec;
        u32 start_sec;
        struct timespec delta;
        ktime_t mc_time;

        if (number_readings == 0)
                return -EAGAIN;

        /* Read the set of results and find the last good host-MC
         * synchronization result. The MC times when it finishes reading the
         * host time so the corrected window time should be fairly constant
         * for a given platform. Increment stats for any results that appear
         * to be erroneous.
         */
        for (i = 0; i < number_readings; i++) {
                s32 window, corrected;
                struct timespec wait;

                efx_ptp_read_timeset(
                        MCDI_ARRAY_STRUCT_PTR(synch_buf,
                                              PTP_OUT_SYNCHRONIZE_TIMESET, i),
                        &ptp->timeset[i]);

                wait = ktime_to_timespec(
                        ptp->nic_to_kernel_time(0, ptp->timeset[i].wait, 0));
                window = ptp->timeset[i].window;
                corrected = window - wait.tv_nsec;

                /* We expect the uncorrected synchronization window to be at
                 * least as large as the interval between host start and end
                 * times. If it is smaller than this then this is mostly likely
                 * to be a consequence of the host's time being adjusted.
                 * Check that the corrected sync window is in a reasonable
                 * range. If it is out of range it is likely to be because an
                 * interrupt or other delay occurred between reading the system
                 * time and writing it to MC memory.
                 */
                if (window < SYNCHRONISATION_GRANULARITY_NS) {
                        ++ptp->invalid_sync_windows;
                } else if (corrected >= MAX_SYNCHRONISATION_NS) {
                        ++ptp->oversize_sync_windows;
                } else if (corrected < ptp->min_synchronisation_ns) {
                        ++ptp->undersize_sync_windows;
                } else {
                        ngood++;
                        last_good = i;
                }
        }

        if (ngood == 0) {
                netif_warn(efx, drv, efx->net_dev,
                           "PTP no suitable synchronisations\n");
                return -EAGAIN;
        }

        /* Convert the NIC time into kernel time. No correction is required-
         * this time is the output of a firmware process.
         */
        mc_time = ptp->nic_to_kernel_time(ptp->timeset[last_good].major,
                                          ptp->timeset[last_good].minor, 0);

        /* Calculate delay from actual PPS to last_time */
        delta = ktime_to_timespec(mc_time);
        delta.tv_nsec +=
                last_time->ts_real.tv_nsec -
                (ptp->timeset[last_good].host_start & MC_NANOSECOND_MASK);

        /* It is possible that the seconds rolled over between taking
         * the start reading and the last value written by the host.  The
         * timescales are such that a gap of more than one second is never
         * expected.
         */
        start_sec = ptp->timeset[last_good].host_start >> MC_NANOSECOND_BITS;
        last_sec = last_time->ts_real.tv_sec & MC_SECOND_MASK;
        if (start_sec != last_sec) {
                if (((start_sec + 1) & MC_SECOND_MASK) != last_sec) {
                        netif_warn(efx, hw, efx->net_dev,
                                   "PTP bad synchronisation seconds\n");
                        return -EAGAIN;
                } else {
                        delta.tv_sec = 1;
                }
        } else {
                delta.tv_sec = 0;
        }

        ptp->host_time_pps = *last_time;
        pps_sub_ts(&ptp->host_time_pps, delta);

        return 0;
}

/* Synchronize times between the host and the MC */
static int efx_ptp_synchronize(struct efx_nic *efx, unsigned int num_readings)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        MCDI_DECLARE_BUF(synch_buf, MC_CMD_PTP_OUT_SYNCHRONIZE_LENMAX);
        size_t response_length;
        int rc;
        unsigned long timeout;
        struct pps_event_time last_time = {};
        unsigned int loops = 0;
        int *start = ptp->start.addr;

        MCDI_SET_DWORD(synch_buf, PTP_IN_OP, MC_CMD_PTP_OP_SYNCHRONIZE);
        MCDI_SET_DWORD(synch_buf, PTP_IN_PERIPH_ID, 0);
        MCDI_SET_DWORD(synch_buf, PTP_IN_SYNCHRONIZE_NUMTIMESETS,
                       num_readings);
        MCDI_SET_QWORD(synch_buf, PTP_IN_SYNCHRONIZE_START_ADDR,
                       ptp->start.dma_addr);

        /* Clear flag that signals MC ready */
        ACCESS_ONCE(*start) = 0;
        rc = efx_mcdi_rpc_start(efx, MC_CMD_PTP, synch_buf,
                                MC_CMD_PTP_IN_SYNCHRONIZE_LEN);
        EFX_BUG_ON_PARANOID(rc);

        /* Wait for start from MCDI (or timeout) */
        timeout = jiffies + msecs_to_jiffies(MAX_SYNCHRONISE_WAIT_MS);
        while (!ACCESS_ONCE(*start) && (time_before(jiffies, timeout))) {
                udelay(20);     /* Usually start MCDI execution quickly */
                loops++;
        }

        if (loops <= 1)
                ++ptp->fast_syncs;
        if (!time_before(jiffies, timeout))
                ++ptp->sync_timeouts;

        if (ACCESS_ONCE(*start))
                efx_ptp_send_times(efx, &last_time);

        /* Collect results */
        rc = efx_mcdi_rpc_finish(efx, MC_CMD_PTP,
                                 MC_CMD_PTP_IN_SYNCHRONIZE_LEN,
                                 synch_buf, sizeof(synch_buf),
                                 &response_length);
        if (rc == 0) {
                rc = efx_ptp_process_times(efx, synch_buf, response_length,
                                           &last_time);
                if (rc == 0)
                        ++ptp->good_syncs;
                else
                        ++ptp->no_time_syncs;
        }

        /* Increment the bad syncs counter if the synchronize fails, whatever
         * the reason.
         */
        if (rc != 0)
                ++ptp->bad_syncs;

        return rc;
}

/* Transmit a PTP packet, via the MCDI interface, to the wire. */
static int efx_ptp_xmit_skb(struct efx_nic *efx, struct sk_buff *skb)
{
        struct efx_ptp_data *ptp_data = efx->ptp_data;
        struct skb_shared_hwtstamps timestamps;
        int rc = -EIO;
        MCDI_DECLARE_BUF(txtime, MC_CMD_PTP_OUT_TRANSMIT_LEN);
        size_t len;

        MCDI_SET_DWORD(ptp_data->txbuf, PTP_IN_OP, MC_CMD_PTP_OP_TRANSMIT);
        MCDI_SET_DWORD(ptp_data->txbuf, PTP_IN_PERIPH_ID, 0);
        MCDI_SET_DWORD(ptp_data->txbuf, PTP_IN_TRANSMIT_LENGTH, skb->len);
        if (skb_shinfo(skb)->nr_frags != 0) {
                rc = skb_linearize(skb);
                if (rc != 0)
                        goto fail;
        }

        if (skb->ip_summed == CHECKSUM_PARTIAL) {
                rc = skb_checksum_help(skb);
                if (rc != 0)
                        goto fail;
        }
        skb_copy_from_linear_data(skb,
                                  MCDI_PTR(ptp_data->txbuf,
                                           PTP_IN_TRANSMIT_PACKET),
                                  skb->len);
        rc = efx_mcdi_rpc(efx, MC_CMD_PTP,
                          ptp_data->txbuf, MC_CMD_PTP_IN_TRANSMIT_LEN(skb->len),
                          txtime, sizeof(txtime), &len);
        if (rc != 0)
                goto fail;

        memset(&timestamps, 0, sizeof(timestamps));
        timestamps.hwtstamp = ptp_data->nic_to_kernel_time(
                MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_MAJOR),
                MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_MINOR),
                ptp_data->ts_corrections.tx);

        skb_tstamp_tx(skb, &timestamps);

        rc = 0;

fail:
        dev_kfree_skb(skb);

        return rc;
}

static void efx_ptp_drop_time_expired_events(struct efx_nic *efx)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct list_head *cursor;
        struct list_head *next;

        if (ptp->rx_ts_inline)
                return;

        /* Drop time-expired events */
        spin_lock_bh(&ptp->evt_lock);
        if (!list_empty(&ptp->evt_list)) {
                list_for_each_safe(cursor, next, &ptp->evt_list) {
                        struct efx_ptp_event_rx *evt;

                        evt = list_entry(cursor, struct efx_ptp_event_rx,
                                         link);
                        if (time_after(jiffies, evt->expiry)) {
                                list_move(&evt->link, &ptp->evt_free_list);
                                netif_warn(efx, hw, efx->net_dev,
                                           "PTP rx event dropped\n");
                        }
                }
        }
        /* If the event overflow flag is set and the event list is now empty
         * clear the flag to re-enable the overflow warning message.
         */
        if (ptp->evt_overflow && list_empty(&ptp->evt_list))
                ptp->evt_overflow = false;
        spin_unlock_bh(&ptp->evt_lock);
}

static enum ptp_packet_state efx_ptp_match_rx(struct efx_nic *efx,
                                              struct sk_buff *skb)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        bool evts_waiting;
        struct list_head *cursor;
        struct list_head *next;
        struct efx_ptp_match *match;
        enum ptp_packet_state rc = PTP_PACKET_STATE_UNMATCHED;

        WARN_ON_ONCE(ptp->rx_ts_inline);

        spin_lock_bh(&ptp->evt_lock);
        evts_waiting = !list_empty(&ptp->evt_list);
        spin_unlock_bh(&ptp->evt_lock);

        if (!evts_waiting)
                return PTP_PACKET_STATE_UNMATCHED;

        match = (struct efx_ptp_match *)skb->cb;
        /* Look for a matching timestamp in the event queue */
        spin_lock_bh(&ptp->evt_lock);
        list_for_each_safe(cursor, next, &ptp->evt_list) {
                struct efx_ptp_event_rx *evt;

                evt = list_entry(cursor, struct efx_ptp_event_rx, link);
                if ((evt->seq0 == match->words[0]) &&
                    (evt->seq1 == match->words[1])) {
                        struct skb_shared_hwtstamps *timestamps;

                        /* Match - add in hardware timestamp */
                        timestamps = skb_hwtstamps(skb);
                        timestamps->hwtstamp = evt->hwtimestamp;

                        match->state = PTP_PACKET_STATE_MATCHED;
                        rc = PTP_PACKET_STATE_MATCHED;
                        list_move(&evt->link, &ptp->evt_free_list);
                        break;
                }
        }
        /* If the event overflow flag is set and the event list is now empty
         * clear the flag to re-enable the overflow warning message.
         */
        if (ptp->evt_overflow && list_empty(&ptp->evt_list))
                ptp->evt_overflow = false;
        spin_unlock_bh(&ptp->evt_lock);

        return rc;
}

/* Process any queued receive events and corresponding packets
 *
 * q is returned with all the packets that are ready for delivery.
 */
static void efx_ptp_process_events(struct efx_nic *efx, struct sk_buff_head *q)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct sk_buff *skb;

        while ((skb = skb_dequeue(&ptp->rxq))) {
                struct efx_ptp_match *match;

                match = (struct efx_ptp_match *)skb->cb;
                if (match->state == PTP_PACKET_STATE_MATCH_UNWANTED) {
                        __skb_queue_tail(q, skb);
                } else if (efx_ptp_match_rx(efx, skb) ==
                           PTP_PACKET_STATE_MATCHED) {
                        __skb_queue_tail(q, skb);
                } else if (time_after(jiffies, match->expiry)) {
                        match->state = PTP_PACKET_STATE_TIMED_OUT;
                        ++ptp->rx_no_timestamp;
                        __skb_queue_tail(q, skb);
                } else {
                        /* Replace unprocessed entry and stop */
                        skb_queue_head(&ptp->rxq, skb);
                        break;
                }
        }
}

/* Complete processing of a received packet */
static inline void efx_ptp_process_rx(struct efx_nic *efx, struct sk_buff *skb)
{
        local_bh_disable();
        netif_receive_skb(skb);
        local_bh_enable();
}

static void efx_ptp_remove_multicast_filters(struct efx_nic *efx)
{
        struct efx_ptp_data *ptp = efx->ptp_data;

        if (ptp->rxfilter_installed) {
                efx_filter_remove_id_safe(efx, EFX_FILTER_PRI_REQUIRED,
                                          ptp->rxfilter_general);
                efx_filter_remove_id_safe(efx, EFX_FILTER_PRI_REQUIRED,
                                          ptp->rxfilter_event);
                ptp->rxfilter_installed = false;
        }
}

static int efx_ptp_insert_multicast_filters(struct efx_nic *efx)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct efx_filter_spec rxfilter;
        int rc;

        if (!ptp->channel || ptp->rxfilter_installed)
                return 0;

        /* Must filter on both event and general ports to ensure
         * that there is no packet re-ordering.
         */
        efx_filter_init_rx(&rxfilter, EFX_FILTER_PRI_REQUIRED, 0,
                           efx_rx_queue_index(
                                   efx_channel_get_rx_queue(ptp->channel)));
        rc = efx_filter_set_ipv4_local(&rxfilter, IPPROTO_UDP,
                                       htonl(PTP_ADDRESS),
                                       htons(PTP_EVENT_PORT));
        if (rc != 0)
                return rc;

        rc = efx_filter_insert_filter(efx, &rxfilter, true);
        if (rc < 0)
                return rc;
        ptp->rxfilter_event = rc;

        efx_filter_init_rx(&rxfilter, EFX_FILTER_PRI_REQUIRED, 0,
                           efx_rx_queue_index(
                                   efx_channel_get_rx_queue(ptp->channel)));
        rc = efx_filter_set_ipv4_local(&rxfilter, IPPROTO_UDP,
                                       htonl(PTP_ADDRESS),
                                       htons(PTP_GENERAL_PORT));
        if (rc != 0)
                goto fail;

        rc = efx_filter_insert_filter(efx, &rxfilter, true);
        if (rc < 0)
                goto fail;
        ptp->rxfilter_general = rc;

        ptp->rxfilter_installed = true;
        return 0;

fail:
        efx_filter_remove_id_safe(efx, EFX_FILTER_PRI_REQUIRED,
                                  ptp->rxfilter_event);
        return rc;
}

static int efx_ptp_start(struct efx_nic *efx)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        int rc;

        ptp->reset_required = false;

        rc = efx_ptp_insert_multicast_filters(efx);
        if (rc)
                return rc;

        rc = efx_ptp_enable(efx);
        if (rc != 0)
                goto fail;

        ptp->evt_frag_idx = 0;
        ptp->current_adjfreq = 0;

        return 0;

fail:
        efx_ptp_remove_multicast_filters(efx);
        return rc;
}

static int efx_ptp_stop(struct efx_nic *efx)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct list_head *cursor;
        struct list_head *next;
        int rc;

        if (ptp == NULL)
                return 0;

        rc = efx_ptp_disable(efx);

        efx_ptp_remove_multicast_filters(efx);

        /* Make sure RX packets are really delivered */
        efx_ptp_deliver_rx_queue(&efx->ptp_data->rxq);
        skb_queue_purge(&efx->ptp_data->txq);

        /* Drop any pending receive events */
        spin_lock_bh(&efx->ptp_data->evt_lock);
        list_for_each_safe(cursor, next, &efx->ptp_data->evt_list) {
                list_move(cursor, &efx->ptp_data->evt_free_list);
        }
        ptp->evt_overflow = false;
        spin_unlock_bh(&efx->ptp_data->evt_lock);

        return rc;
}

static int efx_ptp_restart(struct efx_nic *efx)
{
        if (efx->ptp_data && efx->ptp_data->enabled)
                return efx_ptp_start(efx);
        return 0;
}

static void efx_ptp_pps_worker(struct work_struct *work)
{
        struct efx_ptp_data *ptp =
                container_of(work, struct efx_ptp_data, pps_work);
        struct efx_nic *efx = ptp->efx;
        struct ptp_clock_event ptp_evt;

        if (efx_ptp_synchronize(efx, PTP_SYNC_ATTEMPTS))
                return;

        ptp_evt.type = PTP_CLOCK_PPSUSR;
        ptp_evt.pps_times = ptp->host_time_pps;
        ptp_clock_event(ptp->phc_clock, &ptp_evt);
}

static void efx_ptp_worker(struct work_struct *work)
{
        struct efx_ptp_data *ptp_data =
                container_of(work, struct efx_ptp_data, work);
        struct efx_nic *efx = ptp_data->efx;
        struct sk_buff *skb;
        struct sk_buff_head tempq;

        if (ptp_data->reset_required) {
                efx_ptp_stop(efx);
                efx_ptp_start(efx);
                return;
        }

        efx_ptp_drop_time_expired_events(efx);

        __skb_queue_head_init(&tempq);
        efx_ptp_process_events(efx, &tempq);

        while ((skb = skb_dequeue(&ptp_data->txq)))
                efx_ptp_xmit_skb(efx, skb);

        while ((skb = __skb_dequeue(&tempq)))
                efx_ptp_process_rx(efx, skb);
}

static const struct ptp_clock_info efx_phc_clock_info = {
        .owner          = THIS_MODULE,
        .name           = "sfc",
        .max_adj        = MAX_PPB,
        .n_alarm        = 0,
        .n_ext_ts       = 0,
        .n_per_out      = 0,
        .pps            = 1,
        .adjfreq        = efx_phc_adjfreq,
        .adjtime        = efx_phc_adjtime,
        .gettime        = efx_phc_gettime,
        .settime        = efx_phc_settime,
        .enable         = efx_phc_enable,
};

/* Initialise PTP state. */
int efx_ptp_probe(struct efx_nic *efx, struct efx_channel *channel)
{
        struct efx_ptp_data *ptp;
        int rc = 0;
        unsigned int pos;

        ptp = kzalloc(sizeof(struct efx_ptp_data), GFP_KERNEL);
        efx->ptp_data = ptp;
        if (!efx->ptp_data)
                return -ENOMEM;

        ptp->efx = efx;
        ptp->channel = channel;
        ptp->rx_ts_inline = efx_nic_rev(efx) >= EFX_REV_HUNT_A0;

        rc = efx_nic_alloc_buffer(efx, &ptp->start, sizeof(int), GFP_KERNEL);
        if (rc != 0)
                goto fail1;

        skb_queue_head_init(&ptp->rxq);
        skb_queue_head_init(&ptp->txq);
        ptp->workwq = create_singlethread_workqueue("sfc_ptp");
        if (!ptp->workwq) {
                rc = -ENOMEM;
                goto fail2;
        }

        INIT_WORK(&ptp->work, efx_ptp_worker);
        ptp->config.flags = 0;
        ptp->config.tx_type = HWTSTAMP_TX_OFF;
        ptp->config.rx_filter = HWTSTAMP_FILTER_NONE;
        INIT_LIST_HEAD(&ptp->evt_list);
        INIT_LIST_HEAD(&ptp->evt_free_list);
        spin_lock_init(&ptp->evt_lock);
        for (pos = 0; pos < MAX_RECEIVE_EVENTS; pos++)
                list_add(&ptp->rx_evts[pos].link, &ptp->evt_free_list);
        ptp->evt_overflow = false;

        /* Get the NIC PTP attributes and set up time conversions */
        rc = efx_ptp_get_attributes(efx);
        if (rc < 0)
                goto fail3;

        /* Get the timestamp corrections */
        rc = efx_ptp_get_timestamp_corrections(efx);
        if (rc < 0)
                goto fail3;

        if (efx->mcdi->fn_flags &
            (1 << MC_CMD_DRV_ATTACH_EXT_OUT_FLAG_PRIMARY)) {
                ptp->phc_clock_info = efx_phc_clock_info;
                ptp->phc_clock = ptp_clock_register(&ptp->phc_clock_info,
                                                    &efx->pci_dev->dev);
                if (IS_ERR(ptp->phc_clock)) {
                        rc = PTR_ERR(ptp->phc_clock);
                        goto fail3;
                }

                INIT_WORK(&ptp->pps_work, efx_ptp_pps_worker);
                ptp->pps_workwq = create_singlethread_workqueue("sfc_pps");
                if (!ptp->pps_workwq) {
                        rc = -ENOMEM;
                        goto fail4;
                }
        }
        ptp->nic_ts_enabled = false;

        return 0;
fail4:
        ptp_clock_unregister(efx->ptp_data->phc_clock);

fail3:
        destroy_workqueue(efx->ptp_data->workwq);

fail2:
        efx_nic_free_buffer(efx, &ptp->start);

fail1:
        kfree(efx->ptp_data);
        efx->ptp_data = NULL;

        return rc;
}

/* Initialise PTP channel.
 *
 * Setting core_index to zero causes the queue to be initialised and doesn't
 * overlap with 'rxq0' because ptp.c doesn't use skb_record_rx_queue.
 */
static int efx_ptp_probe_channel(struct efx_channel *channel)
{
        struct efx_nic *efx = channel->efx;

        channel->irq_moderation = 0;
        channel->rx_queue.core_index = 0;

        return efx_ptp_probe(efx, channel);
}

void efx_ptp_remove(struct efx_nic *efx)
{
        if (!efx->ptp_data)
                return;

        (void)efx_ptp_disable(efx);

        cancel_work_sync(&efx->ptp_data->work);
        cancel_work_sync(&efx->ptp_data->pps_work);

        skb_queue_purge(&efx->ptp_data->rxq);
        skb_queue_purge(&efx->ptp_data->txq);

        if (efx->ptp_data->phc_clock) {
                destroy_workqueue(efx->ptp_data->pps_workwq);
                ptp_clock_unregister(efx->ptp_data->phc_clock);
        }

        destroy_workqueue(efx->ptp_data->workwq);

        efx_nic_free_buffer(efx, &efx->ptp_data->start);
        kfree(efx->ptp_data);
}

static void efx_ptp_remove_channel(struct efx_channel *channel)
{
        efx_ptp_remove(channel->efx);
}

static void efx_ptp_get_channel_name(struct efx_channel *channel,
                                     char *buf, size_t len)
{
        snprintf(buf, len, "%s-ptp", channel->efx->name);
}

/* Determine whether this packet should be processed by the PTP module
 * or transmitted conventionally.
 */
bool efx_ptp_is_ptp_tx(struct efx_nic *efx, struct sk_buff *skb)
{
        return efx->ptp_data &&
                efx->ptp_data->enabled &&
                skb->len >= PTP_MIN_LENGTH &&
                skb->len <= MC_CMD_PTP_IN_TRANSMIT_PACKET_MAXNUM &&
                likely(skb->protocol == htons(ETH_P_IP)) &&
                skb_transport_header_was_set(skb) &&
                skb_network_header_len(skb) >= sizeof(struct iphdr) &&
                ip_hdr(skb)->protocol == IPPROTO_UDP &&
                skb_headlen(skb) >=
                skb_transport_offset(skb) + sizeof(struct udphdr) &&
                udp_hdr(skb)->dest == htons(PTP_EVENT_PORT);
}

/* Receive a PTP packet.  Packets are queued until the arrival of
 * the receive timestamp from the MC - this will probably occur after the
 * packet arrival because of the processing in the MC.
 */
static bool efx_ptp_rx(struct efx_channel *channel, struct sk_buff *skb)
{
        struct efx_nic *efx = channel->efx;
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct efx_ptp_match *match = (struct efx_ptp_match *)skb->cb;
        u8 *match_data_012, *match_data_345;
        unsigned int version;

        match->expiry = jiffies + msecs_to_jiffies(PKT_EVENT_LIFETIME_MS);

        /* Correct version? */
        if (ptp->mode == MC_CMD_PTP_MODE_V1) {
                if (!pskb_may_pull(skb, PTP_V1_MIN_LENGTH)) {
                        return false;
                }
                version = ntohs(*(__be16 *)&skb->data[PTP_V1_VERSION_OFFSET]);
                if (version != PTP_VERSION_V1) {
                        return false;
                }

                /* PTP V1 uses all six bytes of the UUID to match the packet
                 * to the timestamp
                 */
                match_data_012 = skb->data + PTP_V1_UUID_OFFSET;
                match_data_345 = skb->data + PTP_V1_UUID_OFFSET + 3;
        } else {
                if (!pskb_may_pull(skb, PTP_V2_MIN_LENGTH)) {
                        return false;
                }
                version = skb->data[PTP_V2_VERSION_OFFSET];
                if ((version & PTP_VERSION_V2_MASK) != PTP_VERSION_V2) {
                        return false;
                }

                /* The original V2 implementation uses bytes 2-7 of
                 * the UUID to match the packet to the timestamp. This
                 * discards two of the bytes of the MAC address used
                 * to create the UUID (SF bug 33070).  The PTP V2
                 * enhanced mode fixes this issue and uses bytes 0-2
                 * and byte 5-7 of the UUID.
                 */
                match_data_345 = skb->data + PTP_V2_UUID_OFFSET + 5;
                if (ptp->mode == MC_CMD_PTP_MODE_V2) {
                        match_data_012 = skb->data + PTP_V2_UUID_OFFSET + 2;
                } else {
                        match_data_012 = skb->data + PTP_V2_UUID_OFFSET + 0;
                        BUG_ON(ptp->mode != MC_CMD_PTP_MODE_V2_ENHANCED);
                }
        }

        /* Does this packet require timestamping? */
        if (ntohs(*(__be16 *)&skb->data[PTP_DPORT_OFFSET]) == PTP_EVENT_PORT) {
                match->state = PTP_PACKET_STATE_UNMATCHED;

                /* We expect the sequence number to be in the same position in
                 * the packet for PTP V1 and V2
                 */
                BUILD_BUG_ON(PTP_V1_SEQUENCE_OFFSET != PTP_V2_SEQUENCE_OFFSET);
                BUILD_BUG_ON(PTP_V1_SEQUENCE_LENGTH != PTP_V2_SEQUENCE_LENGTH);

                /* Extract UUID/Sequence information */
                match->words[0] = (match_data_012[0]         |
                                   (match_data_012[1] << 8)  |
                                   (match_data_012[2] << 16) |
                                   (match_data_345[0] << 24));
                match->words[1] = (match_data_345[1]         |
                                   (match_data_345[2] << 8)  |
                                   (skb->data[PTP_V1_SEQUENCE_OFFSET +
                                              PTP_V1_SEQUENCE_LENGTH - 1] <<
                                    16));
        } else {
                match->state = PTP_PACKET_STATE_MATCH_UNWANTED;
        }

        skb_queue_tail(&ptp->rxq, skb);
        queue_work(ptp->workwq, &ptp->work);

        return true;
}

/* Transmit a PTP packet.  This has to be transmitted by the MC
 * itself, through an MCDI call.  MCDI calls aren't permitted
 * in the transmit path so defer the actual transmission to a suitable worker.
 */
int efx_ptp_tx(struct efx_nic *efx, struct sk_buff *skb)
{
        struct efx_ptp_data *ptp = efx->ptp_data;

        skb_queue_tail(&ptp->txq, skb);

        if ((udp_hdr(skb)->dest == htons(PTP_EVENT_PORT)) &&
            (skb->len <= MC_CMD_PTP_IN_TRANSMIT_PACKET_MAXNUM))
                efx_xmit_hwtstamp_pending(skb);
        queue_work(ptp->workwq, &ptp->work);

        return NETDEV_TX_OK;
}

int efx_ptp_get_mode(struct efx_nic *efx)
{
        return efx->ptp_data->mode;
}

int efx_ptp_change_mode(struct efx_nic *efx, bool enable_wanted,
                        unsigned int new_mode)
{
        if ((enable_wanted != efx->ptp_data->enabled) ||
            (enable_wanted && (efx->ptp_data->mode != new_mode))) {
                int rc = 0;

                if (enable_wanted) {
                        /* Change of mode requires disable */
                        if (efx->ptp_data->enabled &&
                            (efx->ptp_data->mode != new_mode)) {
                                efx->ptp_data->enabled = false;
                                rc = efx_ptp_stop(efx);
                                if (rc != 0)
                                        return rc;
                        }

                        /* Set new operating mode and establish
                         * baseline synchronisation, which must
                         * succeed.
                         */
                        efx->ptp_data->mode = new_mode;
                        if (netif_running(efx->net_dev))
                                rc = efx_ptp_start(efx);
                        if (rc == 0) {
                                rc = efx_ptp_synchronize(efx,
                                                         PTP_SYNC_ATTEMPTS * 2);
                                if (rc != 0)
                                        efx_ptp_stop(efx);
                        }
                } else {
                        rc = efx_ptp_stop(efx);
                }

                if (rc != 0)
                        return rc;

                efx->ptp_data->enabled = enable_wanted;
        }

        return 0;
}

static int efx_ptp_ts_init(struct efx_nic *efx, struct hwtstamp_config *init)
{
        int rc;

        if (init->flags)
                return -EINVAL;

        if ((init->tx_type != HWTSTAMP_TX_OFF) &&
            (init->tx_type != HWTSTAMP_TX_ON))
                return -ERANGE;

        rc = efx->type->ptp_set_ts_config(efx, init);
        if (rc)
                return rc;

        efx->ptp_data->config = *init;
        return 0;
}

void efx_ptp_get_ts_info(struct efx_nic *efx, struct ethtool_ts_info *ts_info)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        struct efx_nic *primary = efx->primary;

        ASSERT_RTNL();

        if (!ptp)
                return;

        ts_info->so_timestamping |= (SOF_TIMESTAMPING_TX_HARDWARE |
                                     SOF_TIMESTAMPING_RX_HARDWARE |
                                     SOF_TIMESTAMPING_RAW_HARDWARE);
        if (primary && primary->ptp_data && primary->ptp_data->phc_clock)
                ts_info->phc_index =
                        ptp_clock_index(primary->ptp_data->phc_clock);
        ts_info->tx_types = 1 << HWTSTAMP_TX_OFF | 1 << HWTSTAMP_TX_ON;
        ts_info->rx_filters = ptp->efx->type->hwtstamp_filters;
}

int efx_ptp_set_ts_config(struct efx_nic *efx, struct ifreq *ifr)
{
        struct hwtstamp_config config;
        int rc;

        /* Not a PTP enabled port */
        if (!efx->ptp_data)
                return -EOPNOTSUPP;

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

        rc = efx_ptp_ts_init(efx, &config);
        if (rc != 0)
                return rc;

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

int efx_ptp_get_ts_config(struct efx_nic *efx, struct ifreq *ifr)
{
        if (!efx->ptp_data)
                return -EOPNOTSUPP;

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

static void ptp_event_failure(struct efx_nic *efx, int expected_frag_len)
{
        struct efx_ptp_data *ptp = efx->ptp_data;

        netif_err(efx, hw, efx->net_dev,
                "PTP unexpected event length: got %d expected %d\n",
                ptp->evt_frag_idx, expected_frag_len);
        ptp->reset_required = true;
        queue_work(ptp->workwq, &ptp->work);
}

/* Process a completed receive event.  Put it on the event queue and
 * start worker thread.  This is required because event and their
 * correspoding packets may come in either order.
 */
static void ptp_event_rx(struct efx_nic *efx, struct efx_ptp_data *ptp)
{
        struct efx_ptp_event_rx *evt = NULL;

        if (WARN_ON_ONCE(ptp->rx_ts_inline))
                return;

        if (ptp->evt_frag_idx != 3) {
                ptp_event_failure(efx, 3);
                return;
        }

        spin_lock_bh(&ptp->evt_lock);
        if (!list_empty(&ptp->evt_free_list)) {
                evt = list_first_entry(&ptp->evt_free_list,
                                       struct efx_ptp_event_rx, link);
                list_del(&evt->link);

                evt->seq0 = EFX_QWORD_FIELD(ptp->evt_frags[2], MCDI_EVENT_DATA);
                evt->seq1 = (EFX_QWORD_FIELD(ptp->evt_frags[2],
                                             MCDI_EVENT_SRC)        |
                             (EFX_QWORD_FIELD(ptp->evt_frags[1],
                                              MCDI_EVENT_SRC) << 8) |
                             (EFX_QWORD_FIELD(ptp->evt_frags[0],
                                              MCDI_EVENT_SRC) << 16));
                evt->hwtimestamp = efx->ptp_data->nic_to_kernel_time(
                        EFX_QWORD_FIELD(ptp->evt_frags[0], MCDI_EVENT_DATA),
                        EFX_QWORD_FIELD(ptp->evt_frags[1], MCDI_EVENT_DATA),
                        ptp->ts_corrections.rx);
                evt->expiry = jiffies + msecs_to_jiffies(PKT_EVENT_LIFETIME_MS);
                list_add_tail(&evt->link, &ptp->evt_list);

                queue_work(ptp->workwq, &ptp->work);
        } else if (!ptp->evt_overflow) {
                /* Log a warning message and set the event overflow flag.
                 * The message won't be logged again until the event queue
                 * becomes empty.
                 */
                netif_err(efx, rx_err, efx->net_dev, "PTP event queue overflow\n");
                ptp->evt_overflow = true;
        }
        spin_unlock_bh(&ptp->evt_lock);
}

static void ptp_event_fault(struct efx_nic *efx, struct efx_ptp_data *ptp)
{
        int code = EFX_QWORD_FIELD(ptp->evt_frags[0], MCDI_EVENT_DATA);
        if (ptp->evt_frag_idx != 1) {
                ptp_event_failure(efx, 1);
                return;
        }

        netif_err(efx, hw, efx->net_dev, "PTP error %d\n", code);
}

static void ptp_event_pps(struct efx_nic *efx, struct efx_ptp_data *ptp)
{
        if (ptp->nic_ts_enabled)
                queue_work(ptp->pps_workwq, &ptp->pps_work);
}

void efx_ptp_event(struct efx_nic *efx, efx_qword_t *ev)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        int code = EFX_QWORD_FIELD(*ev, MCDI_EVENT_CODE);

        if (!ptp) {
                if (net_ratelimit())
                        netif_warn(efx, drv, efx->net_dev,
                                   "Received PTP event but PTP not set up\n");
                return;
        }

        if (!ptp->enabled)
                return;

        if (ptp->evt_frag_idx == 0) {
                ptp->evt_code = code;
        } else if (ptp->evt_code != code) {
                netif_err(efx, hw, efx->net_dev,
                          "PTP out of sequence event %d\n", code);
                ptp->evt_frag_idx = 0;
        }

        ptp->evt_frags[ptp->evt_frag_idx++] = *ev;
        if (!MCDI_EVENT_FIELD(*ev, CONT)) {
                /* Process resulting event */
                switch (code) {
                case MCDI_EVENT_CODE_PTP_RX:
                        ptp_event_rx(efx, ptp);
                        break;
                case MCDI_EVENT_CODE_PTP_FAULT:
                        ptp_event_fault(efx, ptp);
                        break;
                case MCDI_EVENT_CODE_PTP_PPS:
                        ptp_event_pps(efx, ptp);
                        break;
                default:
                        netif_err(efx, hw, efx->net_dev,
                                  "PTP unknown event %d\n", code);
                        break;
                }
                ptp->evt_frag_idx = 0;
        } else if (MAX_EVENT_FRAGS == ptp->evt_frag_idx) {
                netif_err(efx, hw, efx->net_dev,
                          "PTP too many event fragments\n");
                ptp->evt_frag_idx = 0;
        }
}

void efx_time_sync_event(struct efx_channel *channel, efx_qword_t *ev)
{
        channel->sync_timestamp_major = MCDI_EVENT_FIELD(*ev, PTP_TIME_MAJOR);
        channel->sync_timestamp_minor =
                MCDI_EVENT_FIELD(*ev, PTP_TIME_MINOR_26_19) << 19;
        /* if sync events have been disabled then we want to silently ignore
         * this event, so throw away result.
         */
        (void) cmpxchg(&channel->sync_events_state, SYNC_EVENTS_REQUESTED,
                       SYNC_EVENTS_VALID);
}

/* make some assumptions about the time representation rather than abstract it,
 * since we currently only support one type of inline timestamping and only on
 * EF10.
 */
#define MINOR_TICKS_PER_SECOND 0x8000000
/* Fuzz factor for sync events to be out of order with RX events */
#define FUZZ (MINOR_TICKS_PER_SECOND / 10)
#define EXPECTED_SYNC_EVENTS_PER_SECOND 4

static inline u32 efx_rx_buf_timestamp_minor(struct efx_nic *efx, const u8 *eh)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
        return __le32_to_cpup((const __le32 *)(eh + efx->rx_packet_ts_offset));
#else
        const u8 *data = eh + efx->rx_packet_ts_offset;
        return (u32)data[0]       |
               (u32)data[1] << 8  |
               (u32)data[2] << 16 |
               (u32)data[3] << 24;
#endif
}

void __efx_rx_skb_attach_timestamp(struct efx_channel *channel,
                                   struct sk_buff *skb)
{
        struct efx_nic *efx = channel->efx;
        u32 pkt_timestamp_major, pkt_timestamp_minor;
        u32 diff, carry;
        struct skb_shared_hwtstamps *timestamps;

        pkt_timestamp_minor = (efx_rx_buf_timestamp_minor(efx,
                                                          skb_mac_header(skb)) +
                               (u32) efx->ptp_data->ts_corrections.rx) &
                              (MINOR_TICKS_PER_SECOND - 1);

        /* get the difference between the packet and sync timestamps,
         * modulo one second
         */
        diff = (pkt_timestamp_minor - channel->sync_timestamp_minor) &
                (MINOR_TICKS_PER_SECOND - 1);
        /* do we roll over a second boundary and need to carry the one? */
        carry = channel->sync_timestamp_minor + diff > MINOR_TICKS_PER_SECOND ?
                1 : 0;

        if (diff <= MINOR_TICKS_PER_SECOND / EXPECTED_SYNC_EVENTS_PER_SECOND +
                    FUZZ) {
                /* packet is ahead of the sync event by a quarter of a second or
                 * less (allowing for fuzz)
                 */
                pkt_timestamp_major = channel->sync_timestamp_major + carry;
        } else if (diff >= MINOR_TICKS_PER_SECOND - FUZZ) {
                /* packet is behind the sync event but within the fuzz factor.
                 * This means the RX packet and sync event crossed as they were
                 * placed on the event queue, which can sometimes happen.
                 */
                pkt_timestamp_major = channel->sync_timestamp_major - 1 + carry;
        } else {
                /* it's outside tolerance in both directions. this might be
                 * indicative of us missing sync events for some reason, so
                 * we'll call it an error rather than risk giving a bogus
                 * timestamp.
                 */
                netif_vdbg(efx, drv, efx->net_dev,
                          "packet timestamp %x too far from sync event %x:%x\n",
                          pkt_timestamp_minor, channel->sync_timestamp_major,
                          channel->sync_timestamp_minor);
                return;
        }

        /* attach the timestamps to the skb */
        timestamps = skb_hwtstamps(skb);
        timestamps->hwtstamp =
                efx_ptp_s27_to_ktime(pkt_timestamp_major, pkt_timestamp_minor);
}

static int efx_phc_adjfreq(struct ptp_clock_info *ptp, s32 delta)
{
        struct efx_ptp_data *ptp_data = container_of(ptp,
                                                     struct efx_ptp_data,
                                                     phc_clock_info);
        struct efx_nic *efx = ptp_data->efx;
        MCDI_DECLARE_BUF(inadj, MC_CMD_PTP_IN_ADJUST_LEN);
        s64 adjustment_ns;
        int rc;

        if (delta > MAX_PPB)
                delta = MAX_PPB;
        else if (delta < -MAX_PPB)
                delta = -MAX_PPB;

        /* Convert ppb to fixed point ns. */
        adjustment_ns = (((s64)delta * PPB_SCALE_WORD) >>
                         (PPB_EXTRA_BITS + MAX_PPB_BITS));

        MCDI_SET_DWORD(inadj, PTP_IN_OP, MC_CMD_PTP_OP_ADJUST);
        MCDI_SET_DWORD(inadj, PTP_IN_PERIPH_ID, 0);
        MCDI_SET_QWORD(inadj, PTP_IN_ADJUST_FREQ, adjustment_ns);
        MCDI_SET_DWORD(inadj, PTP_IN_ADJUST_SECONDS, 0);
        MCDI_SET_DWORD(inadj, PTP_IN_ADJUST_NANOSECONDS, 0);
        rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inadj, sizeof(inadj),
                          NULL, 0, NULL);
        if (rc != 0)
                return rc;

        ptp_data->current_adjfreq = adjustment_ns;
        return 0;
}

static int efx_phc_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        u32 nic_major, nic_minor;
        struct efx_ptp_data *ptp_data = container_of(ptp,
                                                     struct efx_ptp_data,
                                                     phc_clock_info);
        struct efx_nic *efx = ptp_data->efx;
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_ADJUST_LEN);

        efx->ptp_data->ns_to_nic_time(delta, &nic_major, &nic_minor);

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_ADJUST);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);
        MCDI_SET_QWORD(inbuf, PTP_IN_ADJUST_FREQ, ptp_data->current_adjfreq);
        MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_MAJOR, nic_major);
        MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_MINOR, nic_minor);
        return efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                            NULL, 0, NULL);
}

static int efx_phc_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
{
        struct efx_ptp_data *ptp_data = container_of(ptp,
                                                     struct efx_ptp_data,
                                                     phc_clock_info);
        struct efx_nic *efx = ptp_data->efx;
        MCDI_DECLARE_BUF(inbuf, MC_CMD_PTP_IN_READ_NIC_TIME_LEN);
        MCDI_DECLARE_BUF(outbuf, MC_CMD_PTP_OUT_READ_NIC_TIME_LEN);
        int rc;
        ktime_t kt;

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_READ_NIC_TIME);
        MCDI_SET_DWORD(inbuf, PTP_IN_PERIPH_ID, 0);

        rc = efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                          outbuf, sizeof(outbuf), NULL);
        if (rc != 0)
                return rc;

        kt = ptp_data->nic_to_kernel_time(
                MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_MAJOR),
                MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_MINOR), 0);
        *ts = ktime_to_timespec(kt);
        return 0;
}

static int efx_phc_settime(struct ptp_clock_info *ptp,
                           const struct timespec *e_ts)
{
        /* Get the current NIC time, efx_phc_gettime.
         * Subtract from the desired time to get the offset
         * call efx_phc_adjtime with the offset
         */
        int rc;
        struct timespec time_now;
        struct timespec delta;

        rc = efx_phc_gettime(ptp, &time_now);
        if (rc != 0)
                return rc;

        delta = timespec_sub(*e_ts, time_now);

        rc = efx_phc_adjtime(ptp, timespec_to_ns(&delta));
        if (rc != 0)
                return rc;

        return 0;
}

static int efx_phc_enable(struct ptp_clock_info *ptp,
                          struct ptp_clock_request *request,
                          int enable)
{
        struct efx_ptp_data *ptp_data = container_of(ptp,
                                                     struct efx_ptp_data,
                                                     phc_clock_info);
        if (request->type != PTP_CLK_REQ_PPS)
                return -EOPNOTSUPP;

        ptp_data->nic_ts_enabled = !!enable;
        return 0;
}

static const struct efx_channel_type efx_ptp_channel_type = {
        .handle_no_channel      = efx_ptp_handle_no_channel,
        .pre_probe              = efx_ptp_probe_channel,
        .post_remove            = efx_ptp_remove_channel,
        .get_name               = efx_ptp_get_channel_name,
        /* no copy operation; there is no need to reallocate this channel */
        .receive_skb            = efx_ptp_rx,
        .keep_eventq            = false,
};

void efx_ptp_defer_probe_with_channel(struct efx_nic *efx)
{
        /* Check whether PTP is implemented on this NIC.  The DISABLE
         * operation will succeed if and only if it is implemented.
         */
        if (efx_ptp_disable(efx) == 0)
                efx->extra_channel_type[EFX_EXTRA_CHANNEL_PTP] =
                        &efx_ptp_channel_type;
}

void efx_ptp_start_datapath(struct efx_nic *efx)
{
        if (efx_ptp_restart(efx))
                netif_err(efx, drv, efx->net_dev, "Failed to restart PTP.\n");
        /* re-enable timestamping if it was previously enabled */
        if (efx->type->ptp_set_ts_sync_events)
                efx->type->ptp_set_ts_sync_events(efx, true, true);
}

void efx_ptp_stop_datapath(struct efx_nic *efx)
{
        /* temporarily disable timestamping */
        if (efx->type->ptp_set_ts_sync_events)
                efx->type->ptp_set_ts_sync_events(efx, false, true);
        efx_ptp_stop(efx);
}