/****************************************************************************
 * Driver for Solarflare Solarstorm network controllers and boards
 * Copyright 2011 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 "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 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
 * @seconds: Hardware timestamp, seconds
 * @nanoseconds: Hardware timestamp, nanoseconds
 * @host_end: Host time immediately after hardware timestamp taken
 * @waitns: Number of nanoseconds 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 seconds;
        u32 nanoseconds;
        u32 host_end;
        u32 waitns;
        u32 window;     /* Derived: end - start, allowing for wrap */
};

/**
 * struct efx_ptp_data - Precision Time Protocol (PTP) state
 * @channel: The PTP channel
 * @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
 * @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)
 * @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
 * @last_sync_ns: Last number of nanoseconds between readings when synchronising
 * @base_sync_ns: Number of nanoseconds for last synchronisation.
 * @base_sync_valid: Whether base_sync_time is valid.
 * @current_adjfreq: Current ppb adjustment.
 * @phc_clock: Pointer to registered phc device
 * @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).
 * @debug_ptp_dir: PTP debugfs directory
 * @missed_rx_sync: Number of packets received without syncrhonisation.
 * @good_syncs: Number of successful synchronisations.
 * @no_time_syncs: Number of synchronisations with no good times.
 * @bad_sync_durations: Number of synchronisations with bad durations.
 * @bad_syncs: Number of failed synchronisations.
 * @last_sync_time: Number of nanoseconds for last synchronisation.
 * @sync_timeouts: Number of synchronisation timeouts
 * @fast_syncs: Number of synchronisations requiring short delay
 * @min_sync_delta: Minimum time between event and synchronisation
 * @max_sync_delta: Maximum time between event and synchronisation
 * @average_sync_delta: Average time between event and synchronisation.
 *                      Modified moving average.
 * @last_sync_delta: Last time between event and synchronisation
 * @mc_stats: Context value for MC statistics
 * @timeset: Last set of synchronisation statistics.
 */
struct efx_ptp_data {
        struct efx_channel *channel;
        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;
        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;
        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;
        unsigned last_sync_ns;
        unsigned base_sync_ns;
        bool base_sync_valid;
        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;
        u8 txbuf[ALIGN(MC_CMD_PTP_IN_TRANSMIT_LEN(
                               MC_CMD_PTP_IN_TRANSMIT_PACKET_MAXNUM), 4)];
        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);

/* Enable MCDI PTP support. */
static int efx_ptp_enable(struct efx_nic *efx)
{
        u8 inbuf[MC_CMD_PTP_IN_ENABLE_LEN];

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

        return efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                            NULL, 0, NULL);
}

/* 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)
{
        u8 inbuf[MC_CMD_PTP_IN_DISABLE_LEN];

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_DISABLE);
        return efx_mcdi_rpc(efx, MC_CMD_PTP, inbuf, sizeof(inbuf),
                            NULL, 0, NULL);
}

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_writed(efx, cpu_to_le32(host_time),
                            FR_CZ_MC_TREG_SMEM + MC_SMEM_P0_PTP_TIME_OFST);
        }
        *last_time = now;
}

/* Read a timeset from the MC's results and partial process. */
static void efx_ptp_read_timeset(u8 *data, struct efx_ptp_timeset *timeset)
{
        unsigned start_ns, end_ns;

        timeset->host_start = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_HOSTSTART);
        timeset->seconds = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_SECONDS);
        timeset->nanoseconds = MCDI_DWORD(data,
                                         PTP_OUT_SYNCHRONIZE_NANOSECONDS);
        timeset->host_end = MCDI_DWORD(data, PTP_OUT_SYNCHRONIZE_HOSTEND),
        timeset->waitns = 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, u8 *synch_buf,
                                 size_t response_length,
                                 const struct pps_event_time *last_time)
{
        unsigned number_readings = (response_length /
                               MC_CMD_PTP_OUT_SYNCHRONIZE_TIMESET_LEN);
        unsigned i;
        unsigned total;
        unsigned ngood = 0;
        unsigned last_good = 0;
        struct efx_ptp_data *ptp = efx->ptp_data;
        u32 last_sec;
        u32 start_sec;
        struct timespec delta;

        if (number_readings == 0)
                return -EAGAIN;

        /* Read the set of results and increment stats for any results that
         * appera to be erroneous.
         */
        for (i = 0; i < number_readings; i++) {
                efx_ptp_read_timeset(synch_buf, &ptp->timeset[i]);
                synch_buf += MC_CMD_PTP_OUT_SYNCHRONIZE_TIMESET_LEN;
        }

        /* 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.
         */
        total = 0;
        for (i = 0; i < number_readings; i++)
                if (ptp->timeset[i].window > ptp->timeset[i].waitns) {
                        unsigned win;

                        win = ptp->timeset[i].window - ptp->timeset[i].waitns;
                        if (win >= MIN_SYNCHRONISATION_NS &&
                            win < MAX_SYNCHRONISATION_NS) {
                                total += ptp->timeset[i].window;
                                ngood++;
                                last_good = i;
                        }
                }

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

        /* Average minimum this synchronisation */
        ptp->last_sync_ns = DIV_ROUND_UP(total, ngood);
        if (!ptp->base_sync_valid || (ptp->last_sync_ns < ptp->base_sync_ns)) {
                ptp->base_sync_valid = true;
                ptp->base_sync_ns = ptp->last_sync_ns;
        }

        /* Calculate delay from actual PPS to last_time */
        delta.tv_nsec =
                ptp->timeset[last_good].nanoseconds +
                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;
        u8 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_SYNCHRONIZE_NUMTIMESETS,
                       num_readings);
        MCDI_SET_DWORD(synch_buf, PTP_IN_SYNCHRONIZE_START_ADDR_LO,
                       (u32)ptp->start.dma_addr);
        MCDI_SET_DWORD(synch_buf, PTP_IN_SYNCHRONIZE_START_ADDR_HI,
                       (u32)((u64)ptp->start.dma_addr >> 32));

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

        /* 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 (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);

        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)
{
        u8 *txbuf = efx->ptp_data->txbuf;
        struct skb_shared_hwtstamps timestamps;
        int rc = -EIO;
        /* MCDI driver requires word aligned lengths */
        size_t len = ALIGN(MC_CMD_PTP_IN_TRANSMIT_LEN(skb->len), 4);
        u8 txtime[MC_CMD_PTP_OUT_TRANSMIT_LEN];

        MCDI_SET_DWORD(txbuf, PTP_IN_OP, MC_CMD_PTP_OP_TRANSMIT);
        MCDI_SET_DWORD(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,
                                  &txbuf[MC_CMD_PTP_IN_TRANSMIT_PACKET_OFST],
                                  len);
        rc = efx_mcdi_rpc(efx, MC_CMD_PTP, txbuf, len, txtime,
                          sizeof(txtime), &len);
        if (rc != 0)
                goto fail;

        memset(&timestamps, 0, sizeof(timestamps));
        timestamps.hwtstamp = ktime_set(
                MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_SECONDS),
                MCDI_DWORD(txtime, PTP_OUT_TRANSMIT_NANOSECONDS));

        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;

        /* 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");
                        }
                }
        }
        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;

        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;
                }
        }
        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.
 * true is returned if at least one of those packets requires
 * synchronisation.
 */
static bool efx_ptp_process_events(struct efx_nic *efx, struct sk_buff_head *q)
{
        struct efx_ptp_data *ptp = efx->ptp_data;
        bool rc = false;
        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) {
                        rc = true;
                        __skb_queue_tail(q, skb);
                } else if (time_after(jiffies, match->expiry)) {
                        match->state = PTP_PACKET_STATE_TIMED_OUT;
                        netif_warn(efx, rx_err, efx->net_dev,
                                   "PTP packet - no timestamp seen\n");
                        __skb_queue_tail(q, skb);
                } else {
                        /* Replace unprocessed entry and stop */
                        skb_queue_head(&ptp->rxq, skb);
                        break;
                }
        }

        return rc;
}

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

        ptp->reset_required = false;

        /* 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;

        rc = efx_ptp_enable(efx);
        if (rc != 0)
                goto fail2;

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

        return 0;

fail2:
        efx_filter_remove_id_safe(efx, EFX_FILTER_PRI_REQUIRED,
                                  ptp->rxfilter_general);
fail:
        efx_filter_remove_id_safe(efx, EFX_FILTER_PRI_REQUIRED,
                                  ptp->rxfilter_event);

        return rc;
}

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

        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;
        }

        /* 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);
        }
        spin_unlock_bh(&efx->ptp_data->evt_lock);

        return rc;
}

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->channel->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);
}

/* Process any pending transmissions and timestamp any received packets.
 */
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->channel->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);
        if (efx_ptp_process_events(efx, &tempq) ||
            !skb_queue_empty(&ptp_data->txq)) {

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

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

/* Initialise PTP channel and state.
 *
 * 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;
        struct efx_ptp_data *ptp;
        int rc = 0;
        unsigned int pos;

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

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

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

        ptp->channel = channel;
        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->phc_clock_info.owner = THIS_MODULE;
        snprintf(ptp->phc_clock_info.name,
                 sizeof(ptp->phc_clock_info.name),
                 "%pm", efx->net_dev->perm_addr);
        ptp->phc_clock_info.max_adj = MAX_PPB;
        ptp->phc_clock_info.n_alarm = 0;
        ptp->phc_clock_info.n_ext_ts = 0;
        ptp->phc_clock_info.n_per_out = 0;
        ptp->phc_clock_info.pps = 1;
        ptp->phc_clock_info.adjfreq = efx_phc_adjfreq;
        ptp->phc_clock_info.adjtime = efx_phc_adjtime;
        ptp->phc_clock_info.gettime = efx_phc_gettime;
        ptp->phc_clock_info.settime = efx_phc_settime;
        ptp->phc_clock_info.enable = efx_phc_enable;

        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;
}

static void efx_ptp_remove_channel(struct efx_channel *channel)
{
        struct efx_nic *efx = channel->efx;

        if (!efx->ptp_data)
                return;

        (void)efx_ptp_disable(channel->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);

        ptp_clock_unregister(efx->ptp_data->phc_clock);

        destroy_workqueue(efx->ptp_data->workwq);
        destroy_workqueue(efx->ptp_data->pps_workwq);

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

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)) &&
                ip_hdr(skb)->protocol == IPPROTO_UDP &&
                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) {
                struct skb_shared_hwtstamps *timestamps;

                match->state = PTP_PACKET_STATE_UNMATCHED;

                /* Clear all timestamps held: filled in later */
                timestamps = skb_hwtstamps(skb);
                memset(timestamps, 0, sizeof(*timestamps));

                /* 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;
}

static 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;

                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;
                        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)
{
        bool enable_wanted = false;
        unsigned int new_mode;
        int rc;

        if (init->flags)
                return -EINVAL;

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

        new_mode = efx->ptp_data->mode;
        /* Determine whether any PTP HW operations are required */
        switch (init->rx_filter) {
        case HWTSTAMP_FILTER_NONE:
                break;
        case HWTSTAMP_FILTER_PTP_V1_L4_EVENT:
        case HWTSTAMP_FILTER_PTP_V1_L4_SYNC:
        case HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ:
                init->rx_filter = HWTSTAMP_FILTER_PTP_V1_L4_EVENT;
                new_mode = MC_CMD_PTP_MODE_V1;
                enable_wanted = true;
                break;
        case HWTSTAMP_FILTER_PTP_V2_L4_EVENT:
        case HWTSTAMP_FILTER_PTP_V2_L4_SYNC:
        case HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ:
        /* Although these three are accepted only IPV4 packets will be
         * timestamped
         */
                init->rx_filter = HWTSTAMP_FILTER_PTP_V2_L4_EVENT;
                new_mode = MC_CMD_PTP_MODE_V2_ENHANCED;
                enable_wanted = true;
                break;
        case HWTSTAMP_FILTER_PTP_V2_EVENT:
        case HWTSTAMP_FILTER_PTP_V2_SYNC:
        case HWTSTAMP_FILTER_PTP_V2_DELAY_REQ:
        case HWTSTAMP_FILTER_PTP_V2_L2_EVENT:
        case HWTSTAMP_FILTER_PTP_V2_L2_SYNC:
        case HWTSTAMP_FILTER_PTP_V2_L2_DELAY_REQ:
                /* Non-IP + IPv6 timestamping not supported */
                return -ERANGE;
                break;
        default:
                return -ERANGE;
        }

        if (init->tx_type != HWTSTAMP_TX_OFF)
                enable_wanted = true;

        /* Old versions of the firmware do not support the improved
         * UUID filtering option (SF bug 33070).  If the firmware does
         * not accept the enhanced mode, fall back to the standard PTP
         * v2 UUID filtering.
         */
        rc = efx_ptp_change_mode(efx, enable_wanted, new_mode);
        if ((rc != 0) && (new_mode == MC_CMD_PTP_MODE_V2_ENHANCED))
                rc = efx_ptp_change_mode(efx, enable_wanted, MC_CMD_PTP_MODE_V2);
        if (rc != 0)
                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;

        if (!ptp)
                return;

        ts_info->so_timestamping |= (SOF_TIMESTAMPING_TX_HARDWARE |
                                     SOF_TIMESTAMPING_RX_HARDWARE |
                                     SOF_TIMESTAMPING_RAW_HARDWARE);
        ts_info->phc_index = ptp_clock_index(ptp->phc_clock);
        ts_info->tx_types = 1 << HWTSTAMP_TX_OFF | 1 << HWTSTAMP_TX_ON;
        ts_info->rx_filters = (1 << HWTSTAMP_FILTER_NONE |
                               1 << HWTSTAMP_FILTER_PTP_V1_L4_EVENT |
                               1 << HWTSTAMP_FILTER_PTP_V1_L4_SYNC |
                               1 << HWTSTAMP_FILTER_PTP_V1_L4_DELAY_REQ |
                               1 << HWTSTAMP_FILTER_PTP_V2_L4_EVENT |
                               1 << HWTSTAMP_FILTER_PTP_V2_L4_SYNC |
                               1 << HWTSTAMP_FILTER_PTP_V2_L4_DELAY_REQ);
}

int efx_ptp_ioctl(struct efx_nic *efx, struct ifreq *ifr, int cmd)
{
        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;
}

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 (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 = ktime_set(
                        EFX_QWORD_FIELD(ptp->evt_frags[0], MCDI_EVENT_DATA),
                        EFX_QWORD_FIELD(ptp->evt_frags[1], MCDI_EVENT_DATA));
                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 {
                netif_err(efx, rx_err, efx->net_dev, "No free PTP event");
        }
        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->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;
        }
}

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->channel->efx;
        u8 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_ADJUST_FREQ_LO, (u32)adjustment_ns);
        MCDI_SET_DWORD(inadj, PTP_IN_ADJUST_FREQ_HI,
                       (u32)(adjustment_ns >> 32));
        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 = delta;
        return 0;
}

static int efx_phc_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        struct efx_ptp_data *ptp_data = container_of(ptp,
                                                     struct efx_ptp_data,
                                                     phc_clock_info);
        struct efx_nic *efx = ptp_data->channel->efx;
        struct timespec delta_ts = ns_to_timespec(delta);
        u8 inbuf[MC_CMD_PTP_IN_ADJUST_LEN];

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_ADJUST);
        MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_FREQ_LO, 0);
        MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_FREQ_HI, 0);
        MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_SECONDS, (u32)delta_ts.tv_sec);
        MCDI_SET_DWORD(inbuf, PTP_IN_ADJUST_NANOSECONDS, (u32)delta_ts.tv_nsec);
        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->channel->efx;
        u8 inbuf[MC_CMD_PTP_IN_READ_NIC_TIME_LEN];
        u8 outbuf[MC_CMD_PTP_OUT_READ_NIC_TIME_LEN];
        int rc;

        MCDI_SET_DWORD(inbuf, PTP_IN_OP, MC_CMD_PTP_OP_READ_NIC_TIME);

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

        ts->tv_sec = MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_SECONDS);
        ts->tv_nsec = MCDI_DWORD(outbuf, PTP_OUT_READ_NIC_TIME_NANOSECONDS);
        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_probe(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;
}