ptp.c

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/****************************************************************************
 * 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

/* 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 {
    u32 words[DIV_ROUND_UP(PTP_V1_UUID_LENGTH, 4)];
    unsigned long expiry;
    enum ptp_packet_state state;
};

struct efx_ptp_event_rx {
    struct list_head link;
    u32 seq0;
    u32 seq1;
    ktime_t hwtimestamp;
    unsigned long expiry;
};

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 {
    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 min;
    unsigned min_set = 0;
    unsigned total;
    unsigned ngood = 0;
    unsigned last_good = 0;
    struct efx_ptp_data *ptp = efx->ptp_data;
    bool min_valid = false;
    u32 last_sec;
    u32 start_sec;
    struct timespec delta;

    if (number_readings == 0)
        return -EAGAIN;

    /* Find minimum value in this set of results, discarding clearly
     * erroneous results.
     */
    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;
        if (ptp->timeset[i].window > SYNCHRONISATION_GRANULARITY_NS) {
            if (min_valid) {
                if (ptp->timeset[i].window < min_set)
                    min_set = ptp->timeset[i].window;
            } else {
                min_valid = true;
                min_set = ptp->timeset[i].window;
            }
        }
    }

    if (min_valid) {
        if (ptp->base_sync_valid && (min_set > ptp->base_sync_ns))
            min = ptp->base_sync_ns;
        else
            min = min_set;
    } else {
        min = SYNCHRONISATION_GRANULARITY_NS;
    }

    /* Discard excessively long synchronise durations.  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 %dns\n",
               ptp->base_sync_ns, min_set);
        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 (!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 void 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 *data;
    unsigned int version;

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

    /* Correct version? */
    if (ptp->mode == MC_CMD_PTP_MODE_V1) {
        if (skb->len < PTP_V1_MIN_LENGTH) {
            netif_receive_skb(skb);
            return;
        }
        version = ntohs(*(__be16 *)&skb->data[PTP_V1_VERSION_OFFSET]);
        if (version != PTP_VERSION_V1) {
            netif_receive_skb(skb);
            return;
        }
    } else {
        if (skb->len < PTP_V2_MIN_LENGTH) {
            netif_receive_skb(skb);
            return;
        }
        version = skb->data[PTP_V2_VERSION_OFFSET];

        BUG_ON(ptp->mode != MC_CMD_PTP_MODE_V2);
        BUILD_BUG_ON(PTP_V1_UUID_OFFSET != PTP_V2_MC_UUID_OFFSET);
        BUILD_BUG_ON(PTP_V1_UUID_LENGTH != PTP_V2_MC_UUID_LENGTH);
        BUILD_BUG_ON(PTP_V1_SEQUENCE_OFFSET != PTP_V2_SEQUENCE_OFFSET);
        BUILD_BUG_ON(PTP_V1_SEQUENCE_LENGTH != PTP_V2_SEQUENCE_LENGTH);

        if ((version & PTP_VERSION_V2_MASK) != PTP_VERSION_V2) {
            netif_receive_skb(skb);
            return;
        }
    }

    /* 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));

        /* Extract UUID/Sequence information */
        data = skb->data + PTP_V1_UUID_OFFSET;
        match->words[0] = (data[0]         |
                   (data[1] << 8)  |
                   (data[2] << 16) |
                   (data[3] << 24));
        match->words[1] = (data[4]         |
                   (data[5] << 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);
}

/* 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;
        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;

    rc = efx_ptp_change_mode(efx, enable_wanted, new_mode);
    if (rc != 0)
        return rc;

    efx->ptp_data->config = *init;

    return 0;
}

int
efx_ptp_get_ts_info(struct net_device *net_dev, struct ethtool_ts_info *ts_info)
{
    struct efx_nic *efx = netdev_priv(net_dev);
    struct efx_ptp_data *ptp = efx->ptp_data;

    if (!ptp)
        return -EOPNOTSUPP;

    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);
    return 0;
}

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);

    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;
}