// SPDX-License-Identifier: GPL-2.0+
/*
 * TI Common Platform Time Sync
 *
 * Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
 *
 */
#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/if.h>
#include <linux/hrtimer.h>
#include <linux/module.h>
#include <linux/net_tstamp.h>
#include <linux/ptp_classify.h>
#include <linux/time.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>

#include "cpts.h"

#define CPTS_SKB_TX_WORK_TIMEOUT 1 /* jiffies */

struct cpts_skb_cb_data {
        unsigned long tmo;
};

#define cpts_read32(c, r)       readl_relaxed(&c->reg->r)
#define cpts_write32(c, v, r)   writel_relaxed(v, &c->reg->r)

static int cpts_match(struct sk_buff *skb, unsigned int ptp_class,
                      u16 ts_seqid, u8 ts_msgtype);

static int event_expired(struct cpts_event *event)
{
        return time_after(jiffies, event->tmo);
}

static int event_type(struct cpts_event *event)
{
        return (event->high >> EVENT_TYPE_SHIFT) & EVENT_TYPE_MASK;
}

static int cpts_fifo_pop(struct cpts *cpts, u32 *high, u32 *low)
{
        u32 r = cpts_read32(cpts, intstat_raw);

        if (r & TS_PEND_RAW) {
                *high = cpts_read32(cpts, event_high);
                *low  = cpts_read32(cpts, event_low);
                cpts_write32(cpts, EVENT_POP, event_pop);
                return 0;
        }
        return -1;
}

static int cpts_purge_events(struct cpts *cpts)
{
        struct list_head *this, *next;
        struct cpts_event *event;
        int removed = 0;

        list_for_each_safe(this, next, &cpts->events) {
                event = list_entry(this, struct cpts_event, list);
                if (event_expired(event)) {
                        list_del_init(&event->list);
                        list_add(&event->list, &cpts->pool);
                        ++removed;
                }
        }

        if (removed)
                pr_debug("cpts: event pool cleaned up %d\n", removed);
        return removed ? 0 : -1;
}

static void cpts_purge_txq(struct cpts *cpts)
{
        struct cpts_skb_cb_data *skb_cb;
        struct sk_buff *skb, *tmp;
        int removed = 0;

        skb_queue_walk_safe(&cpts->txq, skb, tmp) {
                skb_cb = (struct cpts_skb_cb_data *)skb->cb;
                if (time_after(jiffies, skb_cb->tmo)) {
                        __skb_unlink(skb, &cpts->txq);
                        dev_consume_skb_any(skb);
                        ++removed;
                }
        }

        if (removed)
                dev_dbg(cpts->dev, "txq cleaned up %d\n", removed);
}

static bool cpts_match_tx_ts(struct cpts *cpts, struct cpts_event *event)
{
        struct sk_buff *skb, *tmp;
        u16 seqid;
        u8 mtype;
        bool found = false;

        mtype = (event->high >> MESSAGE_TYPE_SHIFT) & MESSAGE_TYPE_MASK;
        seqid = (event->high >> SEQUENCE_ID_SHIFT) & SEQUENCE_ID_MASK;

        /* no need to grab txq.lock as access is always done under cpts->lock */
        skb_queue_walk_safe(&cpts->txq, skb, tmp) {
                struct skb_shared_hwtstamps ssh;
                unsigned int class = ptp_classify_raw(skb);
                struct cpts_skb_cb_data *skb_cb =
                                        (struct cpts_skb_cb_data *)skb->cb;

                if (cpts_match(skb, class, seqid, mtype)) {
                        u64 ns = timecounter_cyc2time(&cpts->tc, event->low);

                        memset(&ssh, 0, sizeof(ssh));
                        ssh.hwtstamp = ns_to_ktime(ns);
                        skb_tstamp_tx(skb, &ssh);
                        found = true;
                        __skb_unlink(skb, &cpts->txq);
                        dev_consume_skb_any(skb);
                        dev_dbg(cpts->dev, "match tx timestamp mtype %u seqid %04x\n",
                                mtype, seqid);
                        break;
                }

                if (time_after(jiffies, skb_cb->tmo)) {
                        /* timeout any expired skbs over 1s */
                        dev_dbg(cpts->dev, "expiring tx timestamp from txq\n");
                        __skb_unlink(skb, &cpts->txq);
                        dev_consume_skb_any(skb);
                }
        }

        return found;
}

/*
 * Returns zero if matching event type was found.
 */
static int cpts_fifo_read(struct cpts *cpts, int match)
{
        int i, type = -1;
        u32 hi, lo;
        struct cpts_event *event;

        for (i = 0; i < CPTS_FIFO_DEPTH; i++) {
                if (cpts_fifo_pop(cpts, &hi, &lo))
                        break;

                if (list_empty(&cpts->pool) && cpts_purge_events(cpts)) {
                        pr_err("cpts: event pool empty\n");
                        return -1;
                }

                event = list_first_entry(&cpts->pool, struct cpts_event, list);
                event->tmo = jiffies + 2;
                event->high = hi;
                event->low = lo;
                type = event_type(event);
                switch (type) {
                case CPTS_EV_TX:
                        if (cpts_match_tx_ts(cpts, event)) {
                                /* if the new event matches an existing skb,
                                 * then don't queue it
                                 */
                                break;
                        }
                        /* fall through */
                case CPTS_EV_PUSH:
                case CPTS_EV_RX:
                        list_del_init(&event->list);
                        list_add_tail(&event->list, &cpts->events);
                        break;
                case CPTS_EV_ROLL:
                case CPTS_EV_HALF:
                case CPTS_EV_HW:
                        break;
                default:
                        pr_err("cpts: unknown event type\n");
                        break;
                }
                if (type == match)
                        break;
        }
        return type == match ? 0 : -1;
}

static u64 cpts_systim_read(const struct cyclecounter *cc)
{
        u64 val = 0;
        struct cpts_event *event;
        struct list_head *this, *next;
        struct cpts *cpts = container_of(cc, struct cpts, cc);

        cpts_write32(cpts, TS_PUSH, ts_push);
        if (cpts_fifo_read(cpts, CPTS_EV_PUSH))
                pr_err("cpts: unable to obtain a time stamp\n");

        list_for_each_safe(this, next, &cpts->events) {
                event = list_entry(this, struct cpts_event, list);
                if (event_type(event) == CPTS_EV_PUSH) {
                        list_del_init(&event->list);
                        list_add(&event->list, &cpts->pool);
                        val = event->low;
                        break;
                }
        }

        return val;
}

/* PTP clock operations */

static int cpts_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
{
        u64 adj;
        u32 diff, mult;
        int neg_adj = 0;
        unsigned long flags;
        struct cpts *cpts = container_of(ptp, struct cpts, info);

        if (ppb < 0) {
                neg_adj = 1;
                ppb = -ppb;
        }
        mult = cpts->cc_mult;
        adj = mult;
        adj *= ppb;
        diff = div_u64(adj, 1000000000ULL);

        spin_lock_irqsave(&cpts->lock, flags);

        timecounter_read(&cpts->tc);

        cpts->cc.mult = neg_adj ? mult - diff : mult + diff;

        spin_unlock_irqrestore(&cpts->lock, flags);

        return 0;
}

static int cpts_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        unsigned long flags;
        struct cpts *cpts = container_of(ptp, struct cpts, info);

        spin_lock_irqsave(&cpts->lock, flags);
        timecounter_adjtime(&cpts->tc, delta);
        spin_unlock_irqrestore(&cpts->lock, flags);

        return 0;
}

static int cpts_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
{
        u64 ns;
        unsigned long flags;
        struct cpts *cpts = container_of(ptp, struct cpts, info);

        spin_lock_irqsave(&cpts->lock, flags);
        ns = timecounter_read(&cpts->tc);
        spin_unlock_irqrestore(&cpts->lock, flags);

        *ts = ns_to_timespec64(ns);

        return 0;
}

static int cpts_ptp_settime(struct ptp_clock_info *ptp,
                            const struct timespec64 *ts)
{
        u64 ns;
        unsigned long flags;
        struct cpts *cpts = container_of(ptp, struct cpts, info);

        ns = timespec64_to_ns(ts);

        spin_lock_irqsave(&cpts->lock, flags);
        timecounter_init(&cpts->tc, &cpts->cc, ns);
        spin_unlock_irqrestore(&cpts->lock, flags);

        return 0;
}

static int cpts_ptp_enable(struct ptp_clock_info *ptp,
                           struct ptp_clock_request *rq, int on)
{
        return -EOPNOTSUPP;
}

static long cpts_overflow_check(struct ptp_clock_info *ptp)
{
        struct cpts *cpts = container_of(ptp, struct cpts, info);
        unsigned long delay = cpts->ov_check_period;
        struct timespec64 ts;
        unsigned long flags;

        spin_lock_irqsave(&cpts->lock, flags);
        ts = ns_to_timespec64(timecounter_read(&cpts->tc));

        if (!skb_queue_empty(&cpts->txq)) {
                cpts_purge_txq(cpts);
                if (!skb_queue_empty(&cpts->txq))
                        delay = CPTS_SKB_TX_WORK_TIMEOUT;
        }
        spin_unlock_irqrestore(&cpts->lock, flags);

        pr_debug("cpts overflow check at %lld.%09ld\n",
                 (long long)ts.tv_sec, ts.tv_nsec);
        return (long)delay;
}

static const struct ptp_clock_info cpts_info = {
        .owner          = THIS_MODULE,
        .name           = "CTPS timer",
        .max_adj        = 1000000,
        .n_ext_ts       = 0,
        .n_pins         = 0,
        .pps            = 0,
        .adjfreq        = cpts_ptp_adjfreq,
        .adjtime        = cpts_ptp_adjtime,
        .gettime64      = cpts_ptp_gettime,
        .settime64      = cpts_ptp_settime,
        .enable         = cpts_ptp_enable,
        .do_aux_work    = cpts_overflow_check,
};

static int cpts_match(struct sk_buff *skb, unsigned int ptp_class,
                      u16 ts_seqid, u8 ts_msgtype)
{
        u16 *seqid;
        unsigned int offset = 0;
        u8 *msgtype, *data = skb->data;

        if (ptp_class & PTP_CLASS_VLAN)
                offset += VLAN_HLEN;

        switch (ptp_class & PTP_CLASS_PMASK) {
        case PTP_CLASS_IPV4:
                offset += ETH_HLEN + IPV4_HLEN(data + offset) + UDP_HLEN;
                break;
        case PTP_CLASS_IPV6:
                offset += ETH_HLEN + IP6_HLEN + UDP_HLEN;
                break;
        case PTP_CLASS_L2:
                offset += ETH_HLEN;
                break;
        default:
                return 0;
        }

        if (skb->len + ETH_HLEN < offset + OFF_PTP_SEQUENCE_ID + sizeof(*seqid))
                return 0;

        if (unlikely(ptp_class & PTP_CLASS_V1))
                msgtype = data + offset + OFF_PTP_CONTROL;
        else
                msgtype = data + offset;

        seqid = (u16 *)(data + offset + OFF_PTP_SEQUENCE_ID);

        return (ts_msgtype == (*msgtype & 0xf) && ts_seqid == ntohs(*seqid));
}

static u64 cpts_find_ts(struct cpts *cpts, struct sk_buff *skb, int ev_type)
{
        u64 ns = 0;
        struct cpts_event *event;
        struct list_head *this, *next;
        unsigned int class = ptp_classify_raw(skb);
        unsigned long flags;
        u16 seqid;
        u8 mtype;

        if (class == PTP_CLASS_NONE)
                return 0;

        spin_lock_irqsave(&cpts->lock, flags);
        cpts_fifo_read(cpts, -1);
        list_for_each_safe(this, next, &cpts->events) {
                event = list_entry(this, struct cpts_event, list);
                if (event_expired(event)) {
                        list_del_init(&event->list);
                        list_add(&event->list, &cpts->pool);
                        continue;
                }
                mtype = (event->high >> MESSAGE_TYPE_SHIFT) & MESSAGE_TYPE_MASK;
                seqid = (event->high >> SEQUENCE_ID_SHIFT) & SEQUENCE_ID_MASK;
                if (ev_type == event_type(event) &&
                    cpts_match(skb, class, seqid, mtype)) {
                        ns = timecounter_cyc2time(&cpts->tc, event->low);
                        list_del_init(&event->list);
                        list_add(&event->list, &cpts->pool);
                        break;
                }
        }

        if (ev_type == CPTS_EV_TX && !ns) {
                struct cpts_skb_cb_data *skb_cb =
                                (struct cpts_skb_cb_data *)skb->cb;
                /* Not found, add frame to queue for processing later.
                 * The periodic FIFO check will handle this.
                 */
                skb_get(skb);
                /* get the timestamp for timeouts */
                skb_cb->tmo = jiffies + msecs_to_jiffies(100);
                __skb_queue_tail(&cpts->txq, skb);
                ptp_schedule_worker(cpts->clock, 0);
        }
        spin_unlock_irqrestore(&cpts->lock, flags);

        return ns;
}

void cpts_rx_timestamp(struct cpts *cpts, struct sk_buff *skb)
{
        u64 ns;
        struct skb_shared_hwtstamps *ssh;

        ns = cpts_find_ts(cpts, skb, CPTS_EV_RX);
        if (!ns)
                return;
        ssh = skb_hwtstamps(skb);
        memset(ssh, 0, sizeof(*ssh));
        ssh->hwtstamp = ns_to_ktime(ns);
}
EXPORT_SYMBOL_GPL(cpts_rx_timestamp);

void cpts_tx_timestamp(struct cpts *cpts, struct sk_buff *skb)
{
        u64 ns;
        struct skb_shared_hwtstamps ssh;

        if (!(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
                return;
        ns = cpts_find_ts(cpts, skb, CPTS_EV_TX);
        if (!ns)
                return;
        memset(&ssh, 0, sizeof(ssh));
        ssh.hwtstamp = ns_to_ktime(ns);
        skb_tstamp_tx(skb, &ssh);
}
EXPORT_SYMBOL_GPL(cpts_tx_timestamp);

int cpts_register(struct cpts *cpts)
{
        int err, i;

        skb_queue_head_init(&cpts->txq);
        INIT_LIST_HEAD(&cpts->events);
        INIT_LIST_HEAD(&cpts->pool);
        for (i = 0; i < CPTS_MAX_EVENTS; i++)
                list_add(&cpts->pool_data[i].list, &cpts->pool);

        clk_enable(cpts->refclk);

        cpts_write32(cpts, CPTS_EN, control);
        cpts_write32(cpts, TS_PEND_EN, int_enable);

        timecounter_init(&cpts->tc, &cpts->cc, ktime_to_ns(ktime_get_real()));

        cpts->clock = ptp_clock_register(&cpts->info, cpts->dev);
        if (IS_ERR(cpts->clock)) {
                err = PTR_ERR(cpts->clock);
                cpts->clock = NULL;
                goto err_ptp;
        }
        cpts->phc_index = ptp_clock_index(cpts->clock);

        ptp_schedule_worker(cpts->clock, cpts->ov_check_period);
        return 0;

err_ptp:
        clk_disable(cpts->refclk);
        return err;
}
EXPORT_SYMBOL_GPL(cpts_register);

void cpts_unregister(struct cpts *cpts)
{
        if (WARN_ON(!cpts->clock))
                return;

        ptp_clock_unregister(cpts->clock);
        cpts->clock = NULL;

        cpts_write32(cpts, 0, int_enable);
        cpts_write32(cpts, 0, control);

        /* Drop all packet */
        skb_queue_purge(&cpts->txq);

        clk_disable(cpts->refclk);
}
EXPORT_SYMBOL_GPL(cpts_unregister);

static void cpts_calc_mult_shift(struct cpts *cpts)
{
        u64 frac, maxsec, ns;
        u32 freq;

        freq = clk_get_rate(cpts->refclk);

        /* Calc the maximum number of seconds which we can run before
         * wrapping around.
         */
        maxsec = cpts->cc.mask;
        do_div(maxsec, freq);
        /* limit conversation rate to 10 sec as higher values will produce
         * too small mult factors and so reduce the conversion accuracy
         */
        if (maxsec > 10)
                maxsec = 10;

        /* Calc overflow check period (maxsec / 2) */
        cpts->ov_check_period = (HZ * maxsec) / 2;
        dev_info(cpts->dev, "cpts: overflow check period %lu (jiffies)\n",
                 cpts->ov_check_period);

        if (cpts->cc.mult || cpts->cc.shift)
                return;

        clocks_calc_mult_shift(&cpts->cc.mult, &cpts->cc.shift,
                               freq, NSEC_PER_SEC, maxsec);

        frac = 0;
        ns = cyclecounter_cyc2ns(&cpts->cc, freq, cpts->cc.mask, &frac);

        dev_info(cpts->dev,
                 "CPTS: ref_clk_freq:%u calc_mult:%u calc_shift:%u error:%lld nsec/sec\n",
                 freq, cpts->cc.mult, cpts->cc.shift, (ns - NSEC_PER_SEC));
}

static int cpts_of_mux_clk_setup(struct cpts *cpts, struct device_node *node)
{
        struct device_node *refclk_np;
        const char **parent_names;
        unsigned int num_parents;
        struct clk_hw *clk_hw;
        int ret = -EINVAL;
        u32 *mux_table;

        refclk_np = of_get_child_by_name(node, "cpts-refclk-mux");
        if (!refclk_np)
                /* refclk selection supported not for all SoCs */
                return 0;

        num_parents = of_clk_get_parent_count(refclk_np);
        if (num_parents < 1) {
                dev_err(cpts->dev, "mux-clock %s must have parents\n",
                        refclk_np->name);
                goto mux_fail;
        }

        parent_names = devm_kzalloc(cpts->dev, (sizeof(char *) * num_parents),
                                    GFP_KERNEL);

        mux_table = devm_kzalloc(cpts->dev, sizeof(*mux_table) * num_parents,
                                 GFP_KERNEL);
        if (!mux_table || !parent_names) {
                ret = -ENOMEM;
                goto mux_fail;
        }

        of_clk_parent_fill(refclk_np, parent_names, num_parents);

        ret = of_property_read_variable_u32_array(refclk_np, "ti,mux-tbl",
                                                  mux_table,
                                                  num_parents, num_parents);
        if (ret < 0)
                goto mux_fail;

        clk_hw = clk_hw_register_mux_table(cpts->dev, refclk_np->name,
                                           parent_names, num_parents,
                                           0,
                                           &cpts->reg->rftclk_sel, 0, 0x1F,
                                           0, mux_table, NULL);
        if (IS_ERR(clk_hw)) {
                ret = PTR_ERR(clk_hw);
                goto mux_fail;
        }

        ret = devm_add_action_or_reset(cpts->dev,
                                       (void(*)(void *))clk_hw_unregister_mux,
                                       clk_hw);
        if (ret) {
                dev_err(cpts->dev, "add clkmux unreg action %d", ret);
                goto mux_fail;
        }

        ret = of_clk_add_hw_provider(refclk_np, of_clk_hw_simple_get, clk_hw);
        if (ret)
                goto mux_fail;

        ret = devm_add_action_or_reset(cpts->dev,
                                       (void(*)(void *))of_clk_del_provider,
                                       refclk_np);
        if (ret) {
                dev_err(cpts->dev, "add clkmux provider unreg action %d", ret);
                goto mux_fail;
        }

        return ret;

mux_fail:
        of_node_put(refclk_np);
        return ret;
}

static int cpts_of_parse(struct cpts *cpts, struct device_node *node)
{
        int ret = -EINVAL;
        u32 prop;

        if (!of_property_read_u32(node, "cpts_clock_mult", &prop))
                cpts->cc.mult = prop;

        if (!of_property_read_u32(node, "cpts_clock_shift", &prop))
                cpts->cc.shift = prop;

        if ((cpts->cc.mult && !cpts->cc.shift) ||
            (!cpts->cc.mult && cpts->cc.shift))
                goto of_error;

        return cpts_of_mux_clk_setup(cpts, node);

of_error:
        dev_err(cpts->dev, "CPTS: Missing property in the DT.\n");
        return ret;
}

struct cpts *cpts_create(struct device *dev, void __iomem *regs,
                         struct device_node *node)
{
        struct cpts *cpts;
        int ret;

        cpts = devm_kzalloc(dev, sizeof(*cpts), GFP_KERNEL);
        if (!cpts)
                return ERR_PTR(-ENOMEM);

        cpts->dev = dev;
        cpts->reg = (struct cpsw_cpts __iomem *)regs;
        spin_lock_init(&cpts->lock);

        ret = cpts_of_parse(cpts, node);
        if (ret)
                return ERR_PTR(ret);

        cpts->refclk = devm_get_clk_from_child(dev, node, "cpts");
        if (IS_ERR(cpts->refclk))
                /* try get clk from dev node for compatibility */
                cpts->refclk = devm_clk_get(dev, "cpts");

        if (IS_ERR(cpts->refclk)) {
                dev_err(dev, "Failed to get cpts refclk %ld\n",
                        PTR_ERR(cpts->refclk));
                return ERR_CAST(cpts->refclk);
        }

        ret = clk_prepare(cpts->refclk);
        if (ret)
                return ERR_PTR(ret);

        cpts->cc.read = cpts_systim_read;
        cpts->cc.mask = CLOCKSOURCE_MASK(32);
        cpts->info = cpts_info;

        cpts_calc_mult_shift(cpts);
        /* save cc.mult original value as it can be modified
         * by cpts_ptp_adjfreq().
         */
        cpts->cc_mult = cpts->cc.mult;

        return cpts;
}
EXPORT_SYMBOL_GPL(cpts_create);

void cpts_release(struct cpts *cpts)
{
        if (!cpts)
                return;

        if (WARN_ON(!cpts->refclk))
                return;

        clk_unprepare(cpts->refclk);
}
EXPORT_SYMBOL_GPL(cpts_release);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("TI CPTS driver");
MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");