// SPDX-License-Identifier: GPL-2.0
/*
 * Fast Ethernet Controller (ENET) PTP driver for MX6x.
 *
 * Copyright (C) 2012 Freescale Semiconductor, Inc.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/phy.h>
#include <linux/fec.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_gpio.h>
#include <linux/of_net.h>

#include "fec.h"

/* FEC 1588 register bits */
#define FEC_T_CTRL_SLAVE                0x00002000
#define FEC_T_CTRL_CAPTURE              0x00000800
#define FEC_T_CTRL_RESTART              0x00000200
#define FEC_T_CTRL_PERIOD_RST           0x00000030
#define FEC_T_CTRL_PERIOD_EN            0x00000010
#define FEC_T_CTRL_ENABLE               0x00000001

#define FEC_T_INC_MASK                  0x0000007f
#define FEC_T_INC_OFFSET                0
#define FEC_T_INC_CORR_MASK             0x00007f00
#define FEC_T_INC_CORR_OFFSET           8

#define FEC_T_CTRL_PINPER               0x00000080
#define FEC_T_TF0_MASK                  0x00000001
#define FEC_T_TF0_OFFSET                0
#define FEC_T_TF1_MASK                  0x00000002
#define FEC_T_TF1_OFFSET                1
#define FEC_T_TF2_MASK                  0x00000004
#define FEC_T_TF2_OFFSET                2
#define FEC_T_TF3_MASK                  0x00000008
#define FEC_T_TF3_OFFSET                3
#define FEC_T_TDRE_MASK                 0x00000001
#define FEC_T_TDRE_OFFSET               0
#define FEC_T_TMODE_MASK                0x0000003C
#define FEC_T_TMODE_OFFSET              2
#define FEC_T_TIE_MASK                  0x00000040
#define FEC_T_TIE_OFFSET                6
#define FEC_T_TF_MASK                   0x00000080
#define FEC_T_TF_OFFSET                 7

#define FEC_ATIME_CTRL          0x400
#define FEC_ATIME               0x404
#define FEC_ATIME_EVT_OFFSET    0x408
#define FEC_ATIME_EVT_PERIOD    0x40c
#define FEC_ATIME_CORR          0x410
#define FEC_ATIME_INC           0x414
#define FEC_TS_TIMESTAMP        0x418

#define FEC_TGSR                0x604
#define FEC_TCSR(n)             (0x608 + n * 0x08)
#define FEC_TCCR(n)             (0x60C + n * 0x08)
#define MAX_TIMER_CHANNEL       3
#define FEC_TMODE_TOGGLE        0x05
#define FEC_HIGH_PULSE          0x0F

#define FEC_CC_MULT     (1 << 31)
#define FEC_COUNTER_PERIOD      (1 << 31)
#define PPS_OUPUT_RELOAD_PERIOD NSEC_PER_SEC
#define FEC_CHANNLE_0           0
#define DEFAULT_PPS_CHANNEL     FEC_CHANNLE_0

/**
 * fec_ptp_enable_pps
 * @fep: the fec_enet_private structure handle
 * @enable: enable the channel pps output
 *
 * This function enble the PPS ouput on the timer channel.
 */
static int fec_ptp_enable_pps(struct fec_enet_private *fep, uint enable)
{
        unsigned long flags;
        u32 val, tempval;
        struct timespec64 ts;
        u64 ns;
        val = 0;

        if (fep->pps_enable == enable)
                return 0;

        fep->pps_channel = DEFAULT_PPS_CHANNEL;
        fep->reload_period = PPS_OUPUT_RELOAD_PERIOD;

        spin_lock_irqsave(&fep->tmreg_lock, flags);

        if (enable) {
                /* clear capture or output compare interrupt status if have.
                 */
                writel(FEC_T_TF_MASK, fep->hwp + FEC_TCSR(fep->pps_channel));

                /* It is recommended to double check the TMODE field in the
                 * TCSR register to be cleared before the first compare counter
                 * is written into TCCR register. Just add a double check.
                 */
                val = readl(fep->hwp + FEC_TCSR(fep->pps_channel));
                do {
                        val &= ~(FEC_T_TMODE_MASK);
                        writel(val, fep->hwp + FEC_TCSR(fep->pps_channel));
                        val = readl(fep->hwp + FEC_TCSR(fep->pps_channel));
                } while (val & FEC_T_TMODE_MASK);

                /* Dummy read counter to update the counter */
                timecounter_read(&fep->tc);
                /* We want to find the first compare event in the next
                 * second point. So we need to know what the ptp time
                 * is now and how many nanoseconds is ahead to get next second.
                 * The remaining nanosecond ahead before the next second would be
                 * NSEC_PER_SEC - ts.tv_nsec. Add the remaining nanoseconds
                 * to current timer would be next second.
                 */
                tempval = readl(fep->hwp + FEC_ATIME_CTRL);
                tempval |= FEC_T_CTRL_CAPTURE;
                writel(tempval, fep->hwp + FEC_ATIME_CTRL);

                tempval = readl(fep->hwp + FEC_ATIME);
                /* Convert the ptp local counter to 1588 timestamp */
                ns = timecounter_cyc2time(&fep->tc, tempval);
                ts = ns_to_timespec64(ns);

                /* The tempval is  less than 3 seconds, and  so val is less than
                 * 4 seconds. No overflow for 32bit calculation.
                 */
                val = NSEC_PER_SEC - (u32)ts.tv_nsec + tempval;

                /* Need to consider the situation that the current time is
                 * very close to the second point, which means NSEC_PER_SEC
                 * - ts.tv_nsec is close to be zero(For example 20ns); Since the timer
                 * is still running when we calculate the first compare event, it is
                 * possible that the remaining nanoseonds run out before the compare
                 * counter is calculated and written into TCCR register. To avoid
                 * this possibility, we will set the compare event to be the next
                 * of next second. The current setting is 31-bit timer and wrap
                 * around over 2 seconds. So it is okay to set the next of next
                 * seond for the timer.
                 */
                val += NSEC_PER_SEC;

                /* We add (2 * NSEC_PER_SEC - (u32)ts.tv_nsec) to current
                 * ptp counter, which maybe cause 32-bit wrap. Since the
                 * (NSEC_PER_SEC - (u32)ts.tv_nsec) is less than 2 second.
                 * We can ensure the wrap will not cause issue. If the offset
                 * is bigger than fep->cc.mask would be a error.
                 */
                val &= fep->cc.mask;
                writel(val, fep->hwp + FEC_TCCR(fep->pps_channel));

                /* Calculate the second the compare event timestamp */
                fep->next_counter = (val + fep->reload_period) & fep->cc.mask;

                /* * Enable compare event when overflow */
                val = readl(fep->hwp + FEC_ATIME_CTRL);
                val |= FEC_T_CTRL_PINPER;
                writel(val, fep->hwp + FEC_ATIME_CTRL);

                /* Compare channel setting. */
                val = readl(fep->hwp + FEC_TCSR(fep->pps_channel));
                val |= (1 << FEC_T_TF_OFFSET | 1 << FEC_T_TIE_OFFSET);
                val &= ~(1 << FEC_T_TDRE_OFFSET);
                val &= ~(FEC_T_TMODE_MASK);
                val |= (FEC_HIGH_PULSE << FEC_T_TMODE_OFFSET);
                writel(val, fep->hwp + FEC_TCSR(fep->pps_channel));

                /* Write the second compare event timestamp and calculate
                 * the third timestamp. Refer the TCCR register detail in the spec.
                 */
                writel(fep->next_counter, fep->hwp + FEC_TCCR(fep->pps_channel));
                fep->next_counter = (fep->next_counter + fep->reload_period) & fep->cc.mask;
        } else {
                writel(0, fep->hwp + FEC_TCSR(fep->pps_channel));
        }

        fep->pps_enable = enable;
        spin_unlock_irqrestore(&fep->tmreg_lock, flags);

        return 0;
}

/**
 * fec_ptp_read - read raw cycle counter (to be used by time counter)
 * @cc: the cyclecounter structure
 *
 * this function reads the cyclecounter registers and is called by the
 * cyclecounter structure used to construct a ns counter from the
 * arbitrary fixed point registers
 */
static u64 fec_ptp_read(const struct cyclecounter *cc)
{
        struct fec_enet_private *fep =
                container_of(cc, struct fec_enet_private, cc);
        const struct platform_device_id *id_entry =
                platform_get_device_id(fep->pdev);
        u32 tempval;

        tempval = readl(fep->hwp + FEC_ATIME_CTRL);
        tempval |= FEC_T_CTRL_CAPTURE;
        writel(tempval, fep->hwp + FEC_ATIME_CTRL);

        if (id_entry->driver_data & FEC_QUIRK_BUG_CAPTURE)
                udelay(1);

        return readl(fep->hwp + FEC_ATIME);
}

/**
 * fec_ptp_start_cyclecounter - create the cycle counter from hw
 * @ndev: network device
 *
 * this function initializes the timecounter and cyclecounter
 * structures for use in generated a ns counter from the arbitrary
 * fixed point cycles registers in the hardware.
 */
void fec_ptp_start_cyclecounter(struct net_device *ndev)
{
        struct fec_enet_private *fep = netdev_priv(ndev);
        unsigned long flags;
        int inc;

        inc = 1000000000 / fep->cycle_speed;

        /* grab the ptp lock */
        spin_lock_irqsave(&fep->tmreg_lock, flags);

        /* 1ns counter */
        writel(inc << FEC_T_INC_OFFSET, fep->hwp + FEC_ATIME_INC);

        /* use 31-bit timer counter */
        writel(FEC_COUNTER_PERIOD, fep->hwp + FEC_ATIME_EVT_PERIOD);

        writel(FEC_T_CTRL_ENABLE | FEC_T_CTRL_PERIOD_RST,
                fep->hwp + FEC_ATIME_CTRL);

        memset(&fep->cc, 0, sizeof(fep->cc));
        fep->cc.read = fec_ptp_read;
        fep->cc.mask = CLOCKSOURCE_MASK(31);
        fep->cc.shift = 31;
        fep->cc.mult = FEC_CC_MULT;

        /* reset the ns time counter */
        timecounter_init(&fep->tc, &fep->cc, 0);

        spin_unlock_irqrestore(&fep->tmreg_lock, flags);
}

/**
 * fec_ptp_adjfreq - adjust ptp cycle frequency
 * @ptp: the ptp clock structure
 * @ppb: parts per billion adjustment from base
 *
 * Adjust the frequency of the ptp cycle counter by the
 * indicated ppb from the base frequency.
 *
 * Because ENET hardware frequency adjust is complex,
 * using software method to do that.
 */
static int fec_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
{
        unsigned long flags;
        int neg_adj = 0;
        u32 i, tmp;
        u32 corr_inc, corr_period;
        u32 corr_ns;
        u64 lhs, rhs;

        struct fec_enet_private *fep =
            container_of(ptp, struct fec_enet_private, ptp_caps);

        if (ppb == 0)
                return 0;

        if (ppb < 0) {
                ppb = -ppb;
                neg_adj = 1;
        }

        /* In theory, corr_inc/corr_period = ppb/NSEC_PER_SEC;
         * Try to find the corr_inc  between 1 to fep->ptp_inc to
         * meet adjustment requirement.
         */
        lhs = NSEC_PER_SEC;
        rhs = (u64)ppb * (u64)fep->ptp_inc;
        for (i = 1; i <= fep->ptp_inc; i++) {
                if (lhs >= rhs) {
                        corr_inc = i;
                        corr_period = div_u64(lhs, rhs);
                        break;
                }
                lhs += NSEC_PER_SEC;
        }
        /* Not found? Set it to high value - double speed
         * correct in every clock step.
         */
        if (i > fep->ptp_inc) {
                corr_inc = fep->ptp_inc;
                corr_period = 1;
        }

        if (neg_adj)
                corr_ns = fep->ptp_inc - corr_inc;
        else
                corr_ns = fep->ptp_inc + corr_inc;

        spin_lock_irqsave(&fep->tmreg_lock, flags);

        tmp = readl(fep->hwp + FEC_ATIME_INC) & FEC_T_INC_MASK;
        tmp |= corr_ns << FEC_T_INC_CORR_OFFSET;
        writel(tmp, fep->hwp + FEC_ATIME_INC);
        corr_period = corr_period > 1 ? corr_period - 1 : corr_period;
        writel(corr_period, fep->hwp + FEC_ATIME_CORR);
        /* dummy read to update the timer. */
        timecounter_read(&fep->tc);

        spin_unlock_irqrestore(&fep->tmreg_lock, flags);

        return 0;
}

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

        spin_lock_irqsave(&fep->tmreg_lock, flags);
        timecounter_adjtime(&fep->tc, delta);
        spin_unlock_irqrestore(&fep->tmreg_lock, flags);

        return 0;
}

/**
 * fec_ptp_gettime
 * @ptp: the ptp clock structure
 * @ts: timespec structure to hold the current time value
 *
 * read the timecounter and return the correct value on ns,
 * after converting it into a struct timespec.
 */
static int fec_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
{
        struct fec_enet_private *adapter =
            container_of(ptp, struct fec_enet_private, ptp_caps);
        u64 ns;
        unsigned long flags;

        spin_lock_irqsave(&adapter->tmreg_lock, flags);
        ns = timecounter_read(&adapter->tc);
        spin_unlock_irqrestore(&adapter->tmreg_lock, flags);

        *ts = ns_to_timespec64(ns);

        return 0;
}

/**
 * fec_ptp_settime
 * @ptp: the ptp clock structure
 * @ts: the timespec containing the new time for the cycle counter
 *
 * reset the timecounter to use a new base value instead of the kernel
 * wall timer value.
 */
static int fec_ptp_settime(struct ptp_clock_info *ptp,
                           const struct timespec64 *ts)
{
        struct fec_enet_private *fep =
            container_of(ptp, struct fec_enet_private, ptp_caps);

        u64 ns;
        unsigned long flags;
        u32 counter;

        mutex_lock(&fep->ptp_clk_mutex);
        /* Check the ptp clock */
        if (!fep->ptp_clk_on) {
                mutex_unlock(&fep->ptp_clk_mutex);
                return -EINVAL;
        }

        ns = timespec64_to_ns(ts);
        /* Get the timer value based on timestamp.
         * Update the counter with the masked value.
         */
        counter = ns & fep->cc.mask;

        spin_lock_irqsave(&fep->tmreg_lock, flags);
        writel(counter, fep->hwp + FEC_ATIME);
        timecounter_init(&fep->tc, &fep->cc, ns);
        spin_unlock_irqrestore(&fep->tmreg_lock, flags);
        mutex_unlock(&fep->ptp_clk_mutex);
        return 0;
}

/**
 * fec_ptp_enable
 * @ptp: the ptp clock structure
 * @rq: the requested feature to change
 * @on: whether to enable or disable the feature
 *
 */
static int fec_ptp_enable(struct ptp_clock_info *ptp,
                          struct ptp_clock_request *rq, int on)
{
        struct fec_enet_private *fep =
            container_of(ptp, struct fec_enet_private, ptp_caps);
        int ret = 0;

        if (rq->type == PTP_CLK_REQ_PPS) {
                ret = fec_ptp_enable_pps(fep, on);

                return ret;
        }
        return -EOPNOTSUPP;
}

/**
 * fec_ptp_disable_hwts - disable hardware time stamping
 * @ndev: pointer to net_device
 */
void fec_ptp_disable_hwts(struct net_device *ndev)
{
        struct fec_enet_private *fep = netdev_priv(ndev);

        fep->hwts_tx_en = 0;
        fep->hwts_rx_en = 0;
}

int fec_ptp_set(struct net_device *ndev, struct ifreq *ifr)
{
        struct fec_enet_private *fep = netdev_priv(ndev);

        struct hwtstamp_config config;

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

        /* reserved for future extensions */
        if (config.flags)
                return -EINVAL;

        switch (config.tx_type) {
        case HWTSTAMP_TX_OFF:
                fep->hwts_tx_en = 0;
                break;
        case HWTSTAMP_TX_ON:
                fep->hwts_tx_en = 1;
                break;
        default:
                return -ERANGE;
        }

        switch (config.rx_filter) {
        case HWTSTAMP_FILTER_NONE:
                fep->hwts_rx_en = 0;
                break;

        default:
                fep->hwts_rx_en = 1;
                config.rx_filter = HWTSTAMP_FILTER_ALL;
                break;
        }

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

int fec_ptp_get(struct net_device *ndev, struct ifreq *ifr)
{
        struct fec_enet_private *fep = netdev_priv(ndev);
        struct hwtstamp_config config;

        config.flags = 0;
        config.tx_type = fep->hwts_tx_en ? HWTSTAMP_TX_ON : HWTSTAMP_TX_OFF;
        config.rx_filter = (fep->hwts_rx_en ?
                            HWTSTAMP_FILTER_ALL : HWTSTAMP_FILTER_NONE);

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

/**
 * fec_time_keep - call timecounter_read every second to avoid timer overrun
 *                 because ENET just support 32bit counter, will timeout in 4s
 */
static void fec_time_keep(struct work_struct *work)
{
        struct delayed_work *dwork = to_delayed_work(work);
        struct fec_enet_private *fep = container_of(dwork, struct fec_enet_private, time_keep);
        u64 ns;
        unsigned long flags;

        mutex_lock(&fep->ptp_clk_mutex);
        if (fep->ptp_clk_on) {
                spin_lock_irqsave(&fep->tmreg_lock, flags);
                ns = timecounter_read(&fep->tc);
                spin_unlock_irqrestore(&fep->tmreg_lock, flags);
        }
        mutex_unlock(&fep->ptp_clk_mutex);

        schedule_delayed_work(&fep->time_keep, HZ);
}

/* This function checks the pps event and reloads the timer compare counter. */
static irqreturn_t fec_pps_interrupt(int irq, void *dev_id)
{
        struct net_device *ndev = dev_id;
        struct fec_enet_private *fep = netdev_priv(ndev);
        u32 val;
        u8 channel = fep->pps_channel;
        struct ptp_clock_event event;

        val = readl(fep->hwp + FEC_TCSR(channel));
        if (val & FEC_T_TF_MASK) {
                /* Write the next next compare(not the next according the spec)
                 * value to the register
                 */
                writel(fep->next_counter, fep->hwp + FEC_TCCR(channel));
                do {
                        writel(val, fep->hwp + FEC_TCSR(channel));
                } while (readl(fep->hwp + FEC_TCSR(channel)) & FEC_T_TF_MASK);

                /* Update the counter; */
                fep->next_counter = (fep->next_counter + fep->reload_period) &
                                fep->cc.mask;

                event.type = PTP_CLOCK_PPS;
                ptp_clock_event(fep->ptp_clock, &event);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

/**
 * fec_ptp_init
 * @ndev: The FEC network adapter
 *
 * This function performs the required steps for enabling ptp
 * support. If ptp support has already been loaded it simply calls the
 * cyclecounter init routine and exits.
 */

void fec_ptp_init(struct platform_device *pdev, int irq_idx)
{
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct fec_enet_private *fep = netdev_priv(ndev);
        int irq;
        int ret;

        fep->ptp_caps.owner = THIS_MODULE;
        strlcpy(fep->ptp_caps.name, "fec ptp", sizeof(fep->ptp_caps.name));

        fep->ptp_caps.max_adj = 250000000;
        fep->ptp_caps.n_alarm = 0;
        fep->ptp_caps.n_ext_ts = 0;
        fep->ptp_caps.n_per_out = 0;
        fep->ptp_caps.n_pins = 0;
        fep->ptp_caps.pps = 1;
        fep->ptp_caps.adjfreq = fec_ptp_adjfreq;
        fep->ptp_caps.adjtime = fec_ptp_adjtime;
        fep->ptp_caps.gettime64 = fec_ptp_gettime;
        fep->ptp_caps.settime64 = fec_ptp_settime;
        fep->ptp_caps.enable = fec_ptp_enable;

        fep->cycle_speed = clk_get_rate(fep->clk_ptp);
        fep->ptp_inc = NSEC_PER_SEC / fep->cycle_speed;

        spin_lock_init(&fep->tmreg_lock);

        fec_ptp_start_cyclecounter(ndev);

        INIT_DELAYED_WORK(&fep->time_keep, fec_time_keep);

        irq = platform_get_irq_byname_optional(pdev, "pps");
        if (irq < 0)
                irq = platform_get_irq_optional(pdev, irq_idx);
        /* Failure to get an irq is not fatal,
         * only the PTP_CLOCK_PPS clock events should stop
         */
        if (irq >= 0) {
                ret = devm_request_irq(&pdev->dev, irq, fec_pps_interrupt,
                                       0, pdev->name, ndev);
                if (ret < 0)
                        dev_warn(&pdev->dev, "request for pps irq failed(%d)\n",
                                 ret);
        }

        fep->ptp_clock = ptp_clock_register(&fep->ptp_caps, &pdev->dev);
        if (IS_ERR(fep->ptp_clock)) {
                fep->ptp_clock = NULL;
                dev_err(&pdev->dev, "ptp_clock_register failed\n");
        }

        schedule_delayed_work(&fep->time_keep, HZ);
}

void fec_ptp_stop(struct platform_device *pdev)
{
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct fec_enet_private *fep = netdev_priv(ndev);

        cancel_delayed_work_sync(&fep->time_keep);
        if (fep->ptp_clock)
                ptp_clock_unregister(fep->ptp_clock);
}