/*
 * Fast Ethernet Controller (ENET) PTP driver for MX6x.
 *
 * Copyright (C) 2012 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#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/init.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_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_CC_MULT     (1 << 31)
/**
 * 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);
        u32 tempval;

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

        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 free running count */
        writel(0, fep->hwp + FEC_ATIME_EVT_PERIOD);

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

        memset(&fep->cc, 0, sizeof(fep->cc));
        fep->cc.read = fec_ptp_read;
        fep->cc.mask = CLOCKSOURCE_MASK(32);
        fep->cc.shift = 31;
        fep->cc.mult = FEC_CC_MULT;

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

        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)
{
        u64 diff;
        unsigned long flags;
        int neg_adj = 0;
        u32 mult = FEC_CC_MULT;

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

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

        diff = mult;
        diff *= ppb;
        diff = div_u64(diff, 1000000000ULL);

        spin_lock_irqsave(&fep->tmreg_lock, flags);
        /*
         * dummy read to set cycle_last in tc to now.
         * So use adjusted mult to calculate when next call
         * timercounter_read.
         */
        timecounter_read(&fep->tc);

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

        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;
        u64 now;

        spin_lock_irqsave(&fep->tmreg_lock, flags);

        now = timecounter_read(&fep->tc);
        now += delta;

        /* reset the timecounter */
        timecounter_init(&fep->tc, &fep->cc, now);

        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 timespec *ts)
{
        struct fec_enet_private *adapter =
            container_of(ptp, struct fec_enet_private, ptp_caps);
        u64 ns;
        u32 remainder;
        unsigned long flags;

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

        ts->tv_sec = div_u64_rem(ns, 1000000000ULL, &remainder);
        ts->tv_nsec = remainder;

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

        u64 ns;
        unsigned long flags;

        ns = ts->tv_sec * 1000000000ULL;
        ns += ts->tv_nsec;

        spin_lock_irqsave(&fep->tmreg_lock, flags);
        timecounter_init(&fep->tc, &fep->cc, ns);
        spin_unlock_irqrestore(&fep->tmreg_lock, flags);
        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)
{
        return -EOPNOTSUPP;
}

/**
 * fec_ptp_hwtstamp_ioctl - control hardware time stamping
 * @ndev: pointer to net_device
 * @ifreq: ioctl data
 * @cmd: particular ioctl requested
 */
int fec_ptp_ioctl(struct net_device *ndev, struct ifreq *ifr, int cmd)
{
        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:
                if (fep->hwts_rx_en)
                        fep->hwts_rx_en = 0;
                config.rx_filter = HWTSTAMP_FILTER_NONE;
                break;

        default:
                /*
                 * register RXMTRL must be set in order to do V1 packets,
                 * therefore it is not possible to time stamp both V1 Sync and
                 * Delay_Req messages and hardware does not support
                 * timestamping all packets => return error
                 */
                fep->hwts_rx_en = 1;
                config.rx_filter = HWTSTAMP_FILTER_ALL;
                break;
        }

        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(unsigned long _data)
{
        struct fec_enet_private *fep = (struct fec_enet_private *)_data;
        u64 ns;
        unsigned long flags;

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

        mod_timer(&fep->time_keep, jiffies + HZ);
}

/**
 * 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 net_device *ndev, struct platform_device *pdev)
{
        struct fec_enet_private *fep = netdev_priv(ndev);

        fep->ptp_caps.owner = THIS_MODULE;
        snprintf(fep->ptp_caps.name, 16, "fec ptp");

        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.pps = 0;
        fep->ptp_caps.adjfreq = fec_ptp_adjfreq;
        fep->ptp_caps.adjtime = fec_ptp_adjtime;
        fep->ptp_caps.gettime = fec_ptp_gettime;
        fep->ptp_caps.settime = fec_ptp_settime;
        fep->ptp_caps.enable = fec_ptp_enable;

        fep->cycle_speed = clk_get_rate(fep->clk_ptp);

        spin_lock_init(&fep->tmreg_lock);

        fec_ptp_start_cyclecounter(ndev);

        init_timer(&fep->time_keep);
        fep->time_keep.data = (unsigned long)fep;
        fep->time_keep.function = fec_time_keep;
        fep->time_keep.expires = jiffies + HZ;
        add_timer(&fep->time_keep);

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