/*
 * PTP 1588 clock for Freescale QorIQ 1588 timer
 *
 * Copyright (C) 2010 OMICRON electronics GmbH
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/device.h>
#include <linux/hrtimer.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/timex.h>
#include <linux/slab.h>
#include <linux/clk.h>

#include <linux/fsl/ptp_qoriq.h>

/*
 * Register access functions
 */

/* Caller must hold qoriq_ptp->lock. */
static u64 tmr_cnt_read(struct qoriq_ptp *qoriq_ptp)
{
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;
        u64 ns;
        u32 lo, hi;

        lo = qoriq_read(&regs->ctrl_regs->tmr_cnt_l);
        hi = qoriq_read(&regs->ctrl_regs->tmr_cnt_h);
        ns = ((u64) hi) << 32;
        ns |= lo;
        return ns;
}

/* Caller must hold qoriq_ptp->lock. */
static void tmr_cnt_write(struct qoriq_ptp *qoriq_ptp, u64 ns)
{
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;
        u32 hi = ns >> 32;
        u32 lo = ns & 0xffffffff;

        qoriq_write(&regs->ctrl_regs->tmr_cnt_l, lo);
        qoriq_write(&regs->ctrl_regs->tmr_cnt_h, hi);
}

/* Caller must hold qoriq_ptp->lock. */
static void set_alarm(struct qoriq_ptp *qoriq_ptp)
{
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;
        u64 ns;
        u32 lo, hi;

        ns = tmr_cnt_read(qoriq_ptp) + 1500000000ULL;
        ns = div_u64(ns, 1000000000UL) * 1000000000ULL;
        ns -= qoriq_ptp->tclk_period;
        hi = ns >> 32;
        lo = ns & 0xffffffff;
        qoriq_write(&regs->alarm_regs->tmr_alarm1_l, lo);
        qoriq_write(&regs->alarm_regs->tmr_alarm1_h, hi);
}

/* Caller must hold qoriq_ptp->lock. */
static void set_fipers(struct qoriq_ptp *qoriq_ptp)
{
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;

        set_alarm(qoriq_ptp);
        qoriq_write(&regs->fiper_regs->tmr_fiper1, qoriq_ptp->tmr_fiper1);
        qoriq_write(&regs->fiper_regs->tmr_fiper2, qoriq_ptp->tmr_fiper2);
}

/*
 * Interrupt service routine
 */

static irqreturn_t isr(int irq, void *priv)
{
        struct qoriq_ptp *qoriq_ptp = priv;
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;
        struct ptp_clock_event event;
        u64 ns;
        u32 ack = 0, lo, hi, mask, val;

        val = qoriq_read(&regs->ctrl_regs->tmr_tevent);

        if (val & ETS1) {
                ack |= ETS1;
                hi = qoriq_read(&regs->etts_regs->tmr_etts1_h);
                lo = qoriq_read(&regs->etts_regs->tmr_etts1_l);
                event.type = PTP_CLOCK_EXTTS;
                event.index = 0;
                event.timestamp = ((u64) hi) << 32;
                event.timestamp |= lo;
                ptp_clock_event(qoriq_ptp->clock, &event);
        }

        if (val & ETS2) {
                ack |= ETS2;
                hi = qoriq_read(&regs->etts_regs->tmr_etts2_h);
                lo = qoriq_read(&regs->etts_regs->tmr_etts2_l);
                event.type = PTP_CLOCK_EXTTS;
                event.index = 1;
                event.timestamp = ((u64) hi) << 32;
                event.timestamp |= lo;
                ptp_clock_event(qoriq_ptp->clock, &event);
        }

        if (val & ALM2) {
                ack |= ALM2;
                if (qoriq_ptp->alarm_value) {
                        event.type = PTP_CLOCK_ALARM;
                        event.index = 0;
                        event.timestamp = qoriq_ptp->alarm_value;
                        ptp_clock_event(qoriq_ptp->clock, &event);
                }
                if (qoriq_ptp->alarm_interval) {
                        ns = qoriq_ptp->alarm_value + qoriq_ptp->alarm_interval;
                        hi = ns >> 32;
                        lo = ns & 0xffffffff;
                        spin_lock(&qoriq_ptp->lock);
                        qoriq_write(&regs->alarm_regs->tmr_alarm2_l, lo);
                        qoriq_write(&regs->alarm_regs->tmr_alarm2_h, hi);
                        spin_unlock(&qoriq_ptp->lock);
                        qoriq_ptp->alarm_value = ns;
                } else {
                        qoriq_write(&regs->ctrl_regs->tmr_tevent, ALM2);
                        spin_lock(&qoriq_ptp->lock);
                        mask = qoriq_read(&regs->ctrl_regs->tmr_temask);
                        mask &= ~ALM2EN;
                        qoriq_write(&regs->ctrl_regs->tmr_temask, mask);
                        spin_unlock(&qoriq_ptp->lock);
                        qoriq_ptp->alarm_value = 0;
                        qoriq_ptp->alarm_interval = 0;
                }
        }

        if (val & PP1) {
                ack |= PP1;
                event.type = PTP_CLOCK_PPS;
                ptp_clock_event(qoriq_ptp->clock, &event);
        }

        if (ack) {
                qoriq_write(&regs->ctrl_regs->tmr_tevent, ack);
                return IRQ_HANDLED;
        } else
                return IRQ_NONE;
}

/*
 * PTP clock operations
 */

static int ptp_qoriq_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
{
        u64 adj, diff;
        u32 tmr_add;
        int neg_adj = 0;
        struct qoriq_ptp *qoriq_ptp = container_of(ptp, struct qoriq_ptp, caps);
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;

        if (scaled_ppm < 0) {
                neg_adj = 1;
                scaled_ppm = -scaled_ppm;
        }
        tmr_add = qoriq_ptp->tmr_add;
        adj = tmr_add;

        /* calculate diff as adj*(scaled_ppm/65536)/1000000
         * and round() to the nearest integer
         */
        adj *= scaled_ppm;
        diff = div_u64(adj, 8000000);
        diff = (diff >> 13) + ((diff >> 12) & 1);

        tmr_add = neg_adj ? tmr_add - diff : tmr_add + diff;

        qoriq_write(&regs->ctrl_regs->tmr_add, tmr_add);

        return 0;
}

static int ptp_qoriq_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        s64 now;
        unsigned long flags;
        struct qoriq_ptp *qoriq_ptp = container_of(ptp, struct qoriq_ptp, caps);

        spin_lock_irqsave(&qoriq_ptp->lock, flags);

        now = tmr_cnt_read(qoriq_ptp);
        now += delta;
        tmr_cnt_write(qoriq_ptp, now);
        set_fipers(qoriq_ptp);

        spin_unlock_irqrestore(&qoriq_ptp->lock, flags);

        return 0;
}

static int ptp_qoriq_gettime(struct ptp_clock_info *ptp,
                               struct timespec64 *ts)
{
        u64 ns;
        unsigned long flags;
        struct qoriq_ptp *qoriq_ptp = container_of(ptp, struct qoriq_ptp, caps);

        spin_lock_irqsave(&qoriq_ptp->lock, flags);

        ns = tmr_cnt_read(qoriq_ptp);

        spin_unlock_irqrestore(&qoriq_ptp->lock, flags);

        *ts = ns_to_timespec64(ns);

        return 0;
}

static int ptp_qoriq_settime(struct ptp_clock_info *ptp,
                               const struct timespec64 *ts)
{
        u64 ns;
        unsigned long flags;
        struct qoriq_ptp *qoriq_ptp = container_of(ptp, struct qoriq_ptp, caps);

        ns = timespec64_to_ns(ts);

        spin_lock_irqsave(&qoriq_ptp->lock, flags);

        tmr_cnt_write(qoriq_ptp, ns);
        set_fipers(qoriq_ptp);

        spin_unlock_irqrestore(&qoriq_ptp->lock, flags);

        return 0;
}

static int ptp_qoriq_enable(struct ptp_clock_info *ptp,
                              struct ptp_clock_request *rq, int on)
{
        struct qoriq_ptp *qoriq_ptp = container_of(ptp, struct qoriq_ptp, caps);
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;
        unsigned long flags;
        u32 bit, mask;

        switch (rq->type) {
        case PTP_CLK_REQ_EXTTS:
                switch (rq->extts.index) {
                case 0:
                        bit = ETS1EN;
                        break;
                case 1:
                        bit = ETS2EN;
                        break;
                default:
                        return -EINVAL;
                }
                spin_lock_irqsave(&qoriq_ptp->lock, flags);
                mask = qoriq_read(&regs->ctrl_regs->tmr_temask);
                if (on)
                        mask |= bit;
                else
                        mask &= ~bit;
                qoriq_write(&regs->ctrl_regs->tmr_temask, mask);
                spin_unlock_irqrestore(&qoriq_ptp->lock, flags);
                return 0;

        case PTP_CLK_REQ_PPS:
                spin_lock_irqsave(&qoriq_ptp->lock, flags);
                mask = qoriq_read(&regs->ctrl_regs->tmr_temask);
                if (on)
                        mask |= PP1EN;
                else
                        mask &= ~PP1EN;
                qoriq_write(&regs->ctrl_regs->tmr_temask, mask);
                spin_unlock_irqrestore(&qoriq_ptp->lock, flags);
                return 0;

        default:
                break;
        }

        return -EOPNOTSUPP;
}

static const struct ptp_clock_info ptp_qoriq_caps = {
        .owner          = THIS_MODULE,
        .name           = "qoriq ptp clock",
        .max_adj        = 512000,
        .n_alarm        = 0,
        .n_ext_ts       = N_EXT_TS,
        .n_per_out      = 0,
        .n_pins         = 0,
        .pps            = 1,
        .adjfine        = ptp_qoriq_adjfine,
        .adjtime        = ptp_qoriq_adjtime,
        .gettime64      = ptp_qoriq_gettime,
        .settime64      = ptp_qoriq_settime,
        .enable         = ptp_qoriq_enable,
};

/**
 * qoriq_ptp_nominal_freq - calculate nominal frequency according to
 *                          reference clock frequency
 *
 * @clk_src: reference clock frequency
 *
 * The nominal frequency is the desired clock frequency.
 * It should be less than the reference clock frequency.
 * It should be a factor of 1000MHz.
 *
 * Return the nominal frequency
 */
static u32 qoriq_ptp_nominal_freq(u32 clk_src)
{
        u32 remainder = 0;

        clk_src /= 1000000;
        remainder = clk_src % 100;
        if (remainder) {
                clk_src -= remainder;
                clk_src += 100;
        }

        do {
                clk_src -= 100;

        } while (1000 % clk_src);

        return clk_src * 1000000;
}

/**
 * qoriq_ptp_auto_config - calculate a set of default configurations
 *
 * @qoriq_ptp: pointer to qoriq_ptp
 * @node: pointer to device_node
 *
 * If below dts properties are not provided, this function will be
 * called to calculate a set of default configurations for them.
 *   "fsl,tclk-period"
 *   "fsl,tmr-prsc"
 *   "fsl,tmr-add"
 *   "fsl,tmr-fiper1"
 *   "fsl,tmr-fiper2"
 *   "fsl,max-adj"
 *
 * Return 0 if success
 */
static int qoriq_ptp_auto_config(struct qoriq_ptp *qoriq_ptp,
                                 struct device_node *node)
{
        struct clk *clk;
        u64 freq_comp;
        u64 max_adj;
        u32 nominal_freq;
        u32 remainder = 0;
        u32 clk_src = 0;

        qoriq_ptp->cksel = DEFAULT_CKSEL;

        clk = of_clk_get(node, 0);
        if (!IS_ERR(clk)) {
                clk_src = clk_get_rate(clk);
                clk_put(clk);
        }

        if (clk_src <= 100000000UL) {
                pr_err("error reference clock value, or lower than 100MHz\n");
                return -EINVAL;
        }

        nominal_freq = qoriq_ptp_nominal_freq(clk_src);
        if (!nominal_freq)
                return -EINVAL;

        qoriq_ptp->tclk_period = 1000000000UL / nominal_freq;
        qoriq_ptp->tmr_prsc = DEFAULT_TMR_PRSC;

        /* Calculate initial frequency compensation value for TMR_ADD register.
         * freq_comp = ceil(2^32 / freq_ratio)
         * freq_ratio = reference_clock_freq / nominal_freq
         */
        freq_comp = ((u64)1 << 32) * nominal_freq;
        freq_comp = div_u64_rem(freq_comp, clk_src, &remainder);
        if (remainder)
                freq_comp++;

        qoriq_ptp->tmr_add = freq_comp;
        qoriq_ptp->tmr_fiper1 = DEFAULT_FIPER1_PERIOD - qoriq_ptp->tclk_period;
        qoriq_ptp->tmr_fiper2 = DEFAULT_FIPER2_PERIOD - qoriq_ptp->tclk_period;

        /* max_adj = 1000000000 * (freq_ratio - 1.0) - 1
         * freq_ratio = reference_clock_freq / nominal_freq
         */
        max_adj = 1000000000ULL * (clk_src - nominal_freq);
        max_adj = div_u64(max_adj, nominal_freq) - 1;
        qoriq_ptp->caps.max_adj = max_adj;

        return 0;
}

static int qoriq_ptp_probe(struct platform_device *dev)
{
        struct device_node *node = dev->dev.of_node;
        struct qoriq_ptp *qoriq_ptp;
        struct qoriq_ptp_registers *regs;
        struct timespec64 now;
        int err = -ENOMEM;
        u32 tmr_ctrl;
        unsigned long flags;
        void __iomem *base;

        qoriq_ptp = kzalloc(sizeof(*qoriq_ptp), GFP_KERNEL);
        if (!qoriq_ptp)
                goto no_memory;

        err = -EINVAL;

        qoriq_ptp->caps = ptp_qoriq_caps;

        if (of_property_read_u32(node, "fsl,cksel", &qoriq_ptp->cksel))
                qoriq_ptp->cksel = DEFAULT_CKSEL;

        if (of_property_read_u32(node,
                                 "fsl,tclk-period", &qoriq_ptp->tclk_period) ||
            of_property_read_u32(node,
                                 "fsl,tmr-prsc", &qoriq_ptp->tmr_prsc) ||
            of_property_read_u32(node,
                                 "fsl,tmr-add", &qoriq_ptp->tmr_add) ||
            of_property_read_u32(node,
                                 "fsl,tmr-fiper1", &qoriq_ptp->tmr_fiper1) ||
            of_property_read_u32(node,
                                 "fsl,tmr-fiper2", &qoriq_ptp->tmr_fiper2) ||
            of_property_read_u32(node,
                                 "fsl,max-adj", &qoriq_ptp->caps.max_adj)) {
                pr_warn("device tree node missing required elements, try automatic configuration\n");

                if (qoriq_ptp_auto_config(qoriq_ptp, node))
                        goto no_config;
        }

        err = -ENODEV;

        qoriq_ptp->irq = platform_get_irq(dev, 0);

        if (qoriq_ptp->irq < 0) {
                pr_err("irq not in device tree\n");
                goto no_node;
        }
        if (request_irq(qoriq_ptp->irq, isr, IRQF_SHARED, DRIVER, qoriq_ptp)) {
                pr_err("request_irq failed\n");
                goto no_node;
        }

        qoriq_ptp->rsrc = platform_get_resource(dev, IORESOURCE_MEM, 0);
        if (!qoriq_ptp->rsrc) {
                pr_err("no resource\n");
                goto no_resource;
        }
        if (request_resource(&iomem_resource, qoriq_ptp->rsrc)) {
                pr_err("resource busy\n");
                goto no_resource;
        }

        spin_lock_init(&qoriq_ptp->lock);

        base = ioremap(qoriq_ptp->rsrc->start,
                       resource_size(qoriq_ptp->rsrc));
        if (!base) {
                pr_err("ioremap ptp registers failed\n");
                goto no_ioremap;
        }

        qoriq_ptp->base = base;

        if (of_device_is_compatible(node, "fsl,fman-ptp-timer")) {
                qoriq_ptp->regs.ctrl_regs = base + FMAN_CTRL_REGS_OFFSET;
                qoriq_ptp->regs.alarm_regs = base + FMAN_ALARM_REGS_OFFSET;
                qoriq_ptp->regs.fiper_regs = base + FMAN_FIPER_REGS_OFFSET;
                qoriq_ptp->regs.etts_regs = base + FMAN_ETTS_REGS_OFFSET;
        } else {
                qoriq_ptp->regs.ctrl_regs = base + CTRL_REGS_OFFSET;
                qoriq_ptp->regs.alarm_regs = base + ALARM_REGS_OFFSET;
                qoriq_ptp->regs.fiper_regs = base + FIPER_REGS_OFFSET;
                qoriq_ptp->regs.etts_regs = base + ETTS_REGS_OFFSET;
        }

        ktime_get_real_ts64(&now);
        ptp_qoriq_settime(&qoriq_ptp->caps, &now);

        tmr_ctrl =
          (qoriq_ptp->tclk_period & TCLK_PERIOD_MASK) << TCLK_PERIOD_SHIFT |
          (qoriq_ptp->cksel & CKSEL_MASK) << CKSEL_SHIFT;

        spin_lock_irqsave(&qoriq_ptp->lock, flags);

        regs = &qoriq_ptp->regs;
        qoriq_write(&regs->ctrl_regs->tmr_ctrl,   tmr_ctrl);
        qoriq_write(&regs->ctrl_regs->tmr_add,    qoriq_ptp->tmr_add);
        qoriq_write(&regs->ctrl_regs->tmr_prsc,   qoriq_ptp->tmr_prsc);
        qoriq_write(&regs->fiper_regs->tmr_fiper1, qoriq_ptp->tmr_fiper1);
        qoriq_write(&regs->fiper_regs->tmr_fiper2, qoriq_ptp->tmr_fiper2);
        set_alarm(qoriq_ptp);
        qoriq_write(&regs->ctrl_regs->tmr_ctrl,   tmr_ctrl|FIPERST|RTPE|TE|FRD);

        spin_unlock_irqrestore(&qoriq_ptp->lock, flags);

        qoriq_ptp->clock = ptp_clock_register(&qoriq_ptp->caps, &dev->dev);
        if (IS_ERR(qoriq_ptp->clock)) {
                err = PTR_ERR(qoriq_ptp->clock);
                goto no_clock;
        }
        qoriq_ptp->phc_index = ptp_clock_index(qoriq_ptp->clock);

        platform_set_drvdata(dev, qoriq_ptp);

        return 0;

no_clock:
        iounmap(qoriq_ptp->base);
no_ioremap:
        release_resource(qoriq_ptp->rsrc);
no_resource:
        free_irq(qoriq_ptp->irq, qoriq_ptp);
no_config:
no_node:
        kfree(qoriq_ptp);
no_memory:
        return err;
}

static int qoriq_ptp_remove(struct platform_device *dev)
{
        struct qoriq_ptp *qoriq_ptp = platform_get_drvdata(dev);
        struct qoriq_ptp_registers *regs = &qoriq_ptp->regs;

        qoriq_write(&regs->ctrl_regs->tmr_temask, 0);
        qoriq_write(&regs->ctrl_regs->tmr_ctrl,   0);

        ptp_clock_unregister(qoriq_ptp->clock);
        iounmap(qoriq_ptp->base);
        release_resource(qoriq_ptp->rsrc);
        free_irq(qoriq_ptp->irq, qoriq_ptp);
        kfree(qoriq_ptp);

        return 0;
}

static const struct of_device_id match_table[] = {
        { .compatible = "fsl,etsec-ptp" },
        { .compatible = "fsl,fman-ptp-timer" },
        {},
};
MODULE_DEVICE_TABLE(of, match_table);

static struct platform_driver qoriq_ptp_driver = {
        .driver = {
                .name           = "ptp_qoriq",
                .of_match_table = match_table,
        },
        .probe       = qoriq_ptp_probe,
        .remove      = qoriq_ptp_remove,
};

module_platform_driver(qoriq_ptp_driver);

MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
MODULE_DESCRIPTION("PTP clock for Freescale QorIQ 1588 timer");
MODULE_LICENSE("GPL");