// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PTP 1588 clock using the IXP46X
 *
 * Copyright (C) 2010 OMICRON electronics GmbH
 */
#include <linux/device.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/ptp_clock_kernel.h>
#include <linux/platform_device.h>
#include <linux/soc/ixp4xx/cpu.h>

#include "ixp46x_ts.h"

#define DRIVER          "ptp_ixp46x"
#define N_EXT_TS        2

struct ixp_clock {
        struct ixp46x_ts_regs *regs;
        struct ptp_clock *ptp_clock;
        struct ptp_clock_info caps;
        int exts0_enabled;
        int exts1_enabled;
        int slave_irq;
        int master_irq;
};

static DEFINE_SPINLOCK(register_lock);

/*
 * Register access functions
 */

static u64 ixp_systime_read(struct ixp46x_ts_regs *regs)
{
        u64 ns;
        u32 lo, hi;

        lo = __raw_readl(&regs->systime_lo);
        hi = __raw_readl(&regs->systime_hi);

        ns = ((u64) hi) << 32;
        ns |= lo;
        ns <<= TICKS_NS_SHIFT;

        return ns;
}

static void ixp_systime_write(struct ixp46x_ts_regs *regs, u64 ns)
{
        u32 hi, lo;

        ns >>= TICKS_NS_SHIFT;
        hi = ns >> 32;
        lo = ns & 0xffffffff;

        __raw_writel(lo, &regs->systime_lo);
        __raw_writel(hi, &regs->systime_hi);
}

/*
 * Interrupt service routine
 */

static irqreturn_t isr(int irq, void *priv)
{
        struct ixp_clock *ixp_clock = priv;
        struct ixp46x_ts_regs *regs = ixp_clock->regs;
        struct ptp_clock_event event;
        u32 ack = 0, lo, hi, val;

        val = __raw_readl(&regs->event);

        if (val & TSER_SNS) {
                ack |= TSER_SNS;
                if (ixp_clock->exts0_enabled) {
                        hi = __raw_readl(&regs->asms_hi);
                        lo = __raw_readl(&regs->asms_lo);
                        event.type = PTP_CLOCK_EXTTS;
                        event.index = 0;
                        event.timestamp = ((u64) hi) << 32;
                        event.timestamp |= lo;
                        event.timestamp <<= TICKS_NS_SHIFT;
                        ptp_clock_event(ixp_clock->ptp_clock, &event);
                }
        }

        if (val & TSER_SNM) {
                ack |= TSER_SNM;
                if (ixp_clock->exts1_enabled) {
                        hi = __raw_readl(&regs->amms_hi);
                        lo = __raw_readl(&regs->amms_lo);
                        event.type = PTP_CLOCK_EXTTS;
                        event.index = 1;
                        event.timestamp = ((u64) hi) << 32;
                        event.timestamp |= lo;
                        event.timestamp <<= TICKS_NS_SHIFT;
                        ptp_clock_event(ixp_clock->ptp_clock, &event);
                }
        }

        if (val & TTIPEND)
                ack |= TTIPEND; /* this bit seems to be always set */

        if (ack) {
                __raw_writel(ack, &regs->event);
                return IRQ_HANDLED;
        } else
                return IRQ_NONE;
}

/*
 * PTP clock operations
 */

static int ptp_ixp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
{
        u32 addend;
        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
        struct ixp46x_ts_regs *regs = ixp_clock->regs;

        addend = adjust_by_scaled_ppm(DEFAULT_ADDEND, scaled_ppm);

        __raw_writel(addend, &regs->addend);

        return 0;
}

static int ptp_ixp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        s64 now;
        unsigned long flags;
        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
        struct ixp46x_ts_regs *regs = ixp_clock->regs;

        spin_lock_irqsave(&register_lock, flags);

        now = ixp_systime_read(regs);
        now += delta;
        ixp_systime_write(regs, now);

        spin_unlock_irqrestore(&register_lock, flags);

        return 0;
}

static int ptp_ixp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
{
        u64 ns;
        unsigned long flags;
        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
        struct ixp46x_ts_regs *regs = ixp_clock->regs;

        spin_lock_irqsave(&register_lock, flags);

        ns = ixp_systime_read(regs);

        spin_unlock_irqrestore(&register_lock, flags);

        *ts = ns_to_timespec64(ns);
        return 0;
}

static int ptp_ixp_settime(struct ptp_clock_info *ptp,
                           const struct timespec64 *ts)
{
        u64 ns;
        unsigned long flags;
        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
        struct ixp46x_ts_regs *regs = ixp_clock->regs;

        ns = timespec64_to_ns(ts);

        spin_lock_irqsave(&register_lock, flags);

        ixp_systime_write(regs, ns);

        spin_unlock_irqrestore(&register_lock, flags);

        return 0;
}

static int ptp_ixp_enable(struct ptp_clock_info *ptp,
                          struct ptp_clock_request *rq, int on)
{
        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);

        switch (rq->type) {
        case PTP_CLK_REQ_EXTTS:
                switch (rq->extts.index) {
                case 0:
                        ixp_clock->exts0_enabled = on ? 1 : 0;
                        break;
                case 1:
                        ixp_clock->exts1_enabled = on ? 1 : 0;
                        break;
                default:
                        return -EINVAL;
                }
                return 0;
        default:
                break;
        }

        return -EOPNOTSUPP;
}

static const struct ptp_clock_info ptp_ixp_caps = {
        .owner          = THIS_MODULE,
        .name           = "IXP46X timer",
        .max_adj        = 66666655,
        .n_ext_ts       = N_EXT_TS,
        .n_pins         = 0,
        .pps            = 0,
        .adjfine        = ptp_ixp_adjfine,
        .adjtime        = ptp_ixp_adjtime,
        .gettime64      = ptp_ixp_gettime,
        .settime64      = ptp_ixp_settime,
        .enable         = ptp_ixp_enable,
};

/* module operations */

static struct ixp_clock ixp_clock;

int ixp46x_ptp_find(struct ixp46x_ts_regs *__iomem *regs, int *phc_index)
{
        if (!cpu_is_ixp46x())
                return -ENODEV;

        *regs = ixp_clock.regs;
        *phc_index = ptp_clock_index(ixp_clock.ptp_clock);

        if (!ixp_clock.ptp_clock)
                return -EPROBE_DEFER;

        return 0;
}
EXPORT_SYMBOL_GPL(ixp46x_ptp_find);

/* Called from the registered devm action */
static void ptp_ixp_unregister_action(void *d)
{
        struct ptp_clock *ptp_clock = d;

        ptp_clock_unregister(ptp_clock);
        ixp_clock.ptp_clock = NULL;
}

static int ptp_ixp_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        int ret;

        ixp_clock.regs = devm_platform_ioremap_resource(pdev, 0);
        ixp_clock.master_irq = platform_get_irq(pdev, 0);
        ixp_clock.slave_irq = platform_get_irq(pdev, 1);
        if (IS_ERR(ixp_clock.regs) ||
            ixp_clock.master_irq < 0 || ixp_clock.slave_irq < 0)
                return -ENXIO;

        ixp_clock.caps = ptp_ixp_caps;

        ixp_clock.ptp_clock = ptp_clock_register(&ixp_clock.caps, NULL);

        if (IS_ERR(ixp_clock.ptp_clock))
                return PTR_ERR(ixp_clock.ptp_clock);

        ret = devm_add_action_or_reset(dev, ptp_ixp_unregister_action,
                                       ixp_clock.ptp_clock);
        if (ret) {
                dev_err(dev, "failed to install clock removal handler\n");
                return ret;
        }

        __raw_writel(DEFAULT_ADDEND, &ixp_clock.regs->addend);
        __raw_writel(1, &ixp_clock.regs->trgt_lo);
        __raw_writel(0, &ixp_clock.regs->trgt_hi);
        __raw_writel(TTIPEND, &ixp_clock.regs->event);

        ret = devm_request_irq(dev, ixp_clock.master_irq, isr,
                               0, DRIVER, &ixp_clock);
        if (ret)
                return dev_err_probe(dev, ret,
                                     "request_irq failed for irq %d\n",
                                     ixp_clock.master_irq);

        ret = devm_request_irq(dev, ixp_clock.slave_irq, isr,
                               0, DRIVER, &ixp_clock);
        if (ret)
                return dev_err_probe(dev, ret,
                                     "request_irq failed for irq %d\n",
                                     ixp_clock.slave_irq);

        return 0;
}

static const struct of_device_id ptp_ixp_match[] = {
        {
                .compatible = "intel,ixp46x-ptp-timer",
        },
        { },
};

static struct platform_driver ptp_ixp_driver = {
        .driver = {
                .name = "ptp-ixp46x",
                .of_match_table = ptp_ixp_match,
                .suppress_bind_attrs = true,
        },
        .probe = ptp_ixp_probe,
};
module_platform_driver(ptp_ixp_driver);

MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
MODULE_DESCRIPTION("PTP clock using the IXP46X timer");
MODULE_LICENSE("GPL");