// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Cirrus Logic CLPS711X clocksource driver
 *
 *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
 */

#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#include <linux/slab.h>

enum {
        CLPS711X_CLKSRC_CLOCKSOURCE,
        CLPS711X_CLKSRC_CLOCKEVENT,
};

static void __iomem *tcd;

static u64 notrace clps711x_sched_clock_read(void)
{
        return ~readw(tcd);
}

static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
{
        unsigned long rate = clk_get_rate(clock);

        tcd = base;

        clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
                              clocksource_mmio_readw_down);

        sched_clock_register(clps711x_sched_clock_read, 16, rate);
}

static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *evt = dev_id;

        evt->event_handler(evt);

        return IRQ_HANDLED;
}

static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
                                        unsigned int irq)
{
        struct clock_event_device *clkevt;
        unsigned long rate;

        clkevt = kzalloc_obj(*clkevt);
        if (!clkevt)
                return -ENOMEM;

        rate = clk_get_rate(clock);

        /* Set Timer prescaler */
        writew(DIV_ROUND_CLOSEST(rate, HZ), base);

        clkevt->name = "clps711x-clockevent";
        clkevt->rating = 300;
        clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
        clkevt->cpumask = cpumask_of(0);
        clockevents_config_and_register(clkevt, HZ, 0, 0);

        return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
                           "clps711x-timer", clkevt);
}

static int __init clps711x_timer_init(struct device_node *np)
{
        unsigned int irq = irq_of_parse_and_map(np, 0);
        struct clk *clock = of_clk_get(np, 0);
        void __iomem *base = of_iomap(np, 0);
        int ret = 0;

        if (!base)
                return -ENOMEM;
        if (!irq) {
                ret = -EINVAL;
                goto unmap_io;
        }
        if (IS_ERR(clock)) {
                ret = PTR_ERR(clock);
                goto unmap_io;
        }

        switch (of_alias_get_id(np, "timer")) {
        case CLPS711X_CLKSRC_CLOCKSOURCE:
                clps711x_clksrc_init(clock, base);
                break;
        case CLPS711X_CLKSRC_CLOCKEVENT:
                ret =  _clps711x_clkevt_init(clock, base, irq);
                break;
        default:
                ret = -EINVAL;
                break;
        }

unmap_io:
        iounmap(base);
        return ret;
}
TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);