// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  DS1287 clockevent driver
 *
 *  Copyright (C) 2008  Yoichi Yuasa <yuasa@linux-mips.org>
 */
#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/irq.h>

#include <asm/ds1287.h>
#include <asm/time.h>

int ds1287_timer_state(void)
{
        return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
}

int ds1287_set_base_clock(unsigned int hz)
{
        u8 rate;

        switch (hz) {
        case 128:
                rate = 0x9;
                break;
        case 256:
                rate = 0x8;
                break;
        case 1024:
                rate = 0x6;
                break;
        default:
                return -EINVAL;
        }

        CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A);

        return 0;
}

static int ds1287_set_next_event(unsigned long delta,
                                 struct clock_event_device *evt)
{
        return -EINVAL;
}

static int ds1287_shutdown(struct clock_event_device *evt)
{
        u8 val;

        spin_lock(&rtc_lock);

        val = CMOS_READ(RTC_REG_B);
        val &= ~RTC_PIE;
        CMOS_WRITE(val, RTC_REG_B);

        spin_unlock(&rtc_lock);
        return 0;
}

static int ds1287_set_periodic(struct clock_event_device *evt)
{
        u8 val;

        spin_lock(&rtc_lock);

        val = CMOS_READ(RTC_REG_B);
        val |= RTC_PIE;
        CMOS_WRITE(val, RTC_REG_B);

        spin_unlock(&rtc_lock);
        return 0;
}

static void ds1287_event_handler(struct clock_event_device *dev)
{
}

static struct clock_event_device ds1287_clockevent = {
        .name                   = "ds1287",
        .features               = CLOCK_EVT_FEAT_PERIODIC,
        .set_next_event         = ds1287_set_next_event,
        .set_state_shutdown     = ds1287_shutdown,
        .set_state_periodic     = ds1287_set_periodic,
        .tick_resume            = ds1287_shutdown,
        .event_handler          = ds1287_event_handler,
};

static irqreturn_t ds1287_interrupt(int irq, void *dev_id)
{
        struct clock_event_device *cd = &ds1287_clockevent;

        /* Ack the RTC interrupt. */
        CMOS_READ(RTC_REG_C);

        cd->event_handler(cd);

        return IRQ_HANDLED;
}

int __init ds1287_clockevent_init(int irq)
{
        unsigned long flags = IRQF_PERCPU | IRQF_TIMER;
        struct clock_event_device *cd;

        cd = &ds1287_clockevent;
        cd->rating = 100;
        cd->irq = irq;
        clockevent_set_clock(cd, 32768);
        cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
        cd->max_delta_ticks = 0x7fffffff;
        cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
        cd->min_delta_ticks = 0x300;
        cd->cpumask = cpumask_of(0);

        clockevents_register_device(&ds1287_clockevent);

        return request_irq(irq, ds1287_interrupt, flags, "ds1287", NULL);
}