cevt-ds1287.c

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/*
 *  DS1287 clockevent driver
 *
 *  Copyright (C) 2008  Yoichi Yuasa <[email protected]>
 *
 *  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/irq.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 void ds1287_set_mode(enum clock_event_mode mode,
                struct clock_event_device *evt)
{
    u8 val;

    spin_lock(&rtc_lock);

    val = CMOS_READ(RTC_REG_B);

    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        val |= RTC_PIE;
        break;
    default:
        val &= ~RTC_PIE;
        break;
    }

    CMOS_WRITE(val, RTC_REG_B);

    spin_unlock(&rtc_lock);
}

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_mode   = ds1287_set_mode,
    .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;
}

static struct irqaction ds1287_irqaction = {
    .handler    = ds1287_interrupt,
    .flags      = IRQF_PERCPU | IRQF_TIMER,
    .name       = "ds1287",
};

int __init ds1287_clockevent_init(int irq)
{
    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->min_delta_ns = clockevent_delta2ns(0x300, cd);
    cd->cpumask = cpumask_of(0);

    clockevents_register_device(&ds1287_clockevent);

    return setup_irq(irq, &ds1287_irqaction);
}