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cevt-ds1287.c

/*
 *  DS1287 clockevent driver
 *
 *  Copyright (C) 2008  Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
 *
 *  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 <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,
      .cpumask    = CPU_MASK_CPU0,
      .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_DISABLED | IRQF_PERCPU,
      .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);

      clockevents_register_device(&ds1287_clockevent);

      return setup_irq(irq, &ds1287_irqaction);
}

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