arch/mips/kernel/cevt-ds1287.c

   1 /*
   2  *  DS1287 clockevent driver
   3  *
   4  *  Copyright (C) 2008  Yoichi Yuasa <yuasa@linux-mips.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20 #include <linux/clockchips.h>
  21 #include <linux/init.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/mc146818rtc.h>
  24
  25 #include <asm/time.h>
  26
  27 int ds1287_timer_state(void)
  28 {
  29         return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
  30 }
  31
  32 int ds1287_set_base_clock(unsigned int hz)
  33 {
  34         u8 rate;
  35
  36         switch (hz) {
  37         case 128:
  38                 rate = 0x9;
  39                 break;
  40         case 256:
  41                 rate = 0x8;
  42                 break;
  43         case 1024:
  44                 rate = 0x6;
  45                 break;
  46         default:
  47                 return -EINVAL;
  48         }
  49
  50         CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A);
  51
  52         return 0;
  53 }
  54
  55 static int ds1287_set_next_event(unsigned long delta,
  56                                  struct clock_event_device *evt)
  57 {
  58         return -EINVAL;
  59 }
  60
  61 static void ds1287_set_mode(enum clock_event_mode mode,
  62                             struct clock_event_device *evt)
  63 {
  64         u8 val;
  65
  66         spin_lock(&rtc_lock);
  67
  68         val = CMOS_READ(RTC_REG_B);
  69
  70         switch (mode) {
  71         case CLOCK_EVT_MODE_PERIODIC:
  72                 val |= RTC_PIE;
  73                 break;
  74         default:
  75                 val &= ~RTC_PIE;
  76                 break;
  77         }
  78
  79         CMOS_WRITE(val, RTC_REG_B);
  80
  81         spin_unlock(&rtc_lock);
  82 }
  83
  84 static void ds1287_event_handler(struct clock_event_device *dev)
  85 {
  86 }
  87
  88 static struct clock_event_device ds1287_clockevent = {
  89         .name           = "ds1287",
  90         .features       = CLOCK_EVT_FEAT_PERIODIC,
  91         .set_next_event = ds1287_set_next_event,
  92         .set_mode       = ds1287_set_mode,
  93         .event_handler  = ds1287_event_handler,
  94 };
  95
  96 static irqreturn_t ds1287_interrupt(int irq, void *dev_id)
  97 {
  98         struct clock_event_device *cd = &ds1287_clockevent;
  99
 100         /* Ack the RTC interrupt. */
 101         CMOS_READ(RTC_REG_C);
 102
 103         cd->event_handler(cd);
 104
 105         return IRQ_HANDLED;
 106 }
 107
 108 static struct irqaction ds1287_irqaction = {
 109         .handler        = ds1287_interrupt,
 110         .flags          = IRQF_DISABLED | IRQF_PERCPU,
 111         .name           = "ds1287",
 112 };
 113
 114 int __init ds1287_clockevent_init(int irq)
 115 {
 116         struct clock_event_device *cd;
 117
 118         cd = &ds1287_clockevent;
 119         cd->rating = 100;
 120         cd->irq = irq;
 121         clockevent_set_clock(cd, 32768);
 122         cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
 123         cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
 124         cd->cpumask = cpumask_of(0);
 125
 126         clockevents_register_device(&ds1287_clockevent);
 127
 128         return setup_irq(irq, &ds1287_irqaction);
 129 }