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 #include <linux/irq.h>
  25
  26 #include <asm/time.h>
  27
  28 int ds1287_timer_state(void)
  29 {
  30         return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
  31 }
  32
  33 int ds1287_set_base_clock(unsigned int hz)
  34 {
  35         u8 rate;
  36
  37         switch (hz) {
  38         case 128:
  39                 rate = 0x9;
  40                 break;
  41         case 256:
  42                 rate = 0x8;
  43                 break;
  44         case 1024:
  45                 rate = 0x6;
  46                 break;
  47         default:
  48                 return -EINVAL;
  49         }
  50
  51         CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A);
  52
  53         return 0;
  54 }
  55
  56 static int ds1287_set_next_event(unsigned long delta,
  57                                  struct clock_event_device *evt)
  58 {
  59         return -EINVAL;
  60 }
  61
  62 static int ds1287_shutdown(struct clock_event_device *evt)
  63 {
  64         u8 val;
  65
  66         spin_lock(&rtc_lock);
  67
  68         val = CMOS_READ(RTC_REG_B);
  69         val &= ~RTC_PIE;
  70         CMOS_WRITE(val, RTC_REG_B);
  71
  72         spin_unlock(&rtc_lock);
  73         return 0;
  74 }
  75
  76 static int ds1287_set_periodic(struct clock_event_device *evt)
  77 {
  78         u8 val;
  79
  80         spin_lock(&rtc_lock);
  81
  82         val = CMOS_READ(RTC_REG_B);
  83         val |= RTC_PIE;
  84         CMOS_WRITE(val, RTC_REG_B);
  85
  86         spin_unlock(&rtc_lock);
  87         return 0;
  88 }
  89
  90 static void ds1287_event_handler(struct clock_event_device *dev)
  91 {
  92 }
  93
  94 static struct clock_event_device ds1287_clockevent = {
  95         .name                   = "ds1287",
  96         .features               = CLOCK_EVT_FEAT_PERIODIC,
  97         .set_next_event         = ds1287_set_next_event,
  98         .set_state_shutdown     = ds1287_shutdown,
  99         .set_state_periodic     = ds1287_set_periodic,
 100         .tick_resume            = ds1287_shutdown,
 101         .event_handler          = ds1287_event_handler,
 102 };
 103
 104 static irqreturn_t ds1287_interrupt(int irq, void *dev_id)
 105 {
 106         struct clock_event_device *cd = &ds1287_clockevent;
 107
 108         /* Ack the RTC interrupt. */
 109         CMOS_READ(RTC_REG_C);
 110
 111         cd->event_handler(cd);
 112
 113         return IRQ_HANDLED;
 114 }
 115
 116 static struct irqaction ds1287_irqaction = {
 117         .handler        = ds1287_interrupt,
 118         .flags          = IRQF_PERCPU | IRQF_TIMER,
 119         .name           = "ds1287",
 120 };
 121
 122 int __init ds1287_clockevent_init(int irq)
 123 {
 124         struct clock_event_device *cd;
 125
 126         cd = &ds1287_clockevent;
 127         cd->rating = 100;
 128         cd->irq = irq;
 129         clockevent_set_clock(cd, 32768);
 130         cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
 131         cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
 132         cd->cpumask = cpumask_of(0);
 133
 134         clockevents_register_device(&ds1287_clockevent);
 135
 136         return setup_irq(irq, &ds1287_irqaction);
 137 }