arch/mips/kernel/cevt-ds1287.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  DS1287 clockevent driver
   4  *
   5  *  Copyright (C) 2008  Yoichi Yuasa <yuasa@linux-mips.org>
   6  */
   7 #include <linux/clockchips.h>
   8 #include <linux/init.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/mc146818rtc.h>
  11 #include <linux/irq.h>
  12
  13 #include <asm/time.h>
  14
  15 int ds1287_timer_state(void)
  16 {
  17         return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
  18 }
  19
  20 int ds1287_set_base_clock(unsigned int hz)
  21 {
  22         u8 rate;
  23
  24         switch (hz) {
  25         case 128:
  26                 rate = 0x9;
  27                 break;
  28         case 256:
  29                 rate = 0x8;
  30                 break;
  31         case 1024:
  32                 rate = 0x6;
  33                 break;
  34         default:
  35                 return -EINVAL;
  36         }
  37
  38         CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A);
  39
  40         return 0;
  41 }
  42
  43 static int ds1287_set_next_event(unsigned long delta,
  44                                  struct clock_event_device *evt)
  45 {
  46         return -EINVAL;
  47 }
  48
  49 static int ds1287_shutdown(struct clock_event_device *evt)
  50 {
  51         u8 val;
  52
  53         spin_lock(&rtc_lock);
  54
  55         val = CMOS_READ(RTC_REG_B);
  56         val &= ~RTC_PIE;
  57         CMOS_WRITE(val, RTC_REG_B);
  58
  59         spin_unlock(&rtc_lock);
  60         return 0;
  61 }
  62
  63 static int ds1287_set_periodic(struct clock_event_device *evt)
  64 {
  65         u8 val;
  66
  67         spin_lock(&rtc_lock);
  68
  69         val = CMOS_READ(RTC_REG_B);
  70         val |= RTC_PIE;
  71         CMOS_WRITE(val, RTC_REG_B);
  72
  73         spin_unlock(&rtc_lock);
  74         return 0;
  75 }
  76
  77 static void ds1287_event_handler(struct clock_event_device *dev)
  78 {
  79 }
  80
  81 static struct clock_event_device ds1287_clockevent = {
  82         .name                   = "ds1287",
  83         .features               = CLOCK_EVT_FEAT_PERIODIC,
  84         .set_next_event         = ds1287_set_next_event,
  85         .set_state_shutdown     = ds1287_shutdown,
  86         .set_state_periodic     = ds1287_set_periodic,
  87         .tick_resume            = ds1287_shutdown,
  88         .event_handler          = ds1287_event_handler,
  89 };
  90
  91 static irqreturn_t ds1287_interrupt(int irq, void *dev_id)
  92 {
  93         struct clock_event_device *cd = &ds1287_clockevent;
  94
  95         /* Ack the RTC interrupt. */
  96         CMOS_READ(RTC_REG_C);
  97
  98         cd->event_handler(cd);
  99
 100         return IRQ_HANDLED;
 101 }
 102
 103 int __init ds1287_clockevent_init(int irq)
 104 {
 105         unsigned long flags = IRQF_PERCPU | IRQF_TIMER;
 106         struct clock_event_device *cd;
 107
 108         cd = &ds1287_clockevent;
 109         cd->rating = 100;
 110         cd->irq = irq;
 111         clockevent_set_clock(cd, 32768);
 112         cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
 113         cd->max_delta_ticks = 0x7fffffff;
 114         cd->min_delta_ns = clockevent_delta2ns(0x300, cd);
 115         cd->min_delta_ticks = 0x300;
 116         cd->cpumask = cpumask_of(0);
 117
 118         clockevents_register_device(&ds1287_clockevent);
 119
 120         return request_irq(irq, ds1287_interrupt, flags, "ds1287", NULL);
 121 }