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/ds1287.h>
14#include <asm/time.h>
15
16int ds1287_timer_state(void)
17{
18 return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
19}
20
21int ds1287_set_base_clock(unsigned int hz)
22{
23 u8 rate;
24
25 switch (hz) {
26 case 128:
27 rate = 0x9;
28 break;
29 case 256:
30 rate = 0x8;
31 break;
32 case 1024:
33 rate = 0x6;
34 break;
35 default:
36 return -EINVAL;
37 }
38
39 CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A);
40
41 return 0;
42}
43
44static int ds1287_set_next_event(unsigned long delta,
45 struct clock_event_device *evt)
46{
47 return -EINVAL;
48}
49
50static int ds1287_shutdown(struct clock_event_device *evt)
51{
52 u8 val;
53
54 spin_lock(lock: &rtc_lock);
55
56 val = CMOS_READ(RTC_REG_B);
57 val &= ~RTC_PIE;
58 CMOS_WRITE(val, RTC_REG_B);
59
60 spin_unlock(lock: &rtc_lock);
61 return 0;
62}
63
64static int ds1287_set_periodic(struct clock_event_device *evt)
65{
66 u8 val;
67
68 spin_lock(lock: &rtc_lock);
69
70 val = CMOS_READ(RTC_REG_B);
71 val |= RTC_PIE;
72 CMOS_WRITE(val, RTC_REG_B);
73
74 spin_unlock(lock: &rtc_lock);
75 return 0;
76}
77
78static void ds1287_event_handler(struct clock_event_device *dev)
79{
80}
81
82static struct clock_event_device ds1287_clockevent = {
83 .name = "ds1287",
84 .features = CLOCK_EVT_FEAT_PERIODIC,
85 .set_next_event = ds1287_set_next_event,
86 .set_state_shutdown = ds1287_shutdown,
87 .set_state_periodic = ds1287_set_periodic,
88 .tick_resume = ds1287_shutdown,
89 .event_handler = ds1287_event_handler,
90};
91
92static irqreturn_t ds1287_interrupt(int irq, void *dev_id)
93{
94 struct clock_event_device *cd = &ds1287_clockevent;
95
96 /* Ack the RTC interrupt. */
97 CMOS_READ(RTC_REG_C);
98
99 cd->event_handler(cd);
100
101 return IRQ_HANDLED;
102}
103
104int __init ds1287_clockevent_init(int irq)
105{
106 unsigned long flags = IRQF_PERCPU | IRQF_TIMER;
107 struct clock_event_device *cd;
108
109 cd = &ds1287_clockevent;
110 cd->rating = 100;
111 cd->irq = irq;
112 clockevent_set_clock(cd, 32768);
113 cd->max_delta_ns = clockevent_delta2ns(latch: 0x7fffffff, evt: cd);
114 cd->max_delta_ticks = 0x7fffffff;
115 cd->min_delta_ns = clockevent_delta2ns(latch: 0x300, evt: cd);
116 cd->min_delta_ticks = 0x300;
117 cd->cpumask = cpumask_of(0);
118
119 clockevents_register_device(dev: &ds1287_clockevent);
120
121 return request_irq(irq, handler: ds1287_interrupt, flags, name: "ds1287", NULL);
122}
123

source code of linux/arch/mips/kernel/cevt-ds1287.c