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
15int ds1287_timer_state(void)
16{
17	return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
18}
19
20int 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
43static int ds1287_set_next_event(unsigned long delta,
44				 struct clock_event_device *evt)
45{
46	return -EINVAL;
47}
48
49static 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
63static 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
77static void ds1287_event_handler(struct clock_event_device *dev)
78{
79}
80
81static 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
91static 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
103int __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}
122