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 
ds1287_timer_state(void)15 int ds1287_timer_state(void)
16 {
17 	return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
18 }
19 
ds1287_set_base_clock(unsigned int hz)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 
ds1287_set_next_event(unsigned long delta,struct clock_event_device * evt)43 static int ds1287_set_next_event(unsigned long delta,
44 				 struct clock_event_device *evt)
45 {
46 	return -EINVAL;
47 }
48 
ds1287_shutdown(struct clock_event_device * evt)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 
ds1287_set_periodic(struct clock_event_device * evt)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 
ds1287_event_handler(struct clock_event_device * dev)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 
ds1287_interrupt(int irq,void * dev_id)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 
ds1287_clockevent_init(int irq)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 }
122