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 }
122
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