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 16 int ds1287_timer_state(void) 17 { 18 return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0; 19 } 20 21 int 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 44 static int ds1287_set_next_event(unsigned long delta, 45 struct clock_event_device *evt) 46 { 47 return -EINVAL; 48 } 49 50 static int ds1287_shutdown(struct clock_event_device *evt) 51 { 52 u8 val; 53 54 spin_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(&rtc_lock); 61 return 0; 62 } 63 64 static int ds1287_set_periodic(struct clock_event_device *evt) 65 { 66 u8 val; 67 68 spin_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(&rtc_lock); 75 return 0; 76 } 77 78 static void ds1287_event_handler(struct clock_event_device *dev) 79 { 80 } 81 82 static 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 92 static 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 } 103 104 int __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(0x7fffffff, cd); 114 cd->max_delta_ticks = 0x7fffffff; 115 cd->min_delta_ns = clockevent_delta2ns(0x300, cd); 116 cd->min_delta_ticks = 0x300; 117 cd->cpumask = cpumask_of(0); 118 119 clockevents_register_device(&ds1287_clockevent); 120 121 return request_irq(irq, ds1287_interrupt, flags, "ds1287", NULL); 122 } 123