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