1 /* 2 * DS1287 clockevent driver 3 * 4 * Copyright (C) 2008 Yoichi Yuasa <yuasa@linux-mips.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 #include <linux/clockchips.h> 21 #include <linux/init.h> 22 #include <linux/interrupt.h> 23 #include <linux/mc146818rtc.h> 24 25 #include <asm/time.h> 26 27 int ds1287_timer_state(void) 28 { 29 return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0; 30 } 31 32 int ds1287_set_base_clock(unsigned int hz) 33 { 34 u8 rate; 35 36 switch (hz) { 37 case 128: 38 rate = 0x9; 39 break; 40 case 256: 41 rate = 0x8; 42 break; 43 case 1024: 44 rate = 0x6; 45 break; 46 default: 47 return -EINVAL; 48 } 49 50 CMOS_WRITE(RTC_REF_CLCK_32KHZ | rate, RTC_REG_A); 51 52 return 0; 53 } 54 55 static int ds1287_set_next_event(unsigned long delta, 56 struct clock_event_device *evt) 57 { 58 return -EINVAL; 59 } 60 61 static void ds1287_set_mode(enum clock_event_mode mode, 62 struct clock_event_device *evt) 63 { 64 u8 val; 65 66 spin_lock(&rtc_lock); 67 68 val = CMOS_READ(RTC_REG_B); 69 70 switch (mode) { 71 case CLOCK_EVT_MODE_PERIODIC: 72 val |= RTC_PIE; 73 break; 74 default: 75 val &= ~RTC_PIE; 76 break; 77 } 78 79 CMOS_WRITE(val, RTC_REG_B); 80 81 spin_unlock(&rtc_lock); 82 } 83 84 static void ds1287_event_handler(struct clock_event_device *dev) 85 { 86 } 87 88 static struct clock_event_device ds1287_clockevent = { 89 .name = "ds1287", 90 .features = CLOCK_EVT_FEAT_PERIODIC, 91 .set_next_event = ds1287_set_next_event, 92 .set_mode = ds1287_set_mode, 93 .event_handler = ds1287_event_handler, 94 }; 95 96 static irqreturn_t ds1287_interrupt(int irq, void *dev_id) 97 { 98 struct clock_event_device *cd = &ds1287_clockevent; 99 100 /* Ack the RTC interrupt. */ 101 CMOS_READ(RTC_REG_C); 102 103 cd->event_handler(cd); 104 105 return IRQ_HANDLED; 106 } 107 108 static struct irqaction ds1287_irqaction = { 109 .handler = ds1287_interrupt, 110 .flags = IRQF_DISABLED | IRQF_PERCPU, 111 .name = "ds1287", 112 }; 113 114 int __init ds1287_clockevent_init(int irq) 115 { 116 struct clock_event_device *cd; 117 118 cd = &ds1287_clockevent; 119 cd->rating = 100; 120 cd->irq = irq; 121 clockevent_set_clock(cd, 32768); 122 cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd); 123 cd->min_delta_ns = clockevent_delta2ns(0x300, cd); 124 cd->cpumask = cpumask_of(0); 125 126 clockevents_register_device(&ds1287_clockevent); 127 128 return setup_irq(irq, &ds1287_irqaction); 129 } 130