1 /* 2 * linux/arch/mips/dec/time.c 3 * 4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 5 * Copyright (C) 2000, 2003 Maciej W. Rozycki 6 * 7 * This file contains the time handling details for PC-style clocks as 8 * found in some MIPS systems. 9 * 10 */ 11 #include <linux/bcd.h> 12 #include <linux/errno.h> 13 #include <linux/init.h> 14 #include <linux/interrupt.h> 15 #include <linux/kernel.h> 16 #include <linux/mc146818rtc.h> 17 #include <linux/mm.h> 18 #include <linux/module.h> 19 #include <linux/param.h> 20 #include <linux/sched.h> 21 #include <linux/string.h> 22 #include <linux/time.h> 23 #include <linux/types.h> 24 25 #include <asm/bootinfo.h> 26 #include <asm/cpu.h> 27 #include <asm/div64.h> 28 #include <asm/io.h> 29 #include <asm/irq.h> 30 #include <asm/mipsregs.h> 31 #include <asm/sections.h> 32 #include <asm/time.h> 33 34 #include <asm/dec/interrupts.h> 35 #include <asm/dec/ioasic.h> 36 #include <asm/dec/ioasic_addrs.h> 37 #include <asm/dec/machtype.h> 38 39 static unsigned long dec_rtc_get_time(void) 40 { 41 unsigned int year, mon, day, hour, min, sec, real_year; 42 unsigned long flags; 43 44 spin_lock_irqsave(&rtc_lock, flags); 45 46 do { 47 sec = CMOS_READ(RTC_SECONDS); 48 min = CMOS_READ(RTC_MINUTES); 49 hour = CMOS_READ(RTC_HOURS); 50 day = CMOS_READ(RTC_DAY_OF_MONTH); 51 mon = CMOS_READ(RTC_MONTH); 52 year = CMOS_READ(RTC_YEAR); 53 /* 54 * The PROM will reset the year to either '72 or '73. 55 * Therefore we store the real year separately, in one 56 * of unused BBU RAM locations. 57 */ 58 real_year = CMOS_READ(RTC_DEC_YEAR); 59 } while (sec != CMOS_READ(RTC_SECONDS)); 60 61 spin_unlock_irqrestore(&rtc_lock, flags); 62 63 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 64 sec = BCD2BIN(sec); 65 min = BCD2BIN(min); 66 hour = BCD2BIN(hour); 67 day = BCD2BIN(day); 68 mon = BCD2BIN(mon); 69 year = BCD2BIN(year); 70 } 71 72 year += real_year - 72 + 2000; 73 74 return mktime(year, mon, day, hour, min, sec); 75 } 76 77 /* 78 * In order to set the CMOS clock precisely, dec_rtc_set_mmss has to 79 * be called 500 ms after the second nowtime has started, because when 80 * nowtime is written into the registers of the CMOS clock, it will 81 * jump to the next second precisely 500 ms later. Check the Dallas 82 * DS1287 data sheet for details. 83 */ 84 static int dec_rtc_set_mmss(unsigned long nowtime) 85 { 86 int retval = 0; 87 int real_seconds, real_minutes, cmos_minutes; 88 unsigned char save_control, save_freq_select; 89 90 /* irq are locally disabled here */ 91 spin_lock(&rtc_lock); 92 /* tell the clock it's being set */ 93 save_control = CMOS_READ(RTC_CONTROL); 94 CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL); 95 96 /* stop and reset prescaler */ 97 save_freq_select = CMOS_READ(RTC_FREQ_SELECT); 98 CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT); 99 100 cmos_minutes = CMOS_READ(RTC_MINUTES); 101 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) 102 cmos_minutes = BCD2BIN(cmos_minutes); 103 104 /* 105 * since we're only adjusting minutes and seconds, 106 * don't interfere with hour overflow. This avoids 107 * messing with unknown time zones but requires your 108 * RTC not to be off by more than 15 minutes 109 */ 110 real_seconds = nowtime % 60; 111 real_minutes = nowtime / 60; 112 if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) 113 real_minutes += 30; /* correct for half hour time zone */ 114 real_minutes %= 60; 115 116 if (abs(real_minutes - cmos_minutes) < 30) { 117 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 118 real_seconds = BIN2BCD(real_seconds); 119 real_minutes = BIN2BCD(real_minutes); 120 } 121 CMOS_WRITE(real_seconds, RTC_SECONDS); 122 CMOS_WRITE(real_minutes, RTC_MINUTES); 123 } else { 124 printk(KERN_WARNING 125 "set_rtc_mmss: can't update from %d to %d\n", 126 cmos_minutes, real_minutes); 127 retval = -1; 128 } 129 130 /* The following flags have to be released exactly in this order, 131 * otherwise the DS1287 will not reset the oscillator and will not 132 * update precisely 500 ms later. You won't find this mentioned 133 * in the Dallas Semiconductor data sheets, but who believes data 134 * sheets anyway ... -- Markus Kuhn 135 */ 136 CMOS_WRITE(save_control, RTC_CONTROL); 137 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); 138 spin_unlock(&rtc_lock); 139 140 return retval; 141 } 142 143 144 static int dec_timer_state(void) 145 { 146 return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0; 147 } 148 149 static void dec_timer_ack(void) 150 { 151 CMOS_READ(RTC_REG_C); /* Ack the RTC interrupt. */ 152 } 153 154 static unsigned int dec_ioasic_hpt_read(void) 155 { 156 /* 157 * The free-running counter is 32-bit which is good for about 158 * 2 minutes, 50 seconds at possible count rates of up to 25MHz. 159 */ 160 return ioasic_read(IO_REG_FCTR); 161 } 162 163 static void dec_ioasic_hpt_init(unsigned int count) 164 { 165 ioasic_write(IO_REG_FCTR, ioasic_read(IO_REG_FCTR) - count); 166 } 167 168 169 void __init dec_time_init(void) 170 { 171 rtc_mips_get_time = dec_rtc_get_time; 172 rtc_mips_set_mmss = dec_rtc_set_mmss; 173 174 mips_timer_state = dec_timer_state; 175 mips_timer_ack = dec_timer_ack; 176 177 if (!cpu_has_counter && IOASIC) { 178 /* For pre-R4k systems we use the I/O ASIC's counter. */ 179 mips_hpt_read = dec_ioasic_hpt_read; 180 mips_hpt_init = dec_ioasic_hpt_init; 181 } 182 183 /* Set up the rate of periodic DS1287 interrupts. */ 184 CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - __ffs(HZ)), RTC_REG_A); 185 } 186 187 EXPORT_SYMBOL(do_settimeofday); 188 189 void __init dec_timer_setup(struct irqaction *irq) 190 { 191 setup_irq(dec_interrupt[DEC_IRQ_RTC], irq); 192 193 /* Enable periodic DS1287 interrupts. */ 194 CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B); 195 } 196