1 /* 2 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 3 * Copyright (C) 2000, 2003 Maciej W. Rozycki 4 * 5 * This file contains the time handling details for PC-style clocks as 6 * found in some MIPS systems. 7 * 8 */ 9 #include <linux/bcd.h> 10 #include <linux/init.h> 11 #include <linux/mc146818rtc.h> 12 #include <linux/param.h> 13 14 #include <asm/cpu-features.h> 15 #include <asm/ds1287.h> 16 #include <asm/time.h> 17 #include <asm/dec/interrupts.h> 18 #include <asm/dec/ioasic.h> 19 #include <asm/dec/machtype.h> 20 21 unsigned long read_persistent_clock(void) 22 { 23 unsigned int year, mon, day, hour, min, sec, real_year; 24 unsigned long flags; 25 26 spin_lock_irqsave(&rtc_lock, flags); 27 28 do { 29 sec = CMOS_READ(RTC_SECONDS); 30 min = CMOS_READ(RTC_MINUTES); 31 hour = CMOS_READ(RTC_HOURS); 32 day = CMOS_READ(RTC_DAY_OF_MONTH); 33 mon = CMOS_READ(RTC_MONTH); 34 year = CMOS_READ(RTC_YEAR); 35 /* 36 * The PROM will reset the year to either '72 or '73. 37 * Therefore we store the real year separately, in one 38 * of unused BBU RAM locations. 39 */ 40 real_year = CMOS_READ(RTC_DEC_YEAR); 41 } while (sec != CMOS_READ(RTC_SECONDS)); 42 43 spin_unlock_irqrestore(&rtc_lock, flags); 44 45 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 46 sec = bcd2bin(sec); 47 min = bcd2bin(min); 48 hour = bcd2bin(hour); 49 day = bcd2bin(day); 50 mon = bcd2bin(mon); 51 year = bcd2bin(year); 52 } 53 54 year += real_year - 72 + 2000; 55 56 return mktime(year, mon, day, hour, min, sec); 57 } 58 59 /* 60 * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to 61 * be called 500 ms after the second nowtime has started, because when 62 * nowtime is written into the registers of the CMOS clock, it will 63 * jump to the next second precisely 500 ms later. Check the Dallas 64 * DS1287 data sheet for details. 65 */ 66 int rtc_mips_set_mmss(unsigned long nowtime) 67 { 68 int retval = 0; 69 int real_seconds, real_minutes, cmos_minutes; 70 unsigned char save_control, save_freq_select; 71 72 /* irq are locally disabled here */ 73 spin_lock(&rtc_lock); 74 /* tell the clock it's being set */ 75 save_control = CMOS_READ(RTC_CONTROL); 76 CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL); 77 78 /* stop and reset prescaler */ 79 save_freq_select = CMOS_READ(RTC_FREQ_SELECT); 80 CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT); 81 82 cmos_minutes = CMOS_READ(RTC_MINUTES); 83 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) 84 cmos_minutes = bcd2bin(cmos_minutes); 85 86 /* 87 * since we're only adjusting minutes and seconds, 88 * don't interfere with hour overflow. This avoids 89 * messing with unknown time zones but requires your 90 * RTC not to be off by more than 15 minutes 91 */ 92 real_seconds = nowtime % 60; 93 real_minutes = nowtime / 60; 94 if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) 95 real_minutes += 30; /* correct for half hour time zone */ 96 real_minutes %= 60; 97 98 if (abs(real_minutes - cmos_minutes) < 30) { 99 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { 100 real_seconds = bin2bcd(real_seconds); 101 real_minutes = bin2bcd(real_minutes); 102 } 103 CMOS_WRITE(real_seconds, RTC_SECONDS); 104 CMOS_WRITE(real_minutes, RTC_MINUTES); 105 } else { 106 printk(KERN_WARNING 107 "set_rtc_mmss: can't update from %d to %d\n", 108 cmos_minutes, real_minutes); 109 retval = -1; 110 } 111 112 /* The following flags have to be released exactly in this order, 113 * otherwise the DS1287 will not reset the oscillator and will not 114 * update precisely 500 ms later. You won't find this mentioned 115 * in the Dallas Semiconductor data sheets, but who believes data 116 * sheets anyway ... -- Markus Kuhn 117 */ 118 CMOS_WRITE(save_control, RTC_CONTROL); 119 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); 120 spin_unlock(&rtc_lock); 121 122 return retval; 123 } 124 125 void __init plat_time_init(void) 126 { 127 u32 start, end; 128 int i = HZ / 10; 129 130 /* Set up the rate of periodic DS1287 interrupts. */ 131 ds1287_set_base_clock(HZ); 132 133 if (cpu_has_counter) { 134 while (!ds1287_timer_state()) 135 ; 136 137 start = read_c0_count(); 138 139 while (i--) 140 while (!ds1287_timer_state()) 141 ; 142 143 end = read_c0_count(); 144 145 mips_hpt_frequency = (end - start) * 10; 146 printk(KERN_INFO "MIPS counter frequency %dHz\n", 147 mips_hpt_frequency); 148 } else if (IOASIC) 149 /* For pre-R4k systems we use the I/O ASIC's counter. */ 150 dec_ioasic_clocksource_init(); 151 152 ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]); 153 } 154