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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 | /* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Machine dependent access functions for RTC registers. */ #ifndef __ASM_MC146818_TIME_H #define __ASM_MC146818_TIME_H #include <linux/bcd.h> #include <linux/mc146818rtc.h> #include <linux/time.h> /* * For check timing call set_rtc_mmss() 500ms; used in timer interrupt. */ #define USEC_AFTER 500000 #define USEC_BEFORE 500000 /* * In order to set the CMOS clock precisely, set_rtc_mmss has to be * called 500 ms after the second nowtime has started, because when * nowtime is written into the registers of the CMOS clock, it will * jump to the next second precisely 500 ms later. Check the Motorola * MC146818A or Dallas DS12887 data sheet for details. * * BUG: This routine does not handle hour overflow properly; it just * sets the minutes. Usually you'll only notice that after reboot! */ static inline int mc146818_set_rtc_mmss(unsigned long nowtime) { int real_seconds, real_minutes, cmos_minutes; unsigned char save_control, save_freq_select; int retval = 0; unsigned long flags; spin_lock_irqsave(&rtc_lock, flags); save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */ CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */ CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); cmos_minutes = CMOS_READ(RTC_MINUTES); if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) cmos_minutes = bcd2bin(cmos_minutes); /* * since we're only adjusting minutes and seconds, * don't interfere with hour overflow. This avoids * messing with unknown time zones but requires your * RTC not to be off by more than 15 minutes */ real_seconds = nowtime % 60; real_minutes = nowtime / 60; if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) real_minutes += 30; /* correct for half hour time zone */ real_minutes %= 60; if (abs(real_minutes - cmos_minutes) < 30) { if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { real_seconds = bin2bcd(real_seconds); real_minutes = bin2bcd(real_minutes); } CMOS_WRITE(real_seconds, RTC_SECONDS); CMOS_WRITE(real_minutes, RTC_MINUTES); } else { printk_once(KERN_NOTICE "set_rtc_mmss: can't update from %d to %d\n", cmos_minutes, real_minutes); retval = -1; } /* The following flags have to be released exactly in this order, * otherwise the DS12887 (popular MC146818A clone with integrated * battery and quartz) will not reset the oscillator and will not * update precisely 500 ms later. You won't find this mentioned in * the Dallas Semiconductor data sheets, but who believes data * sheets anyway ... -- Markus Kuhn */ CMOS_WRITE(save_control, RTC_CONTROL); CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); spin_unlock_irqrestore(&rtc_lock, flags); return retval; } static inline unsigned long mc146818_get_cmos_time(void) { unsigned int year, mon, day, hour, min, sec; unsigned long flags; spin_lock_irqsave(&rtc_lock, flags); do { sec = CMOS_READ(RTC_SECONDS); min = CMOS_READ(RTC_MINUTES); hour = CMOS_READ(RTC_HOURS); day = CMOS_READ(RTC_DAY_OF_MONTH); mon = CMOS_READ(RTC_MONTH); year = CMOS_READ(RTC_YEAR); } while (sec != CMOS_READ(RTC_SECONDS)); if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { sec = bcd2bin(sec); min = bcd2bin(min); hour = bcd2bin(hour); day = bcd2bin(day); mon = bcd2bin(mon); year = bcd2bin(year); } spin_unlock_irqrestore(&rtc_lock, flags); year = mc146818_decode_year(year); return mktime(year, mon, day, hour, min, sec); } #endif /* __ASM_MC146818_TIME_H */ |