Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * This file is subject to the terms and conditions of the GNU General Public |
| 3 | * License. See the file "COPYING" in the main directory of this archive |
| 4 | * for more details. |
| 5 | * |
| 6 | * Machine dependent access functions for RTC registers. |
| 7 | */ |
| 8 | #ifndef __ASM_MC146818_TIME_H |
| 9 | #define __ASM_MC146818_TIME_H |
| 10 | |
| 11 | #include <linux/bcd.h> |
| 12 | #include <linux/mc146818rtc.h> |
| 13 | #include <linux/time.h> |
| 14 | |
| 15 | /* |
| 16 | * For check timing call set_rtc_mmss() 500ms; used in timer interrupt. |
| 17 | */ |
| 18 | #define USEC_AFTER 500000 |
| 19 | #define USEC_BEFORE 500000 |
| 20 | |
| 21 | /* |
| 22 | * In order to set the CMOS clock precisely, set_rtc_mmss has to be |
| 23 | * called 500 ms after the second nowtime has started, because when |
| 24 | * nowtime is written into the registers of the CMOS clock, it will |
| 25 | * jump to the next second precisely 500 ms later. Check the Motorola |
| 26 | * MC146818A or Dallas DS12887 data sheet for details. |
| 27 | * |
| 28 | * BUG: This routine does not handle hour overflow properly; it just |
| 29 | * sets the minutes. Usually you'll only notice that after reboot! |
| 30 | */ |
| 31 | static inline int mc146818_set_rtc_mmss(unsigned long nowtime) |
| 32 | { |
| 33 | int real_seconds, real_minutes, cmos_minutes; |
| 34 | unsigned char save_control, save_freq_select; |
| 35 | int retval = 0; |
Atsushi Nemoto | 53c2df2 | 2005-11-03 01:01:15 +0900 | [diff] [blame] | 36 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | |
Atsushi Nemoto | 53c2df2 | 2005-11-03 01:01:15 +0900 | [diff] [blame] | 38 | spin_lock_irqsave(&rtc_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */ |
| 40 | CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); |
| 41 | |
| 42 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */ |
| 43 | CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); |
| 44 | |
| 45 | cmos_minutes = CMOS_READ(RTC_MINUTES); |
| 46 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) |
| 47 | BCD_TO_BIN(cmos_minutes); |
| 48 | |
| 49 | /* |
| 50 | * since we're only adjusting minutes and seconds, |
| 51 | * don't interfere with hour overflow. This avoids |
| 52 | * messing with unknown time zones but requires your |
| 53 | * RTC not to be off by more than 15 minutes |
| 54 | */ |
| 55 | real_seconds = nowtime % 60; |
| 56 | real_minutes = nowtime / 60; |
| 57 | if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) |
| 58 | real_minutes += 30; /* correct for half hour time zone */ |
| 59 | real_minutes %= 60; |
| 60 | |
| 61 | if (abs(real_minutes - cmos_minutes) < 30) { |
| 62 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
| 63 | BIN_TO_BCD(real_seconds); |
| 64 | BIN_TO_BCD(real_minutes); |
| 65 | } |
Ralf Baechle | 21a151d | 2007-10-11 23:46:15 +0100 | [diff] [blame] | 66 | CMOS_WRITE(real_seconds, RTC_SECONDS); |
| 67 | CMOS_WRITE(real_minutes, RTC_MINUTES); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | } else { |
| 69 | printk(KERN_WARNING |
| 70 | "set_rtc_mmss: can't update from %d to %d\n", |
| 71 | cmos_minutes, real_minutes); |
| 72 | retval = -1; |
| 73 | } |
| 74 | |
| 75 | /* The following flags have to be released exactly in this order, |
| 76 | * otherwise the DS12887 (popular MC146818A clone with integrated |
| 77 | * battery and quartz) will not reset the oscillator and will not |
| 78 | * update precisely 500 ms later. You won't find this mentioned in |
| 79 | * the Dallas Semiconductor data sheets, but who believes data |
| 80 | * sheets anyway ... -- Markus Kuhn |
| 81 | */ |
| 82 | CMOS_WRITE(save_control, RTC_CONTROL); |
| 83 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); |
Atsushi Nemoto | 53c2df2 | 2005-11-03 01:01:15 +0900 | [diff] [blame] | 84 | spin_unlock_irqrestore(&rtc_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | |
| 86 | return retval; |
| 87 | } |
| 88 | |
| 89 | static inline unsigned long mc146818_get_cmos_time(void) |
| 90 | { |
| 91 | unsigned int year, mon, day, hour, min, sec; |
Atsushi Nemoto | 53c2df2 | 2005-11-03 01:01:15 +0900 | [diff] [blame] | 92 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 93 | |
Atsushi Nemoto | 53c2df2 | 2005-11-03 01:01:15 +0900 | [diff] [blame] | 94 | spin_lock_irqsave(&rtc_lock, flags); |
Matt Mackall | da2468b | 2006-03-28 01:56:05 -0800 | [diff] [blame] | 95 | |
| 96 | do { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 97 | sec = CMOS_READ(RTC_SECONDS); |
| 98 | min = CMOS_READ(RTC_MINUTES); |
| 99 | hour = CMOS_READ(RTC_HOURS); |
| 100 | day = CMOS_READ(RTC_DAY_OF_MONTH); |
| 101 | mon = CMOS_READ(RTC_MONTH); |
| 102 | year = CMOS_READ(RTC_YEAR); |
| 103 | } while (sec != CMOS_READ(RTC_SECONDS)); |
| 104 | |
| 105 | if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
| 106 | BCD_TO_BIN(sec); |
| 107 | BCD_TO_BIN(min); |
| 108 | BCD_TO_BIN(hour); |
| 109 | BCD_TO_BIN(day); |
| 110 | BCD_TO_BIN(mon); |
| 111 | BCD_TO_BIN(year); |
| 112 | } |
Atsushi Nemoto | 53c2df2 | 2005-11-03 01:01:15 +0900 | [diff] [blame] | 113 | spin_unlock_irqrestore(&rtc_lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | year = mc146818_decode_year(year); |
| 115 | |
| 116 | return mktime(year, mon, day, hour, min, sec); |
| 117 | } |
| 118 | |
| 119 | #endif /* __ASM_MC146818_TIME_H */ |