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12 | 12 | #include <linux/mc146818rtc.h>
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13 | 13 | #include <linux/time.h>
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14 | 14 |
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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; |
36 |
| - unsigned long flags; |
37 |
| - |
38 |
| - spin_lock_irqsave(&rtc_lock, flags); |
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 |
| - cmos_minutes = bcd2bin(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 |
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| - * 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 |
| - real_seconds = bin2bcd(real_seconds); |
64 |
| - real_minutes = bin2bcd(real_minutes); |
65 |
| - } |
66 |
| - CMOS_WRITE(real_seconds, RTC_SECONDS); |
67 |
| - CMOS_WRITE(real_minutes, RTC_MINUTES); |
68 |
| - } else { |
69 |
| - printk_once(KERN_NOTICE |
70 |
| - "set_rtc_mmss: can't update from %d to %d\n", |
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| - 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 |
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| - * update precisely 500 ms later. You won't find this mentioned in |
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| - * 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); |
84 |
| - spin_unlock_irqrestore(&rtc_lock, flags); |
85 |
| - |
86 |
| - return retval; |
87 |
| -} |
88 |
| - |
89 | 15 | static inline time64_t mc146818_get_cmos_time(void)
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90 | 16 | {
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91 | 17 | unsigned int year, mon, day, hour, min, sec;
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