diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-mips/mc146818-time.h |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/asm-mips/mc146818-time.h')
-rw-r--r-- | include/asm-mips/mc146818-time.h | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/include/asm-mips/mc146818-time.h b/include/asm-mips/mc146818-time.h new file mode 100644 index 000000000000..a2c2d2c24303 --- /dev/null +++ b/include/asm-mips/mc146818-time.h | |||
@@ -0,0 +1,128 @@ | |||
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; | ||
36 | |||
37 | save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */ | ||
38 | CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); | ||
39 | |||
40 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */ | ||
41 | CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); | ||
42 | |||
43 | cmos_minutes = CMOS_READ(RTC_MINUTES); | ||
44 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) | ||
45 | BCD_TO_BIN(cmos_minutes); | ||
46 | |||
47 | /* | ||
48 | * since we're only adjusting minutes and seconds, | ||
49 | * don't interfere with hour overflow. This avoids | ||
50 | * messing with unknown time zones but requires your | ||
51 | * RTC not to be off by more than 15 minutes | ||
52 | */ | ||
53 | real_seconds = nowtime % 60; | ||
54 | real_minutes = nowtime / 60; | ||
55 | if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) | ||
56 | real_minutes += 30; /* correct for half hour time zone */ | ||
57 | real_minutes %= 60; | ||
58 | |||
59 | if (abs(real_minutes - cmos_minutes) < 30) { | ||
60 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { | ||
61 | BIN_TO_BCD(real_seconds); | ||
62 | BIN_TO_BCD(real_minutes); | ||
63 | } | ||
64 | CMOS_WRITE(real_seconds,RTC_SECONDS); | ||
65 | CMOS_WRITE(real_minutes,RTC_MINUTES); | ||
66 | } else { | ||
67 | printk(KERN_WARNING | ||
68 | "set_rtc_mmss: can't update from %d to %d\n", | ||
69 | cmos_minutes, real_minutes); | ||
70 | retval = -1; | ||
71 | } | ||
72 | |||
73 | /* The following flags have to be released exactly in this order, | ||
74 | * otherwise the DS12887 (popular MC146818A clone with integrated | ||
75 | * battery and quartz) will not reset the oscillator and will not | ||
76 | * update precisely 500 ms later. You won't find this mentioned in | ||
77 | * the Dallas Semiconductor data sheets, but who believes data | ||
78 | * sheets anyway ... -- Markus Kuhn | ||
79 | */ | ||
80 | CMOS_WRITE(save_control, RTC_CONTROL); | ||
81 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); | ||
82 | |||
83 | return retval; | ||
84 | } | ||
85 | |||
86 | static inline unsigned long mc146818_get_cmos_time(void) | ||
87 | { | ||
88 | unsigned int year, mon, day, hour, min, sec; | ||
89 | int i; | ||
90 | |||
91 | /* | ||
92 | * The Linux interpretation of the CMOS clock register contents: | ||
93 | * When the Update-In-Progress (UIP) flag goes from 1 to 0, the | ||
94 | * RTC registers show the second which has precisely just started. | ||
95 | * Let's hope other operating systems interpret the RTC the same way. | ||
96 | */ | ||
97 | |||
98 | /* read RTC exactly on falling edge of update flag */ | ||
99 | for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */ | ||
100 | if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) | ||
101 | break; | ||
102 | for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */ | ||
103 | if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)) | ||
104 | break; | ||
105 | |||
106 | do { /* Isn't this overkill ? UIP above should guarantee consistency */ | ||
107 | sec = CMOS_READ(RTC_SECONDS); | ||
108 | min = CMOS_READ(RTC_MINUTES); | ||
109 | hour = CMOS_READ(RTC_HOURS); | ||
110 | day = CMOS_READ(RTC_DAY_OF_MONTH); | ||
111 | mon = CMOS_READ(RTC_MONTH); | ||
112 | year = CMOS_READ(RTC_YEAR); | ||
113 | } while (sec != CMOS_READ(RTC_SECONDS)); | ||
114 | |||
115 | if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { | ||
116 | BCD_TO_BIN(sec); | ||
117 | BCD_TO_BIN(min); | ||
118 | BCD_TO_BIN(hour); | ||
119 | BCD_TO_BIN(day); | ||
120 | BCD_TO_BIN(mon); | ||
121 | BCD_TO_BIN(year); | ||
122 | } | ||
123 | year = mc146818_decode_year(year); | ||
124 | |||
125 | return mktime(year, mon, day, hour, min, sec); | ||
126 | } | ||
127 | |||
128 | #endif /* __ASM_MC146818_TIME_H */ | ||