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0c86edc0 AZ |
1 | /* |
2 | * RTC subsystem, initialize system time on startup | |
3 | * | |
4 | * Copyright (C) 2005 Tower Technologies | |
5 | * Author: Alessandro Zummo <a.zummo@towertech.it> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
12 | #include <linux/rtc.h> | |
13 | ||
14 | /* IMPORTANT: the RTC only stores whole seconds. It is arbitrary | |
15 | * whether it stores the most close value or the value with partial | |
16 | * seconds truncated. However, it is important that we use it to store | |
17 | * the truncated value. This is because otherwise it is necessary, | |
18 | * in an rtc sync function, to read both xtime.tv_sec and | |
19 | * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read | |
20 | * of >32bits is not possible. So storing the most close value would | |
21 | * slow down the sync API. So here we have the truncated value and | |
22 | * the best guess is to add 0.5s. | |
23 | */ | |
24 | ||
25 | static int __init rtc_hctosys(void) | |
26 | { | |
27 | int err; | |
28 | struct rtc_time tm; | |
ab6a2d70 | 29 | struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE); |
0c86edc0 | 30 | |
ab6a2d70 | 31 | if (rtc == NULL) { |
0c86edc0 AZ |
32 | printk("%s: unable to open rtc device (%s)\n", |
33 | __FILE__, CONFIG_RTC_HCTOSYS_DEVICE); | |
34 | return -ENODEV; | |
35 | } | |
36 | ||
ab6a2d70 | 37 | err = rtc_read_time(rtc, &tm); |
0c86edc0 AZ |
38 | if (err == 0) { |
39 | err = rtc_valid_tm(&tm); | |
40 | if (err == 0) { | |
41 | struct timespec tv; | |
42 | ||
43 | tv.tv_nsec = NSEC_PER_SEC >> 1; | |
44 | ||
45 | rtc_tm_to_time(&tm, &tv.tv_sec); | |
46 | ||
47 | do_settimeofday(&tv); | |
48 | ||
cd966209 | 49 | dev_info(rtc->dev.parent, |
779d2089 DB |
50 | "setting system clock to " |
51 | "%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n", | |
0c86edc0 AZ |
52 | tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, |
53 | tm.tm_hour, tm.tm_min, tm.tm_sec, | |
54 | (unsigned int) tv.tv_sec); | |
55 | } | |
56 | else | |
cd966209 | 57 | dev_err(rtc->dev.parent, |
0c86edc0 AZ |
58 | "hctosys: invalid date/time\n"); |
59 | } | |
60 | else | |
cd966209 | 61 | dev_err(rtc->dev.parent, |
0c86edc0 AZ |
62 | "hctosys: unable to read the hardware clock\n"); |
63 | ||
ab6a2d70 | 64 | rtc_class_close(rtc); |
0c86edc0 AZ |
65 | |
66 | return 0; | |
67 | } | |
68 | ||
69 | late_initcall(rtc_hctosys); |