Commit | Line | Data |
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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 | { | |
d0ab4a4d | 27 | int err = -ENODEV; |
0c86edc0 | 28 | struct rtc_time tm; |
d0ab4a4d UKK |
29 | struct timespec tv = { |
30 | .tv_nsec = NSEC_PER_SEC >> 1, | |
31 | }; | |
ab6a2d70 | 32 | struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE); |
0c86edc0 | 33 | |
ab6a2d70 | 34 | if (rtc == NULL) { |
d0ab4a4d | 35 | pr_err("%s: unable to open rtc device (%s)\n", |
0c86edc0 | 36 | __FILE__, CONFIG_RTC_HCTOSYS_DEVICE); |
d0ab4a4d | 37 | goto err_open; |
0c86edc0 AZ |
38 | } |
39 | ||
ab6a2d70 | 40 | err = rtc_read_time(rtc, &tm); |
d0ab4a4d UKK |
41 | if (err) { |
42 | dev_err(rtc->dev.parent, | |
43 | "hctosys: unable to read the hardware clock\n"); | |
44 | goto err_read; | |
0c86edc0 | 45 | |
d0ab4a4d | 46 | } |
0c86edc0 | 47 | |
d0ab4a4d UKK |
48 | err = rtc_valid_tm(&tm); |
49 | if (err) { | |
50 | dev_err(rtc->dev.parent, | |
51 | "hctosys: invalid date/time\n"); | |
52 | goto err_invalid; | |
53 | } | |
0c86edc0 | 54 | |
d0ab4a4d | 55 | rtc_tm_to_time(&tm, &tv.tv_sec); |
0c86edc0 | 56 | |
4c24e29e | 57 | err = do_settimeofday(&tv); |
0c86edc0 | 58 | |
d0ab4a4d UKK |
59 | dev_info(rtc->dev.parent, |
60 | "setting system clock to " | |
61 | "%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n", | |
62 | tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, | |
63 | tm.tm_hour, tm.tm_min, tm.tm_sec, | |
64 | (unsigned int) tv.tv_sec); | |
65 | ||
66 | err_invalid: | |
67 | err_read: | |
ab6a2d70 | 68 | rtc_class_close(rtc); |
0c86edc0 | 69 | |
d0ab4a4d UKK |
70 | err_open: |
71 | rtc_hctosys_ret = err; | |
72 | ||
73 | return err; | |
0c86edc0 AZ |
74 | } |
75 | ||
76 | late_initcall(rtc_hctosys); |