Commit | Line | Data |
---|---|---|
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; |
a6d6e1c8 | 29 | struct timespec64 tv64 = { |
d0ab4a4d UKK |
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 | |
a6d6e1c8 | 48 | tv64.tv_sec = rtc_tm_to_time64(&tm); |
0c86edc0 | 49 | |
a6d6e1c8 | 50 | err = do_settimeofday64(&tv64); |
0c86edc0 | 51 | |
d0ab4a4d UKK |
52 | dev_info(rtc->dev.parent, |
53 | "setting system clock to " | |
a6d6e1c8 | 54 | "%d-%02d-%02d %02d:%02d:%02d UTC (%lld)\n", |
d0ab4a4d UKK |
55 | tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, |
56 | tm.tm_hour, tm.tm_min, tm.tm_sec, | |
a6d6e1c8 | 57 | (long long) tv64.tv_sec); |
d0ab4a4d | 58 | |
d0ab4a4d | 59 | err_read: |
ab6a2d70 | 60 | rtc_class_close(rtc); |
0c86edc0 | 61 | |
d0ab4a4d UKK |
62 | err_open: |
63 | rtc_hctosys_ret = err; | |
64 | ||
65 | return err; | |
0c86edc0 AZ |
66 | } |
67 | ||
68 | late_initcall(rtc_hctosys); |