projects / linux.git / blame
| 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 <[email protected]> | |
| 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 | ||
| a737e835 JP |
12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 13 | ||
| 0c86edc0 AZ |
14 | #include <linux/rtc.h> |
| 15 | ||
| 16 | /* IMPORTANT: the RTC only stores whole seconds. It is arbitrary | |
| 17 | * whether it stores the most close value or the value with partial | |
| 18 | * seconds truncated. However, it is important that we use it to store | |
| 19 | * the truncated value. This is because otherwise it is necessary, | |
| 20 | * in an rtc sync function, to read both xtime.tv_sec and | |
| 21 | * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read | |
| 22 | * of >32bits is not possible. So storing the most close value would | |
| 23 | * slow down the sync API. So here we have the truncated value and | |
| 24 | * the best guess is to add 0.5s. | |
| 25 | */ | |
| 26 | ||
| 27 | static int __init rtc_hctosys(void) | |
| 28 | { | |
| d0ab4a4d | 29 | int err = -ENODEV; |
| 0c86edc0 | 30 | struct rtc_time tm; |
| a6d6e1c8 | 31 | struct timespec64 tv64 = { |
| d0ab4a4d UKK |
32 | .tv_nsec = NSEC_PER_SEC >> 1, |
| 33 | }; | |
| ab6a2d70 | 34 | struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE); |
| 0c86edc0 | 35 | |
| ab6a2d70 | 36 | if (rtc == NULL) { |
| a737e835 JP |
37 | pr_info("unable to open rtc device (%s)\n", |
| 38 | CONFIG_RTC_HCTOSYS_DEVICE); | |
| d0ab4a4d | 39 | goto err_open; |
| 0c86edc0 AZ |
40 | } |
| 41 | ||
| ab6a2d70 | 42 | err = rtc_read_time(rtc, &tm); |
| d0ab4a4d UKK |
43 | if (err) { |
| 44 | dev_err(rtc->dev.parent, | |
| 45 | "hctosys: unable to read the hardware clock\n"); | |
| 46 | goto err_read; | |
| 0c86edc0 | 47 | |
| d0ab4a4d | 48 | } |
| 0c86edc0 | 49 | |
| a6d6e1c8 | 50 | tv64.tv_sec = rtc_tm_to_time64(&tm); |
| 0c86edc0 | 51 | |
| b3a5ac42 | 52 | #if BITS_PER_LONG == 32 |
| 7ce9a992 MR |
53 | if (tv64.tv_sec > INT_MAX) { |
| 54 | err = -ERANGE; | |
| b3a5ac42 | 55 | goto err_read; |
| 7ce9a992 | 56 | } |
| b3a5ac42 AB |
57 | #endif |
| 58 | ||
| a6d6e1c8 | 59 | err = do_settimeofday64(&tv64); |
| 0c86edc0 | 60 | |
| d0ab4a4d UKK |
61 | dev_info(rtc->dev.parent, |
| 62 | "setting system clock to " | |
| a6d6e1c8 | 63 | "%d-%02d-%02d %02d:%02d:%02d UTC (%lld)\n", |
| d0ab4a4d UKK |
64 | tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, |
| 65 | tm.tm_hour, tm.tm_min, tm.tm_sec, | |
| a6d6e1c8 | 66 | (long long) tv64.tv_sec); |
| d0ab4a4d | 67 | |
| d0ab4a4d | 68 | err_read: |
| ab6a2d70 | 69 | rtc_class_close(rtc); |
| 0c86edc0 | 70 | |
| d0ab4a4d UKK |
71 | err_open: |
| 72 | rtc_hctosys_ret = err; | |
| 73 | ||
| 74 | return err; | |
| 0c86edc0 AZ |
75 | } |
| 76 | ||
| 77 | late_initcall(rtc_hctosys); |