70 строки
1.9 KiB
C
70 строки
1.9 KiB
C
/*
|
|
* RTC subsystem, initialize system time on startup
|
|
*
|
|
* Copyright (C) 2005 Tower Technologies
|
|
* Author: Alessandro Zummo <a.zummo@towertech.it>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/rtc.h>
|
|
|
|
/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
|
|
* whether it stores the most close value or the value with partial
|
|
* seconds truncated. However, it is important that we use it to store
|
|
* the truncated value. This is because otherwise it is necessary,
|
|
* in an rtc sync function, to read both xtime.tv_sec and
|
|
* xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
|
|
* of >32bits is not possible. So storing the most close value would
|
|
* slow down the sync API. So here we have the truncated value and
|
|
* the best guess is to add 0.5s.
|
|
*/
|
|
|
|
static int __init rtc_hctosys(void)
|
|
{
|
|
int err;
|
|
struct rtc_time tm;
|
|
struct class_device *class_dev = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
|
|
|
|
if (class_dev == NULL) {
|
|
printk("%s: unable to open rtc device (%s)\n",
|
|
__FILE__, CONFIG_RTC_HCTOSYS_DEVICE);
|
|
return -ENODEV;
|
|
}
|
|
|
|
err = rtc_read_time(class_dev, &tm);
|
|
if (err == 0) {
|
|
err = rtc_valid_tm(&tm);
|
|
if (err == 0) {
|
|
struct timespec tv;
|
|
|
|
tv.tv_nsec = NSEC_PER_SEC >> 1;
|
|
|
|
rtc_tm_to_time(&tm, &tv.tv_sec);
|
|
|
|
do_settimeofday(&tv);
|
|
|
|
dev_info(class_dev->dev,
|
|
"setting the system clock to "
|
|
"%d-%02d-%02d %02d:%02d:%02d (%u)\n",
|
|
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
|
|
tm.tm_hour, tm.tm_min, tm.tm_sec,
|
|
(unsigned int) tv.tv_sec);
|
|
}
|
|
else
|
|
dev_err(class_dev->dev,
|
|
"hctosys: invalid date/time\n");
|
|
}
|
|
else
|
|
dev_err(class_dev->dev,
|
|
"hctosys: unable to read the hardware clock\n");
|
|
|
|
rtc_class_close(class_dev);
|
|
|
|
return 0;
|
|
}
|
|
|
|
late_initcall(rtc_hctosys);
|