[net-next-2.6.git] / drivers / rtc / hctosys.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.
 */

int rtc_hctosys_ret = -ENODEV;

static int __init rtc_hctosys(void)
{
	int err = -ENODEV;
	struct rtc_time tm;
	struct timespec tv = {
		.tv_nsec = NSEC_PER_SEC >> 1,
	};
	struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);

	if (rtc == NULL) {
		pr_err("%s: unable to open rtc device (%s)\n",
			__FILE__, CONFIG_RTC_HCTOSYS_DEVICE);
		goto err_open;
	}

	err = rtc_read_time(rtc, &tm);
	if (err) {
		dev_err(rtc->dev.parent,
			"hctosys: unable to read the hardware clock\n");
		goto err_read;

	}

	err = rtc_valid_tm(&tm);
	if (err) {
		dev_err(rtc->dev.parent,
			"hctosys: invalid date/time\n");
		goto err_invalid;
	}

	rtc_tm_to_time(&tm, &tv.tv_sec);

	do_settimeofday(&tv);

	dev_info(rtc->dev.parent,
		"setting system clock to "
		"%d-%02d-%02d %02d:%02d:%02d UTC (%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);

err_invalid:
err_read:
	rtc_class_close(rtc);

err_open:
	rtc_hctosys_ret = err;

	return err;
}

late_initcall(rtc_hctosys);
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
d0ab4a4d UKK	25	int rtc_hctosys_ret = -ENODEV;
d0ab4a4d UKK	26
0c86edc0 AZ	27	static int __init rtc_hctosys(void)
0c86edc0 AZ	28	{
d0ab4a4d	29	int err = -ENODEV;
0c86edc0	30	struct rtc_time tm;
d0ab4a4d UKK	31	struct timespec tv = {
	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) {
d0ab4a4d	37	pr_err("%s: unable to open rtc device (%s)\n",
0c86edc0	38	__FILE__, CONFIG_RTC_HCTOSYS_DEVICE);
d0ab4a4d	39	goto err_open;
0c86edc0 AZ	40	}
0c86edc0 AZ	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
d0ab4a4d UKK	50	err = rtc_valid_tm(&tm);
	51	if (err) {
	52	dev_err(rtc->dev.parent,
	53	"hctosys: invalid date/time\n");
	54	goto err_invalid;
	55	}
0c86edc0	56
d0ab4a4d	57	rtc_tm_to_time(&tm, &tv.tv_sec);
0c86edc0	58
d0ab4a4d	59	do_settimeofday(&tv);
0c86edc0	60
d0ab4a4d UKK	61	dev_info(rtc->dev.parent,
	62	"setting system clock to "
	63	"%d-%02d-%02d %02d:%02d:%02d UTC (%u)\n",
	64	tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
	65	tm.tm_hour, tm.tm_min, tm.tm_sec,
	66	(unsigned int) tv.tv_sec);
	67
	68	err_invalid:
	69	err_read:
ab6a2d70	70	rtc_class_close(rtc);
0c86edc0	71
d0ab4a4d UKK	72	err_open:
	73	rtc_hctosys_ret = err;
	74
	75	return err;
0c86edc0 AZ	76	}
	77
	78	late_initcall(rtc_hctosys);