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/*
* RTC subsystem, sysfs interface
*
* 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/module.h>
#include <linux/rtc.h>
#include "rtc-core.h"
/* device attributes */
static ssize_t
rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
}
static ssize_t
rtc_sysfs_show_date(struct device *dev, struct device_attribute *attr,
char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
retval = sprintf(buf, "%04d-%02d-%02d\n",
tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
}
return retval;
}
static ssize_t
rtc_sysfs_show_time(struct device *dev, struct device_attribute *attr,
char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
retval = sprintf(buf, "%02d:%02d:%02d\n",
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
return retval;
}
static ssize_t
rtc_sysfs_show_since_epoch(struct device *dev, struct device_attribute *attr,
char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(to_rtc_device(dev), &tm);
if (retval == 0) {
unsigned long time;
rtc_tm_to_time(&tm, &time);
retval = sprintf(buf, "%lu\n", time);
}
return retval;
}
static struct device_attribute rtc_attrs[] = {
__ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
__ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
__ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL),
__ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
{ },
};
static ssize_t
rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr,
char *buf)
{
ssize_t retval;
unsigned long alarm;
struct rtc_wkalrm alm;
/* Don't show disabled alarms; but the RTC could leave the
* alarm enabled after it's already triggered. Alarms are
* conceptually one-shot, even though some common hardware
* (PCs) doesn't actually work that way.
*
* REVISIT maybe we should require RTC implementations to
* disable the RTC alarm after it triggers, for uniformity.
*/
retval = rtc_read_alarm(to_rtc_device(dev), &alm);
if (retval == 0 && alm.enabled) {
rtc_tm_to_time(&alm.time, &alarm);
retval = sprintf(buf, "%lu\n", alarm);
}
return retval;
}
static ssize_t
rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
{
ssize_t retval;
unsigned long now, alarm;
struct rtc_wkalrm alm;
struct rtc_device *rtc = to_rtc_device(dev);
/* Only request alarms that trigger in the future. Disable them
* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
*/
retval = rtc_read_time(rtc, &alm.time);
if (retval < 0)
return retval;
rtc_tm_to_time(&alm.time, &now);
alarm = simple_strtoul(buf, NULL, 0);
if (alarm > now) {
/* Avoid accidentally clobbering active alarms; we can't
* entirely prevent that here, without even the minimal
* locking from the /dev/rtcN api.
*/
retval = rtc_read_alarm(rtc, &alm);
if (retval < 0)
return retval;
if (alm.enabled)
return -EBUSY;
alm.enabled = 1;
} else {
alm.enabled = 0;
/* Provide a valid future alarm time. Linux isn't EFI,
* this time won't be ignored when disabling the alarm.
*/
alarm = now + 300;
}
rtc_time_to_tm(alarm, &alm.time);
retval = rtc_set_alarm(rtc, &alm);
return (retval < 0) ? retval : n;
}
static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
/* The reason to trigger an alarm with no process watching it (via sysfs)
* is its side effect: waking from a system state like suspend-to-RAM or
* suspend-to-disk. So: no attribute unless that side effect is possible.
* (Userspace may disable that mechanism later.)
*/
static inline int rtc_does_wakealarm(struct rtc_device *rtc)
{
if (!device_can_wakeup(rtc->dev.parent))
return 0;
return rtc->ops->set_alarm != NULL;
}
void rtc_sysfs_add_device(struct rtc_device *rtc)
{
int err;
/* not all RTCs support both alarms and wakeup */
if (!rtc_does_wakealarm(rtc))
return;
err = device_create_file(&rtc->dev, &dev_attr_wakealarm);
if (err)
dev_err(rtc->dev.parent, "failed to create "
"alarm attribute, %d",
err);
}
void rtc_sysfs_del_device(struct rtc_device *rtc)
{
/* REVISIT did we add it successfully? */
if (rtc_does_wakealarm(rtc))
device_remove_file(&rtc->dev, &dev_attr_wakealarm);
}
void __init rtc_sysfs_init(struct class *rtc_class)
{
rtc_class->dev_attrs = rtc_attrs;
}
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