/*
* 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>
/* device attributes */
static ssize_t rtc_sysfs_show_name(struct class_device *dev, char *buf)
{
return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
}
static CLASS_DEVICE_ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL);
static ssize_t rtc_sysfs_show_date(struct class_device *dev, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(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 CLASS_DEVICE_ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL);
static ssize_t rtc_sysfs_show_time(struct class_device *dev, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(dev, &tm);
if (retval == 0) {
retval = sprintf(buf, "%02d:%02d:%02d\n",
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
return retval;
}
static CLASS_DEVICE_ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL);
static ssize_t rtc_sysfs_show_since_epoch(struct class_device *dev, char *buf)
{
ssize_t retval;
struct rtc_time tm;
retval = rtc_read_time(dev, &tm);
if (retval == 0) {
unsigned long time;
rtc_tm_to_time(&tm, &time);
retval = sprintf(buf, "%lu\n", time);
}
return retval;
}
static CLASS_DEVICE_ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL);
static struct attribute *rtc_attrs[] = {
&class_device_attr_name.attr,
&class_device_attr_date.attr,
&class_device_attr_time.attr,
&class_device_attr_since_epoch.attr,
NULL,
};
static struct attribute_group rtc_attr_group = {
.attrs = rtc_attrs,
};
static ssize_t
rtc_sysfs_show_wakealarm(struct class_device *dev, 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(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 class_device *dev, const char *buf, size_t n)
{
ssize_t retval;
unsigned long now, alarm;
struct rtc_wkalrm alm;
/* 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(dev, &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(dev, &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(dev, &alm);
return (retval < 0) ? retval : n;
}
static const CLASS_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 class_device *class_dev)
{
struct rtc_device *rtc;
if (!device_can_wakeup(class_dev->dev))
return 0;
rtc = to_rtc_device(class_dev);
return rtc->ops->set_alarm != NULL;
}
static int rtc_sysfs_add_device(struct class_device *class_dev,
struct class_interface *class_intf)
{
int err;
dev_dbg(class_dev->dev, "rtc intf: sysfs\n");
err = sysfs_create_group(&class_dev->kobj, &rtc_attr_group);
if (err)
dev_err(class_dev->dev, "failed to create %s\n",
"sysfs attributes");
else if (rtc_does_wakealarm(class_dev)) {
/* not all RTCs support both alarms and wakeup */
err = class_device_create_file(class_dev,
&class_device_attr_wakealarm);
if (err) {
dev_err(class_dev->dev, "failed to create %s\n",
"alarm attribute");
sysfs_remove_group(&class_dev->kobj, &rtc_attr_group);
}
}
return err;
}
static void rtc_sysfs_remove_device(struct class_device *class_dev,
struct class_interface *class_intf)
{
if (rtc_does_wakealarm(class_dev))
class_device_remove_file(class_dev,
&class_device_attr_wakealarm);
sysfs_remove_group(&class_dev->kobj, &rtc_attr_group);
}
/* interface registration */
static struct class_interface rtc_sysfs_interface = {
.add = &rtc_sysfs_add_device,
.remove = &rtc_sysfs_remove_device,
};
static int __init rtc_sysfs_init(void)
{
return rtc_interface_register(&rtc_sysfs_interface);
}
static void __exit rtc_sysfs_exit(void)
{
class_interface_unregister(&rtc_sysfs_interface);
}
subsys_initcall(rtc_sysfs_init);
module_exit(rtc_sysfs_exit);
MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("RTC class sysfs interface");
MODULE_LICENSE("GPL");
