/* * 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_trtc_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_trtc_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");