/* * 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 */ /* * NOTE:  RTC times displayed in sysfs use the RTC's timezone.  That's * ideally UTC.  However, PCs that also boot to MS-Windows normally use * the local time and change to match daylight savings time.  That affects * attributes including date, time, since_epoch, and wakealarm. */ static ssize_tname_show(struct device *dev, struct device_attribute *attr, char *buf){	return sprintf(buf, "%s\n", to_rtc_device(dev)->name);}static DEVICE_ATTR_RO(name); static ssize_tdate_show(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 DEVICE_ATTR_RO(date); static ssize_ttime_show(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 DEVICE_ATTR_RO(time); static ssize_tsince_epoch_show(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 DEVICE_ATTR_RO(since_epoch); static ssize_tmax_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf){	return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);} static ssize_tmax_user_freq_store(struct device *dev, struct device_attribute *attr,		const char *buf, size_t n){	struct rtc_device *rtc = to_rtc_device(dev);	unsigned long val = simple_strtoul(buf, NULL, 0); 	if (val >= 4096 || val == 0)		return -EINVAL; 	rtc->max_user_freq = (int)val; 	return n;}static DEVICE_ATTR_RW(max_user_freq); /** * rtc_sysfs_show_hctosys - indicate if the given RTC set the system time * * Returns 1 if the system clock was set by this RTC at the last * boot or resume event. */static ssize_thctosys_show(struct device *dev, struct device_attribute *attr, char *buf){#ifdef CONFIG_RTC_HCTOSYS_DEVICE	if (rtc_hctosys_ret == 0 &&			strcmp(dev_name(&to_rtc_device(dev)->dev),				CONFIG_RTC_HCTOSYS_DEVICE) == 0)		return sprintf(buf, "1\n");	else#endif		return sprintf(buf, "0\n");}static DEVICE_ATTR_RO(hctosys); static struct attribute *rtc_attrs[] = {	&dev_attr_name.attr,	&dev_attr_date.attr,	&dev_attr_time.attr,	&dev_attr_since_epoch.attr,	&dev_attr_max_user_freq.attr,	&dev_attr_hctosys.attr,	NULL,};ATTRIBUTE_GROUPS(rtc); static ssize_trtc_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.  For uniformity, RTC alarms are	 * conceptually one-shot, even though some common RTCs (on PCs)	 * don't actually work that way.	 *	 * NOTE: RTC implementations where the alarm doesn't match an	 * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC	 * alarms after they trigger, to ensure one-shot semantics.	 */	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_trtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,		const char *buf, size_t n){	ssize_t retval;	unsigned long now, alarm;	unsigned long push = 0;	struct rtc_wkalrm alm;	struct rtc_device *rtc = to_rtc_device(dev);	char *buf_ptr;	int adjust = 0; 	/* 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); 	buf_ptr = (char *)buf;	if (*buf_ptr == '+') {		buf_ptr++;		if (*buf_ptr == '=') {			buf_ptr++;			push = 1;		} else			adjust = 1;	}	alarm = simple_strtoul(buf_ptr, NULL, 0);	if (adjust) {		alarm += now;	}	if (alarm > now || push) {		/* 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) {			if (push) {				rtc_tm_to_time(&alm.time, &push);				alarm += push;			} else				return -EBUSY;		} else if (push)			return -EINVAL;		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\n", 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_groups = rtc_groups;}