// SPDX-License-Identifier: GPL-2.0/* * RTC subsystem, sysfs interface * * Copyright (C) 2005 Tower Technologies * Author: Alessandro Zummo <a.zummo@towertech.it> */ #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 %s\n", dev_driver_string(dev->parent),		       dev_name(dev->parent));}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)		return retval; 	return sprintf(buf, "%ptRd\n", &tm);}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)		return retval; 	return sprintf(buf, "%ptRt\n", &tm);}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) {		time64_t time; 		time = rtc_tm_to_time64(&tm);		retval = sprintf(buf, "%lld\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;	int err; 	err = kstrtoul(buf, 0, &val);	if (err)		return err; 	if (val >= 4096 || val == 0)		return -EINVAL; 	rtc->max_user_freq = (int)val; 	return n;}static DEVICE_ATTR_RW(max_user_freq); /** * hctosys_show - indicate if the given RTC set the system time * @dev: The device that the attribute belongs to. * @attr: The attribute being read. * @buf: The result buffer. * * buf is "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");#endif	return sprintf(buf, "0\n");}static DEVICE_ATTR_RO(hctosys); static ssize_twakealarm_show(struct device *dev, struct device_attribute *attr, char *buf){	ssize_t retval;	time64_t 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) {		alarm = rtc_tm_to_time64(&alm.time);		retval = sprintf(buf, "%lld\n", alarm);	} 	return retval;} static ssize_twakealarm_store(struct device *dev, struct device_attribute *attr,		const char *buf, size_t n){	ssize_t retval;	time64_t now, alarm;	time64_t push = 0;	struct rtc_wkalrm alm;	struct rtc_device *rtc = to_rtc_device(dev);	const 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;	now = rtc_tm_to_time64(&alm.time); 	buf_ptr = buf;	if (*buf_ptr == '+') {		buf_ptr++;		if (*buf_ptr == '=') {			buf_ptr++;			push = 1;		} else {			adjust = 1;		}	}	retval = kstrtos64(buf_ptr, 0, &alarm);	if (retval)		return retval;	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) {				push = rtc_tm_to_time64(&alm.time);				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_time64_to_tm(alarm, &alm.time); 	retval = rtc_set_alarm(rtc, &alm);	return (retval < 0) ? retval : n;}static DEVICE_ATTR_RW(wakealarm); static ssize_toffset_show(struct device *dev, struct device_attribute *attr, char *buf){	ssize_t retval;	long offset; 	retval = rtc_read_offset(to_rtc_device(dev), &offset);	if (retval == 0)		retval = sprintf(buf, "%ld\n", offset); 	return retval;} static ssize_toffset_store(struct device *dev, struct device_attribute *attr,	     const char *buf, size_t n){	ssize_t retval;	long offset; 	retval = kstrtol(buf, 10, &offset);	if (retval == 0)		retval = rtc_set_offset(to_rtc_device(dev), offset); 	return (retval < 0) ? retval : n;}static DEVICE_ATTR_RW(offset); static ssize_trange_show(struct device *dev, struct device_attribute *attr, char *buf){	return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,		       to_rtc_device(dev)->range_max);}static DEVICE_ATTR_RO(range); 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,	&dev_attr_wakealarm.attr,	&dev_attr_offset.attr,	&dev_attr_range.attr,	NULL,}; /* 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 bool rtc_does_wakealarm(struct rtc_device *rtc){	if (!device_can_wakeup(rtc->dev.parent))		return false; 	return !!test_bit(RTC_FEATURE_ALARM, rtc->features);} static umode_t rtc_attr_is_visible(struct kobject *kobj,				   struct attribute *attr, int n){	struct device *dev = kobj_to_dev(kobj);	struct rtc_device *rtc = to_rtc_device(dev);	umode_t mode = attr->mode; 	if (attr == &dev_attr_wakealarm.attr) {		if (!rtc_does_wakealarm(rtc))			mode = 0;	} else if (attr == &dev_attr_offset.attr) {		if (!rtc->ops->set_offset)			mode = 0;	} else if (attr == &dev_attr_range.attr) {		if (!(rtc->range_max - rtc->range_min))			mode = 0;	} 	return mode;} static struct attribute_group rtc_attr_group = {	.is_visible	= rtc_attr_is_visible,	.attrs		= rtc_attrs,}; static const struct attribute_group *rtc_attr_groups[] = {	&rtc_attr_group,	NULL}; const struct attribute_group **rtc_get_dev_attribute_groups(void){	return rtc_attr_groups;} int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps){	size_t old_cnt = 0, add_cnt = 0, new_cnt;	const struct attribute_group **groups, **old; 	if (!grps)		return -EINVAL; 	groups = rtc->dev.groups;	if (groups)		for (; *groups; groups++)			old_cnt++; 	for (groups = grps; *groups; groups++)		add_cnt++; 	new_cnt = old_cnt + add_cnt + 1;	groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);	if (!groups)		return -ENOMEM;	memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));	memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));	groups[old_cnt + add_cnt] = NULL; 	old = rtc->dev.groups;	rtc->dev.groups = groups;	if (old && old != rtc_attr_groups)		devm_kfree(&rtc->dev, old); 	return 0;}EXPORT_SYMBOL(rtc_add_groups); int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp){	const struct attribute_group *groups[] = { grp, NULL }; 	return rtc_add_groups(rtc, groups);}EXPORT_SYMBOL(rtc_add_group);