[mirror_ubuntu-jammy-kernel.git] / drivers / rtc / sysfs.c

// 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_t
name_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_t
date_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_t
time_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_t
since_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_t
max_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_t
max_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_t
hctosys_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_t
wakealarm_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_t
wakealarm_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_t
offset_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_t
offset_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_t
range_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);
Commit	Line	Data
cdf7545a	1	// SPDX-License-Identifier: GPL-2.0
c5c3e192 AZ	2	/*
	3	* RTC subsystem, sysfs interface
	4	*
	5	* Copyright (C) 2005 Tower Technologies
	6	* Author: Alessandro Zummo <a.zummo@towertech.it>
cdf7545a	7	*/
c5c3e192 AZ	8
	9	#include <linux/module.h>
	10	#include <linux/rtc.h>
	11
ab6a2d70 DB	12	#include "rtc-core.h"
ab6a2d70 DB	13
c5c3e192 AZ	14	/* device attributes */
c5c3e192 AZ	15
8a0bdfd7 DB	16	/*
	17	* NOTE: RTC times displayed in sysfs use the RTC's timezone. That's
	18	* ideally UTC. However, PCs that also boot to MS-Windows normally use
	19	* the local time and change to match daylight savings time. That affects
	20	* attributes including date, time, since_epoch, and wakealarm.
	21	*/
	22
cd966209	23	static ssize_t
f21e6835	24	name_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192	25	{
77a73f3c AB	26	return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),
77a73f3c AB	27	dev_name(dev->parent));
c5c3e192	28	}
f21e6835	29	static DEVICE_ATTR_RO(name);
c5c3e192	30
cd966209	31	static ssize_t
f21e6835	32	date_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192 AZ	33	{
	34	ssize_t retval;
	35	struct rtc_time tm;
	36
ab6a2d70	37	retval = rtc_read_time(to_rtc_device(dev), &tm);
5548cbf7 AS	38	if (retval)
5548cbf7 AS	39	return retval;
c5c3e192	40
5548cbf7	41	return sprintf(buf, "%ptRd\n", &tm);
c5c3e192	42	}
f21e6835	43	static DEVICE_ATTR_RO(date);
c5c3e192	44
cd966209	45	static ssize_t
f21e6835	46	time_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192 AZ	47	{
	48	ssize_t retval;
	49	struct rtc_time tm;
	50
ab6a2d70	51	retval = rtc_read_time(to_rtc_device(dev), &tm);
5548cbf7 AS	52	if (retval)
5548cbf7 AS	53	return retval;
c5c3e192	54
5548cbf7	55	return sprintf(buf, "%ptRt\n", &tm);
c5c3e192	56	}
f21e6835	57	static DEVICE_ATTR_RO(time);
c5c3e192	58
cd966209	59	static ssize_t
f21e6835	60	since_epoch_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192 AZ	61	{
	62	ssize_t retval;
	63	struct rtc_time tm;
	64
ab6a2d70	65	retval = rtc_read_time(to_rtc_device(dev), &tm);
c5c3e192	66	if (retval == 0) {
9a06da2e BW	67	time64_t time;
	68
	69	time = rtc_tm_to_time64(&tm);
	70	retval = sprintf(buf, "%lld\n", time);
c5c3e192 AZ	71	}
	72
	73	return retval;
	74	}
f21e6835	75	static DEVICE_ATTR_RO(since_epoch);
c5c3e192	76
06c65eb4	77	static ssize_t
f21e6835	78	max_user_freq_show(struct device dev, struct device_attribute attr, char *buf)
06c65eb4 BK	79	{
	80	return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
	81	}
	82
	83	static ssize_t
f21e6835	84	max_user_freq_store(struct device dev, struct device_attribute attr,
606cc43c	85	const char *buf, size_t n)
06c65eb4 BK	86	{
06c65eb4 BK	87	struct rtc_device *rtc = to_rtc_device(dev);
f571287b LC	88	unsigned long val;
	89	int err;
	90
	91	err = kstrtoul(buf, 0, &val);
	92	if (err)
	93	return err;
06c65eb4 BK	94
	95	if (val >= 4096 \|\| val == 0)
	96	return -EINVAL;
	97
	98	rtc->max_user_freq = (int)val;
	99
	100	return n;
	101	}
f21e6835	102	static DEVICE_ATTR_RW(max_user_freq);
06c65eb4	103
4c24e29e	104	/**
a8fdbefd	105	* hctosys_show - indicate if the given RTC set the system time
6f693192 AB	106	* @dev: The device that the attribute belongs to.
	107	* @attr: The attribute being read.
	108	* @buf: The result buffer.
4c24e29e	109	*
6f693192	110	* buf is "1" if the system clock was set by this RTC at the last
4c24e29e DF	111	* boot or resume event.
4c24e29e DF	112	*/
d8c1acb1	113	static ssize_t
f21e6835	114	hctosys_show(struct device dev, struct device_attribute attr, char *buf)
d8c1acb1 MG	115	{
d8c1acb1 MG	116	#ifdef CONFIG_RTC_HCTOSYS_DEVICE
d0ab4a4d	117	if (rtc_hctosys_ret == 0 &&
606cc43c AB	118	strcmp(dev_name(&to_rtc_device(dev)->dev),
606cc43c AB	119	CONFIG_RTC_HCTOSYS_DEVICE) == 0)
d8c1acb1	120	return sprintf(buf, "1\n");
d8c1acb1	121	#endif
606cc43c	122	return sprintf(buf, "0\n");
d8c1acb1	123	}
f21e6835 GKH	124	static DEVICE_ATTR_RO(hctosys);
f21e6835 GKH	125
3925a5ce	126	static ssize_t
a17ccd1c	127	wakealarm_show(struct device dev, struct device_attribute attr, char *buf)
3925a5ce DB	128	{
3925a5ce DB	129	ssize_t retval;
9a06da2e	130	time64_t alarm;
3925a5ce DB	131	struct rtc_wkalrm alm;
3925a5ce DB	132
8a0bdfd7 DB	133	/* Don't show disabled alarms. For uniformity, RTC alarms are
	134	* conceptually one-shot, even though some common RTCs (on PCs)
	135	* don't actually work that way.
3925a5ce	136	*
8a0bdfd7 DB	137	* NOTE: RTC implementations where the alarm doesn't match an
	138	* exact YYYY-MM-DD HH:MM[:SS] date must disable their RTC
	139	* alarms after they trigger, to ensure one-shot semantics.
3925a5ce	140	*/
ab6a2d70	141	retval = rtc_read_alarm(to_rtc_device(dev), &alm);
3925a5ce	142	if (retval == 0 && alm.enabled) {
9a06da2e BW	143	alarm = rtc_tm_to_time64(&alm.time);
9a06da2e BW	144	retval = sprintf(buf, "%lld\n", alarm);
3925a5ce DB	145	}
	146
	147	return retval;
	148	}
	149
	150	static ssize_t
a17ccd1c	151	wakealarm_store(struct device dev, struct device_attribute attr,
cd966209	152	const char *buf, size_t n)
3925a5ce DB	153	{
3925a5ce DB	154	ssize_t retval;
9a06da2e BW	155	time64_t now, alarm;
9a06da2e BW	156	time64_t push = 0;
3925a5ce	157	struct rtc_wkalrm alm;
ab6a2d70	158	struct rtc_device *rtc = to_rtc_device(dev);
84281c2d	159	const char *buf_ptr;
c116bc2a	160	int adjust = 0;
3925a5ce DB	161
	162	/* Only request alarms that trigger in the future. Disable them
	163	* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
	164	*/
ab6a2d70	165	retval = rtc_read_time(rtc, &alm.time);
3925a5ce DB	166	if (retval < 0)
3925a5ce DB	167	return retval;
9a06da2e	168	now = rtc_tm_to_time64(&alm.time);
3925a5ce	169
84281c2d	170	buf_ptr = buf;
c116bc2a ZY	171	if (*buf_ptr == '+') {
c116bc2a ZY	172	buf_ptr++;
1df0a471 BT	173	if (*buf_ptr == '=') {
	174	buf_ptr++;
	175	push = 1;
606cc43c	176	} else {
1df0a471	177	adjust = 1;
606cc43c	178	}
c116bc2a	179	}
9a06da2e	180	retval = kstrtos64(buf_ptr, 0, &alarm);
f571287b LC	181	if (retval)
f571287b LC	182	return retval;
606cc43c	183	if (adjust)
c116bc2a	184	alarm += now;
1df0a471	185	if (alarm > now \|\| push) {
3925a5ce DB	186	/* Avoid accidentally clobbering active alarms; we can't
	187	* entirely prevent that here, without even the minimal
	188	* locking from the /dev/rtcN api.
	189	*/
ab6a2d70	190	retval = rtc_read_alarm(rtc, &alm);
3925a5ce DB	191	if (retval < 0)
3925a5ce DB	192	return retval;
1df0a471 BT	193	if (alm.enabled) {
1df0a471 BT	194	if (push) {
9a06da2e	195	push = rtc_tm_to_time64(&alm.time);
1df0a471 BT	196	alarm += push;
	197	} else
	198	return -EBUSY;
	199	} else if (push)
	200	return -EINVAL;
3925a5ce DB	201	alm.enabled = 1;
	202	} else {
	203	alm.enabled = 0;
	204
	205	/* Provide a valid future alarm time. Linux isn't EFI,
	206	* this time won't be ignored when disabling the alarm.
	207	*/
	208	alarm = now + 300;
	209	}
9a06da2e	210	rtc_time64_to_tm(alarm, &alm.time);
3925a5ce	211
ab6a2d70	212	retval = rtc_set_alarm(rtc, &alm);
3925a5ce DB	213	return (retval < 0) ? retval : n;
3925a5ce DB	214	}
a17ccd1c	215	static DEVICE_ATTR_RW(wakealarm);
3925a5ce	216
5495a415 JC	217	static ssize_t
	218	offset_show(struct device dev, struct device_attribute attr, char *buf)
	219	{
	220	ssize_t retval;
	221	long offset;
	222
	223	retval = rtc_read_offset(to_rtc_device(dev), &offset);
	224	if (retval == 0)
	225	retval = sprintf(buf, "%ld\n", offset);
	226
	227	return retval;
	228	}
	229
	230	static ssize_t
	231	offset_store(struct device dev, struct device_attribute attr,
	232	const char *buf, size_t n)
	233	{
	234	ssize_t retval;
	235	long offset;
	236
	237	retval = kstrtol(buf, 10, &offset);
	238	if (retval == 0)
	239	retval = rtc_set_offset(to_rtc_device(dev), offset);
	240
	241	return (retval < 0) ? retval : n;
	242	}
	243	static DEVICE_ATTR_RW(offset);
	244
71db049e AB	245	static ssize_t
	246	range_show(struct device dev, struct device_attribute attr, char *buf)
	247	{
	248	return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
	249	to_rtc_device(dev)->range_max);
	250	}
	251	static DEVICE_ATTR_RO(range);
	252
3ee2c40b DT	253	static struct attribute *rtc_attrs[] = {
	254	&dev_attr_name.attr,
	255	&dev_attr_date.attr,
	256	&dev_attr_time.attr,
	257	&dev_attr_since_epoch.attr,
	258	&dev_attr_max_user_freq.attr,
	259	&dev_attr_hctosys.attr,
	260	&dev_attr_wakealarm.attr,
5495a415	261	&dev_attr_offset.attr,
71db049e	262	&dev_attr_range.attr,
3ee2c40b DT	263	NULL,
3ee2c40b DT	264	};
3925a5ce DB	265
	266	/* The reason to trigger an alarm with no process watching it (via sysfs)
	267	* is its side effect: waking from a system state like suspend-to-RAM or
	268	* suspend-to-disk. So: no attribute unless that side effect is possible.
	269	* (Userspace may disable that mechanism later.)
	270	*/
df100c01	271	static bool rtc_does_wakealarm(struct rtc_device *rtc)
3925a5ce	272	{
cd966209	273	if (!device_can_wakeup(rtc->dev.parent))
df100c01 DT	274	return false;
df100c01 DT	275
4d0185e6	276	return !!test_bit(RTC_FEATURE_ALARM, rtc->features);
3925a5ce DB	277	}
3925a5ce DB	278
3ee2c40b DT	279	static umode_t rtc_attr_is_visible(struct kobject *kobj,
3ee2c40b DT	280	struct attribute *attr, int n)
c5c3e192	281	{
ae243ef0	282	struct device *dev = kobj_to_dev(kobj);
3ee2c40b DT	283	struct rtc_device *rtc = to_rtc_device(dev);
3ee2c40b DT	284	umode_t mode = attr->mode;
c5c3e192	285
5495a415	286	if (attr == &dev_attr_wakealarm.attr) {
3ee2c40b DT	287	if (!rtc_does_wakealarm(rtc))
3ee2c40b DT	288	mode = 0;
5495a415 JC	289	} else if (attr == &dev_attr_offset.attr) {
	290	if (!rtc->ops->set_offset)
	291	mode = 0;
71db049e AB	292	} else if (attr == &dev_attr_range.attr) {
	293	if (!(rtc->range_max - rtc->range_min))
	294	mode = 0;
5495a415	295	}
c5c3e192	296
3ee2c40b	297	return mode;
c5c3e192 AZ	298	}
c5c3e192 AZ	299
3ee2c40b DT	300	static struct attribute_group rtc_attr_group = {
	301	.is_visible = rtc_attr_is_visible,
	302	.attrs = rtc_attrs,
	303	};
	304
	305	static const struct attribute_group *rtc_attr_groups[] = {
	306	&rtc_attr_group,
	307	NULL
	308	};
c5c3e192	309
3ee2c40b	310	const struct attribute_group **rtc_get_dev_attribute_groups(void)
c5c3e192	311	{
3ee2c40b	312	return rtc_attr_groups;
c5c3e192	313	}
a0a1a1ba DO	314
	315	int rtc_add_groups(struct rtc_device rtc, const struct attribute_group *grps)
	316	{
	317	size_t old_cnt = 0, add_cnt = 0, new_cnt;
	318	const struct attribute_group groups, old;
	319
a0a1a1ba DO	320	if (!grps)
	321	return -EINVAL;
	322
	323	groups = rtc->dev.groups;
	324	if (groups)
	325	for (; *groups; groups++)
	326	old_cnt++;
	327
	328	for (groups = grps; *groups; groups++)
	329	add_cnt++;
	330
	331	new_cnt = old_cnt + add_cnt + 1;
	332	groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);
777d8ae5 DC	333	if (!groups)
777d8ae5 DC	334	return -ENOMEM;
a0a1a1ba DO	335	memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));
	336	memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));
	337	groups[old_cnt + add_cnt] = NULL;
	338
	339	old = rtc->dev.groups;
	340	rtc->dev.groups = groups;
	341	if (old && old != rtc_attr_groups)
	342	devm_kfree(&rtc->dev, old);
	343
	344	return 0;
	345	}
	346	EXPORT_SYMBOL(rtc_add_groups);
	347
	348	int rtc_add_group(struct rtc_device rtc, const struct attribute_group grp)
	349	{
	350	const struct attribute_group *groups[] = { grp, NULL };
	351
	352	return rtc_add_groups(rtc, groups);
	353	}
	354	EXPORT_SYMBOL(rtc_add_group);