[linux-2.6-block.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/kstrtox.h>
#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	8
e59b3c73	9	#include <linux/kstrtox.h>
c5c3e192 AZ	10	#include <linux/module.h>
	11	#include <linux/rtc.h>
	12
ab6a2d70 DB	13	#include "rtc-core.h"
ab6a2d70 DB	14
c5c3e192 AZ	15	/* device attributes */
c5c3e192 AZ	16
8a0bdfd7 DB	17	/*
	18	* NOTE: RTC times displayed in sysfs use the RTC's timezone. That's
	19	* ideally UTC. However, PCs that also boot to MS-Windows normally use
	20	* the local time and change to match daylight savings time. That affects
	21	* attributes including date, time, since_epoch, and wakealarm.
	22	*/
	23
cd966209	24	static ssize_t
f21e6835	25	name_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192	26	{
77a73f3c AB	27	return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),
77a73f3c AB	28	dev_name(dev->parent));
c5c3e192	29	}
f21e6835	30	static DEVICE_ATTR_RO(name);
c5c3e192	31
cd966209	32	static ssize_t
f21e6835	33	date_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192 AZ	34	{
	35	ssize_t retval;
	36	struct rtc_time tm;
	37
ab6a2d70	38	retval = rtc_read_time(to_rtc_device(dev), &tm);
5548cbf7 AS	39	if (retval)
5548cbf7 AS	40	return retval;
c5c3e192	41
5548cbf7	42	return sprintf(buf, "%ptRd\n", &tm);
c5c3e192	43	}
f21e6835	44	static DEVICE_ATTR_RO(date);
c5c3e192	45
cd966209	46	static ssize_t
f21e6835	47	time_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192 AZ	48	{
	49	ssize_t retval;
	50	struct rtc_time tm;
	51
ab6a2d70	52	retval = rtc_read_time(to_rtc_device(dev), &tm);
5548cbf7 AS	53	if (retval)
5548cbf7 AS	54	return retval;
c5c3e192	55
5548cbf7	56	return sprintf(buf, "%ptRt\n", &tm);
c5c3e192	57	}
f21e6835	58	static DEVICE_ATTR_RO(time);
c5c3e192	59
cd966209	60	static ssize_t
f21e6835	61	since_epoch_show(struct device dev, struct device_attribute attr, char *buf)
c5c3e192 AZ	62	{
	63	ssize_t retval;
	64	struct rtc_time tm;
	65
ab6a2d70	66	retval = rtc_read_time(to_rtc_device(dev), &tm);
c5c3e192	67	if (retval == 0) {
9a06da2e BW	68	time64_t time;
	69
	70	time = rtc_tm_to_time64(&tm);
	71	retval = sprintf(buf, "%lld\n", time);
c5c3e192 AZ	72	}
	73
	74	return retval;
	75	}
f21e6835	76	static DEVICE_ATTR_RO(since_epoch);
c5c3e192	77
06c65eb4	78	static ssize_t
f21e6835	79	max_user_freq_show(struct device dev, struct device_attribute attr, char *buf)
06c65eb4 BK	80	{
	81	return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
	82	}
	83
	84	static ssize_t
f21e6835	85	max_user_freq_store(struct device dev, struct device_attribute attr,
606cc43c	86	const char *buf, size_t n)
06c65eb4 BK	87	{
06c65eb4 BK	88	struct rtc_device *rtc = to_rtc_device(dev);
f571287b LC	89	unsigned long val;
	90	int err;
	91
	92	err = kstrtoul(buf, 0, &val);
	93	if (err)
	94	return err;
06c65eb4 BK	95
	96	if (val >= 4096 \|\| val == 0)
	97	return -EINVAL;
	98
	99	rtc->max_user_freq = (int)val;
	100
	101	return n;
	102	}
f21e6835	103	static DEVICE_ATTR_RW(max_user_freq);
06c65eb4	104
4c24e29e	105	/**
a8fdbefd	106	* hctosys_show - indicate if the given RTC set the system time
6f693192 AB	107	* @dev: The device that the attribute belongs to.
	108	* @attr: The attribute being read.
	109	* @buf: The result buffer.
4c24e29e	110	*
6f693192	111	* buf is "1" if the system clock was set by this RTC at the last
4c24e29e DF	112	* boot or resume event.
4c24e29e DF	113	*/
d8c1acb1	114	static ssize_t
f21e6835	115	hctosys_show(struct device dev, struct device_attribute attr, char *buf)
d8c1acb1 MG	116	{
d8c1acb1 MG	117	#ifdef CONFIG_RTC_HCTOSYS_DEVICE
d0ab4a4d	118	if (rtc_hctosys_ret == 0 &&
606cc43c AB	119	strcmp(dev_name(&to_rtc_device(dev)->dev),
606cc43c AB	120	CONFIG_RTC_HCTOSYS_DEVICE) == 0)
d8c1acb1	121	return sprintf(buf, "1\n");
d8c1acb1	122	#endif
606cc43c	123	return sprintf(buf, "0\n");
d8c1acb1	124	}
f21e6835 GKH	125	static DEVICE_ATTR_RO(hctosys);
f21e6835 GKH	126
3925a5ce	127	static ssize_t
a17ccd1c	128	wakealarm_show(struct device dev, struct device_attribute attr, char *buf)
3925a5ce DB	129	{
3925a5ce DB	130	ssize_t retval;
9a06da2e	131	time64_t alarm;
3925a5ce DB	132	struct rtc_wkalrm alm;
3925a5ce DB	133
8a0bdfd7 DB	134	/* Don't show disabled alarms. For uniformity, RTC alarms are
	135	* conceptually one-shot, even though some common RTCs (on PCs)
	136	* don't actually work that way.
3925a5ce	137	*
8a0bdfd7 DB	138	* NOTE: RTC implementations where the alarm doesn't match an
	139	* exact YYYY-MM-DD HH:MM[:SS] date must disable their RTC
	140	* alarms after they trigger, to ensure one-shot semantics.
3925a5ce	141	*/
ab6a2d70	142	retval = rtc_read_alarm(to_rtc_device(dev), &alm);
3925a5ce	143	if (retval == 0 && alm.enabled) {
9a06da2e BW	144	alarm = rtc_tm_to_time64(&alm.time);
9a06da2e BW	145	retval = sprintf(buf, "%lld\n", alarm);
3925a5ce DB	146	}
	147
	148	return retval;
	149	}
	150
	151	static ssize_t
a17ccd1c	152	wakealarm_store(struct device dev, struct device_attribute attr,
cd966209	153	const char *buf, size_t n)
3925a5ce DB	154	{
3925a5ce DB	155	ssize_t retval;
9a06da2e BW	156	time64_t now, alarm;
9a06da2e BW	157	time64_t push = 0;
3925a5ce	158	struct rtc_wkalrm alm;
ab6a2d70	159	struct rtc_device *rtc = to_rtc_device(dev);
84281c2d	160	const char *buf_ptr;
c116bc2a	161	int adjust = 0;
3925a5ce DB	162
	163	/* Only request alarms that trigger in the future. Disable them
	164	* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
	165	*/
ab6a2d70	166	retval = rtc_read_time(rtc, &alm.time);
3925a5ce DB	167	if (retval < 0)
3925a5ce DB	168	return retval;
9a06da2e	169	now = rtc_tm_to_time64(&alm.time);
3925a5ce	170
84281c2d	171	buf_ptr = buf;
c116bc2a ZY	172	if (*buf_ptr == '+') {
c116bc2a ZY	173	buf_ptr++;
1df0a471 BT	174	if (*buf_ptr == '=') {
	175	buf_ptr++;
	176	push = 1;
606cc43c	177	} else {
1df0a471	178	adjust = 1;
606cc43c	179	}
c116bc2a	180	}
9a06da2e	181	retval = kstrtos64(buf_ptr, 0, &alarm);
f571287b LC	182	if (retval)
f571287b LC	183	return retval;
606cc43c	184	if (adjust)
c116bc2a	185	alarm += now;
1df0a471	186	if (alarm > now \|\| push) {
3925a5ce DB	187	/* Avoid accidentally clobbering active alarms; we can't
	188	* entirely prevent that here, without even the minimal
	189	* locking from the /dev/rtcN api.
	190	*/
ab6a2d70	191	retval = rtc_read_alarm(rtc, &alm);
3925a5ce DB	192	if (retval < 0)
3925a5ce DB	193	return retval;
1df0a471 BT	194	if (alm.enabled) {
1df0a471 BT	195	if (push) {
9a06da2e	196	push = rtc_tm_to_time64(&alm.time);
1df0a471 BT	197	alarm += push;
	198	} else
	199	return -EBUSY;
	200	} else if (push)
	201	return -EINVAL;
3925a5ce DB	202	alm.enabled = 1;
	203	} else {
	204	alm.enabled = 0;
	205
	206	/* Provide a valid future alarm time. Linux isn't EFI,
	207	* this time won't be ignored when disabling the alarm.
	208	*/
	209	alarm = now + 300;
	210	}
9a06da2e	211	rtc_time64_to_tm(alarm, &alm.time);
3925a5ce	212
ab6a2d70	213	retval = rtc_set_alarm(rtc, &alm);
3925a5ce DB	214	return (retval < 0) ? retval : n;
3925a5ce DB	215	}
a17ccd1c	216	static DEVICE_ATTR_RW(wakealarm);
3925a5ce	217
5495a415 JC	218	static ssize_t
	219	offset_show(struct device dev, struct device_attribute attr, char *buf)
	220	{
	221	ssize_t retval;
	222	long offset;
	223
	224	retval = rtc_read_offset(to_rtc_device(dev), &offset);
	225	if (retval == 0)
	226	retval = sprintf(buf, "%ld\n", offset);
	227
	228	return retval;
	229	}
	230
	231	static ssize_t
	232	offset_store(struct device dev, struct device_attribute attr,
	233	const char *buf, size_t n)
	234	{
	235	ssize_t retval;
	236	long offset;
	237
	238	retval = kstrtol(buf, 10, &offset);
	239	if (retval == 0)
	240	retval = rtc_set_offset(to_rtc_device(dev), offset);
	241
	242	return (retval < 0) ? retval : n;
	243	}
	244	static DEVICE_ATTR_RW(offset);
	245
71db049e AB	246	static ssize_t
	247	range_show(struct device dev, struct device_attribute attr, char *buf)
	248	{
	249	return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
	250	to_rtc_device(dev)->range_max);
	251	}
	252	static DEVICE_ATTR_RO(range);
	253
3ee2c40b DT	254	static struct attribute *rtc_attrs[] = {
	255	&dev_attr_name.attr,
	256	&dev_attr_date.attr,
	257	&dev_attr_time.attr,
	258	&dev_attr_since_epoch.attr,
	259	&dev_attr_max_user_freq.attr,
	260	&dev_attr_hctosys.attr,
	261	&dev_attr_wakealarm.attr,
5495a415	262	&dev_attr_offset.attr,
71db049e	263	&dev_attr_range.attr,
3ee2c40b DT	264	NULL,
3ee2c40b DT	265	};
3925a5ce DB	266
	267	/* The reason to trigger an alarm with no process watching it (via sysfs)
	268	* is its side effect: waking from a system state like suspend-to-RAM or
	269	* suspend-to-disk. So: no attribute unless that side effect is possible.
	270	* (Userspace may disable that mechanism later.)
	271	*/
df100c01	272	static bool rtc_does_wakealarm(struct rtc_device *rtc)
3925a5ce	273	{
cd966209	274	if (!device_can_wakeup(rtc->dev.parent))
df100c01 DT	275	return false;
df100c01 DT	276
4d0185e6	277	return !!test_bit(RTC_FEATURE_ALARM, rtc->features);
3925a5ce DB	278	}
3925a5ce DB	279
3ee2c40b DT	280	static umode_t rtc_attr_is_visible(struct kobject *kobj,
3ee2c40b DT	281	struct attribute *attr, int n)
c5c3e192	282	{
ae243ef0	283	struct device *dev = kobj_to_dev(kobj);
3ee2c40b DT	284	struct rtc_device *rtc = to_rtc_device(dev);
3ee2c40b DT	285	umode_t mode = attr->mode;
c5c3e192	286
5495a415	287	if (attr == &dev_attr_wakealarm.attr) {
3ee2c40b DT	288	if (!rtc_does_wakealarm(rtc))
3ee2c40b DT	289	mode = 0;
5495a415 JC	290	} else if (attr == &dev_attr_offset.attr) {
	291	if (!rtc->ops->set_offset)
	292	mode = 0;
71db049e AB	293	} else if (attr == &dev_attr_range.attr) {
	294	if (!(rtc->range_max - rtc->range_min))
	295	mode = 0;
5495a415	296	}
c5c3e192	297
3ee2c40b	298	return mode;
c5c3e192 AZ	299	}
c5c3e192 AZ	300
3ee2c40b DT	301	static struct attribute_group rtc_attr_group = {
	302	.is_visible = rtc_attr_is_visible,
	303	.attrs = rtc_attrs,
	304	};
	305
	306	static const struct attribute_group *rtc_attr_groups[] = {
	307	&rtc_attr_group,
	308	NULL
	309	};
c5c3e192	310
3ee2c40b	311	const struct attribute_group **rtc_get_dev_attribute_groups(void)
c5c3e192	312	{
3ee2c40b	313	return rtc_attr_groups;
c5c3e192	314	}
a0a1a1ba DO	315
	316	int rtc_add_groups(struct rtc_device rtc, const struct attribute_group *grps)
	317	{
	318	size_t old_cnt = 0, add_cnt = 0, new_cnt;
	319	const struct attribute_group groups, old;
	320
a0a1a1ba DO	321	if (!grps)
	322	return -EINVAL;
	323
	324	groups = rtc->dev.groups;
	325	if (groups)
	326	for (; *groups; groups++)
	327	old_cnt++;
	328
	329	for (groups = grps; *groups; groups++)
	330	add_cnt++;
	331
	332	new_cnt = old_cnt + add_cnt + 1;
	333	groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);
777d8ae5 DC	334	if (!groups)
777d8ae5 DC	335	return -ENOMEM;
a0a1a1ba DO	336	memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));
	337	memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));
	338	groups[old_cnt + add_cnt] = NULL;
	339
	340	old = rtc->dev.groups;
	341	rtc->dev.groups = groups;
	342	if (old && old != rtc_attr_groups)
	343	devm_kfree(&rtc->dev, old);
	344
	345	return 0;
	346	}
	347	EXPORT_SYMBOL(rtc_add_groups);
	348
	349	int rtc_add_group(struct rtc_device rtc, const struct attribute_group grp)
	350	{
	351	const struct attribute_group *groups[] = { grp, NULL };
	352
	353	return rtc_add_groups(rtc, groups);
	354	}
	355	EXPORT_SYMBOL(rtc_add_group);