xref: /openbmc/linux/drivers/rtc/sysfs.c (revision e59b3c73)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * RTC subsystem, sysfs interface
4  *
5  * Copyright (C) 2005 Tower Technologies
6  * Author: Alessandro Zummo <a.zummo@towertech.it>
7  */
8 
9 #include <linux/kstrtox.h>
10 #include <linux/module.h>
11 #include <linux/rtc.h>
12 
13 #include "rtc-core.h"
14 
15 /* device attributes */
16 
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 
24 static ssize_t
name_show(struct device * dev,struct device_attribute * attr,char * buf)25 name_show(struct device *dev, struct device_attribute *attr, char *buf)
26 {
27 	return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),
28 		       dev_name(dev->parent));
29 }
30 static DEVICE_ATTR_RO(name);
31 
32 static ssize_t
date_show(struct device * dev,struct device_attribute * attr,char * buf)33 date_show(struct device *dev, struct device_attribute *attr, char *buf)
34 {
35 	ssize_t retval;
36 	struct rtc_time tm;
37 
38 	retval = rtc_read_time(to_rtc_device(dev), &tm);
39 	if (retval)
40 		return retval;
41 
42 	return sprintf(buf, "%ptRd\n", &tm);
43 }
44 static DEVICE_ATTR_RO(date);
45 
46 static ssize_t
time_show(struct device * dev,struct device_attribute * attr,char * buf)47 time_show(struct device *dev, struct device_attribute *attr, char *buf)
48 {
49 	ssize_t retval;
50 	struct rtc_time tm;
51 
52 	retval = rtc_read_time(to_rtc_device(dev), &tm);
53 	if (retval)
54 		return retval;
55 
56 	return sprintf(buf, "%ptRt\n", &tm);
57 }
58 static DEVICE_ATTR_RO(time);
59 
60 static ssize_t
since_epoch_show(struct device * dev,struct device_attribute * attr,char * buf)61 since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
62 {
63 	ssize_t retval;
64 	struct rtc_time tm;
65 
66 	retval = rtc_read_time(to_rtc_device(dev), &tm);
67 	if (retval == 0) {
68 		time64_t time;
69 
70 		time = rtc_tm_to_time64(&tm);
71 		retval = sprintf(buf, "%lld\n", time);
72 	}
73 
74 	return retval;
75 }
76 static DEVICE_ATTR_RO(since_epoch);
77 
78 static ssize_t
max_user_freq_show(struct device * dev,struct device_attribute * attr,char * buf)79 max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
80 {
81 	return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
82 }
83 
84 static ssize_t
max_user_freq_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)85 max_user_freq_store(struct device *dev, struct device_attribute *attr,
86 		    const char *buf, size_t n)
87 {
88 	struct rtc_device *rtc = to_rtc_device(dev);
89 	unsigned long val;
90 	int err;
91 
92 	err = kstrtoul(buf, 0, &val);
93 	if (err)
94 		return err;
95 
96 	if (val >= 4096 || val == 0)
97 		return -EINVAL;
98 
99 	rtc->max_user_freq = (int)val;
100 
101 	return n;
102 }
103 static DEVICE_ATTR_RW(max_user_freq);
104 
105 /**
106  * hctosys_show - indicate if the given RTC set the system time
107  * @dev: The device that the attribute belongs to.
108  * @attr: The attribute being read.
109  * @buf: The result buffer.
110  *
111  * buf is "1" if the system clock was set by this RTC at the last
112  * boot or resume event.
113  */
114 static ssize_t
hctosys_show(struct device * dev,struct device_attribute * attr,char * buf)115 hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
116 {
117 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
118 	if (rtc_hctosys_ret == 0 &&
119 	    strcmp(dev_name(&to_rtc_device(dev)->dev),
120 		   CONFIG_RTC_HCTOSYS_DEVICE) == 0)
121 		return sprintf(buf, "1\n");
122 #endif
123 	return sprintf(buf, "0\n");
124 }
125 static DEVICE_ATTR_RO(hctosys);
126 
127 static ssize_t
wakealarm_show(struct device * dev,struct device_attribute * attr,char * buf)128 wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)
129 {
130 	ssize_t retval;
131 	time64_t alarm;
132 	struct rtc_wkalrm alm;
133 
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.
137 	 *
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.
141 	 */
142 	retval = rtc_read_alarm(to_rtc_device(dev), &alm);
143 	if (retval == 0 && alm.enabled) {
144 		alarm = rtc_tm_to_time64(&alm.time);
145 		retval = sprintf(buf, "%lld\n", alarm);
146 	}
147 
148 	return retval;
149 }
150 
151 static ssize_t
wakealarm_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)152 wakealarm_store(struct device *dev, struct device_attribute *attr,
153 		const char *buf, size_t n)
154 {
155 	ssize_t retval;
156 	time64_t now, alarm;
157 	time64_t push = 0;
158 	struct rtc_wkalrm alm;
159 	struct rtc_device *rtc = to_rtc_device(dev);
160 	const char *buf_ptr;
161 	int adjust = 0;
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 	 */
166 	retval = rtc_read_time(rtc, &alm.time);
167 	if (retval < 0)
168 		return retval;
169 	now = rtc_tm_to_time64(&alm.time);
170 
171 	buf_ptr = buf;
172 	if (*buf_ptr == '+') {
173 		buf_ptr++;
174 		if (*buf_ptr == '=') {
175 			buf_ptr++;
176 			push = 1;
177 		} else {
178 			adjust = 1;
179 		}
180 	}
181 	retval = kstrtos64(buf_ptr, 0, &alarm);
182 	if (retval)
183 		return retval;
184 	if (adjust)
185 		alarm += now;
186 	if (alarm > now || push) {
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 		 */
191 		retval = rtc_read_alarm(rtc, &alm);
192 		if (retval < 0)
193 			return retval;
194 		if (alm.enabled) {
195 			if (push) {
196 				push = rtc_tm_to_time64(&alm.time);
197 				alarm += push;
198 			} else
199 				return -EBUSY;
200 		} else if (push)
201 			return -EINVAL;
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 	}
211 	rtc_time64_to_tm(alarm, &alm.time);
212 
213 	retval = rtc_set_alarm(rtc, &alm);
214 	return (retval < 0) ? retval : n;
215 }
216 static DEVICE_ATTR_RW(wakealarm);
217 
218 static ssize_t
offset_show(struct device * dev,struct device_attribute * attr,char * buf)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
offset_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)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 
246 static ssize_t
range_show(struct device * dev,struct device_attribute * attr,char * buf)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 
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,
262 	&dev_attr_offset.attr,
263 	&dev_attr_range.attr,
264 	NULL,
265 };
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  */
rtc_does_wakealarm(struct rtc_device * rtc)272 static bool rtc_does_wakealarm(struct rtc_device *rtc)
273 {
274 	if (!device_can_wakeup(rtc->dev.parent))
275 		return false;
276 
277 	return !!test_bit(RTC_FEATURE_ALARM, rtc->features);
278 }
279 
rtc_attr_is_visible(struct kobject * kobj,struct attribute * attr,int n)280 static umode_t rtc_attr_is_visible(struct kobject *kobj,
281 				   struct attribute *attr, int n)
282 {
283 	struct device *dev = kobj_to_dev(kobj);
284 	struct rtc_device *rtc = to_rtc_device(dev);
285 	umode_t mode = attr->mode;
286 
287 	if (attr == &dev_attr_wakealarm.attr) {
288 		if (!rtc_does_wakealarm(rtc))
289 			mode = 0;
290 	} else if (attr == &dev_attr_offset.attr) {
291 		if (!rtc->ops->set_offset)
292 			mode = 0;
293 	} else if (attr == &dev_attr_range.attr) {
294 		if (!(rtc->range_max - rtc->range_min))
295 			mode = 0;
296 	}
297 
298 	return mode;
299 }
300 
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 };
310 
rtc_get_dev_attribute_groups(void)311 const struct attribute_group **rtc_get_dev_attribute_groups(void)
312 {
313 	return rtc_attr_groups;
314 }
315 
rtc_add_groups(struct rtc_device * rtc,const struct attribute_group ** grps)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 
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);
334 	if (!groups)
335 		return -ENOMEM;
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 
rtc_add_group(struct rtc_device * rtc,const struct attribute_group * grp)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);
356