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