1 /*
2 * RTC subsystem, sysfs interface
3 *
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/module.h>
13 #include <linux/rtc.h>
14
15 #include "rtc-core.h"
16
17
18 /* device attributes */
19
20 /*
21 * NOTE: RTC times displayed in sysfs use the RTC's timezone. That's
22 * ideally UTC. However, PCs that also boot to MS-Windows normally use
23 * the local time and change to match daylight savings time. That affects
24 * attributes including date, time, since_epoch, and wakealarm.
25 */
26
27 static ssize_t
name_show(struct device * dev,struct device_attribute * attr,char * buf)28 name_show(struct device *dev, struct device_attribute *attr, char *buf)
29 {
30 return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
31 }
32 static DEVICE_ATTR_RO(name);
33
34 static ssize_t
date_show(struct device * dev,struct device_attribute * attr,char * buf)35 date_show(struct device *dev, struct device_attribute *attr, char *buf)
36 {
37 ssize_t retval;
38 struct rtc_time tm;
39
40 retval = rtc_read_time(to_rtc_device(dev), &tm);
41 if (retval == 0) {
42 retval = sprintf(buf, "%04d-%02d-%02d\n",
43 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
44 }
45
46 return retval;
47 }
48 static DEVICE_ATTR_RO(date);
49
50 static ssize_t
time_show(struct device * dev,struct device_attribute * attr,char * buf)51 time_show(struct device *dev, struct device_attribute *attr, char *buf)
52 {
53 ssize_t retval;
54 struct rtc_time tm;
55
56 retval = rtc_read_time(to_rtc_device(dev), &tm);
57 if (retval == 0) {
58 retval = sprintf(buf, "%02d:%02d:%02d\n",
59 tm.tm_hour, tm.tm_min, tm.tm_sec);
60 }
61
62 return retval;
63 }
64 static DEVICE_ATTR_RO(time);
65
66 static ssize_t
since_epoch_show(struct device * dev,struct device_attribute * attr,char * buf)67 since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
68 {
69 ssize_t retval;
70 struct rtc_time tm;
71
72 retval = rtc_read_time(to_rtc_device(dev), &tm);
73 if (retval == 0) {
74 unsigned long time;
75 rtc_tm_to_time(&tm, &time);
76 retval = sprintf(buf, "%lu\n", time);
77 }
78
79 return retval;
80 }
81 static DEVICE_ATTR_RO(since_epoch);
82
83 static ssize_t
max_user_freq_show(struct device * dev,struct device_attribute * attr,char * buf)84 max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
85 {
86 return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
87 }
88
89 static ssize_t
max_user_freq_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)90 max_user_freq_store(struct device *dev, struct device_attribute *attr,
91 const char *buf, size_t n)
92 {
93 struct rtc_device *rtc = to_rtc_device(dev);
94 unsigned long val = simple_strtoul(buf, NULL, 0);
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 * rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
107 *
108 * Returns 1 if the system clock was set by this RTC at the last
109 * boot or resume event.
110 */
111 static ssize_t
hctosys_show(struct device * dev,struct device_attribute * attr,char * buf)112 hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
113 {
114 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
115 if (rtc_hctosys_ret == 0 &&
116 strcmp(dev_name(&to_rtc_device(dev)->dev),
117 CONFIG_RTC_HCTOSYS_DEVICE) == 0)
118 return sprintf(buf, "1\n");
119 else
120 #endif
121 return sprintf(buf, "0\n");
122 }
123 static DEVICE_ATTR_RO(hctosys);
124
125 static struct attribute *rtc_attrs[] = {
126 &dev_attr_name.attr,
127 &dev_attr_date.attr,
128 &dev_attr_time.attr,
129 &dev_attr_since_epoch.attr,
130 &dev_attr_max_user_freq.attr,
131 &dev_attr_hctosys.attr,
132 NULL,
133 };
134 ATTRIBUTE_GROUPS(rtc);
135
136 static ssize_t
rtc_sysfs_show_wakealarm(struct device * dev,struct device_attribute * attr,char * buf)137 rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr,
138 char *buf)
139 {
140 ssize_t retval;
141 unsigned long alarm;
142 struct rtc_wkalrm alm;
143
144 /* Don't show disabled alarms. For uniformity, RTC alarms are
145 * conceptually one-shot, even though some common RTCs (on PCs)
146 * don't actually work that way.
147 *
148 * NOTE: RTC implementations where the alarm doesn't match an
149 * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
150 * alarms after they trigger, to ensure one-shot semantics.
151 */
152 retval = rtc_read_alarm(to_rtc_device(dev), &alm);
153 if (retval == 0 && alm.enabled) {
154 rtc_tm_to_time(&alm.time, &alarm);
155 retval = sprintf(buf, "%lu\n", alarm);
156 }
157
158 return retval;
159 }
160
161 static ssize_t
rtc_sysfs_set_wakealarm(struct device * dev,struct device_attribute * attr,const char * buf,size_t n)162 rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
163 const char *buf, size_t n)
164 {
165 ssize_t retval;
166 unsigned long now, alarm;
167 unsigned long push = 0;
168 struct rtc_wkalrm alm;
169 struct rtc_device *rtc = to_rtc_device(dev);
170 char *buf_ptr;
171 int adjust = 0;
172
173 /* Only request alarms that trigger in the future. Disable them
174 * by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
175 */
176 retval = rtc_read_time(rtc, &alm.time);
177 if (retval < 0)
178 return retval;
179 rtc_tm_to_time(&alm.time, &now);
180
181 buf_ptr = (char *)buf;
182 if (*buf_ptr == '+') {
183 buf_ptr++;
184 if (*buf_ptr == '=') {
185 buf_ptr++;
186 push = 1;
187 } else
188 adjust = 1;
189 }
190 alarm = simple_strtoul(buf_ptr, NULL, 0);
191 if (adjust) {
192 alarm += now;
193 }
194 if (alarm > now || push) {
195 /* Avoid accidentally clobbering active alarms; we can't
196 * entirely prevent that here, without even the minimal
197 * locking from the /dev/rtcN api.
198 */
199 retval = rtc_read_alarm(rtc, &alm);
200 if (retval < 0)
201 return retval;
202 if (alm.enabled) {
203 if (push) {
204 rtc_tm_to_time(&alm.time, &push);
205 alarm += push;
206 } else
207 return -EBUSY;
208 } else if (push)
209 return -EINVAL;
210 alm.enabled = 1;
211 } else {
212 alm.enabled = 0;
213
214 /* Provide a valid future alarm time. Linux isn't EFI,
215 * this time won't be ignored when disabling the alarm.
216 */
217 alarm = now + 300;
218 }
219 rtc_time_to_tm(alarm, &alm.time);
220
221 retval = rtc_set_alarm(rtc, &alm);
222 return (retval < 0) ? retval : n;
223 }
224 static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
225 rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
226
227
228 /* The reason to trigger an alarm with no process watching it (via sysfs)
229 * is its side effect: waking from a system state like suspend-to-RAM or
230 * suspend-to-disk. So: no attribute unless that side effect is possible.
231 * (Userspace may disable that mechanism later.)
232 */
rtc_does_wakealarm(struct rtc_device * rtc)233 static inline int rtc_does_wakealarm(struct rtc_device *rtc)
234 {
235 if (!device_can_wakeup(rtc->dev.parent))
236 return 0;
237 return rtc->ops->set_alarm != NULL;
238 }
239
240
rtc_sysfs_add_device(struct rtc_device * rtc)241 void rtc_sysfs_add_device(struct rtc_device *rtc)
242 {
243 int err;
244
245 /* not all RTCs support both alarms and wakeup */
246 if (!rtc_does_wakealarm(rtc))
247 return;
248
249 err = device_create_file(&rtc->dev, &dev_attr_wakealarm);
250 if (err)
251 dev_err(rtc->dev.parent,
252 "failed to create alarm attribute, %d\n", err);
253 }
254
rtc_sysfs_del_device(struct rtc_device * rtc)255 void rtc_sysfs_del_device(struct rtc_device *rtc)
256 {
257 /* REVISIT did we add it successfully? */
258 if (rtc_does_wakealarm(rtc))
259 device_remove_file(&rtc->dev, &dev_attr_wakealarm);
260 }
261
rtc_sysfs_init(struct class * rtc_class)262 void __init rtc_sysfs_init(struct class *rtc_class)
263 {
264 rtc_class->dev_groups = rtc_groups;
265 }
266