Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
20static ssize_t
21rtc_sysfs_show_name(struct device *dev, struct device_attribute *attr,
22 char *buf)
23{
24 return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
25}
26
27static ssize_t
28rtc_sysfs_show_date(struct device *dev, struct device_attribute *attr,
29 char *buf)
30{
31 ssize_t retval;
32 struct rtc_time tm;
33
34 retval = rtc_read_time(to_rtc_device(dev), &tm);
35 if (retval == 0) {
36 retval = sprintf(buf, "%04d-%02d-%02d\n",
37 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
38 }
39
40 return retval;
41}
42
43static ssize_t
44rtc_sysfs_show_time(struct device *dev, struct device_attribute *attr,
45 char *buf)
46{
47 ssize_t retval;
48 struct rtc_time tm;
49
50 retval = rtc_read_time(to_rtc_device(dev), &tm);
51 if (retval == 0) {
52 retval = sprintf(buf, "%02d:%02d:%02d\n",
53 tm.tm_hour, tm.tm_min, tm.tm_sec);
54 }
55
56 return retval;
57}
58
59static ssize_t
60rtc_sysfs_show_since_epoch(struct device *dev, struct device_attribute *attr,
61 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 unsigned long time;
69 rtc_tm_to_time(&tm, &time);
70 retval = sprintf(buf, "%lu\n", time);
71 }
72
73 return retval;
74}
75
76static struct device_attribute rtc_attrs[] = {
77 __ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL),
78 __ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL),
79 __ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL),
80 __ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL),
81 { },
82};
83
84static ssize_t
85rtc_sysfs_show_wakealarm(struct device *dev, struct device_attribute *attr,
86 char *buf)
87{
88 ssize_t retval;
89 unsigned long alarm;
90 struct rtc_wkalrm alm;
91
92 /* Don't show disabled alarms; but the RTC could leave the
93 * alarm enabled after it's already triggered. Alarms are
94 * conceptually one-shot, even though some common hardware
95 * (PCs) doesn't actually work that way.
96 *
97 * REVISIT maybe we should require RTC implementations to
98 * disable the RTC alarm after it triggers, for uniformity.
99 */
100 retval = rtc_read_alarm(to_rtc_device(dev), &alm);
101 if (retval == 0 && alm.enabled) {
102 rtc_tm_to_time(&alm.time, &alarm);
103 retval = sprintf(buf, "%lu\n", alarm);
104 }
105
106 return retval;
107}
108
109static ssize_t
110rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
111 const char *buf, size_t n)
112{
113 ssize_t retval;
114 unsigned long now, alarm;
115 struct rtc_wkalrm alm;
116 struct rtc_device *rtc = to_rtc_device(dev);
117
118 /* Only request alarms that trigger in the future. Disable them
119 * by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
120 */
121 retval = rtc_read_time(rtc, &alm.time);
122 if (retval < 0)
123 return retval;
124 rtc_tm_to_time(&alm.time, &now);
125
126 alarm = simple_strtoul(buf, NULL, 0);
127 if (alarm > now) {
128 /* Avoid accidentally clobbering active alarms; we can't
129 * entirely prevent that here, without even the minimal
130 * locking from the /dev/rtcN api.
131 */
132 retval = rtc_read_alarm(rtc, &alm);
133 if (retval < 0)
134 return retval;
135 if (alm.enabled)
136 return -EBUSY;
137
138 alm.enabled = 1;
139 } else {
140 alm.enabled = 0;
141
142 /* Provide a valid future alarm time. Linux isn't EFI,
143 * this time won't be ignored when disabling the alarm.
144 */
145 alarm = now + 300;
146 }
147 rtc_time_to_tm(alarm, &alm.time);
148
149 retval = rtc_set_alarm(rtc, &alm);
150 return (retval < 0) ? retval : n;
151}
152static DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
153 rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
154
155
156/* The reason to trigger an alarm with no process watching it (via sysfs)
157 * is its side effect: waking from a system state like suspend-to-RAM or
158 * suspend-to-disk. So: no attribute unless that side effect is possible.
159 * (Userspace may disable that mechanism later.)
160 */
161static inline int rtc_does_wakealarm(struct rtc_device *rtc)
162{
163 if (!device_can_wakeup(rtc->dev.parent))
164 return 0;
165 return rtc->ops->set_alarm != NULL;
166}
167
168
169void rtc_sysfs_add_device(struct rtc_device *rtc)
170{
171 int err;
172
173 /* not all RTCs support both alarms and wakeup */
174 if (!rtc_does_wakealarm(rtc))
175 return;
176
177 err = device_create_file(&rtc->dev, &dev_attr_wakealarm);
178 if (err)
179 dev_err(rtc->dev.parent, "failed to create "
180 "alarm attribute, %d",
181 err);
182}
183
184void rtc_sysfs_del_device(struct rtc_device *rtc)
185{
186 /* REVISIT did we add it successfully? */
187 if (rtc_does_wakealarm(rtc))
188 device_remove_file(&rtc->dev, &dev_attr_wakealarm);
189}
190
191void __init rtc_sysfs_init(struct class *rtc_class)
192{
193 rtc_class->dev_attrs = rtc_attrs;
194}