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
 27static ssize_t
 28name_show(struct device *dev, struct device_attribute *attr, char *buf)
 29{
 30	return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),
 31		       dev_name(dev->parent));
 32}
 33static DEVICE_ATTR_RO(name);
 34
 35static ssize_t
 36date_show(struct device *dev, struct device_attribute *attr, char *buf)
 37{
 38	ssize_t retval;
 39	struct rtc_time tm;
 40
 41	retval = rtc_read_time(to_rtc_device(dev), &tm);
 42	if (retval == 0) {
 43		retval = sprintf(buf, "%04d-%02d-%02d\n",
 44			tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 45	}
 46
 47	return retval;
 48}
 49static DEVICE_ATTR_RO(date);
 50
 51static ssize_t
 52time_show(struct device *dev, struct device_attribute *attr, char *buf)
 53{
 54	ssize_t retval;
 55	struct rtc_time tm;
 56
 57	retval = rtc_read_time(to_rtc_device(dev), &tm);
 58	if (retval == 0) {
 59		retval = sprintf(buf, "%02d:%02d:%02d\n",
 60			tm.tm_hour, tm.tm_min, tm.tm_sec);
 61	}
 62
 63	return retval;
 64}
 65static DEVICE_ATTR_RO(time);
 66
 67static ssize_t
 68since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)
 69{
 70	ssize_t retval;
 71	struct rtc_time tm;
 72
 73	retval = rtc_read_time(to_rtc_device(dev), &tm);
 74	if (retval == 0) {
 75		time64_t time;
 76
 77		time = rtc_tm_to_time64(&tm);
 78		retval = sprintf(buf, "%lld\n", time);
 79	}
 80
 81	return retval;
 82}
 83static DEVICE_ATTR_RO(since_epoch);
 84
 85static ssize_t
 86max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)
 87{
 88	return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);
 89}
 90
 91static ssize_t
 92max_user_freq_store(struct device *dev, struct device_attribute *attr,
 93		const char *buf, size_t n)
 94{
 95	struct rtc_device *rtc = to_rtc_device(dev);
 96	unsigned long val;
 97	int err;
 98
 99	err = kstrtoul(buf, 0, &val);
100	if (err)
101		return err;
102
103	if (val >= 4096 || val == 0)
104		return -EINVAL;
105
106	rtc->max_user_freq = (int)val;
107
108	return n;
109}
110static DEVICE_ATTR_RW(max_user_freq);
111
112/**
113 * rtc_sysfs_show_hctosys - indicate if the given RTC set the system time
114 *
115 * Returns 1 if the system clock was set by this RTC at the last
116 * boot or resume event.
117 */
118static ssize_t
119hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)
120{
121#ifdef CONFIG_RTC_HCTOSYS_DEVICE
122	if (rtc_hctosys_ret == 0 &&
123			strcmp(dev_name(&to_rtc_device(dev)->dev),
124				CONFIG_RTC_HCTOSYS_DEVICE) == 0)
125		return sprintf(buf, "1\n");
126	else
127#endif
128		return sprintf(buf, "0\n");
129}
130static DEVICE_ATTR_RO(hctosys);
131
132static ssize_t
133wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)
134{
135	ssize_t retval;
136	time64_t alarm;
137	struct rtc_wkalrm alm;
138
139	/* Don't show disabled alarms.  For uniformity, RTC alarms are
140	 * conceptually one-shot, even though some common RTCs (on PCs)
141	 * don't actually work that way.
142	 *
143	 * NOTE: RTC implementations where the alarm doesn't match an
144	 * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC
145	 * alarms after they trigger, to ensure one-shot semantics.
146	 */
147	retval = rtc_read_alarm(to_rtc_device(dev), &alm);
148	if (retval == 0 && alm.enabled) {
149		alarm = rtc_tm_to_time64(&alm.time);
150		retval = sprintf(buf, "%lld\n", alarm);
151	}
152
153	return retval;
154}
155
156static ssize_t
157wakealarm_store(struct device *dev, struct device_attribute *attr,
158		const char *buf, size_t n)
159{
160	ssize_t retval;
161	time64_t now, alarm;
162	time64_t push = 0;
163	struct rtc_wkalrm alm;
164	struct rtc_device *rtc = to_rtc_device(dev);
165	const char *buf_ptr;
166	int adjust = 0;
167
168	/* Only request alarms that trigger in the future.  Disable them
169	 * by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
170	 */
171	retval = rtc_read_time(rtc, &alm.time);
172	if (retval < 0)
173		return retval;
174	now = rtc_tm_to_time64(&alm.time);
175
176	buf_ptr = buf;
177	if (*buf_ptr == '+') {
178		buf_ptr++;
179		if (*buf_ptr == '=') {
180			buf_ptr++;
181			push = 1;
182		} else
183			adjust = 1;
184	}
185	retval = kstrtos64(buf_ptr, 0, &alarm);
186	if (retval)
187		return retval;
188	if (adjust) {
189		alarm += now;
190	}
191	if (alarm > now || push) {
192		/* Avoid accidentally clobbering active alarms; we can't
193		 * entirely prevent that here, without even the minimal
194		 * locking from the /dev/rtcN api.
195		 */
196		retval = rtc_read_alarm(rtc, &alm);
197		if (retval < 0)
198			return retval;
199		if (alm.enabled) {
200			if (push) {
201				push = rtc_tm_to_time64(&alm.time);
202				alarm += push;
203			} else
204				return -EBUSY;
205		} else if (push)
206			return -EINVAL;
207		alm.enabled = 1;
208	} else {
209		alm.enabled = 0;
210
211		/* Provide a valid future alarm time.  Linux isn't EFI,
212		 * this time won't be ignored when disabling the alarm.
213		 */
214		alarm = now + 300;
215	}
216	rtc_time64_to_tm(alarm, &alm.time);
217
218	retval = rtc_set_alarm(rtc, &alm);
219	return (retval < 0) ? retval : n;
220}
221static DEVICE_ATTR_RW(wakealarm);
222
223static ssize_t
224offset_show(struct device *dev, struct device_attribute *attr, char *buf)
225{
226	ssize_t retval;
227	long offset;
228
229	retval = rtc_read_offset(to_rtc_device(dev), &offset);
230	if (retval == 0)
231		retval = sprintf(buf, "%ld\n", offset);
232
233	return retval;
234}
235
236static ssize_t
237offset_store(struct device *dev, struct device_attribute *attr,
238	     const char *buf, size_t n)
239{
240	ssize_t retval;
241	long offset;
242
243	retval = kstrtol(buf, 10, &offset);
244	if (retval == 0)
245		retval = rtc_set_offset(to_rtc_device(dev), offset);
246
247	return (retval < 0) ? retval : n;
248}
249static DEVICE_ATTR_RW(offset);
250
251static ssize_t
252range_show(struct device *dev, struct device_attribute *attr, char *buf)
253{
254	return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,
255		       to_rtc_device(dev)->range_max);
256}
257static DEVICE_ATTR_RO(range);
258
259static struct attribute *rtc_attrs[] = {
260	&dev_attr_name.attr,
261	&dev_attr_date.attr,
262	&dev_attr_time.attr,
263	&dev_attr_since_epoch.attr,
264	&dev_attr_max_user_freq.attr,
265	&dev_attr_hctosys.attr,
266	&dev_attr_wakealarm.attr,
267	&dev_attr_offset.attr,
268	&dev_attr_range.attr,
269	NULL,
270};
271
272/* The reason to trigger an alarm with no process watching it (via sysfs)
273 * is its side effect:  waking from a system state like suspend-to-RAM or
274 * suspend-to-disk.  So: no attribute unless that side effect is possible.
275 * (Userspace may disable that mechanism later.)
276 */
277static bool rtc_does_wakealarm(struct rtc_device *rtc)
278{
279	if (!device_can_wakeup(rtc->dev.parent))
280		return false;
281
282	return rtc->ops->set_alarm != NULL;
283}
284
285static umode_t rtc_attr_is_visible(struct kobject *kobj,
286				   struct attribute *attr, int n)
287{
288	struct device *dev = container_of(kobj, struct device, kobj);
289	struct rtc_device *rtc = to_rtc_device(dev);
290	umode_t mode = attr->mode;
291
292	if (attr == &dev_attr_wakealarm.attr) {
293		if (!rtc_does_wakealarm(rtc))
294			mode = 0;
295	} else if (attr == &dev_attr_offset.attr) {
296		if (!rtc->ops->set_offset)
297			mode = 0;
298	} else if (attr == &dev_attr_range.attr) {
299		if (!(rtc->range_max - rtc->range_min))
300			mode = 0;
301	}
302
303	return mode;
304}
305
306static struct attribute_group rtc_attr_group = {
307	.is_visible	= rtc_attr_is_visible,
308	.attrs		= rtc_attrs,
309};
310
311static const struct attribute_group *rtc_attr_groups[] = {
312	&rtc_attr_group,
313	NULL
314};
315
316const struct attribute_group **rtc_get_dev_attribute_groups(void)
317{
318	return rtc_attr_groups;
319}