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\n", to_rtc_device(dev)->name);
 31}
 32static DEVICE_ATTR_RO(name);
 33
 34static ssize_t
 35date_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}
 48static DEVICE_ATTR_RO(date);
 49
 50static ssize_t
 51time_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}
 64static DEVICE_ATTR_RO(time);
 65
 66static ssize_t
 67since_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}
 81static DEVICE_ATTR_RO(since_epoch);
 82
 83static ssize_t
 84max_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
 89static ssize_t
 90max_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}
103static 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 */
111static ssize_t
112hctosys_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}
123static DEVICE_ATTR_RO(hctosys);
124
125static 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};
134ATTRIBUTE_GROUPS(rtc);
135
136static ssize_t
137rtc_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
161static ssize_t
162rtc_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}
224static 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 */
233static 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
241void 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
255void 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
262void __init rtc_sysfs_init(struct class *rtc_class)
263{
264	rtc_class->dev_groups = rtc_groups;
265}