1/*
2 * RTC subsystem, base class
3 *
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * class skeleton from drivers/hwmon/hwmon.c
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12*/
13
14#include <linux/module.h>
15#include <linux/rtc.h>
16#include <linux/kdev_t.h>
17#include <linux/idr.h>
18
19#include "rtc-core.h"
20
21
22static DEFINE_IDR(rtc_idr);
23static DEFINE_MUTEX(idr_lock);
24struct class *rtc_class;
25
26static void rtc_device_release(struct device *dev)
27{
28	struct rtc_device *rtc = to_rtc_device(dev);
29	mutex_lock(&idr_lock);
30	idr_remove(&rtc_idr, rtc->id);
31	mutex_unlock(&idr_lock);
32	kfree(rtc);
33}
34
35#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
36
37/*
38 * On suspend(), measure the delta between one RTC and the
39 * system's wall clock; restore it on resume().
40 */
41
42static struct timespec	delta;
43static time_t		oldtime;
44
45static int rtc_suspend(struct device *dev, pm_message_t mesg)
46{
47	struct rtc_device	*rtc = to_rtc_device(dev);
48	struct rtc_time		tm;
49
50	if (strncmp(rtc->dev.bus_id,
51				CONFIG_RTC_HCTOSYS_DEVICE,
52				BUS_ID_SIZE) != 0)
53		return 0;
54
55	rtc_read_time(rtc, &tm);
56	rtc_tm_to_time(&tm, &oldtime);
57
58	/* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
59	set_normalized_timespec(&delta,
60				xtime.tv_sec - oldtime,
61				xtime.tv_nsec - (NSEC_PER_SEC >> 1));
62
63	return 0;
64}
65
66static int rtc_resume(struct device *dev)
67{
68	struct rtc_device	*rtc = to_rtc_device(dev);
69	struct rtc_time		tm;
70	time_t			newtime;
71	struct timespec		time;
72
73	if (strncmp(rtc->dev.bus_id,
74				CONFIG_RTC_HCTOSYS_DEVICE,
75				BUS_ID_SIZE) != 0)
76		return 0;
77
78	rtc_read_time(rtc, &tm);
79	if (rtc_valid_tm(&tm) != 0) {
80		pr_debug("%s:  bogus resume time\n", rtc->dev.bus_id);
81		return 0;
82	}
83	rtc_tm_to_time(&tm, &newtime);
84	if (newtime <= oldtime) {
85		if (newtime < oldtime)
86			pr_debug("%s:  time travel!\n", rtc->dev.bus_id);
87		return 0;
88	}
89
90	/* restore wall clock using delta against this RTC;
91	 * adjust again for avg 1/2 second RTC sampling error
92	 */
93	set_normalized_timespec(&time,
94				newtime + delta.tv_sec,
95				(NSEC_PER_SEC >> 1) + delta.tv_nsec);
96	do_settimeofday(&time);
97
98	return 0;
99}
100
101#else
102#define rtc_suspend	NULL
103#define rtc_resume	NULL
104#endif
105
106
107/**
108 * rtc_device_register - register w/ RTC class
109 * @dev: the device to register
110 *
111 * rtc_device_unregister() must be called when the class device is no
112 * longer needed.
113 *
114 * Returns the pointer to the new struct class device.
115 */
116struct rtc_device *rtc_device_register(const char *name, struct device *dev,
117					const struct rtc_class_ops *ops,
118					struct module *owner)
119{
120	struct rtc_device *rtc;
121	int id, err;
122
123	if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
124		err = -ENOMEM;
125		goto exit;
126	}
127
128
129	mutex_lock(&idr_lock);
130	err = idr_get_new(&rtc_idr, NULL, &id);
131	mutex_unlock(&idr_lock);
132
133	if (err < 0)
134		goto exit;
135
136	id = id & MAX_ID_MASK;
137
138	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
139	if (rtc == NULL) {
140		err = -ENOMEM;
141		goto exit_idr;
142	}
143
144	rtc->id = id;
145	rtc->ops = ops;
146	rtc->owner = owner;
147	rtc->max_user_freq = 64;
148	rtc->dev.parent = dev;
149	rtc->dev.class = rtc_class;
150	rtc->dev.release = rtc_device_release;
151
152	mutex_init(&rtc->ops_lock);
153	spin_lock_init(&rtc->irq_lock);
154	spin_lock_init(&rtc->irq_task_lock);
155
156	strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
157	snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id);
158
159	rtc_dev_prepare(rtc);
160
161	err = device_register(&rtc->dev);
162	if (err)
163		goto exit_kfree;
164
165	rtc_dev_add_device(rtc);
166	rtc_sysfs_add_device(rtc);
167	rtc_proc_add_device(rtc);
168
169	dev_info(dev, "rtc core: registered %s as %s\n",
170			rtc->name, rtc->dev.bus_id);
171
172	return rtc;
173
174exit_kfree:
175	kfree(rtc);
176
177exit_idr:
178	mutex_lock(&idr_lock);
179	idr_remove(&rtc_idr, id);
180	mutex_unlock(&idr_lock);
181
182exit:
183	dev_err(dev, "rtc core: unable to register %s, err = %d\n",
184			name, err);
185	return ERR_PTR(err);
186}
187EXPORT_SYMBOL_GPL(rtc_device_register);
188
189
190/**
191 * rtc_device_unregister - removes the previously registered RTC class device
192 *
193 * @rtc: the RTC class device to destroy
194 */
195void rtc_device_unregister(struct rtc_device *rtc)
196{
197	if (get_device(&rtc->dev) != NULL) {
198		mutex_lock(&rtc->ops_lock);
199		/* remove innards of this RTC, then disable it, before
200		 * letting any rtc_class_open() users access it again
201		 */
202		rtc_sysfs_del_device(rtc);
203		rtc_dev_del_device(rtc);
204		rtc_proc_del_device(rtc);
205		device_unregister(&rtc->dev);
206		rtc->ops = NULL;
207		mutex_unlock(&rtc->ops_lock);
208		put_device(&rtc->dev);
209	}
210}
211EXPORT_SYMBOL_GPL(rtc_device_unregister);
212
213static int __init rtc_init(void)
214{
215	rtc_class = class_create(THIS_MODULE, "rtc");
216	if (IS_ERR(rtc_class)) {
217		printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
218		return PTR_ERR(rtc_class);
219	}
220	rtc_class->suspend = rtc_suspend;
221	rtc_class->resume = rtc_resume;
222	rtc_dev_init();
223	rtc_sysfs_init(rtc_class);
224	return 0;
225}
226
227static void __exit rtc_exit(void)
228{
229	rtc_dev_exit();
230	class_destroy(rtc_class);
231}
232
233subsys_initcall(rtc_init);
234module_exit(rtc_exit);
235
236MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
237MODULE_DESCRIPTION("RTC class support");
238MODULE_LICENSE("GPL");
239