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
22 static DEFINE_IDR(rtc_idr);
23 static DEFINE_MUTEX(idr_lock);
24 struct class *rtc_class;
25
26 static 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
42 static struct timespec delta;
43 static time_t oldtime;
44
45 static 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 struct timespec ts = current_kernel_time();
50
51 if (strncmp(rtc->dev.bus_id,
52 CONFIG_RTC_HCTOSYS_DEVICE,
53 BUS_ID_SIZE) != 0)
54 return 0;
55
56 rtc_read_time(rtc, &tm);
57 rtc_tm_to_time(&tm, &oldtime);
58
59 /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
60 set_normalized_timespec(&delta,
61 ts.tv_sec - oldtime,
62 ts.tv_nsec - (NSEC_PER_SEC >> 1));
63
64 return 0;
65 }
66
67 static int rtc_resume(struct device *dev)
68 {
69 struct rtc_device *rtc = to_rtc_device(dev);
70 struct rtc_time tm;
71 time_t newtime;
72 struct timespec time;
73
74 if (strncmp(rtc->dev.bus_id,
75 CONFIG_RTC_HCTOSYS_DEVICE,
76 BUS_ID_SIZE) != 0)
77 return 0;
78
79 rtc_read_time(rtc, &tm);
80 if (rtc_valid_tm(&tm) != 0) {
81 pr_debug("%s: bogus resume time\n", rtc->dev.bus_id);
82 return 0;
83 }
84 rtc_tm_to_time(&tm, &newtime);
85 if (newtime <= oldtime) {
86 if (newtime < oldtime)
87 pr_debug("%s: time travel!\n", rtc->dev.bus_id);
88 return 0;
89 }
90
91 /* restore wall clock using delta against this RTC;
92 * adjust again for avg 1/2 second RTC sampling error
93 */
94 set_normalized_timespec(&time,
95 newtime + delta.tv_sec,
96 (NSEC_PER_SEC >> 1) + delta.tv_nsec);
97 do_settimeofday(&time);
98
99 return 0;
100 }
101
102 #else
103 #define rtc_suspend NULL
104 #define rtc_resume NULL
105 #endif
106
107
108 /**
109 * rtc_device_register - register w/ RTC class
110 * @dev: the device to register
111 *
112 * rtc_device_unregister() must be called when the class device is no
113 * longer needed.
114 *
115 * Returns the pointer to the new struct class device.
116 */
117 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
118 const struct rtc_class_ops *ops,
119 struct module *owner)
120 {
121 struct rtc_device *rtc;
122 int id, err;
123
124 if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
125 err = -ENOMEM;
126 goto exit;
127 }
128
129
130 mutex_lock(&idr_lock);
131 err = idr_get_new(&rtc_idr, NULL, &id);
132 mutex_unlock(&idr_lock);
133
134 if (err < 0)
135 goto exit;
136
137 id = id & MAX_ID_MASK;
138
139 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
140 if (rtc == NULL) {
141 err = -ENOMEM;
142 goto exit_idr;
143 }
144
145 rtc->id = id;
146 rtc->ops = ops;
147 rtc->owner = owner;
148 rtc->max_user_freq = 64;
149 rtc->dev.parent = dev;
150 rtc->dev.class = rtc_class;
151 rtc->dev.release = rtc_device_release;
152
153 mutex_init(&rtc->ops_lock);
154 spin_lock_init(&rtc->irq_lock);
155 spin_lock_init(&rtc->irq_task_lock);
156 init_waitqueue_head(&rtc->irq_queue);
157
158 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
159 snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id);
160
161 rtc_dev_prepare(rtc);
162
163 err = device_register(&rtc->dev);
164 if (err)
165 goto exit_kfree;
166
167 rtc_dev_add_device(rtc);
168 rtc_sysfs_add_device(rtc);
169 rtc_proc_add_device(rtc);
170
171 dev_info(dev, "rtc core: registered %s as %s\n",
172 rtc->name, rtc->dev.bus_id);
173
174 return rtc;
175
176 exit_kfree:
177 kfree(rtc);
178
179 exit_idr:
180 mutex_lock(&idr_lock);
181 idr_remove(&rtc_idr, id);
182 mutex_unlock(&idr_lock);
183
184 exit:
185 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
186 name, err);
187 return ERR_PTR(err);
188 }
189 EXPORT_SYMBOL_GPL(rtc_device_register);
190
191
192 /**
193 * rtc_device_unregister - removes the previously registered RTC class device
194 *
195 * @rtc: the RTC class device to destroy
196 */
197 void rtc_device_unregister(struct rtc_device *rtc)
198 {
199 if (get_device(&rtc->dev) != NULL) {
200 mutex_lock(&rtc->ops_lock);
201 /* remove innards of this RTC, then disable it, before
202 * letting any rtc_class_open() users access it again
203 */
204 rtc_sysfs_del_device(rtc);
205 rtc_dev_del_device(rtc);
206 rtc_proc_del_device(rtc);
207 device_unregister(&rtc->dev);
208 rtc->ops = NULL;
209 mutex_unlock(&rtc->ops_lock);
210 put_device(&rtc->dev);
211 }
212 }
213 EXPORT_SYMBOL_GPL(rtc_device_unregister);
214
215 static int __init rtc_init(void)
216 {
217 rtc_class = class_create(THIS_MODULE, "rtc");
218 if (IS_ERR(rtc_class)) {
219 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
220 return PTR_ERR(rtc_class);
221 }
222 rtc_class->suspend = rtc_suspend;
223 rtc_class->resume = rtc_resume;
224 rtc_dev_init();
225 rtc_sysfs_init(rtc_class);
226 return 0;
227 }
228
229 static void __exit rtc_exit(void)
230 {
231 rtc_dev_exit();
232 class_destroy(rtc_class);
233 }
234
235 subsys_initcall(rtc_init);
236 module_exit(rtc_exit);
237
238 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
239 MODULE_DESCRIPTION("RTC class support");
240 MODULE_LICENSE("GPL");
241
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