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 #include <linux/slab.h>
19 #include <linux/workqueue.h>
20
21 #include "rtc-core.h"
22
23
24 static DEFINE_IDA(rtc_ida);
25 struct class *rtc_class;
26
rtc_device_release(struct device * dev)27 static void rtc_device_release(struct device *dev)
28 {
29 struct rtc_device *rtc = to_rtc_device(dev);
30 ida_simple_remove(&rtc_ida, rtc->id);
31 kfree(rtc);
32 }
33
34 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
35
36 /*
37 * On suspend(), measure the delta between one RTC and the
38 * system's wall clock; restore it on resume().
39 */
40
41 static struct timespec old_rtc, old_system, old_delta;
42
43
rtc_suspend(struct device * dev,pm_message_t mesg)44 static int rtc_suspend(struct device *dev, pm_message_t mesg)
45 {
46 struct rtc_device *rtc = to_rtc_device(dev);
47 struct rtc_time tm;
48 struct timespec delta, delta_delta;
49 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
50 return 0;
51
52 /* snapshot the current RTC and system time at suspend*/
53 rtc_read_time(rtc, &tm);
54 getnstimeofday(&old_system);
55 rtc_tm_to_time(&tm, &old_rtc.tv_sec);
56
57
58 /*
59 * To avoid drift caused by repeated suspend/resumes,
60 * which each can add ~1 second drift error,
61 * try to compensate so the difference in system time
62 * and rtc time stays close to constant.
63 */
64 delta = timespec_sub(old_system, old_rtc);
65 delta_delta = timespec_sub(delta, old_delta);
66 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
67 /*
68 * if delta_delta is too large, assume time correction
69 * has occured and set old_delta to the current delta.
70 */
71 old_delta = delta;
72 } else {
73 /* Otherwise try to adjust old_system to compensate */
74 old_system = timespec_sub(old_system, delta_delta);
75 }
76
77 return 0;
78 }
79
rtc_resume(struct device * dev)80 static int rtc_resume(struct device *dev)
81 {
82 struct rtc_device *rtc = to_rtc_device(dev);
83 struct rtc_time tm;
84 struct timespec new_system, new_rtc;
85 struct timespec sleep_time;
86
87 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
88 return 0;
89
90 /* snapshot the current rtc and system time at resume */
91 getnstimeofday(&new_system);
92 rtc_read_time(rtc, &tm);
93 if (rtc_valid_tm(&tm) != 0) {
94 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev));
95 return 0;
96 }
97 rtc_tm_to_time(&tm, &new_rtc.tv_sec);
98 new_rtc.tv_nsec = 0;
99
100 if (new_rtc.tv_sec < old_rtc.tv_sec) {
101 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
102 return 0;
103 }
104
105 /* calculate the RTC time delta (sleep time)*/
106 sleep_time = timespec_sub(new_rtc, old_rtc);
107
108 /*
109 * Since these RTC suspend/resume handlers are not called
110 * at the very end of suspend or the start of resume,
111 * some run-time may pass on either sides of the sleep time
112 * so subtract kernel run-time between rtc_suspend to rtc_resume
113 * to keep things accurate.
114 */
115 sleep_time = timespec_sub(sleep_time,
116 timespec_sub(new_system, old_system));
117
118 if (sleep_time.tv_sec >= 0)
119 timekeeping_inject_sleeptime(&sleep_time);
120 return 0;
121 }
122
123 #else
124 #define rtc_suspend NULL
125 #define rtc_resume NULL
126 #endif
127
128
129 /**
130 * rtc_device_register - register w/ RTC class
131 * @dev: the device to register
132 *
133 * rtc_device_unregister() must be called when the class device is no
134 * longer needed.
135 *
136 * Returns the pointer to the new struct class device.
137 */
rtc_device_register(const char * name,struct device * dev,const struct rtc_class_ops * ops,struct module * owner)138 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
139 const struct rtc_class_ops *ops,
140 struct module *owner)
141 {
142 struct rtc_device *rtc;
143 struct rtc_wkalrm alrm;
144 int id, err;
145
146 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
147 if (id < 0) {
148 err = id;
149 goto exit;
150 }
151
152 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
153 if (rtc == NULL) {
154 err = -ENOMEM;
155 goto exit_ida;
156 }
157
158 rtc->id = id;
159 rtc->ops = ops;
160 rtc->owner = owner;
161 rtc->irq_freq = 1;
162 rtc->max_user_freq = 64;
163 rtc->dev.parent = dev;
164 rtc->dev.class = rtc_class;
165 rtc->dev.release = rtc_device_release;
166
167 mutex_init(&rtc->ops_lock);
168 spin_lock_init(&rtc->irq_lock);
169 spin_lock_init(&rtc->irq_task_lock);
170 init_waitqueue_head(&rtc->irq_queue);
171
172 /* Init timerqueue */
173 timerqueue_init_head(&rtc->timerqueue);
174 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
175 /* Init aie timer */
176 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
177 /* Init uie timer */
178 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
179 /* Init pie timer */
180 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
181 rtc->pie_timer.function = rtc_pie_update_irq;
182 rtc->pie_enabled = 0;
183
184 /* Check to see if there is an ALARM already set in hw */
185 err = __rtc_read_alarm(rtc, &alrm);
186
187 if (!err && !rtc_valid_tm(&alrm.time))
188 rtc_initialize_alarm(rtc, &alrm);
189
190 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
191 dev_set_name(&rtc->dev, "rtc%d", id);
192
193 rtc_dev_prepare(rtc);
194
195 err = device_register(&rtc->dev);
196 if (err) {
197 put_device(&rtc->dev);
198 goto exit_kfree;
199 }
200
201 rtc_dev_add_device(rtc);
202 rtc_sysfs_add_device(rtc);
203 rtc_proc_add_device(rtc);
204
205 dev_info(dev, "rtc core: registered %s as %s\n",
206 rtc->name, dev_name(&rtc->dev));
207
208 return rtc;
209
210 exit_kfree:
211 kfree(rtc);
212
213 exit_ida:
214 ida_simple_remove(&rtc_ida, id);
215
216 exit:
217 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
218 name, err);
219 return ERR_PTR(err);
220 }
221 EXPORT_SYMBOL_GPL(rtc_device_register);
222
223
224 /**
225 * rtc_device_unregister - removes the previously registered RTC class device
226 *
227 * @rtc: the RTC class device to destroy
228 */
rtc_device_unregister(struct rtc_device * rtc)229 void rtc_device_unregister(struct rtc_device *rtc)
230 {
231 if (get_device(&rtc->dev) != NULL) {
232 mutex_lock(&rtc->ops_lock);
233 /* remove innards of this RTC, then disable it, before
234 * letting any rtc_class_open() users access it again
235 */
236 rtc_sysfs_del_device(rtc);
237 rtc_dev_del_device(rtc);
238 rtc_proc_del_device(rtc);
239 device_unregister(&rtc->dev);
240 rtc->ops = NULL;
241 mutex_unlock(&rtc->ops_lock);
242 put_device(&rtc->dev);
243 }
244 }
245 EXPORT_SYMBOL_GPL(rtc_device_unregister);
246
rtc_init(void)247 static int __init rtc_init(void)
248 {
249 rtc_class = class_create(THIS_MODULE, "rtc");
250 if (IS_ERR(rtc_class)) {
251 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
252 return PTR_ERR(rtc_class);
253 }
254 rtc_class->suspend = rtc_suspend;
255 rtc_class->resume = rtc_resume;
256 rtc_dev_init();
257 rtc_sysfs_init(rtc_class);
258 return 0;
259 }
260
rtc_exit(void)261 static void __exit rtc_exit(void)
262 {
263 rtc_dev_exit();
264 class_destroy(rtc_class);
265 ida_destroy(&rtc_ida);
266 }
267
268 subsys_initcall(rtc_init);
269 module_exit(rtc_exit);
270
271 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
272 MODULE_DESCRIPTION("RTC class support");
273 MODULE_LICENSE("GPL");
274