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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/module.h>
17 #include <linux/rtc.h>
18 #include <linux/kdev_t.h>
19 #include <linux/idr.h>
20 #include <linux/slab.h>
21 #include <linux/workqueue.h>
22
23 #include "rtc-core.h"
24
25
26 static DEFINE_IDA(rtc_ida);
27 struct class *rtc_class;
28
rtc_device_release(struct device * dev)29 static void rtc_device_release(struct device *dev)
30 {
31 struct rtc_device *rtc = to_rtc_device(dev);
32 ida_simple_remove(&rtc_ida, rtc->id);
33 kfree(rtc);
34 }
35
36 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
37 /* Result of the last RTC to system clock attempt. */
38 int rtc_hctosys_ret = -ENODEV;
39 #endif
40
41 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
42 /*
43 * On suspend(), measure the delta between one RTC and the
44 * system's wall clock; restore it on resume().
45 */
46
47 static struct timespec old_rtc, old_system, old_delta;
48
49
rtc_suspend(struct device * dev,pm_message_t mesg)50 static int rtc_suspend(struct device *dev, pm_message_t mesg)
51 {
52 struct rtc_device *rtc = to_rtc_device(dev);
53 struct rtc_time tm;
54 struct timespec delta, delta_delta;
55
56 if (has_persistent_clock())
57 return 0;
58
59 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
60 return 0;
61
62 /* snapshot the current RTC and system time at suspend*/
63 rtc_read_time(rtc, &tm);
64 getnstimeofday(&old_system);
65 rtc_tm_to_time(&tm, &old_rtc.tv_sec);
66
67
68 /*
69 * To avoid drift caused by repeated suspend/resumes,
70 * which each can add ~1 second drift error,
71 * try to compensate so the difference in system time
72 * and rtc time stays close to constant.
73 */
74 delta = timespec_sub(old_system, old_rtc);
75 delta_delta = timespec_sub(delta, old_delta);
76 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
77 /*
78 * if delta_delta is too large, assume time correction
79 * has occured and set old_delta to the current delta.
80 */
81 old_delta = delta;
82 } else {
83 /* Otherwise try to adjust old_system to compensate */
84 old_system = timespec_sub(old_system, delta_delta);
85 }
86
87 return 0;
88 }
89
rtc_resume(struct device * dev)90 static int rtc_resume(struct device *dev)
91 {
92 struct rtc_device *rtc = to_rtc_device(dev);
93 struct rtc_time tm;
94 struct timespec new_system, new_rtc;
95 struct timespec sleep_time;
96
97 if (has_persistent_clock())
98 return 0;
99
100 rtc_hctosys_ret = -ENODEV;
101 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
102 return 0;
103
104 /* snapshot the current rtc and system time at resume */
105 getnstimeofday(&new_system);
106 rtc_read_time(rtc, &tm);
107 if (rtc_valid_tm(&tm) != 0) {
108 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev));
109 return 0;
110 }
111 rtc_tm_to_time(&tm, &new_rtc.tv_sec);
112 new_rtc.tv_nsec = 0;
113
114 if (new_rtc.tv_sec < old_rtc.tv_sec) {
115 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
116 return 0;
117 }
118
119 /* calculate the RTC time delta (sleep time)*/
120 sleep_time = timespec_sub(new_rtc, old_rtc);
121
122 /*
123 * Since these RTC suspend/resume handlers are not called
124 * at the very end of suspend or the start of resume,
125 * some run-time may pass on either sides of the sleep time
126 * so subtract kernel run-time between rtc_suspend to rtc_resume
127 * to keep things accurate.
128 */
129 sleep_time = timespec_sub(sleep_time,
130 timespec_sub(new_system, old_system));
131
132 if (sleep_time.tv_sec >= 0)
133 timekeeping_inject_sleeptime(&sleep_time);
134 rtc_hctosys_ret = 0;
135 return 0;
136 }
137
138 #else
139 #define rtc_suspend NULL
140 #define rtc_resume NULL
141 #endif
142
143
144 /**
145 * rtc_device_register - register w/ RTC class
146 * @dev: the device to register
147 *
148 * rtc_device_unregister() must be called when the class device is no
149 * longer needed.
150 *
151 * Returns the pointer to the new struct class device.
152 */
rtc_device_register(const char * name,struct device * dev,const struct rtc_class_ops * ops,struct module * owner)153 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
154 const struct rtc_class_ops *ops,
155 struct module *owner)
156 {
157 struct rtc_device *rtc;
158 struct rtc_wkalrm alrm;
159 int id, err;
160
161 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
162 if (id < 0) {
163 err = id;
164 goto exit;
165 }
166
167 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
168 if (rtc == NULL) {
169 err = -ENOMEM;
170 goto exit_ida;
171 }
172
173 rtc->id = id;
174 rtc->ops = ops;
175 rtc->owner = owner;
176 rtc->irq_freq = 1;
177 rtc->max_user_freq = 64;
178 rtc->dev.parent = dev;
179 rtc->dev.class = rtc_class;
180 rtc->dev.release = rtc_device_release;
181
182 mutex_init(&rtc->ops_lock);
183 spin_lock_init(&rtc->irq_lock);
184 spin_lock_init(&rtc->irq_task_lock);
185 init_waitqueue_head(&rtc->irq_queue);
186
187 /* Init timerqueue */
188 timerqueue_init_head(&rtc->timerqueue);
189 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
190 /* Init aie timer */
191 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
192 /* Init uie timer */
193 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
194 /* Init pie timer */
195 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
196 rtc->pie_timer.function = rtc_pie_update_irq;
197 rtc->pie_enabled = 0;
198
199 /* Check to see if there is an ALARM already set in hw */
200 err = __rtc_read_alarm(rtc, &alrm);
201
202 if (!err && !rtc_valid_tm(&alrm.time))
203 rtc_initialize_alarm(rtc, &alrm);
204
205 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
206 dev_set_name(&rtc->dev, "rtc%d", id);
207
208 rtc_dev_prepare(rtc);
209
210 err = device_register(&rtc->dev);
211 if (err) {
212 put_device(&rtc->dev);
213 goto exit_kfree;
214 }
215
216 rtc_dev_add_device(rtc);
217 rtc_sysfs_add_device(rtc);
218 rtc_proc_add_device(rtc);
219
220 dev_info(dev, "rtc core: registered %s as %s\n",
221 rtc->name, dev_name(&rtc->dev));
222
223 return rtc;
224
225 exit_kfree:
226 kfree(rtc);
227
228 exit_ida:
229 ida_simple_remove(&rtc_ida, id);
230
231 exit:
232 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
233 name, err);
234 return ERR_PTR(err);
235 }
236 EXPORT_SYMBOL_GPL(rtc_device_register);
237
238
239 /**
240 * rtc_device_unregister - removes the previously registered RTC class device
241 *
242 * @rtc: the RTC class device to destroy
243 */
rtc_device_unregister(struct rtc_device * rtc)244 void rtc_device_unregister(struct rtc_device *rtc)
245 {
246 if (get_device(&rtc->dev) != NULL) {
247 mutex_lock(&rtc->ops_lock);
248 /* remove innards of this RTC, then disable it, before
249 * letting any rtc_class_open() users access it again
250 */
251 rtc_sysfs_del_device(rtc);
252 rtc_dev_del_device(rtc);
253 rtc_proc_del_device(rtc);
254 device_unregister(&rtc->dev);
255 rtc->ops = NULL;
256 mutex_unlock(&rtc->ops_lock);
257 put_device(&rtc->dev);
258 }
259 }
260 EXPORT_SYMBOL_GPL(rtc_device_unregister);
261
devm_rtc_device_release(struct device * dev,void * res)262 static void devm_rtc_device_release(struct device *dev, void *res)
263 {
264 struct rtc_device *rtc = *(struct rtc_device **)res;
265
266 rtc_device_unregister(rtc);
267 }
268
devm_rtc_device_match(struct device * dev,void * res,void * data)269 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
270 {
271 struct rtc **r = res;
272
273 return *r == data;
274 }
275
276 /**
277 * devm_rtc_device_register - resource managed rtc_device_register()
278 * @dev: the device to register
279 * @name: the name of the device
280 * @ops: the rtc operations structure
281 * @owner: the module owner
282 *
283 * @return a struct rtc on success, or an ERR_PTR on error
284 *
285 * Managed rtc_device_register(). The rtc_device returned from this function
286 * are automatically freed on driver detach. See rtc_device_register()
287 * for more information.
288 */
289
devm_rtc_device_register(struct device * dev,const char * name,const struct rtc_class_ops * ops,struct module * owner)290 struct rtc_device *devm_rtc_device_register(struct device *dev,
291 const char *name,
292 const struct rtc_class_ops *ops,
293 struct module *owner)
294 {
295 struct rtc_device **ptr, *rtc;
296
297 ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
298 if (!ptr)
299 return ERR_PTR(-ENOMEM);
300
301 rtc = rtc_device_register(name, dev, ops, owner);
302 if (!IS_ERR(rtc)) {
303 *ptr = rtc;
304 devres_add(dev, ptr);
305 } else {
306 devres_free(ptr);
307 }
308
309 return rtc;
310 }
311 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
312
313 /**
314 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
315 * @dev: the device to unregister
316 * @rtc: the RTC class device to unregister
317 *
318 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
319 * function will not need to be called and the resource management code will
320 * ensure that the resource is freed.
321 */
devm_rtc_device_unregister(struct device * dev,struct rtc_device * rtc)322 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
323 {
324 int rc;
325
326 rc = devres_release(dev, devm_rtc_device_release,
327 devm_rtc_device_match, rtc);
328 WARN_ON(rc);
329 }
330 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
331
rtc_init(void)332 static int __init rtc_init(void)
333 {
334 rtc_class = class_create(THIS_MODULE, "rtc");
335 if (IS_ERR(rtc_class)) {
336 pr_err("couldn't create class\n");
337 return PTR_ERR(rtc_class);
338 }
339 rtc_class->suspend = rtc_suspend;
340 rtc_class->resume = rtc_resume;
341 rtc_dev_init();
342 rtc_sysfs_init(rtc_class);
343 return 0;
344 }
345
rtc_exit(void)346 static void __exit rtc_exit(void)
347 {
348 rtc_dev_exit();
349 class_destroy(rtc_class);
350 ida_destroy(&rtc_ida);
351 }
352
353 subsys_initcall(rtc_init);
354 module_exit(rtc_exit);
355
356 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
357 MODULE_DESCRIPTION("RTC class support");
358 MODULE_LICENSE("GPL");
359