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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