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/of.h>
18 #include <linux/rtc.h>
19 #include <linux/kdev_t.h>
20 #include <linux/idr.h>
21 #include <linux/slab.h>
22 #include <linux/workqueue.h>
23 
24 #include "rtc-core.h"
25 
26 
27 static DEFINE_IDA(rtc_ida);
28 struct class *rtc_class;
29 
rtc_device_release(struct device * dev)30 static void rtc_device_release(struct device *dev)
31 {
32 	struct rtc_device *rtc = to_rtc_device(dev);
33 	ida_simple_remove(&rtc_ida, rtc->id);
34 	kfree(rtc);
35 }
36 
37 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
38 /* Result of the last RTC to system clock attempt. */
39 int rtc_hctosys_ret = -ENODEV;
40 #endif
41 
42 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
43 /*
44  * On suspend(), measure the delta between one RTC and the
45  * system's wall clock; restore it on resume().
46  */
47 
48 static struct timespec64 old_rtc, old_system, old_delta;
49 
50 
rtc_suspend(struct device * dev)51 static int rtc_suspend(struct device *dev)
52 {
53 	struct rtc_device	*rtc = to_rtc_device(dev);
54 	struct rtc_time		tm;
55 	struct timespec64	delta, delta_delta;
56 	int err;
57 
58 	if (timekeeping_rtc_skipsuspend())
59 		return 0;
60 
61 	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
62 		return 0;
63 
64 	/* snapshot the current RTC and system time at suspend*/
65 	err = rtc_read_time(rtc, &tm);
66 	if (err < 0) {
67 		pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));
68 		return 0;
69 	}
70 
71 	ktime_get_real_ts64(&old_system);
72 	old_rtc.tv_sec = rtc_tm_to_time64(&tm);
73 
74 
75 	/*
76 	 * To avoid drift caused by repeated suspend/resumes,
77 	 * which each can add ~1 second drift error,
78 	 * try to compensate so the difference in system time
79 	 * and rtc time stays close to constant.
80 	 */
81 	delta = timespec64_sub(old_system, old_rtc);
82 	delta_delta = timespec64_sub(delta, old_delta);
83 	if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
84 		/*
85 		 * if delta_delta is too large, assume time correction
86 		 * has occured and set old_delta to the current delta.
87 		 */
88 		old_delta = delta;
89 	} else {
90 		/* Otherwise try to adjust old_system to compensate */
91 		old_system = timespec64_sub(old_system, delta_delta);
92 	}
93 
94 	return 0;
95 }
96 
rtc_resume(struct device * dev)97 static int rtc_resume(struct device *dev)
98 {
99 	struct rtc_device	*rtc = to_rtc_device(dev);
100 	struct rtc_time		tm;
101 	struct timespec64	new_system, new_rtc;
102 	struct timespec64	sleep_time;
103 	int err;
104 
105 	if (timekeeping_rtc_skipresume())
106 		return 0;
107 
108 	rtc_hctosys_ret = -ENODEV;
109 	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
110 		return 0;
111 
112 	/* snapshot the current rtc and system time at resume */
113 	ktime_get_real_ts64(&new_system);
114 	err = rtc_read_time(rtc, &tm);
115 	if (err < 0) {
116 		pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));
117 		return 0;
118 	}
119 
120 	new_rtc.tv_sec = rtc_tm_to_time64(&tm);
121 	new_rtc.tv_nsec = 0;
122 
123 	if (new_rtc.tv_sec < old_rtc.tv_sec) {
124 		pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
125 		return 0;
126 	}
127 
128 	/* calculate the RTC time delta (sleep time)*/
129 	sleep_time = timespec64_sub(new_rtc, old_rtc);
130 
131 	/*
132 	 * Since these RTC suspend/resume handlers are not called
133 	 * at the very end of suspend or the start of resume,
134 	 * some run-time may pass on either sides of the sleep time
135 	 * so subtract kernel run-time between rtc_suspend to rtc_resume
136 	 * to keep things accurate.
137 	 */
138 	sleep_time = timespec64_sub(sleep_time,
139 			timespec64_sub(new_system, old_system));
140 
141 	if (sleep_time.tv_sec >= 0)
142 		timekeeping_inject_sleeptime64(&sleep_time);
143 	rtc_hctosys_ret = 0;
144 	return 0;
145 }
146 
147 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
148 #define RTC_CLASS_DEV_PM_OPS	(&rtc_class_dev_pm_ops)
149 #else
150 #define RTC_CLASS_DEV_PM_OPS	NULL
151 #endif
152 
153 /* Ensure the caller will set the id before releasing the device */
rtc_allocate_device(void)154 static struct rtc_device *rtc_allocate_device(void)
155 {
156 	struct rtc_device *rtc;
157 
158 	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
159 	if (!rtc)
160 		return NULL;
161 
162 	device_initialize(&rtc->dev);
163 
164 	/* Drivers can revise this default after allocating the device. */
165 	rtc->set_offset_nsec =  NSEC_PER_SEC / 2;
166 
167 	rtc->irq_freq = 1;
168 	rtc->max_user_freq = 64;
169 	rtc->dev.class = rtc_class;
170 	rtc->dev.groups = rtc_get_dev_attribute_groups();
171 	rtc->dev.release = rtc_device_release;
172 
173 	mutex_init(&rtc->ops_lock);
174 	spin_lock_init(&rtc->irq_lock);
175 	init_waitqueue_head(&rtc->irq_queue);
176 
177 	/* Init timerqueue */
178 	timerqueue_init_head(&rtc->timerqueue);
179 	INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
180 	/* Init aie timer */
181 	rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
182 	/* Init uie timer */
183 	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
184 	/* Init pie timer */
185 	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
186 	rtc->pie_timer.function = rtc_pie_update_irq;
187 	rtc->pie_enabled = 0;
188 
189 	return rtc;
190 }
191 
rtc_device_get_id(struct device * dev)192 static int rtc_device_get_id(struct device *dev)
193 {
194 	int of_id = -1, id = -1;
195 
196 	if (dev->of_node)
197 		of_id = of_alias_get_id(dev->of_node, "rtc");
198 	else if (dev->parent && dev->parent->of_node)
199 		of_id = of_alias_get_id(dev->parent->of_node, "rtc");
200 
201 	if (of_id >= 0) {
202 		id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
203 		if (id < 0)
204 			dev_warn(dev, "/aliases ID %d not available\n", of_id);
205 	}
206 
207 	if (id < 0)
208 		id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
209 
210 	return id;
211 }
212 
rtc_device_get_offset(struct rtc_device * rtc)213 static void rtc_device_get_offset(struct rtc_device *rtc)
214 {
215 	time64_t range_secs;
216 	u32 start_year;
217 	int ret;
218 
219 	/*
220 	 * If RTC driver did not implement the range of RTC hardware device,
221 	 * then we can not expand the RTC range by adding or subtracting one
222 	 * offset.
223 	 */
224 	if (rtc->range_min == rtc->range_max)
225 		return;
226 
227 	ret = device_property_read_u32(rtc->dev.parent, "start-year",
228 				       &start_year);
229 	if (!ret) {
230 		rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
231 		rtc->set_start_time = true;
232 	}
233 
234 	/*
235 	 * If user did not implement the start time for RTC driver, then no
236 	 * need to expand the RTC range.
237 	 */
238 	if (!rtc->set_start_time)
239 		return;
240 
241 	range_secs = rtc->range_max - rtc->range_min + 1;
242 
243 	/*
244 	 * If the start_secs is larger than the maximum seconds (rtc->range_max)
245 	 * supported by RTC hardware or the maximum seconds of new expanded
246 	 * range (start_secs + rtc->range_max - rtc->range_min) is less than
247 	 * rtc->range_min, which means the minimum seconds (rtc->range_min) of
248 	 * RTC hardware will be mapped to start_secs by adding one offset, so
249 	 * the offset seconds calculation formula should be:
250 	 * rtc->offset_secs = rtc->start_secs - rtc->range_min;
251 	 *
252 	 * If the start_secs is larger than the minimum seconds (rtc->range_min)
253 	 * supported by RTC hardware, then there is one region is overlapped
254 	 * between the original RTC hardware range and the new expanded range,
255 	 * and this overlapped region do not need to be mapped into the new
256 	 * expanded range due to it is valid for RTC device. So the minimum
257 	 * seconds of RTC hardware (rtc->range_min) should be mapped to
258 	 * rtc->range_max + 1, then the offset seconds formula should be:
259 	 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
260 	 *
261 	 * If the start_secs is less than the minimum seconds (rtc->range_min),
262 	 * which is similar to case 2. So the start_secs should be mapped to
263 	 * start_secs + rtc->range_max - rtc->range_min + 1, then the
264 	 * offset seconds formula should be:
265 	 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
266 	 *
267 	 * Otherwise the offset seconds should be 0.
268 	 */
269 	if (rtc->start_secs > rtc->range_max ||
270 	    rtc->start_secs + range_secs - 1 < rtc->range_min)
271 		rtc->offset_secs = rtc->start_secs - rtc->range_min;
272 	else if (rtc->start_secs > rtc->range_min)
273 		rtc->offset_secs = range_secs;
274 	else if (rtc->start_secs < rtc->range_min)
275 		rtc->offset_secs = -range_secs;
276 	else
277 		rtc->offset_secs = 0;
278 }
279 
280 /**
281  * rtc_device_register - register w/ RTC class
282  * @dev: the device to register
283  *
284  * rtc_device_unregister() must be called when the class device is no
285  * longer needed.
286  *
287  * Returns the pointer to the new struct class device.
288  */
rtc_device_register(const char * name,struct device * dev,const struct rtc_class_ops * ops,struct module * owner)289 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
290 					const struct rtc_class_ops *ops,
291 					struct module *owner)
292 {
293 	struct rtc_device *rtc;
294 	struct rtc_wkalrm alrm;
295 	int id, err;
296 
297 	id = rtc_device_get_id(dev);
298 	if (id < 0) {
299 		err = id;
300 		goto exit;
301 	}
302 
303 	rtc = rtc_allocate_device();
304 	if (!rtc) {
305 		err = -ENOMEM;
306 		goto exit_ida;
307 	}
308 
309 	rtc->id = id;
310 	rtc->ops = ops;
311 	rtc->owner = owner;
312 	rtc->dev.parent = dev;
313 
314 	dev_set_name(&rtc->dev, "rtc%d", id);
315 
316 	rtc_device_get_offset(rtc);
317 
318 	/* Check to see if there is an ALARM already set in hw */
319 	err = __rtc_read_alarm(rtc, &alrm);
320 
321 	if (!err && !rtc_valid_tm(&alrm.time))
322 		rtc_initialize_alarm(rtc, &alrm);
323 
324 	rtc_dev_prepare(rtc);
325 
326 	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
327 	if (err) {
328 		dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
329 			 name, MAJOR(rtc->dev.devt), rtc->id);
330 
331 		/* This will free both memory and the ID */
332 		put_device(&rtc->dev);
333 		goto exit;
334 	} else {
335 		dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", name,
336 			MAJOR(rtc->dev.devt), rtc->id);
337 	}
338 
339 	rtc_proc_add_device(rtc);
340 
341 	dev_info(dev, "rtc core: registered %s as %s\n",
342 			name, dev_name(&rtc->dev));
343 
344 	return rtc;
345 
346 exit_ida:
347 	ida_simple_remove(&rtc_ida, id);
348 
349 exit:
350 	dev_err(dev, "rtc core: unable to register %s, err = %d\n",
351 			name, err);
352 	return ERR_PTR(err);
353 }
354 EXPORT_SYMBOL_GPL(rtc_device_register);
355 
356 
357 /**
358  * rtc_device_unregister - removes the previously registered RTC class device
359  *
360  * @rtc: the RTC class device to destroy
361  */
rtc_device_unregister(struct rtc_device * rtc)362 void rtc_device_unregister(struct rtc_device *rtc)
363 {
364 	mutex_lock(&rtc->ops_lock);
365 	/*
366 	 * Remove innards of this RTC, then disable it, before
367 	 * letting any rtc_class_open() users access it again
368 	 */
369 	rtc_proc_del_device(rtc);
370 	cdev_device_del(&rtc->char_dev, &rtc->dev);
371 	rtc->ops = NULL;
372 	mutex_unlock(&rtc->ops_lock);
373 	put_device(&rtc->dev);
374 }
375 EXPORT_SYMBOL_GPL(rtc_device_unregister);
376 
devm_rtc_device_release(struct device * dev,void * res)377 static void devm_rtc_device_release(struct device *dev, void *res)
378 {
379 	struct rtc_device *rtc = *(struct rtc_device **)res;
380 
381 	rtc_nvmem_unregister(rtc);
382 	rtc_device_unregister(rtc);
383 }
384 
devm_rtc_device_match(struct device * dev,void * res,void * data)385 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
386 {
387 	struct rtc **r = res;
388 
389 	return *r == data;
390 }
391 
392 /**
393  * devm_rtc_device_register - resource managed rtc_device_register()
394  * @dev: the device to register
395  * @name: the name of the device
396  * @ops: the rtc operations structure
397  * @owner: the module owner
398  *
399  * @return a struct rtc on success, or an ERR_PTR on error
400  *
401  * Managed rtc_device_register(). The rtc_device returned from this function
402  * are automatically freed on driver detach. See rtc_device_register()
403  * for more information.
404  */
405 
devm_rtc_device_register(struct device * dev,const char * name,const struct rtc_class_ops * ops,struct module * owner)406 struct rtc_device *devm_rtc_device_register(struct device *dev,
407 					const char *name,
408 					const struct rtc_class_ops *ops,
409 					struct module *owner)
410 {
411 	struct rtc_device **ptr, *rtc;
412 
413 	ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
414 	if (!ptr)
415 		return ERR_PTR(-ENOMEM);
416 
417 	rtc = rtc_device_register(name, dev, ops, owner);
418 	if (!IS_ERR(rtc)) {
419 		*ptr = rtc;
420 		devres_add(dev, ptr);
421 	} else {
422 		devres_free(ptr);
423 	}
424 
425 	return rtc;
426 }
427 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
428 
429 /**
430  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
431  * @dev: the device to unregister
432  * @rtc: the RTC class device to unregister
433  *
434  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
435  * function will not need to be called and the resource management code will
436  * ensure that the resource is freed.
437  */
devm_rtc_device_unregister(struct device * dev,struct rtc_device * rtc)438 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
439 {
440 	int rc;
441 
442 	rc = devres_release(dev, devm_rtc_device_release,
443 				devm_rtc_device_match, rtc);
444 	WARN_ON(rc);
445 }
446 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
447 
devm_rtc_release_device(struct device * dev,void * res)448 static void devm_rtc_release_device(struct device *dev, void *res)
449 {
450 	struct rtc_device *rtc = *(struct rtc_device **)res;
451 
452 	rtc_nvmem_unregister(rtc);
453 
454 	if (rtc->registered)
455 		rtc_device_unregister(rtc);
456 	else
457 		put_device(&rtc->dev);
458 }
459 
devm_rtc_allocate_device(struct device * dev)460 struct rtc_device *devm_rtc_allocate_device(struct device *dev)
461 {
462 	struct rtc_device **ptr, *rtc;
463 	int id, err;
464 
465 	id = rtc_device_get_id(dev);
466 	if (id < 0)
467 		return ERR_PTR(id);
468 
469 	ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
470 	if (!ptr) {
471 		err = -ENOMEM;
472 		goto exit_ida;
473 	}
474 
475 	rtc = rtc_allocate_device();
476 	if (!rtc) {
477 		err = -ENOMEM;
478 		goto exit_devres;
479 	}
480 
481 	*ptr = rtc;
482 	devres_add(dev, ptr);
483 
484 	rtc->id = id;
485 	rtc->dev.parent = dev;
486 	dev_set_name(&rtc->dev, "rtc%d", id);
487 
488 	return rtc;
489 
490 exit_devres:
491 	devres_free(ptr);
492 exit_ida:
493 	ida_simple_remove(&rtc_ida, id);
494 	return ERR_PTR(err);
495 }
496 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
497 
__rtc_register_device(struct module * owner,struct rtc_device * rtc)498 int __rtc_register_device(struct module *owner, struct rtc_device *rtc)
499 {
500 	struct rtc_wkalrm alrm;
501 	int err;
502 
503 	if (!rtc->ops)
504 		return -EINVAL;
505 
506 	rtc->owner = owner;
507 	rtc_device_get_offset(rtc);
508 
509 	/* Check to see if there is an ALARM already set in hw */
510 	err = __rtc_read_alarm(rtc, &alrm);
511 	if (!err && !rtc_valid_tm(&alrm.time))
512 		rtc_initialize_alarm(rtc, &alrm);
513 
514 	rtc_dev_prepare(rtc);
515 
516 	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
517 	if (err)
518 		dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
519 			 MAJOR(rtc->dev.devt), rtc->id);
520 	else
521 		dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
522 			MAJOR(rtc->dev.devt), rtc->id);
523 
524 	rtc_proc_add_device(rtc);
525 
526 	rtc->registered = true;
527 	dev_info(rtc->dev.parent, "registered as %s\n",
528 		 dev_name(&rtc->dev));
529 
530 	return 0;
531 }
532 EXPORT_SYMBOL_GPL(__rtc_register_device);
533 
rtc_init(void)534 static int __init rtc_init(void)
535 {
536 	rtc_class = class_create(THIS_MODULE, "rtc");
537 	if (IS_ERR(rtc_class)) {
538 		pr_err("couldn't create class\n");
539 		return PTR_ERR(rtc_class);
540 	}
541 	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
542 	rtc_dev_init();
543 	return 0;
544 }
545 subsys_initcall(rtc_init);
546