xref: /openbmc/linux/drivers/rtc/class.c (revision 4da722ca)
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 
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 
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 	getnstimeofday64(&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 
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 	getnstimeofday64(&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 */
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 	rtc->irq_freq = 1;
165 	rtc->max_user_freq = 64;
166 	rtc->dev.class = rtc_class;
167 	rtc->dev.groups = rtc_get_dev_attribute_groups();
168 	rtc->dev.release = rtc_device_release;
169 
170 	mutex_init(&rtc->ops_lock);
171 	spin_lock_init(&rtc->irq_lock);
172 	spin_lock_init(&rtc->irq_task_lock);
173 	init_waitqueue_head(&rtc->irq_queue);
174 
175 	/* Init timerqueue */
176 	timerqueue_init_head(&rtc->timerqueue);
177 	INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
178 	/* Init aie timer */
179 	rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
180 	/* Init uie timer */
181 	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
182 	/* Init pie timer */
183 	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
184 	rtc->pie_timer.function = rtc_pie_update_irq;
185 	rtc->pie_enabled = 0;
186 
187 	return rtc;
188 }
189 
190 static int rtc_device_get_id(struct device *dev)
191 {
192 	int of_id = -1, id = -1;
193 
194 	if (dev->of_node)
195 		of_id = of_alias_get_id(dev->of_node, "rtc");
196 	else if (dev->parent && dev->parent->of_node)
197 		of_id = of_alias_get_id(dev->parent->of_node, "rtc");
198 
199 	if (of_id >= 0) {
200 		id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
201 		if (id < 0)
202 			dev_warn(dev, "/aliases ID %d not available\n", of_id);
203 	}
204 
205 	if (id < 0)
206 		id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
207 
208 	return id;
209 }
210 
211 /**
212  * rtc_device_register - register w/ RTC class
213  * @dev: the device to register
214  *
215  * rtc_device_unregister() must be called when the class device is no
216  * longer needed.
217  *
218  * Returns the pointer to the new struct class device.
219  */
220 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
221 					const struct rtc_class_ops *ops,
222 					struct module *owner)
223 {
224 	struct rtc_device *rtc;
225 	struct rtc_wkalrm alrm;
226 	int id, err;
227 
228 	id = rtc_device_get_id(dev);
229 	if (id < 0) {
230 		err = id;
231 		goto exit;
232 	}
233 
234 	rtc = rtc_allocate_device();
235 	if (!rtc) {
236 		err = -ENOMEM;
237 		goto exit_ida;
238 	}
239 
240 	rtc->id = id;
241 	rtc->ops = ops;
242 	rtc->owner = owner;
243 	rtc->dev.parent = dev;
244 
245 	dev_set_name(&rtc->dev, "rtc%d", id);
246 
247 	/* Check to see if there is an ALARM already set in hw */
248 	err = __rtc_read_alarm(rtc, &alrm);
249 
250 	if (!err && !rtc_valid_tm(&alrm.time))
251 		rtc_initialize_alarm(rtc, &alrm);
252 
253 	rtc_dev_prepare(rtc);
254 
255 	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
256 	if (err) {
257 		dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
258 			 name, MAJOR(rtc->dev.devt), rtc->id);
259 
260 		/* This will free both memory and the ID */
261 		put_device(&rtc->dev);
262 		goto exit;
263 	} else {
264 		dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", name,
265 			MAJOR(rtc->dev.devt), rtc->id);
266 	}
267 
268 	rtc_proc_add_device(rtc);
269 
270 	dev_info(dev, "rtc core: registered %s as %s\n",
271 			name, dev_name(&rtc->dev));
272 
273 	return rtc;
274 
275 exit_ida:
276 	ida_simple_remove(&rtc_ida, id);
277 
278 exit:
279 	dev_err(dev, "rtc core: unable to register %s, err = %d\n",
280 			name, err);
281 	return ERR_PTR(err);
282 }
283 EXPORT_SYMBOL_GPL(rtc_device_register);
284 
285 
286 /**
287  * rtc_device_unregister - removes the previously registered RTC class device
288  *
289  * @rtc: the RTC class device to destroy
290  */
291 void rtc_device_unregister(struct rtc_device *rtc)
292 {
293 	rtc_nvmem_unregister(rtc);
294 
295 	mutex_lock(&rtc->ops_lock);
296 	/*
297 	 * Remove innards of this RTC, then disable it, before
298 	 * letting any rtc_class_open() users access it again
299 	 */
300 	rtc_proc_del_device(rtc);
301 	cdev_device_del(&rtc->char_dev, &rtc->dev);
302 	rtc->ops = NULL;
303 	mutex_unlock(&rtc->ops_lock);
304 	put_device(&rtc->dev);
305 }
306 EXPORT_SYMBOL_GPL(rtc_device_unregister);
307 
308 static void devm_rtc_device_release(struct device *dev, void *res)
309 {
310 	struct rtc_device *rtc = *(struct rtc_device **)res;
311 
312 	rtc_device_unregister(rtc);
313 }
314 
315 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
316 {
317 	struct rtc **r = res;
318 
319 	return *r == data;
320 }
321 
322 /**
323  * devm_rtc_device_register - resource managed rtc_device_register()
324  * @dev: the device to register
325  * @name: the name of the device
326  * @ops: the rtc operations structure
327  * @owner: the module owner
328  *
329  * @return a struct rtc on success, or an ERR_PTR on error
330  *
331  * Managed rtc_device_register(). The rtc_device returned from this function
332  * are automatically freed on driver detach. See rtc_device_register()
333  * for more information.
334  */
335 
336 struct rtc_device *devm_rtc_device_register(struct device *dev,
337 					const char *name,
338 					const struct rtc_class_ops *ops,
339 					struct module *owner)
340 {
341 	struct rtc_device **ptr, *rtc;
342 
343 	ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
344 	if (!ptr)
345 		return ERR_PTR(-ENOMEM);
346 
347 	rtc = rtc_device_register(name, dev, ops, owner);
348 	if (!IS_ERR(rtc)) {
349 		*ptr = rtc;
350 		devres_add(dev, ptr);
351 	} else {
352 		devres_free(ptr);
353 	}
354 
355 	return rtc;
356 }
357 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
358 
359 /**
360  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
361  * @dev: the device to unregister
362  * @rtc: the RTC class device to unregister
363  *
364  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
365  * function will not need to be called and the resource management code will
366  * ensure that the resource is freed.
367  */
368 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
369 {
370 	int rc;
371 
372 	rc = devres_release(dev, devm_rtc_device_release,
373 				devm_rtc_device_match, rtc);
374 	WARN_ON(rc);
375 }
376 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
377 
378 static void devm_rtc_release_device(struct device *dev, void *res)
379 {
380 	struct rtc_device *rtc = *(struct rtc_device **)res;
381 
382 	if (rtc->registered)
383 		rtc_device_unregister(rtc);
384 	else
385 		put_device(&rtc->dev);
386 }
387 
388 struct rtc_device *devm_rtc_allocate_device(struct device *dev)
389 {
390 	struct rtc_device **ptr, *rtc;
391 	int id, err;
392 
393 	id = rtc_device_get_id(dev);
394 	if (id < 0)
395 		return ERR_PTR(id);
396 
397 	ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
398 	if (!ptr) {
399 		err = -ENOMEM;
400 		goto exit_ida;
401 	}
402 
403 	rtc = rtc_allocate_device();
404 	if (!rtc) {
405 		err = -ENOMEM;
406 		goto exit_devres;
407 	}
408 
409 	*ptr = rtc;
410 	devres_add(dev, ptr);
411 
412 	rtc->id = id;
413 	rtc->dev.parent = dev;
414 	dev_set_name(&rtc->dev, "rtc%d", id);
415 
416 	return rtc;
417 
418 exit_devres:
419 	devres_free(ptr);
420 exit_ida:
421 	ida_simple_remove(&rtc_ida, id);
422 	return ERR_PTR(err);
423 }
424 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
425 
426 int __rtc_register_device(struct module *owner, struct rtc_device *rtc)
427 {
428 	struct rtc_wkalrm alrm;
429 	int err;
430 
431 	if (!rtc->ops)
432 		return -EINVAL;
433 
434 	rtc->owner = owner;
435 
436 	/* Check to see if there is an ALARM already set in hw */
437 	err = __rtc_read_alarm(rtc, &alrm);
438 	if (!err && !rtc_valid_tm(&alrm.time))
439 		rtc_initialize_alarm(rtc, &alrm);
440 
441 	rtc_dev_prepare(rtc);
442 
443 	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
444 	if (err)
445 		dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
446 			 MAJOR(rtc->dev.devt), rtc->id);
447 	else
448 		dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
449 			MAJOR(rtc->dev.devt), rtc->id);
450 
451 	rtc_proc_add_device(rtc);
452 
453 	rtc_nvmem_register(rtc);
454 
455 	rtc->registered = true;
456 	dev_info(rtc->dev.parent, "registered as %s\n",
457 		 dev_name(&rtc->dev));
458 
459 	return 0;
460 }
461 EXPORT_SYMBOL_GPL(__rtc_register_device);
462 
463 static int __init rtc_init(void)
464 {
465 	rtc_class = class_create(THIS_MODULE, "rtc");
466 	if (IS_ERR(rtc_class)) {
467 		pr_err("couldn't create class\n");
468 		return PTR_ERR(rtc_class);
469 	}
470 	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
471 	rtc_dev_init();
472 	return 0;
473 }
474 subsys_initcall(rtc_init);
475