summaryrefslogtreecommitdiff
path: root/drivers/rtc/class.c
blob: 0fca4d74c76b34a645d3b65382a46f16c9bf9501 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
/*
 * RTC subsystem, base class
 *
 * Copyright (C) 2005 Tower Technologies
 * Author: Alessandro Zummo <a.zummo@towertech.it>
 *
 * class skeleton from drivers/hwmon/hwmon.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/of.h>
#include <linux/rtc.h>
#include <linux/kdev_t.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

#include "rtc-core.h"


static DEFINE_IDA(rtc_ida);
struct class *rtc_class;

static void rtc_device_release(struct device *dev)
{
	struct rtc_device *rtc = to_rtc_device(dev);
	ida_simple_remove(&rtc_ida, rtc->id);
	kfree(rtc);
}

#ifdef CONFIG_RTC_HCTOSYS_DEVICE
/* Result of the last RTC to system clock attempt. */
int rtc_hctosys_ret = -ENODEV;
#endif

#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
/*
 * On suspend(), measure the delta between one RTC and the
 * system's wall clock; restore it on resume().
 */

static struct timespec64 old_rtc, old_system, old_delta;


static int rtc_suspend(struct device *dev)
{
	struct rtc_device	*rtc = to_rtc_device(dev);
	struct rtc_time		tm;
	struct timespec64	delta, delta_delta;
	int err;

	if (timekeeping_rtc_skipsuspend())
		return 0;

	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
		return 0;

	/* snapshot the current RTC and system time at suspend*/
	err = rtc_read_time(rtc, &tm);
	if (err < 0) {
		pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));
		return 0;
	}

	ktime_get_real_ts64(&old_system);
	old_rtc.tv_sec = rtc_tm_to_time64(&tm);


	/*
	 * To avoid drift caused by repeated suspend/resumes,
	 * which each can add ~1 second drift error,
	 * try to compensate so the difference in system time
	 * and rtc time stays close to constant.
	 */
	delta = timespec64_sub(old_system, old_rtc);
	delta_delta = timespec64_sub(delta, old_delta);
	if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
		/*
		 * if delta_delta is too large, assume time correction
		 * has occured and set old_delta to the current delta.
		 */
		old_delta = delta;
	} else {
		/* Otherwise try to adjust old_system to compensate */
		old_system = timespec64_sub(old_system, delta_delta);
	}

	return 0;
}

static int rtc_resume(struct device *dev)
{
	struct rtc_device	*rtc = to_rtc_device(dev);
	struct rtc_time		tm;
	struct timespec64	new_system, new_rtc;
	struct timespec64	sleep_time;
	int err;

	if (timekeeping_rtc_skipresume())
		return 0;

	rtc_hctosys_ret = -ENODEV;
	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
		return 0;

	/* snapshot the current rtc and system time at resume */
	ktime_get_real_ts64(&new_system);
	err = rtc_read_time(rtc, &tm);
	if (err < 0) {
		pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));
		return 0;
	}

	new_rtc.tv_sec = rtc_tm_to_time64(&tm);
	new_rtc.tv_nsec = 0;

	if (new_rtc.tv_sec < old_rtc.tv_sec) {
		pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
		return 0;
	}

	/* calculate the RTC time delta (sleep time)*/
	sleep_time = timespec64_sub(new_rtc, old_rtc);

	/*
	 * Since these RTC suspend/resume handlers are not called
	 * at the very end of suspend or the start of resume,
	 * some run-time may pass on either sides of the sleep time
	 * so subtract kernel run-time between rtc_suspend to rtc_resume
	 * to keep things accurate.
	 */
	sleep_time = timespec64_sub(sleep_time,
			timespec64_sub(new_system, old_system));

	if (sleep_time.tv_sec >= 0)
		timekeeping_inject_sleeptime64(&sleep_time);
	rtc_hctosys_ret = 0;
	return 0;
}

static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
#define RTC_CLASS_DEV_PM_OPS	(&rtc_class_dev_pm_ops)
#else
#define RTC_CLASS_DEV_PM_OPS	NULL
#endif

/* Ensure the caller will set the id before releasing the device */
static struct rtc_device *rtc_allocate_device(void)
{
	struct rtc_device *rtc;

	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
	if (!rtc)
		return NULL;

	device_initialize(&rtc->dev);

	/* Drivers can revise this default after allocating the device. */
	rtc->set_offset_nsec =  NSEC_PER_SEC / 2;

	rtc->irq_freq = 1;
	rtc->max_user_freq = 64;
	rtc->dev.class = rtc_class;
	rtc->dev.groups = rtc_get_dev_attribute_groups();
	rtc->dev.release = rtc_device_release;

	mutex_init(&rtc->ops_lock);
	spin_lock_init(&rtc->irq_lock);
	init_waitqueue_head(&rtc->irq_queue);

	/* Init timerqueue */
	timerqueue_init_head(&rtc->timerqueue);
	INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
	/* Init aie timer */
	rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
	/* Init uie timer */
	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
	/* Init pie timer */
	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	rtc->pie_timer.function = rtc_pie_update_irq;
	rtc->pie_enabled = 0;

	return rtc;
}

static int rtc_device_get_id(struct device *dev)
{
	int of_id = -1, id = -1;

	if (dev->of_node)
		of_id = of_alias_get_id(dev->of_node, "rtc");
	else if (dev->parent && dev->parent->of_node)
		of_id = of_alias_get_id(dev->parent->of_node, "rtc");

	if (of_id >= 0) {
		id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
		if (id < 0)
			dev_warn(dev, "/aliases ID %d not available\n", of_id);
	}

	if (id < 0)
		id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);

	return id;
}

static void rtc_device_get_offset(struct rtc_device *rtc)
{
	time64_t range_secs;
	u32 start_year;
	int ret;

	/*
	 * If RTC driver did not implement the range of RTC hardware device,
	 * then we can not expand the RTC range by adding or subtracting one
	 * offset.
	 */
	if (rtc->range_min == rtc->range_max)
		return;

	ret = device_property_read_u32(rtc->dev.parent, "start-year",
				       &start_year);
	if (!ret) {
		rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
		rtc->set_start_time = true;
	}

	/*
	 * If user did not implement the start time for RTC driver, then no
	 * need to expand the RTC range.
	 */
	if (!rtc->set_start_time)
		return;

	range_secs = rtc->range_max - rtc->range_min + 1;

	/*
	 * If the start_secs is larger than the maximum seconds (rtc->range_max)
	 * supported by RTC hardware or the maximum seconds of new expanded
	 * range (start_secs + rtc->range_max - rtc->range_min) is less than
	 * rtc->range_min, which means the minimum seconds (rtc->range_min) of
	 * RTC hardware will be mapped to start_secs by adding one offset, so
	 * the offset seconds calculation formula should be:
	 * rtc->offset_secs = rtc->start_secs - rtc->range_min;
	 *
	 * If the start_secs is larger than the minimum seconds (rtc->range_min)
	 * supported by RTC hardware, then there is one region is overlapped
	 * between the original RTC hardware range and the new expanded range,
	 * and this overlapped region do not need to be mapped into the new
	 * expanded range due to it is valid for RTC device. So the minimum
	 * seconds of RTC hardware (rtc->range_min) should be mapped to
	 * rtc->range_max + 1, then the offset seconds formula should be:
	 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
	 *
	 * If the start_secs is less than the minimum seconds (rtc->range_min),
	 * which is similar to case 2. So the start_secs should be mapped to
	 * start_secs + rtc->range_max - rtc->range_min + 1, then the
	 * offset seconds formula should be:
	 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
	 *
	 * Otherwise the offset seconds should be 0.
	 */
	if (rtc->start_secs > rtc->range_max ||
	    rtc->start_secs + range_secs - 1 < rtc->range_min)
		rtc->offset_secs = rtc->start_secs - rtc->range_min;
	else if (rtc->start_secs > rtc->range_min)
		rtc->offset_secs = range_secs;
	else if (rtc->start_secs < rtc->range_min)
		rtc->offset_secs = -range_secs;
	else
		rtc->offset_secs = 0;
}

/**
 * rtc_device_register - register w/ RTC class
 * @dev: the device to register
 *
 * rtc_device_unregister() must be called when the class device is no
 * longer needed.
 *
 * Returns the pointer to the new struct class device.
 */
struct rtc_device *rtc_device_register(const char *name, struct device *dev,
					const struct rtc_class_ops *ops,
					struct module *owner)
{
	struct rtc_device *rtc;
	struct rtc_wkalrm alrm;
	int id, err;

	id = rtc_device_get_id(dev);
	if (id < 0) {
		err = id;
		goto exit;
	}

	rtc = rtc_allocate_device();
	if (!rtc) {
		err = -ENOMEM;
		goto exit_ida;
	}

	rtc->id = id;
	rtc->ops = ops;
	rtc->owner = owner;
	rtc->dev.parent = dev;

	dev_set_name(&rtc->dev, "rtc%d", id);

	rtc_device_get_offset(rtc);

	/* Check to see if there is an ALARM already set in hw */
	err = __rtc_read_alarm(rtc, &alrm);

	if (!err && !rtc_valid_tm(&alrm.time))
		rtc_initialize_alarm(rtc, &alrm);

	rtc_dev_prepare(rtc);

	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
	if (err) {
		dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
			 name, MAJOR(rtc->dev.devt), rtc->id);

		/* This will free both memory and the ID */
		put_device(&rtc->dev);
		goto exit;
	} else {
		dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", name,
			MAJOR(rtc->dev.devt), rtc->id);
	}

	rtc_proc_add_device(rtc);

	dev_info(dev, "rtc core: registered %s as %s\n",
			name, dev_name(&rtc->dev));

	return rtc;

exit_ida:
	ida_simple_remove(&rtc_ida, id);

exit:
	dev_err(dev, "rtc core: unable to register %s, err = %d\n",
			name, err);
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(rtc_device_register);


/**
 * rtc_device_unregister - removes the previously registered RTC class device
 *
 * @rtc: the RTC class device to destroy
 */
void rtc_device_unregister(struct rtc_device *rtc)
{
	mutex_lock(&rtc->ops_lock);
	/*
	 * Remove innards of this RTC, then disable it, before
	 * letting any rtc_class_open() users access it again
	 */
	rtc_proc_del_device(rtc);
	cdev_device_del(&rtc->char_dev, &rtc->dev);
	rtc->ops = NULL;
	mutex_unlock(&rtc->ops_lock);
	put_device(&rtc->dev);
}
EXPORT_SYMBOL_GPL(rtc_device_unregister);

static void devm_rtc_device_release(struct device *dev, void *res)
{
	struct rtc_device *rtc = *(struct rtc_device **)res;

	rtc_nvmem_unregister(rtc);
	rtc_device_unregister(rtc);
}

static int devm_rtc_device_match(struct device *dev, void *res, void *data)
{
	struct rtc **r = res;

	return *r == data;
}

/**
 * devm_rtc_device_register - resource managed rtc_device_register()
 * @dev: the device to register
 * @name: the name of the device
 * @ops: the rtc operations structure
 * @owner: the module owner
 *
 * @return a struct rtc on success, or an ERR_PTR on error
 *
 * Managed rtc_device_register(). The rtc_device returned from this function
 * are automatically freed on driver detach. See rtc_device_register()
 * for more information.
 */

struct rtc_device *devm_rtc_device_register(struct device *dev,
					const char *name,
					const struct rtc_class_ops *ops,
					struct module *owner)
{
	struct rtc_device **ptr, *rtc;

	ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	rtc = rtc_device_register(name, dev, ops, owner);
	if (!IS_ERR(rtc)) {
		*ptr = rtc;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return rtc;
}
EXPORT_SYMBOL_GPL(devm_rtc_device_register);

/**
 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 * @dev: the device to unregister
 * @rtc: the RTC class device to unregister
 *
 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 * function will not need to be called and the resource management code will
 * ensure that the resource is freed.
 */
void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
{
	int rc;

	rc = devres_release(dev, devm_rtc_device_release,
				devm_rtc_device_match, rtc);
	WARN_ON(rc);
}
EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);

static void devm_rtc_release_device(struct device *dev, void *res)
{
	struct rtc_device *rtc = *(struct rtc_device **)res;

	rtc_nvmem_unregister(rtc);

	if (rtc->registered)
		rtc_device_unregister(rtc);
	else
		put_device(&rtc->dev);
}

struct rtc_device *devm_rtc_allocate_device(struct device *dev)
{
	struct rtc_device **ptr, *rtc;
	int id, err;

	id = rtc_device_get_id(dev);
	if (id < 0)
		return ERR_PTR(id);

	ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
	if (!ptr) {
		err = -ENOMEM;
		goto exit_ida;
	}

	rtc = rtc_allocate_device();
	if (!rtc) {
		err = -ENOMEM;
		goto exit_devres;
	}

	*ptr = rtc;
	devres_add(dev, ptr);

	rtc->id = id;
	rtc->dev.parent = dev;
	dev_set_name(&rtc->dev, "rtc%d", id);

	return rtc;

exit_devres:
	devres_free(ptr);
exit_ida:
	ida_simple_remove(&rtc_ida, id);
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);

int __rtc_register_device(struct module *owner, struct rtc_device *rtc)
{
	struct rtc_wkalrm alrm;
	int err;

	if (!rtc->ops)
		return -EINVAL;

	rtc->owner = owner;
	rtc_device_get_offset(rtc);

	/* Check to see if there is an ALARM already set in hw */
	err = __rtc_read_alarm(rtc, &alrm);
	if (!err && !rtc_valid_tm(&alrm.time))
		rtc_initialize_alarm(rtc, &alrm);

	rtc_dev_prepare(rtc);

	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
	if (err)
		dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
			 MAJOR(rtc->dev.devt), rtc->id);
	else
		dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
			MAJOR(rtc->dev.devt), rtc->id);

	rtc_proc_add_device(rtc);

	rtc->registered = true;
	dev_info(rtc->dev.parent, "registered as %s\n",
		 dev_name(&rtc->dev));

	return 0;
}
EXPORT_SYMBOL_GPL(__rtc_register_device);

static int __init rtc_init(void)
{
	rtc_class = class_create(THIS_MODULE, "rtc");
	if (IS_ERR(rtc_class)) {
		pr_err("couldn't create class\n");
		return PTR_ERR(rtc_class);
	}
	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
	rtc_dev_init();
	return 0;
}
subsys_initcall(rtc_init);