summaryrefslogtreecommitdiffstats
path: root/drivers/rtc/class.c
blob: c29ba7e1430482c1ffe6c6ec92e1bd5cc7b06743 (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
/*
 * 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;
	}

	getnstimeofday64(&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 */
	getnstimeofday64(&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


/**
 * 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 of_id = -1, id = -1, err;

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

	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
	if (rtc == NULL) {
		err = -ENOMEM;
		goto exit_ida;
	}

	rtc->id = id;
	rtc->ops = ops;
	rtc->owner = owner;
	rtc->irq_freq = 1;
	rtc->max_user_freq = 64;
	rtc->dev.parent = dev;
	rtc->dev.class = rtc_class;
	rtc->dev.release = rtc_device_release;

	mutex_init(&rtc->ops_lock);
	spin_lock_init(&rtc->irq_lock);
	spin_lock_init(&rtc->irq_task_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;

	/* 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);

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

	rtc_dev_prepare(rtc);

	err = device_register(&rtc->dev);
	if (err) {
		put_device(&rtc->dev);
		goto exit_kfree;
	}

	rtc_dev_add_device(rtc);
	rtc_sysfs_add_device(rtc);
	rtc_proc_add_device(rtc);

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

	return rtc;

exit_kfree:
	kfree(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)
{
	if (get_device(&rtc->dev) != NULL) {
		mutex_lock(&rtc->ops_lock);
		/* remove innards of this RTC, then disable it, before
		 * letting any rtc_class_open() users access it again
		 */
		rtc_sysfs_del_device(rtc);
		rtc_dev_del_device(rtc);
		rtc_proc_del_device(rtc);
		device_unregister(&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_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 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();
	rtc_sysfs_init(rtc_class);
	return 0;
}

static void __exit rtc_exit(void)
{
	rtc_dev_exit();
	class_destroy(rtc_class);
	ida_destroy(&rtc_ida);
}

subsys_initcall(rtc_init);
module_exit(rtc_exit);

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("RTC class support");
MODULE_LICENSE("GPL");