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
27static DEFINE_IDA(rtc_ida);
28struct class *rtc_class;
29
30static 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. */
39int 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
48static struct timespec64 old_rtc, old_system, old_delta;
49
50
51static 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
97static 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
147static 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
154/**
155 * rtc_device_register - register w/ RTC class
156 * @dev: the device to register
157 *
158 * rtc_device_unregister() must be called when the class device is no
159 * longer needed.
160 *
161 * Returns the pointer to the new struct class device.
162 */
163struct rtc_device *rtc_device_register(const char *name, struct device *dev,
164					const struct rtc_class_ops *ops,
165					struct module *owner)
166{
167	struct rtc_device *rtc;
168	struct rtc_wkalrm alrm;
169	int of_id = -1, id = -1, err;
170
171	if (dev->of_node)
172		of_id = of_alias_get_id(dev->of_node, "rtc");
173	else if (dev->parent && dev->parent->of_node)
174		of_id = of_alias_get_id(dev->parent->of_node, "rtc");
175
176	if (of_id >= 0) {
177		id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
178				    GFP_KERNEL);
179		if (id < 0)
180			dev_warn(dev, "/aliases ID %d not available\n",
181				    of_id);
182	}
183
184	if (id < 0) {
185		id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
186		if (id < 0) {
187			err = id;
188			goto exit;
189		}
190	}
191
192	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
193	if (rtc == NULL) {
194		err = -ENOMEM;
195		goto exit_ida;
196	}
197
198	rtc->id = id;
199	rtc->ops = ops;
200	rtc->owner = owner;
201	rtc->irq_freq = 1;
202	rtc->max_user_freq = 64;
203	rtc->dev.parent = dev;
204	rtc->dev.class = rtc_class;
205	rtc->dev.release = rtc_device_release;
206
207	mutex_init(&rtc->ops_lock);
208	spin_lock_init(&rtc->irq_lock);
209	spin_lock_init(&rtc->irq_task_lock);
210	init_waitqueue_head(&rtc->irq_queue);
211
212	/* Init timerqueue */
213	timerqueue_init_head(&rtc->timerqueue);
214	INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
215	/* Init aie timer */
216	rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
217	/* Init uie timer */
218	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
219	/* Init pie timer */
220	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
221	rtc->pie_timer.function = rtc_pie_update_irq;
222	rtc->pie_enabled = 0;
223
224	strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
225	dev_set_name(&rtc->dev, "rtc%d", id);
226
227	/* Check to see if there is an ALARM already set in hw */
228	err = __rtc_read_alarm(rtc, &alrm);
229
230	if (!err && !rtc_valid_tm(&alrm.time))
231		rtc_initialize_alarm(rtc, &alrm);
232
233	rtc_dev_prepare(rtc);
234
235	err = device_register(&rtc->dev);
236	if (err) {
237		put_device(&rtc->dev);
238		goto exit_kfree;
239	}
240
241	rtc_dev_add_device(rtc);
242	rtc_sysfs_add_device(rtc);
243	rtc_proc_add_device(rtc);
244
245	dev_info(dev, "rtc core: registered %s as %s\n",
246			rtc->name, dev_name(&rtc->dev));
247
248	return rtc;
249
250exit_kfree:
251	kfree(rtc);
252
253exit_ida:
254	ida_simple_remove(&rtc_ida, id);
255
256exit:
257	dev_err(dev, "rtc core: unable to register %s, err = %d\n",
258			name, err);
259	return ERR_PTR(err);
260}
261EXPORT_SYMBOL_GPL(rtc_device_register);
262
263
264/**
265 * rtc_device_unregister - removes the previously registered RTC class device
266 *
267 * @rtc: the RTC class device to destroy
268 */
269void rtc_device_unregister(struct rtc_device *rtc)
270{
271	if (get_device(&rtc->dev) != NULL) {
272		mutex_lock(&rtc->ops_lock);
273		/* remove innards of this RTC, then disable it, before
274		 * letting any rtc_class_open() users access it again
275		 */
276		rtc_sysfs_del_device(rtc);
277		rtc_dev_del_device(rtc);
278		rtc_proc_del_device(rtc);
279		device_unregister(&rtc->dev);
280		rtc->ops = NULL;
281		mutex_unlock(&rtc->ops_lock);
282		put_device(&rtc->dev);
283	}
284}
285EXPORT_SYMBOL_GPL(rtc_device_unregister);
286
287static void devm_rtc_device_release(struct device *dev, void *res)
288{
289	struct rtc_device *rtc = *(struct rtc_device **)res;
290
291	rtc_device_unregister(rtc);
292}
293
294static int devm_rtc_device_match(struct device *dev, void *res, void *data)
295{
296	struct rtc **r = res;
297
298	return *r == data;
299}
300
301/**
302 * devm_rtc_device_register - resource managed rtc_device_register()
303 * @dev: the device to register
304 * @name: the name of the device
305 * @ops: the rtc operations structure
306 * @owner: the module owner
307 *
308 * @return a struct rtc on success, or an ERR_PTR on error
309 *
310 * Managed rtc_device_register(). The rtc_device returned from this function
311 * are automatically freed on driver detach. See rtc_device_register()
312 * for more information.
313 */
314
315struct rtc_device *devm_rtc_device_register(struct device *dev,
316					const char *name,
317					const struct rtc_class_ops *ops,
318					struct module *owner)
319{
320	struct rtc_device **ptr, *rtc;
321
322	ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
323	if (!ptr)
324		return ERR_PTR(-ENOMEM);
325
326	rtc = rtc_device_register(name, dev, ops, owner);
327	if (!IS_ERR(rtc)) {
328		*ptr = rtc;
329		devres_add(dev, ptr);
330	} else {
331		devres_free(ptr);
332	}
333
334	return rtc;
335}
336EXPORT_SYMBOL_GPL(devm_rtc_device_register);
337
338/**
339 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
340 * @dev: the device to unregister
341 * @rtc: the RTC class device to unregister
342 *
343 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
344 * function will not need to be called and the resource management code will
345 * ensure that the resource is freed.
346 */
347void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
348{
349	int rc;
350
351	rc = devres_release(dev, devm_rtc_device_release,
352				devm_rtc_device_match, rtc);
353	WARN_ON(rc);
354}
355EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
356
357static int __init rtc_init(void)
358{
359	rtc_class = class_create(THIS_MODULE, "rtc");
360	if (IS_ERR(rtc_class)) {
361		pr_err("couldn't create class\n");
362		return PTR_ERR(rtc_class);
363	}
364	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
365	rtc_dev_init();
366	rtc_sysfs_init(rtc_class);
367	return 0;
368}
369
370static void __exit rtc_exit(void)
371{
372	rtc_dev_exit();
373	class_destroy(rtc_class);
374	ida_destroy(&rtc_ida);
375}
376
377subsys_initcall(rtc_init);
378module_exit(rtc_exit);
379
380MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
381MODULE_DESCRIPTION("RTC class support");
382MODULE_LICENSE("GPL");
383