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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
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 */
163 struct 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.groups = rtc_get_dev_attribute_groups();
206 rtc->dev.release = rtc_device_release;
207
208 mutex_init(&rtc->ops_lock);
209 spin_lock_init(&rtc->irq_lock);
210 spin_lock_init(&rtc->irq_task_lock);
211 init_waitqueue_head(&rtc->irq_queue);
212
213 /* Init timerqueue */
214 timerqueue_init_head(&rtc->timerqueue);
215 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
216 /* Init aie timer */
217 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
218 /* Init uie timer */
219 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
220 /* Init pie timer */
221 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
222 rtc->pie_timer.function = rtc_pie_update_irq;
223 rtc->pie_enabled = 0;
224
225 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
226 dev_set_name(&rtc->dev, "rtc%d", id);
227
228 /* Check to see if there is an ALARM already set in hw */
229 err = __rtc_read_alarm(rtc, &alrm);
230
231 if (!err && !rtc_valid_tm(&alrm.time))
232 rtc_initialize_alarm(rtc, &alrm);
233
234 rtc_dev_prepare(rtc);
235
236 err = device_register(&rtc->dev);
237 if (err) {
238 /* This will free both memory and the ID */
239 put_device(&rtc->dev);
240 goto exit;
241 }
242
243 rtc_dev_add_device(rtc);
244 rtc_proc_add_device(rtc);
245
246 dev_info(dev, "rtc core: registered %s as %s\n",
247 rtc->name, dev_name(&rtc->dev));
248
249 return rtc;
250
251 exit_ida:
252 ida_simple_remove(&rtc_ida, id);
253
254 exit:
255 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
256 name, err);
257 return ERR_PTR(err);
258 }
259 EXPORT_SYMBOL_GPL(rtc_device_register);
260
261
262 /**
263 * rtc_device_unregister - removes the previously registered RTC class device
264 *
265 * @rtc: the RTC class device to destroy
266 */
267 void rtc_device_unregister(struct rtc_device *rtc)
268 {
269 mutex_lock(&rtc->ops_lock);
270 /*
271 * Remove innards of this RTC, then disable it, before
272 * letting any rtc_class_open() users access it again
273 */
274 rtc_dev_del_device(rtc);
275 rtc_proc_del_device(rtc);
276 device_del(&rtc->dev);
277 rtc->ops = NULL;
278 mutex_unlock(&rtc->ops_lock);
279 put_device(&rtc->dev);
280 }
281 EXPORT_SYMBOL_GPL(rtc_device_unregister);
282
283 static void devm_rtc_device_release(struct device *dev, void *res)
284 {
285 struct rtc_device *rtc = *(struct rtc_device **)res;
286
287 rtc_device_unregister(rtc);
288 }
289
290 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
291 {
292 struct rtc **r = res;
293
294 return *r == data;
295 }
296
297 /**
298 * devm_rtc_device_register - resource managed rtc_device_register()
299 * @dev: the device to register
300 * @name: the name of the device
301 * @ops: the rtc operations structure
302 * @owner: the module owner
303 *
304 * @return a struct rtc on success, or an ERR_PTR on error
305 *
306 * Managed rtc_device_register(). The rtc_device returned from this function
307 * are automatically freed on driver detach. See rtc_device_register()
308 * for more information.
309 */
310
311 struct rtc_device *devm_rtc_device_register(struct device *dev,
312 const char *name,
313 const struct rtc_class_ops *ops,
314 struct module *owner)
315 {
316 struct rtc_device **ptr, *rtc;
317
318 ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
319 if (!ptr)
320 return ERR_PTR(-ENOMEM);
321
322 rtc = rtc_device_register(name, dev, ops, owner);
323 if (!IS_ERR(rtc)) {
324 *ptr = rtc;
325 devres_add(dev, ptr);
326 } else {
327 devres_free(ptr);
328 }
329
330 return rtc;
331 }
332 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
333
334 /**
335 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
336 * @dev: the device to unregister
337 * @rtc: the RTC class device to unregister
338 *
339 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
340 * function will not need to be called and the resource management code will
341 * ensure that the resource is freed.
342 */
343 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
344 {
345 int rc;
346
347 rc = devres_release(dev, devm_rtc_device_release,
348 devm_rtc_device_match, rtc);
349 WARN_ON(rc);
350 }
351 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
352
353 static int __init rtc_init(void)
354 {
355 rtc_class = class_create(THIS_MODULE, "rtc");
356 if (IS_ERR(rtc_class)) {
357 pr_err("couldn't create class\n");
358 return PTR_ERR(rtc_class);
359 }
360 rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
361 rtc_dev_init();
362 return 0;
363 }
364 subsys_initcall(rtc_init);