1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * RTC subsystem, base class
4 *
5 * Copyright (C) 2005 Tower Technologies
6 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 *
8 * class skeleton from drivers/hwmon/hwmon.c
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/rtc.h>
16 #include <linux/kdev_t.h>
17 #include <linux/idr.h>
18 #include <linux/slab.h>
19 #include <linux/workqueue.h>
20
21 #include "rtc-core.h"
22
23 static DEFINE_IDA(rtc_ida);
24
rtc_device_release(struct device * dev)25 static void rtc_device_release(struct device *dev)
26 {
27 struct rtc_device *rtc = to_rtc_device(dev);
28 struct timerqueue_head *head = &rtc->timerqueue;
29 struct timerqueue_node *node;
30
31 mutex_lock(&rtc->ops_lock);
32 while ((node = timerqueue_getnext(head)))
33 timerqueue_del(head, node);
34 mutex_unlock(&rtc->ops_lock);
35
36 cancel_work_sync(&rtc->irqwork);
37
38 ida_free(&rtc_ida, rtc->id);
39 mutex_destroy(&rtc->ops_lock);
40 kfree(rtc);
41 }
42
43 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
44 /* Result of the last RTC to system clock attempt. */
45 int rtc_hctosys_ret = -ENODEV;
46
47 /* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
48 * whether it stores the most close value or the value with partial
49 * seconds truncated. However, it is important that we use it to store
50 * the truncated value. This is because otherwise it is necessary,
51 * in an rtc sync function, to read both xtime.tv_sec and
52 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
53 * of >32bits is not possible. So storing the most close value would
54 * slow down the sync API. So here we have the truncated value and
55 * the best guess is to add 0.5s.
56 */
57
rtc_hctosys(struct rtc_device * rtc)58 static void rtc_hctosys(struct rtc_device *rtc)
59 {
60 int err;
61 struct rtc_time tm;
62 struct timespec64 tv64 = {
63 .tv_nsec = NSEC_PER_SEC >> 1,
64 };
65
66 err = rtc_read_time(rtc, &tm);
67 if (err) {
68 dev_err(rtc->dev.parent,
69 "hctosys: unable to read the hardware clock\n");
70 goto err_read;
71 }
72
73 tv64.tv_sec = rtc_tm_to_time64(&tm);
74
75 #if BITS_PER_LONG == 32
76 if (tv64.tv_sec > INT_MAX) {
77 err = -ERANGE;
78 goto err_read;
79 }
80 #endif
81
82 err = do_settimeofday64(&tv64);
83
84 dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n",
85 &tm, (long long)tv64.tv_sec);
86
87 err_read:
88 rtc_hctosys_ret = err;
89 }
90 #endif
91
92 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
93 /*
94 * On suspend(), measure the delta between one RTC and the
95 * system's wall clock; restore it on resume().
96 */
97
98 static struct timespec64 old_rtc, old_system, old_delta;
99
rtc_suspend(struct device * dev)100 static int rtc_suspend(struct device *dev)
101 {
102 struct rtc_device *rtc = to_rtc_device(dev);
103 struct rtc_time tm;
104 struct timespec64 delta, delta_delta;
105 int err;
106
107 if (timekeeping_rtc_skipsuspend())
108 return 0;
109
110 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
111 return 0;
112
113 /* snapshot the current RTC and system time at suspend*/
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 ktime_get_real_ts64(&old_system);
121 old_rtc.tv_sec = rtc_tm_to_time64(&tm);
122
123 /*
124 * To avoid drift caused by repeated suspend/resumes,
125 * which each can add ~1 second drift error,
126 * try to compensate so the difference in system time
127 * and rtc time stays close to constant.
128 */
129 delta = timespec64_sub(old_system, old_rtc);
130 delta_delta = timespec64_sub(delta, old_delta);
131 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
132 /*
133 * if delta_delta is too large, assume time correction
134 * has occurred and set old_delta to the current delta.
135 */
136 old_delta = delta;
137 } else {
138 /* Otherwise try to adjust old_system to compensate */
139 old_system = timespec64_sub(old_system, delta_delta);
140 }
141
142 return 0;
143 }
144
rtc_resume(struct device * dev)145 static int rtc_resume(struct device *dev)
146 {
147 struct rtc_device *rtc = to_rtc_device(dev);
148 struct rtc_time tm;
149 struct timespec64 new_system, new_rtc;
150 struct timespec64 sleep_time;
151 int err;
152
153 if (timekeeping_rtc_skipresume())
154 return 0;
155
156 rtc_hctosys_ret = -ENODEV;
157 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
158 return 0;
159
160 /* snapshot the current rtc and system time at resume */
161 ktime_get_real_ts64(&new_system);
162 err = rtc_read_time(rtc, &tm);
163 if (err < 0) {
164 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));
165 return 0;
166 }
167
168 new_rtc.tv_sec = rtc_tm_to_time64(&tm);
169 new_rtc.tv_nsec = 0;
170
171 if (new_rtc.tv_sec < old_rtc.tv_sec) {
172 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
173 return 0;
174 }
175
176 /* calculate the RTC time delta (sleep time)*/
177 sleep_time = timespec64_sub(new_rtc, old_rtc);
178
179 /*
180 * Since these RTC suspend/resume handlers are not called
181 * at the very end of suspend or the start of resume,
182 * some run-time may pass on either sides of the sleep time
183 * so subtract kernel run-time between rtc_suspend to rtc_resume
184 * to keep things accurate.
185 */
186 sleep_time = timespec64_sub(sleep_time,
187 timespec64_sub(new_system, old_system));
188
189 if (sleep_time.tv_sec >= 0)
190 timekeeping_inject_sleeptime64(&sleep_time);
191 rtc_hctosys_ret = 0;
192 return 0;
193 }
194
195 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
196 #define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops)
197 #else
198 #define RTC_CLASS_DEV_PM_OPS NULL
199 #endif
200
201 const struct class rtc_class = {
202 .name = "rtc",
203 .pm = RTC_CLASS_DEV_PM_OPS,
204 };
205
206 /* Ensure the caller will set the id before releasing the device */
rtc_allocate_device(void)207 static struct rtc_device *rtc_allocate_device(void)
208 {
209 struct rtc_device *rtc;
210
211 rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
212 if (!rtc)
213 return NULL;
214
215 device_initialize(&rtc->dev);
216
217 /*
218 * Drivers can revise this default after allocating the device.
219 * The default is what most RTCs do: Increment seconds exactly one
220 * second after the write happened. This adds a default transport
221 * time of 5ms which is at least halfways close to reality.
222 */
223 rtc->set_offset_nsec = NSEC_PER_SEC + 5 * NSEC_PER_MSEC;
224
225 rtc->irq_freq = 1;
226 rtc->max_user_freq = 64;
227 rtc->dev.class = &rtc_class;
228 rtc->dev.groups = rtc_get_dev_attribute_groups();
229 rtc->dev.release = rtc_device_release;
230
231 mutex_init(&rtc->ops_lock);
232 spin_lock_init(&rtc->irq_lock);
233 init_waitqueue_head(&rtc->irq_queue);
234
235 /* Init timerqueue */
236 timerqueue_init_head(&rtc->timerqueue);
237 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
238 /* Init aie timer */
239 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc);
240 /* Init uie timer */
241 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc);
242 /* Init pie timer */
243 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
244 rtc->pie_timer.function = rtc_pie_update_irq;
245 rtc->pie_enabled = 0;
246
247 set_bit(RTC_FEATURE_ALARM, rtc->features);
248 set_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
249
250 return rtc;
251 }
252
rtc_device_get_id(struct device * dev)253 static int rtc_device_get_id(struct device *dev)
254 {
255 int of_id = -1, id = -1;
256
257 if (dev->of_node)
258 of_id = of_alias_get_id(dev->of_node, "rtc");
259 else if (dev->parent && dev->parent->of_node)
260 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
261
262 if (of_id >= 0) {
263 id = ida_alloc_range(&rtc_ida, of_id, of_id, GFP_KERNEL);
264 if (id < 0)
265 dev_warn(dev, "/aliases ID %d not available\n", of_id);
266 }
267
268 if (id < 0)
269 id = ida_alloc(&rtc_ida, GFP_KERNEL);
270
271 return id;
272 }
273
rtc_device_get_offset(struct rtc_device * rtc)274 static void rtc_device_get_offset(struct rtc_device *rtc)
275 {
276 time64_t range_secs;
277 u32 start_year;
278 int ret;
279
280 /*
281 * If RTC driver did not implement the range of RTC hardware device,
282 * then we can not expand the RTC range by adding or subtracting one
283 * offset.
284 */
285 if (rtc->range_min == rtc->range_max)
286 return;
287
288 ret = device_property_read_u32(rtc->dev.parent, "start-year",
289 &start_year);
290 if (!ret) {
291 rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
292 rtc->set_start_time = true;
293 }
294
295 /*
296 * If user did not implement the start time for RTC driver, then no
297 * need to expand the RTC range.
298 */
299 if (!rtc->set_start_time)
300 return;
301
302 range_secs = rtc->range_max - rtc->range_min + 1;
303
304 /*
305 * If the start_secs is larger than the maximum seconds (rtc->range_max)
306 * supported by RTC hardware or the maximum seconds of new expanded
307 * range (start_secs + rtc->range_max - rtc->range_min) is less than
308 * rtc->range_min, which means the minimum seconds (rtc->range_min) of
309 * RTC hardware will be mapped to start_secs by adding one offset, so
310 * the offset seconds calculation formula should be:
311 * rtc->offset_secs = rtc->start_secs - rtc->range_min;
312 *
313 * If the start_secs is larger than the minimum seconds (rtc->range_min)
314 * supported by RTC hardware, then there is one region is overlapped
315 * between the original RTC hardware range and the new expanded range,
316 * and this overlapped region do not need to be mapped into the new
317 * expanded range due to it is valid for RTC device. So the minimum
318 * seconds of RTC hardware (rtc->range_min) should be mapped to
319 * rtc->range_max + 1, then the offset seconds formula should be:
320 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
321 *
322 * If the start_secs is less than the minimum seconds (rtc->range_min),
323 * which is similar to case 2. So the start_secs should be mapped to
324 * start_secs + rtc->range_max - rtc->range_min + 1, then the
325 * offset seconds formula should be:
326 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
327 *
328 * Otherwise the offset seconds should be 0.
329 */
330 if (rtc->start_secs > rtc->range_max ||
331 rtc->start_secs + range_secs - 1 < rtc->range_min)
332 rtc->offset_secs = rtc->start_secs - rtc->range_min;
333 else if (rtc->start_secs > rtc->range_min)
334 rtc->offset_secs = range_secs;
335 else if (rtc->start_secs < rtc->range_min)
336 rtc->offset_secs = -range_secs;
337 else
338 rtc->offset_secs = 0;
339 }
340
devm_rtc_unregister_device(void * data)341 static void devm_rtc_unregister_device(void *data)
342 {
343 struct rtc_device *rtc = data;
344
345 mutex_lock(&rtc->ops_lock);
346 /*
347 * Remove innards of this RTC, then disable it, before
348 * letting any rtc_class_open() users access it again
349 */
350 rtc_proc_del_device(rtc);
351 if (!test_bit(RTC_NO_CDEV, &rtc->flags))
352 cdev_device_del(&rtc->char_dev, &rtc->dev);
353 rtc->ops = NULL;
354 mutex_unlock(&rtc->ops_lock);
355 }
356
devm_rtc_release_device(void * res)357 static void devm_rtc_release_device(void *res)
358 {
359 struct rtc_device *rtc = res;
360
361 put_device(&rtc->dev);
362 }
363
devm_rtc_allocate_device(struct device * dev)364 struct rtc_device *devm_rtc_allocate_device(struct device *dev)
365 {
366 struct rtc_device *rtc;
367 int id, err;
368
369 id = rtc_device_get_id(dev);
370 if (id < 0)
371 return ERR_PTR(id);
372
373 rtc = rtc_allocate_device();
374 if (!rtc) {
375 ida_free(&rtc_ida, id);
376 return ERR_PTR(-ENOMEM);
377 }
378
379 rtc->id = id;
380 rtc->dev.parent = dev;
381 err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
382 if (err)
383 return ERR_PTR(err);
384
385 err = dev_set_name(&rtc->dev, "rtc%d", id);
386 if (err)
387 return ERR_PTR(err);
388
389 return rtc;
390 }
391 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
392
__devm_rtc_register_device(struct module * owner,struct rtc_device * rtc)393 int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc)
394 {
395 struct rtc_wkalrm alrm;
396 int err;
397
398 if (!rtc->ops) {
399 dev_dbg(&rtc->dev, "no ops set\n");
400 return -EINVAL;
401 }
402
403 if (!rtc->ops->set_alarm)
404 clear_bit(RTC_FEATURE_ALARM, rtc->features);
405
406 if (rtc->ops->set_offset)
407 set_bit(RTC_FEATURE_CORRECTION, rtc->features);
408
409 rtc->owner = owner;
410 rtc_device_get_offset(rtc);
411
412 /* Check to see if there is an ALARM already set in hw */
413 err = __rtc_read_alarm(rtc, &alrm);
414 if (!err && !rtc_valid_tm(&alrm.time))
415 rtc_initialize_alarm(rtc, &alrm);
416
417 rtc_dev_prepare(rtc);
418
419 err = cdev_device_add(&rtc->char_dev, &rtc->dev);
420 if (err) {
421 set_bit(RTC_NO_CDEV, &rtc->flags);
422 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
423 MAJOR(rtc->dev.devt), rtc->id);
424 } else {
425 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
426 MAJOR(rtc->dev.devt), rtc->id);
427 }
428
429 rtc_proc_add_device(rtc);
430
431 dev_info(rtc->dev.parent, "registered as %s\n",
432 dev_name(&rtc->dev));
433
434 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
435 if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE))
436 rtc_hctosys(rtc);
437 #endif
438
439 return devm_add_action_or_reset(rtc->dev.parent,
440 devm_rtc_unregister_device, rtc);
441 }
442 EXPORT_SYMBOL_GPL(__devm_rtc_register_device);
443
444 /**
445 * devm_rtc_device_register - resource managed rtc_device_register()
446 * @dev: the device to register
447 * @name: the name of the device (unused)
448 * @ops: the rtc operations structure
449 * @owner: the module owner
450 *
451 * @return a struct rtc on success, or an ERR_PTR on error
452 *
453 * Managed rtc_device_register(). The rtc_device returned from this function
454 * are automatically freed on driver detach.
455 * This function is deprecated, use devm_rtc_allocate_device and
456 * rtc_register_device instead
457 */
devm_rtc_device_register(struct device * dev,const char * name,const struct rtc_class_ops * ops,struct module * owner)458 struct rtc_device *devm_rtc_device_register(struct device *dev,
459 const char *name,
460 const struct rtc_class_ops *ops,
461 struct module *owner)
462 {
463 struct rtc_device *rtc;
464 int err;
465
466 rtc = devm_rtc_allocate_device(dev);
467 if (IS_ERR(rtc))
468 return rtc;
469
470 rtc->ops = ops;
471
472 err = __devm_rtc_register_device(owner, rtc);
473 if (err)
474 return ERR_PTR(err);
475
476 return rtc;
477 }
478 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
479
rtc_init(void)480 static int __init rtc_init(void)
481 {
482 int err;
483
484 err = class_register(&rtc_class);
485 if (err)
486 return err;
487
488 rtc_dev_init();
489
490 return 0;
491 }
492 subsys_initcall(rtc_init);
493