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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * RTC subsystem, base class
4 *
5 * Copyright (C) 2005 Tower Technologies
6 * Author: Alessandro Zummo <[email protected]>
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
23static DEFINE_IDA(rtc_ida);
24
25static 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. */
45int 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
58static 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
87err_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
98static struct timespec64 old_rtc, old_system, old_delta;
99
100static 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
145static 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
195static 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
201const 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 */
207static struct rtc_device *rtc_allocate_device(void)
208{
209 struct rtc_device *rtc;
210
211 rtc = kzalloc_obj(*rtc);
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_setup(&rtc->pie_timer, rtc_pie_update_irq, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
244 rtc->pie_enabled = 0;
245
246 set_bit(RTC_FEATURE_ALARM, rtc->features);
247 set_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
248
249 return rtc;
250}
251
252static int rtc_device_get_id(struct device *dev)
253{
254 int of_id = -1, id = -1;
255
256 if (dev->of_node)
257 of_id = of_alias_get_id(dev->of_node, "rtc");
258 else if (dev->parent && dev->parent->of_node)
259 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
260
261 if (of_id >= 0) {
262 id = ida_alloc_range(&rtc_ida, of_id, of_id, GFP_KERNEL);
263 if (id < 0)
264 dev_warn(dev, "/aliases ID %d not available\n", of_id);
265 }
266
267 if (id < 0)
268 id = ida_alloc(&rtc_ida, GFP_KERNEL);
269
270 return id;
271}
272
273static void rtc_device_get_offset(struct rtc_device *rtc)
274{
275 time64_t range_secs;
276 u32 start_year;
277 int ret;
278
279 /*
280 * If RTC driver did not implement the range of RTC hardware device,
281 * then we can not expand the RTC range by adding or subtracting one
282 * offset.
283 */
284 if (rtc->range_min == rtc->range_max)
285 return;
286
287 ret = device_property_read_u32(rtc->dev.parent, "start-year",
288 &start_year);
289 if (!ret) {
290 rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
291 rtc->set_start_time = true;
292 }
293
294 /*
295 * If user did not implement the start time for RTC driver, then no
296 * need to expand the RTC range.
297 */
298 if (!rtc->set_start_time)
299 return;
300
301 range_secs = rtc->range_max - rtc->range_min + 1;
302
303 /*
304 * If the start_secs is larger than the maximum seconds (rtc->range_max)
305 * supported by RTC hardware or the maximum seconds of new expanded
306 * range (start_secs + rtc->range_max - rtc->range_min) is less than
307 * rtc->range_min, which means the minimum seconds (rtc->range_min) of
308 * RTC hardware will be mapped to start_secs by adding one offset, so
309 * the offset seconds calculation formula should be:
310 * rtc->offset_secs = rtc->start_secs - rtc->range_min;
311 *
312 * If the start_secs is larger than the minimum seconds (rtc->range_min)
313 * supported by RTC hardware, then there is one region is overlapped
314 * between the original RTC hardware range and the new expanded range,
315 * and this overlapped region do not need to be mapped into the new
316 * expanded range due to it is valid for RTC device. So the minimum
317 * seconds of RTC hardware (rtc->range_min) should be mapped to
318 * rtc->range_max + 1, then the offset seconds formula should be:
319 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
320 *
321 * If the start_secs is less than the minimum seconds (rtc->range_min),
322 * which is similar to case 2. So the start_secs should be mapped to
323 * start_secs + rtc->range_max - rtc->range_min + 1, then the
324 * offset seconds formula should be:
325 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
326 *
327 * Otherwise the offset seconds should be 0.
328 */
329 if ((rtc->start_secs >= 0 && rtc->start_secs > rtc->range_max) ||
330 rtc->start_secs + range_secs - 1 < rtc->range_min)
331 rtc->offset_secs = rtc->start_secs - rtc->range_min;
332 else if (rtc->start_secs > rtc->range_min)
333 rtc->offset_secs = range_secs;
334 else if (rtc->start_secs < rtc->range_min)
335 rtc->offset_secs = -range_secs;
336 else
337 rtc->offset_secs = 0;
338}
339
340static void devm_rtc_unregister_device(void *data)
341{
342 struct rtc_device *rtc = data;
343
344 mutex_lock(&rtc->ops_lock);
345 /*
346 * Remove innards of this RTC, then disable it, before
347 * letting any rtc_class_open() users access it again
348 */
349 rtc_proc_del_device(rtc);
350 if (!test_bit(RTC_NO_CDEV, &rtc->flags))
351 cdev_device_del(&rtc->char_dev, &rtc->dev);
352 rtc->ops = NULL;
353 mutex_unlock(&rtc->ops_lock);
354}
355
356static void devm_rtc_release_device(void *res)
357{
358 struct rtc_device *rtc = res;
359
360 put_device(&rtc->dev);
361}
362
363struct rtc_device *devm_rtc_allocate_device(struct device *dev)
364{
365 struct rtc_device *rtc;
366 int id, err;
367
368 id = rtc_device_get_id(dev);
369 if (id < 0)
370 return ERR_PTR(id);
371
372 rtc = rtc_allocate_device();
373 if (!rtc) {
374 ida_free(&rtc_ida, id);
375 return ERR_PTR(-ENOMEM);
376 }
377
378 rtc->id = id;
379 rtc->dev.parent = dev;
380 err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
381 if (err)
382 return ERR_PTR(err);
383
384 err = dev_set_name(&rtc->dev, "rtc%d", id);
385 if (err)
386 return ERR_PTR(err);
387
388 return rtc;
389}
390EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
391
392int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc)
393{
394 struct rtc_wkalrm alrm;
395 int err;
396
397 if (!rtc->ops) {
398 dev_dbg(&rtc->dev, "no ops set\n");
399 return -EINVAL;
400 }
401
402 if (!rtc->ops->set_alarm)
403 clear_bit(RTC_FEATURE_ALARM, rtc->features);
404
405 if (rtc->ops->set_offset)
406 set_bit(RTC_FEATURE_CORRECTION, rtc->features);
407
408 rtc->owner = owner;
409 rtc_device_get_offset(rtc);
410
411 /* Check to see if there is an ALARM already set in hw */
412 err = __rtc_read_alarm(rtc, &alrm);
413 if (!err)
414 rtc_initialize_alarm(rtc, &alrm);
415
416 rtc_dev_prepare(rtc);
417
418 err = cdev_device_add(&rtc->char_dev, &rtc->dev);
419 if (err) {
420 set_bit(RTC_NO_CDEV, &rtc->flags);
421 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
422 MAJOR(rtc->dev.devt), rtc->id);
423 } else {
424 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
425 MAJOR(rtc->dev.devt), rtc->id);
426 }
427
428 rtc_proc_add_device(rtc);
429
430 dev_info(rtc->dev.parent, "registered as %s\n",
431 dev_name(&rtc->dev));
432
433#ifdef CONFIG_RTC_HCTOSYS_DEVICE
434 if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE))
435 rtc_hctosys(rtc);
436#endif
437
438 return devm_add_action_or_reset(rtc->dev.parent,
439 devm_rtc_unregister_device, rtc);
440}
441EXPORT_SYMBOL_GPL(__devm_rtc_register_device);
442
443/**
444 * devm_rtc_device_register - resource managed rtc_device_register()
445 * @dev: the device to register
446 * @name: the name of the device (unused)
447 * @ops: the rtc operations structure
448 * @owner: the module owner
449 *
450 * @return a struct rtc on success, or an ERR_PTR on error
451 *
452 * Managed rtc_device_register(). The rtc_device returned from this function
453 * are automatically freed on driver detach.
454 * This function is deprecated, use devm_rtc_allocate_device and
455 * rtc_register_device instead
456 */
457struct rtc_device *devm_rtc_device_register(struct device *dev,
458 const char *name,
459 const struct rtc_class_ops *ops,
460 struct module *owner)
461{
462 struct rtc_device *rtc;
463 int err;
464
465 rtc = devm_rtc_allocate_device(dev);
466 if (IS_ERR(rtc))
467 return rtc;
468
469 rtc->ops = ops;
470
471 err = __devm_rtc_register_device(owner, rtc);
472 if (err)
473 return ERR_PTR(err);
474
475 return rtc;
476}
477EXPORT_SYMBOL_GPL(devm_rtc_device_register);
478
479static int __init rtc_init(void)
480{
481 int err;
482
483 err = class_register(&rtc_class);
484 if (err)
485 return err;
486
487 rtc_dev_init();
488
489 return 0;
490}
491subsys_initcall(rtc_init);