projects/linux·blob v6.2 · refs

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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);
24struct class *rtc_class;
25
26static void rtc_device_release(struct device *dev)
27{
28 struct rtc_device *rtc = to_rtc_device(dev);
29 struct timerqueue_head *head = &rtc->timerqueue;
30 struct timerqueue_node *node;
31
32 mutex_lock(&rtc->ops_lock);
33 while ((node = timerqueue_getnext(head)))
34 timerqueue_del(head, node);
35 mutex_unlock(&rtc->ops_lock);
36
37 cancel_work_sync(&rtc->irqwork);
38
39 ida_free(&rtc_ida, rtc->id);
40 mutex_destroy(&rtc->ops_lock);
41 kfree(rtc);
42}
43
44#ifdef CONFIG_RTC_HCTOSYS_DEVICE
45/* Result of the last RTC to system clock attempt. */
46int rtc_hctosys_ret = -ENODEV;
47
48/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
49 * whether it stores the most close value or the value with partial
50 * seconds truncated. However, it is important that we use it to store
51 * the truncated value. This is because otherwise it is necessary,
52 * in an rtc sync function, to read both xtime.tv_sec and
53 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
54 * of >32bits is not possible. So storing the most close value would
55 * slow down the sync API. So here we have the truncated value and
56 * the best guess is to add 0.5s.
57 */
58
59static void rtc_hctosys(struct rtc_device *rtc)
60{
61 int err;
62 struct rtc_time tm;
63 struct timespec64 tv64 = {
64 .tv_nsec = NSEC_PER_SEC >> 1,
65 };
66
67 err = rtc_read_time(rtc, &tm);
68 if (err) {
69 dev_err(rtc->dev.parent,
70 "hctosys: unable to read the hardware clock\n");
71 goto err_read;
72 }
73
74 tv64.tv_sec = rtc_tm_to_time64(&tm);
75
76#if BITS_PER_LONG == 32
77 if (tv64.tv_sec > INT_MAX) {
78 err = -ERANGE;
79 goto err_read;
80 }
81#endif
82
83 err = do_settimeofday64(&tv64);
84
85 dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n",
86 &tm, (long long)tv64.tv_sec);
87
88err_read:
89 rtc_hctosys_ret = err;
90}
91#endif
92
93#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
94/*
95 * On suspend(), measure the delta between one RTC and the
96 * system's wall clock; restore it on resume().
97 */
98
99static struct timespec64 old_rtc, old_system, old_delta;
100
101static int rtc_suspend(struct device *dev)
102{
103 struct rtc_device *rtc = to_rtc_device(dev);
104 struct rtc_time tm;
105 struct timespec64 delta, delta_delta;
106 int err;
107
108 if (timekeeping_rtc_skipsuspend())
109 return 0;
110
111 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
112 return 0;
113
114 /* snapshot the current RTC and system time at suspend*/
115 err = rtc_read_time(rtc, &tm);
116 if (err < 0) {
117 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));
118 return 0;
119 }
120
121 ktime_get_real_ts64(&old_system);
122 old_rtc.tv_sec = rtc_tm_to_time64(&tm);
123
124 /*
125 * To avoid drift caused by repeated suspend/resumes,
126 * which each can add ~1 second drift error,
127 * try to compensate so the difference in system time
128 * and rtc time stays close to constant.
129 */
130 delta = timespec64_sub(old_system, old_rtc);
131 delta_delta = timespec64_sub(delta, old_delta);
132 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
133 /*
134 * if delta_delta is too large, assume time correction
135 * has occurred and set old_delta to the current delta.
136 */
137 old_delta = delta;
138 } else {
139 /* Otherwise try to adjust old_system to compensate */
140 old_system = timespec64_sub(old_system, delta_delta);
141 }
142
143 return 0;
144}
145
146static int rtc_resume(struct device *dev)
147{
148 struct rtc_device *rtc = to_rtc_device(dev);
149 struct rtc_time tm;
150 struct timespec64 new_system, new_rtc;
151 struct timespec64 sleep_time;
152 int err;
153
154 if (timekeeping_rtc_skipresume())
155 return 0;
156
157 rtc_hctosys_ret = -ENODEV;
158 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
159 return 0;
160
161 /* snapshot the current rtc and system time at resume */
162 ktime_get_real_ts64(&new_system);
163 err = rtc_read_time(rtc, &tm);
164 if (err < 0) {
165 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));
166 return 0;
167 }
168
169 new_rtc.tv_sec = rtc_tm_to_time64(&tm);
170 new_rtc.tv_nsec = 0;
171
172 if (new_rtc.tv_sec < old_rtc.tv_sec) {
173 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
174 return 0;
175 }
176
177 /* calculate the RTC time delta (sleep time)*/
178 sleep_time = timespec64_sub(new_rtc, old_rtc);
179
180 /*
181 * Since these RTC suspend/resume handlers are not called
182 * at the very end of suspend or the start of resume,
183 * some run-time may pass on either sides of the sleep time
184 * so subtract kernel run-time between rtc_suspend to rtc_resume
185 * to keep things accurate.
186 */
187 sleep_time = timespec64_sub(sleep_time,
188 timespec64_sub(new_system, old_system));
189
190 if (sleep_time.tv_sec >= 0)
191 timekeeping_inject_sleeptime64(&sleep_time);
192 rtc_hctosys_ret = 0;
193 return 0;
194}
195
196static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
197#define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops)
198#else
199#define RTC_CLASS_DEV_PM_OPS NULL
200#endif
201
202/* Ensure the caller will set the id before releasing the device */
203static struct rtc_device *rtc_allocate_device(void)
204{
205 struct rtc_device *rtc;
206
207 rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
208 if (!rtc)
209 return NULL;
210
211 device_initialize(&rtc->dev);
212
213 /*
214 * Drivers can revise this default after allocating the device.
215 * The default is what most RTCs do: Increment seconds exactly one
216 * second after the write happened. This adds a default transport
217 * time of 5ms which is at least halfways close to reality.
218 */
219 rtc->set_offset_nsec = NSEC_PER_SEC + 5 * NSEC_PER_MSEC;
220
221 rtc->irq_freq = 1;
222 rtc->max_user_freq = 64;
223 rtc->dev.class = rtc_class;
224 rtc->dev.groups = rtc_get_dev_attribute_groups();
225 rtc->dev.release = rtc_device_release;
226
227 mutex_init(&rtc->ops_lock);
228 spin_lock_init(&rtc->irq_lock);
229 init_waitqueue_head(&rtc->irq_queue);
230
231 /* Init timerqueue */
232 timerqueue_init_head(&rtc->timerqueue);
233 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
234 /* Init aie timer */
235 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc);
236 /* Init uie timer */
237 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc);
238 /* Init pie timer */
239 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
240 rtc->pie_timer.function = rtc_pie_update_irq;
241 rtc->pie_enabled = 0;
242
243 set_bit(RTC_FEATURE_ALARM, rtc->features);
244 set_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
245
246 return rtc;
247}
248
249static int rtc_device_get_id(struct device *dev)
250{
251 int of_id = -1, id = -1;
252
253 if (dev->of_node)
254 of_id = of_alias_get_id(dev->of_node, "rtc");
255 else if (dev->parent && dev->parent->of_node)
256 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
257
258 if (of_id >= 0) {
259 id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
260 if (id < 0)
261 dev_warn(dev, "/aliases ID %d not available\n", of_id);
262 }
263
264 if (id < 0)
265 id = ida_alloc(&rtc_ida, GFP_KERNEL);
266
267 return id;
268}
269
270static void rtc_device_get_offset(struct rtc_device *rtc)
271{
272 time64_t range_secs;
273 u32 start_year;
274 int ret;
275
276 /*
277 * If RTC driver did not implement the range of RTC hardware device,
278 * then we can not expand the RTC range by adding or subtracting one
279 * offset.
280 */
281 if (rtc->range_min == rtc->range_max)
282 return;
283
284 ret = device_property_read_u32(rtc->dev.parent, "start-year",
285 &start_year);
286 if (!ret) {
287 rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
288 rtc->set_start_time = true;
289 }
290
291 /*
292 * If user did not implement the start time for RTC driver, then no
293 * need to expand the RTC range.
294 */
295 if (!rtc->set_start_time)
296 return;
297
298 range_secs = rtc->range_max - rtc->range_min + 1;
299
300 /*
301 * If the start_secs is larger than the maximum seconds (rtc->range_max)
302 * supported by RTC hardware or the maximum seconds of new expanded
303 * range (start_secs + rtc->range_max - rtc->range_min) is less than
304 * rtc->range_min, which means the minimum seconds (rtc->range_min) of
305 * RTC hardware will be mapped to start_secs by adding one offset, so
306 * the offset seconds calculation formula should be:
307 * rtc->offset_secs = rtc->start_secs - rtc->range_min;
308 *
309 * If the start_secs is larger than the minimum seconds (rtc->range_min)
310 * supported by RTC hardware, then there is one region is overlapped
311 * between the original RTC hardware range and the new expanded range,
312 * and this overlapped region do not need to be mapped into the new
313 * expanded range due to it is valid for RTC device. So the minimum
314 * seconds of RTC hardware (rtc->range_min) should be mapped to
315 * rtc->range_max + 1, then the offset seconds formula should be:
316 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
317 *
318 * If the start_secs is less than the minimum seconds (rtc->range_min),
319 * which is similar to case 2. So the start_secs should be mapped to
320 * start_secs + rtc->range_max - rtc->range_min + 1, then the
321 * offset seconds formula should be:
322 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
323 *
324 * Otherwise the offset seconds should be 0.
325 */
326 if (rtc->start_secs > rtc->range_max ||
327 rtc->start_secs + range_secs - 1 < rtc->range_min)
328 rtc->offset_secs = rtc->start_secs - rtc->range_min;
329 else if (rtc->start_secs > rtc->range_min)
330 rtc->offset_secs = range_secs;
331 else if (rtc->start_secs < rtc->range_min)
332 rtc->offset_secs = -range_secs;
333 else
334 rtc->offset_secs = 0;
335}
336
337static void devm_rtc_unregister_device(void *data)
338{
339 struct rtc_device *rtc = data;
340
341 mutex_lock(&rtc->ops_lock);
342 /*
343 * Remove innards of this RTC, then disable it, before
344 * letting any rtc_class_open() users access it again
345 */
346 rtc_proc_del_device(rtc);
347 if (!test_bit(RTC_NO_CDEV, &rtc->flags))
348 cdev_device_del(&rtc->char_dev, &rtc->dev);
349 rtc->ops = NULL;
350 mutex_unlock(&rtc->ops_lock);
351}
352
353static void devm_rtc_release_device(void *res)
354{
355 struct rtc_device *rtc = res;
356
357 put_device(&rtc->dev);
358}
359
360struct rtc_device *devm_rtc_allocate_device(struct device *dev)
361{
362 struct rtc_device *rtc;
363 int id, err;
364
365 id = rtc_device_get_id(dev);
366 if (id < 0)
367 return ERR_PTR(id);
368
369 rtc = rtc_allocate_device();
370 if (!rtc) {
371 ida_free(&rtc_ida, id);
372 return ERR_PTR(-ENOMEM);
373 }
374
375 rtc->id = id;
376 rtc->dev.parent = dev;
377 err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
378 if (err)
379 return ERR_PTR(err);
380
381 err = dev_set_name(&rtc->dev, "rtc%d", id);
382 if (err)
383 return ERR_PTR(err);
384
385 return rtc;
386}
387EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
388
389int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc)
390{
391 struct rtc_wkalrm alrm;
392 int err;
393
394 if (!rtc->ops) {
395 dev_dbg(&rtc->dev, "no ops set\n");
396 return -EINVAL;
397 }
398
399 if (!rtc->ops->set_alarm)
400 clear_bit(RTC_FEATURE_ALARM, rtc->features);
401
402 if (rtc->ops->set_offset)
403 set_bit(RTC_FEATURE_CORRECTION, rtc->features);
404
405 rtc->owner = owner;
406 rtc_device_get_offset(rtc);
407
408 /* Check to see if there is an ALARM already set in hw */
409 err = __rtc_read_alarm(rtc, &alrm);
410 if (!err && !rtc_valid_tm(&alrm.time))
411 rtc_initialize_alarm(rtc, &alrm);
412
413 rtc_dev_prepare(rtc);
414
415 err = cdev_device_add(&rtc->char_dev, &rtc->dev);
416 if (err) {
417 set_bit(RTC_NO_CDEV, &rtc->flags);
418 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
419 MAJOR(rtc->dev.devt), rtc->id);
420 } else {
421 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
422 MAJOR(rtc->dev.devt), rtc->id);
423 }
424
425 rtc_proc_add_device(rtc);
426
427 dev_info(rtc->dev.parent, "registered as %s\n",
428 dev_name(&rtc->dev));
429
430#ifdef CONFIG_RTC_HCTOSYS_DEVICE
431 if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE))
432 rtc_hctosys(rtc);
433#endif
434
435 return devm_add_action_or_reset(rtc->dev.parent,
436 devm_rtc_unregister_device, rtc);
437}
438EXPORT_SYMBOL_GPL(__devm_rtc_register_device);
439
440/**
441 * devm_rtc_device_register - resource managed rtc_device_register()
442 * @dev: the device to register
443 * @name: the name of the device (unused)
444 * @ops: the rtc operations structure
445 * @owner: the module owner
446 *
447 * @return a struct rtc on success, or an ERR_PTR on error
448 *
449 * Managed rtc_device_register(). The rtc_device returned from this function
450 * are automatically freed on driver detach.
451 * This function is deprecated, use devm_rtc_allocate_device and
452 * rtc_register_device instead
453 */
454struct rtc_device *devm_rtc_device_register(struct device *dev,
455 const char *name,
456 const struct rtc_class_ops *ops,
457 struct module *owner)
458{
459 struct rtc_device *rtc;
460 int err;
461
462 rtc = devm_rtc_allocate_device(dev);
463 if (IS_ERR(rtc))
464 return rtc;
465
466 rtc->ops = ops;
467
468 err = __devm_rtc_register_device(owner, rtc);
469 if (err)
470 return ERR_PTR(err);
471
472 return rtc;
473}
474EXPORT_SYMBOL_GPL(devm_rtc_device_register);
475
476static int __init rtc_init(void)
477{
478 rtc_class = class_create(THIS_MODULE, "rtc");
479 if (IS_ERR(rtc_class)) {
480 pr_err("couldn't create class\n");
481 return PTR_ERR(rtc_class);
482 }
483 rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
484 rtc_dev_init();
485 return 0;
486}
487subsys_initcall(rtc_init);