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 | |
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(lock: &rtc->ops_lock); |
35 | |
36 | cancel_work_sync(work: &rtc->irqwork); |
37 | |
38 | ida_free(&rtc_ida, id: rtc->id); |
39 | mutex_destroy(lock: &rtc->ops_lock); |
40 | kfree(objp: 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 | |
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: &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: &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(ts: &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 | |
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(dev: &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: &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(tv: &old_system); |
121 | old_rtc.tv_sec = rtc_tm_to_time64(tm: &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(lhs: old_system, rhs: old_rtc); |
130 | delta_delta = timespec64_sub(lhs: delta, rhs: 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(lhs: old_system, rhs: delta_delta); |
140 | } |
141 | |
142 | return 0; |
143 | } |
144 | |
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(dev: &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(tv: &new_system); |
162 | err = rtc_read_time(rtc, tm: &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: &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(lhs: new_rtc, rhs: 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(lhs: sleep_time, |
187 | rhs: timespec64_sub(lhs: new_system, rhs: old_system)); |
188 | |
189 | if (sleep_time.tv_sec >= 0) |
190 | timekeeping_inject_sleeptime64(delta: &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 */ |
207 | static struct rtc_device *rtc_allocate_device(void) |
208 | { |
209 | struct rtc_device *rtc; |
210 | |
211 | rtc = kzalloc(size: sizeof(*rtc), GFP_KERNEL); |
212 | if (!rtc) |
213 | return NULL; |
214 | |
215 | device_initialize(dev: &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(head: &rtc->timerqueue); |
237 | INIT_WORK(&rtc->irqwork, rtc_timer_do_work); |
238 | /* Init aie timer */ |
239 | rtc_timer_init(timer: &rtc->aie_timer, f: rtc_aie_update_irq, rtc); |
240 | /* Init uie timer */ |
241 | rtc_timer_init(timer: &rtc->uie_rtctimer, f: rtc_uie_update_irq, rtc); |
242 | /* Init pie timer */ |
243 | hrtimer_init(timer: &rtc->pie_timer, CLOCK_MONOTONIC, mode: HRTIMER_MODE_REL); |
244 | rtc->pie_timer.function = rtc_pie_update_irq; |
245 | rtc->pie_enabled = 0; |
246 | |
247 | set_bit(RTC_FEATURE_ALARM, addr: rtc->features); |
248 | set_bit(RTC_FEATURE_UPDATE_INTERRUPT, addr: rtc->features); |
249 | |
250 | return rtc; |
251 | } |
252 | |
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(np: dev->of_node, stem: "rtc" ); |
259 | else if (dev->parent && dev->parent->of_node) |
260 | of_id = of_alias_get_id(np: dev->parent->of_node, stem: "rtc" ); |
261 | |
262 | if (of_id >= 0) { |
263 | id = ida_alloc_range(&rtc_ida, min: of_id, max: 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(ida: &rtc_ida, GFP_KERNEL); |
270 | |
271 | return id; |
272 | } |
273 | |
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(dev: rtc->dev.parent, propname: "start-year" , |
289 | val: &start_year); |
290 | if (!ret) { |
291 | rtc->start_secs = mktime64(year: start_year, mon: 1, day: 1, hour: 0, min: 0, sec: 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 | |
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(cdev: &rtc->char_dev, dev: &rtc->dev); |
353 | rtc->ops = NULL; |
354 | mutex_unlock(lock: &rtc->ops_lock); |
355 | } |
356 | |
357 | static void devm_rtc_release_device(void *res) |
358 | { |
359 | struct rtc_device *rtc = res; |
360 | |
361 | put_device(dev: &rtc->dev); |
362 | } |
363 | |
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(error: id); |
372 | |
373 | rtc = rtc_allocate_device(); |
374 | if (!rtc) { |
375 | ida_free(&rtc_ida, id); |
376 | return ERR_PTR(error: -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(error: err); |
384 | |
385 | err = dev_set_name(dev: &rtc->dev, name: "rtc%d" , id); |
386 | if (err) |
387 | return ERR_PTR(error: err); |
388 | |
389 | return rtc; |
390 | } |
391 | EXPORT_SYMBOL_GPL(devm_rtc_allocate_device); |
392 | |
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, addr: rtc->features); |
405 | |
406 | if (rtc->ops->set_offset) |
407 | set_bit(RTC_FEATURE_CORRECTION, addr: 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, alarm: &alrm); |
414 | if (!err && !rtc_valid_tm(tm: &alrm.time)) |
415 | rtc_initialize_alarm(rtc, alrm: &alrm); |
416 | |
417 | rtc_dev_prepare(rtc); |
418 | |
419 | err = cdev_device_add(cdev: &rtc->char_dev, dev: &rtc->dev); |
420 | if (err) { |
421 | set_bit(RTC_NO_CDEV, addr: &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(dev: &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 | */ |
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(ptr: 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(error: err); |
475 | |
476 | return rtc; |
477 | } |
478 | EXPORT_SYMBOL_GPL(devm_rtc_device_register); |
479 | |
480 | static int __init rtc_init(void) |
481 | { |
482 | int err; |
483 | |
484 | err = class_register(class: &rtc_class); |
485 | if (err) |
486 | return err; |
487 | |
488 | rtc_dev_init(); |
489 | |
490 | return 0; |
491 | } |
492 | subsys_initcall(rtc_init); |
493 | |