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 | struct class *rtc_class; |
25 | |
26 | static 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(lock: &rtc->ops_lock); |
36 | |
37 | cancel_work_sync(work: &rtc->irqwork); |
38 | |
39 | ida_free(&rtc_ida, id: rtc->id); |
40 | mutex_destroy(lock: &rtc->ops_lock); |
41 | kfree(objp: rtc); |
42 | } |
43 | |
44 | #ifdef CONFIG_RTC_HCTOSYS_DEVICE |
45 | /* Result of the last RTC to system clock attempt. */ |
46 | int 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 | |
59 | static 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: &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: &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(ts: &tv64); |
84 | |
85 | dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n" , |
86 | &tm, (long long)tv64.tv_sec); |
87 | |
88 | err_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 | |
99 | static struct timespec64 old_rtc, old_system, old_delta; |
100 | |
101 | static 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(dev: &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: &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(tv: &old_system); |
122 | old_rtc.tv_sec = rtc_tm_to_time64(tm: &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(lhs: old_system, rhs: old_rtc); |
131 | delta_delta = timespec64_sub(lhs: delta, rhs: 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(lhs: old_system, rhs: delta_delta); |
141 | } |
142 | |
143 | return 0; |
144 | } |
145 | |
146 | static 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(dev: &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(tv: &new_system); |
163 | err = rtc_read_time(rtc, tm: &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: &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(lhs: new_rtc, rhs: 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(lhs: sleep_time, |
188 | rhs: timespec64_sub(lhs: new_system, rhs: old_system)); |
189 | |
190 | if (sleep_time.tv_sec >= 0) |
191 | timekeeping_inject_sleeptime64(delta: &sleep_time); |
192 | rtc_hctosys_ret = 0; |
193 | return 0; |
194 | } |
195 | |
196 | static 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 */ |
203 | static struct rtc_device *rtc_allocate_device(void) |
204 | { |
205 | struct rtc_device *rtc; |
206 | |
207 | rtc = kzalloc(size: sizeof(*rtc), GFP_KERNEL); |
208 | if (!rtc) |
209 | return NULL; |
210 | |
211 | device_initialize(dev: &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(head: &rtc->timerqueue); |
233 | INIT_WORK(&rtc->irqwork, rtc_timer_do_work); |
234 | /* Init aie timer */ |
235 | rtc_timer_init(timer: &rtc->aie_timer, f: rtc_aie_update_irq, rtc); |
236 | /* Init uie timer */ |
237 | rtc_timer_init(timer: &rtc->uie_rtctimer, f: rtc_uie_update_irq, rtc); |
238 | /* Init pie timer */ |
239 | hrtimer_init(timer: &rtc->pie_timer, CLOCK_MONOTONIC, mode: HRTIMER_MODE_REL); |
240 | rtc->pie_timer.function = rtc_pie_update_irq; |
241 | rtc->pie_enabled = 0; |
242 | |
243 | set_bit(RTC_FEATURE_ALARM, addr: rtc->features); |
244 | set_bit(RTC_FEATURE_UPDATE_INTERRUPT, addr: rtc->features); |
245 | |
246 | return rtc; |
247 | } |
248 | |
249 | static 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(np: dev->of_node, stem: "rtc" ); |
255 | else if (dev->parent && dev->parent->of_node) |
256 | of_id = of_alias_get_id(np: dev->parent->of_node, stem: "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(ida: &rtc_ida, GFP_KERNEL); |
266 | |
267 | return id; |
268 | } |
269 | |
270 | static 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(dev: rtc->dev.parent, propname: "start-year" , |
285 | val: &start_year); |
286 | if (!ret) { |
287 | rtc->start_secs = mktime64(year: start_year, mon: 1, day: 1, hour: 0, min: 0, sec: 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 | |
337 | static 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(cdev: &rtc->char_dev, dev: &rtc->dev); |
349 | rtc->ops = NULL; |
350 | mutex_unlock(lock: &rtc->ops_lock); |
351 | } |
352 | |
353 | static void devm_rtc_release_device(void *res) |
354 | { |
355 | struct rtc_device *rtc = res; |
356 | |
357 | put_device(dev: &rtc->dev); |
358 | } |
359 | |
360 | struct 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(error: id); |
368 | |
369 | rtc = rtc_allocate_device(); |
370 | if (!rtc) { |
371 | ida_free(&rtc_ida, id); |
372 | return ERR_PTR(error: -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(error: err); |
380 | |
381 | err = dev_set_name(dev: &rtc->dev, name: "rtc%d" , id); |
382 | if (err) |
383 | return ERR_PTR(error: err); |
384 | |
385 | return rtc; |
386 | } |
387 | EXPORT_SYMBOL_GPL(devm_rtc_allocate_device); |
388 | |
389 | int __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, addr: rtc->features); |
401 | |
402 | if (rtc->ops->set_offset) |
403 | set_bit(RTC_FEATURE_CORRECTION, addr: 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, alarm: &alrm); |
410 | if (!err && !rtc_valid_tm(tm: &alrm.time)) |
411 | rtc_initialize_alarm(rtc, alrm: &alrm); |
412 | |
413 | rtc_dev_prepare(rtc); |
414 | |
415 | err = cdev_device_add(cdev: &rtc->char_dev, dev: &rtc->dev); |
416 | if (err) { |
417 | set_bit(RTC_NO_CDEV, addr: &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(dev: &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 | } |
438 | EXPORT_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 | */ |
454 | struct 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(ptr: 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(error: err); |
471 | |
472 | return rtc; |
473 | } |
474 | EXPORT_SYMBOL_GPL(devm_rtc_device_register); |
475 | |
476 | static int __init rtc_init(void) |
477 | { |
478 | rtc_class = class_create(name: "rtc" ); |
479 | if (IS_ERR(ptr: rtc_class)) { |
480 | pr_err("couldn't create class\n" ); |
481 | return PTR_ERR(ptr: rtc_class); |
482 | } |
483 | rtc_class->pm = RTC_CLASS_DEV_PM_OPS; |
484 | rtc_dev_init(); |
485 | return 0; |
486 | } |
487 | subsys_initcall(rtc_init); |
488 | |