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