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