projects/linux·blob v4.2 · refs

382 lines · 9.3 KiB

1/*
2 * RTC subsystem, base class
3 *
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <[email protected]>
6 *
7 * class skeleton from drivers/hwmon/hwmon.c
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12*/
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/of.h>
18#include <linux/rtc.h>
19#include <linux/kdev_t.h>
20#include <linux/idr.h>
21#include <linux/slab.h>
22#include <linux/workqueue.h>
23
24#include "rtc-core.h"
25
26
27static DEFINE_IDA(rtc_ida);
28struct class *rtc_class;
29
30static void rtc_device_release(struct device *dev)
31{
32 struct rtc_device *rtc = to_rtc_device(dev);
33 ida_simple_remove(&rtc_ida, rtc->id);
34 kfree(rtc);
35}
36
37#ifdef CONFIG_RTC_HCTOSYS_DEVICE
38/* Result of the last RTC to system clock attempt. */
39int rtc_hctosys_ret = -ENODEV;
40#endif
41
42#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
43/*
44 * On suspend(), measure the delta between one RTC and the
45 * system's wall clock; restore it on resume().
46 */
47
48static struct timespec64 old_rtc, old_system, old_delta;
49
50
51static int rtc_suspend(struct device *dev)
52{
53 struct rtc_device *rtc = to_rtc_device(dev);
54 struct rtc_time tm;
55 struct timespec64 delta, delta_delta;
56 int err;
57
58 if (timekeeping_rtc_skipsuspend())
59 return 0;
60
61 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
62 return 0;
63
64 /* snapshot the current RTC and system time at suspend*/
65 err = rtc_read_time(rtc, &tm);
66 if (err < 0) {
67 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));
68 return 0;
69 }
70
71 getnstimeofday64(&old_system);
72 old_rtc.tv_sec = rtc_tm_to_time64(&tm);
73
74
75 /*
76 * To avoid drift caused by repeated suspend/resumes,
77 * which each can add ~1 second drift error,
78 * try to compensate so the difference in system time
79 * and rtc time stays close to constant.
80 */
81 delta = timespec64_sub(old_system, old_rtc);
82 delta_delta = timespec64_sub(delta, old_delta);
83 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
84 /*
85 * if delta_delta is too large, assume time correction
86 * has occured and set old_delta to the current delta.
87 */
88 old_delta = delta;
89 } else {
90 /* Otherwise try to adjust old_system to compensate */
91 old_system = timespec64_sub(old_system, delta_delta);
92 }
93
94 return 0;
95}
96
97static int rtc_resume(struct device *dev)
98{
99 struct rtc_device *rtc = to_rtc_device(dev);
100 struct rtc_time tm;
101 struct timespec64 new_system, new_rtc;
102 struct timespec64 sleep_time;
103 int err;
104
105 if (timekeeping_rtc_skipresume())
106 return 0;
107
108 rtc_hctosys_ret = -ENODEV;
109 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
110 return 0;
111
112 /* snapshot the current rtc and system time at resume */
113 getnstimeofday64(&new_system);
114 err = rtc_read_time(rtc, &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 new_rtc.tv_sec = rtc_tm_to_time64(&tm);
121 new_rtc.tv_nsec = 0;
122
123 if (new_rtc.tv_sec < old_rtc.tv_sec) {
124 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
125 return 0;
126 }
127
128 /* calculate the RTC time delta (sleep time)*/
129 sleep_time = timespec64_sub(new_rtc, old_rtc);
130
131 /*
132 * Since these RTC suspend/resume handlers are not called
133 * at the very end of suspend or the start of resume,
134 * some run-time may pass on either sides of the sleep time
135 * so subtract kernel run-time between rtc_suspend to rtc_resume
136 * to keep things accurate.
137 */
138 sleep_time = timespec64_sub(sleep_time,
139 timespec64_sub(new_system, old_system));
140
141 if (sleep_time.tv_sec >= 0)
142 timekeeping_inject_sleeptime64(&sleep_time);
143 rtc_hctosys_ret = 0;
144 return 0;
145}
146
147static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
148#define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops)
149#else
150#define RTC_CLASS_DEV_PM_OPS NULL
151#endif
152
153
154/**
155 * rtc_device_register - register w/ RTC class
156 * @dev: the device to register
157 *
158 * rtc_device_unregister() must be called when the class device is no
159 * longer needed.
160 *
161 * Returns the pointer to the new struct class device.
162 */
163struct rtc_device *rtc_device_register(const char *name, struct device *dev,
164 const struct rtc_class_ops *ops,
165 struct module *owner)
166{
167 struct rtc_device *rtc;
168 struct rtc_wkalrm alrm;
169 int of_id = -1, id = -1, err;
170
171 if (dev->of_node)
172 of_id = of_alias_get_id(dev->of_node, "rtc");
173 else if (dev->parent && dev->parent->of_node)
174 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
175
176 if (of_id >= 0) {
177 id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
178 GFP_KERNEL);
179 if (id < 0)
180 dev_warn(dev, "/aliases ID %d not available\n",
181 of_id);
182 }
183
184 if (id < 0) {
185 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
186 if (id < 0) {
187 err = id;
188 goto exit;
189 }
190 }
191
192 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
193 if (rtc == NULL) {
194 err = -ENOMEM;
195 goto exit_ida;
196 }
197
198 rtc->id = id;
199 rtc->ops = ops;
200 rtc->owner = owner;
201 rtc->irq_freq = 1;
202 rtc->max_user_freq = 64;
203 rtc->dev.parent = dev;
204 rtc->dev.class = rtc_class;
205 rtc->dev.release = rtc_device_release;
206
207 mutex_init(&rtc->ops_lock);
208 spin_lock_init(&rtc->irq_lock);
209 spin_lock_init(&rtc->irq_task_lock);
210 init_waitqueue_head(&rtc->irq_queue);
211
212 /* Init timerqueue */
213 timerqueue_init_head(&rtc->timerqueue);
214 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
215 /* Init aie timer */
216 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
217 /* Init uie timer */
218 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
219 /* Init pie timer */
220 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
221 rtc->pie_timer.function = rtc_pie_update_irq;
222 rtc->pie_enabled = 0;
223
224 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
225 dev_set_name(&rtc->dev, "rtc%d", id);
226
227 /* Check to see if there is an ALARM already set in hw */
228 err = __rtc_read_alarm(rtc, &alrm);
229
230 if (!err && !rtc_valid_tm(&alrm.time))
231 rtc_initialize_alarm(rtc, &alrm);
232
233 rtc_dev_prepare(rtc);
234
235 err = device_register(&rtc->dev);
236 if (err) {
237 put_device(&rtc->dev);
238 goto exit_kfree;
239 }
240
241 rtc_dev_add_device(rtc);
242 rtc_sysfs_add_device(rtc);
243 rtc_proc_add_device(rtc);
244
245 dev_info(dev, "rtc core: registered %s as %s\n",
246 rtc->name, dev_name(&rtc->dev));
247
248 return rtc;
249
250exit_kfree:
251 kfree(rtc);
252
253exit_ida:
254 ida_simple_remove(&rtc_ida, id);
255
256exit:
257 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
258 name, err);
259 return ERR_PTR(err);
260}
261EXPORT_SYMBOL_GPL(rtc_device_register);
262
263
264/**
265 * rtc_device_unregister - removes the previously registered RTC class device
266 *
267 * @rtc: the RTC class device to destroy
268 */
269void rtc_device_unregister(struct rtc_device *rtc)
270{
271 if (get_device(&rtc->dev) != NULL) {
272 mutex_lock(&rtc->ops_lock);
273 /* remove innards of this RTC, then disable it, before
274 * letting any rtc_class_open() users access it again
275 */
276 rtc_sysfs_del_device(rtc);
277 rtc_dev_del_device(rtc);
278 rtc_proc_del_device(rtc);
279 device_unregister(&rtc->dev);
280 rtc->ops = NULL;
281 mutex_unlock(&rtc->ops_lock);
282 put_device(&rtc->dev);
283 }
284}
285EXPORT_SYMBOL_GPL(rtc_device_unregister);
286
287static void devm_rtc_device_release(struct device *dev, void *res)
288{
289 struct rtc_device *rtc = *(struct rtc_device **)res;
290
291 rtc_device_unregister(rtc);
292}
293
294static int devm_rtc_device_match(struct device *dev, void *res, void *data)
295{
296 struct rtc **r = res;
297
298 return *r == data;
299}
300
301/**
302 * devm_rtc_device_register - resource managed rtc_device_register()
303 * @dev: the device to register
304 * @name: the name of the device
305 * @ops: the rtc operations structure
306 * @owner: the module owner
307 *
308 * @return a struct rtc on success, or an ERR_PTR on error
309 *
310 * Managed rtc_device_register(). The rtc_device returned from this function
311 * are automatically freed on driver detach. See rtc_device_register()
312 * for more information.
313 */
314
315struct rtc_device *devm_rtc_device_register(struct device *dev,
316 const char *name,
317 const struct rtc_class_ops *ops,
318 struct module *owner)
319{
320 struct rtc_device **ptr, *rtc;
321
322 ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
323 if (!ptr)
324 return ERR_PTR(-ENOMEM);
325
326 rtc = rtc_device_register(name, dev, ops, owner);
327 if (!IS_ERR(rtc)) {
328 *ptr = rtc;
329 devres_add(dev, ptr);
330 } else {
331 devres_free(ptr);
332 }
333
334 return rtc;
335}
336EXPORT_SYMBOL_GPL(devm_rtc_device_register);
337
338/**
339 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
340 * @dev: the device to unregister
341 * @rtc: the RTC class device to unregister
342 *
343 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
344 * function will not need to be called and the resource management code will
345 * ensure that the resource is freed.
346 */
347void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
348{
349 int rc;
350
351 rc = devres_release(dev, devm_rtc_device_release,
352 devm_rtc_device_match, rtc);
353 WARN_ON(rc);
354}
355EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
356
357static int __init rtc_init(void)
358{
359 rtc_class = class_create(THIS_MODULE, "rtc");
360 if (IS_ERR(rtc_class)) {
361 pr_err("couldn't create class\n");
362 return PTR_ERR(rtc_class);
363 }
364 rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
365 rtc_dev_init();
366 rtc_sysfs_init(rtc_class);
367 return 0;
368}
369
370static void __exit rtc_exit(void)
371{
372 rtc_dev_exit();
373 class_destroy(rtc_class);
374 ida_destroy(&rtc_ida);
375}
376
377subsys_initcall(rtc_init);
378module_exit(rtc_exit);
379
380MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
381MODULE_DESCRIPTION("RTC class support");
382MODULE_LICENSE("GPL");