drivers/rtc/class.c

   1 /*
   2  * RTC subsystem, base class
   3  *
   4  * Copyright (C) 2005 Tower Technologies
   5  * Author: Alessandro Zummo <a.zummo@towertech.it>
   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
  27 static DEFINE_IDA(rtc_ida);
  28 struct class *rtc_class;
  29
  30 static 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. */
  39 int 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
  48 static struct timespec64 old_rtc, old_system, old_delta;
  49
  50
  51 static 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
  97 static 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
 147 static 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 /* Ensure the caller will set the id before releasing the device */
 154 static struct rtc_device *rtc_allocate_device(void)
 155 {
 156         struct rtc_device *rtc;
 157
 158         rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
 159         if (!rtc)
 160                 return NULL;
 161
 162         device_initialize(&rtc->dev);
 163
 164         /* Drivers can revise this default after allocating the device. */
 165         rtc->set_offset_nsec =  NSEC_PER_SEC / 2;
 166
 167         rtc->irq_freq = 1;
 168         rtc->max_user_freq = 64;
 169         rtc->dev.class = rtc_class;
 170         rtc->dev.groups = rtc_get_dev_attribute_groups();
 171         rtc->dev.release = rtc_device_release;
 172
 173         mutex_init(&rtc->ops_lock);
 174         spin_lock_init(&rtc->irq_lock);
 175         spin_lock_init(&rtc->irq_task_lock);
 176         init_waitqueue_head(&rtc->irq_queue);
 177
 178         /* Init timerqueue */
 179         timerqueue_init_head(&rtc->timerqueue);
 180         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 181         /* Init aie timer */
 182         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 183         /* Init uie timer */
 184         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 185         /* Init pie timer */
 186         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 187         rtc->pie_timer.function = rtc_pie_update_irq;
 188         rtc->pie_enabled = 0;
 189
 190         return rtc;
 191 }
 192
 193 static int rtc_device_get_id(struct device *dev)
 194 {
 195         int of_id = -1, id = -1;
 196
 197         if (dev->of_node)
 198                 of_id = of_alias_get_id(dev->of_node, "rtc");
 199         else if (dev->parent && dev->parent->of_node)
 200                 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
 201
 202         if (of_id >= 0) {
 203                 id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
 204                 if (id < 0)
 205                         dev_warn(dev, "/aliases ID %d not available\n", of_id);
 206         }
 207
 208         if (id < 0)
 209                 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 210
 211         return id;
 212 }
 213
 214 /**
 215  * rtc_device_register - register w/ RTC class
 216  * @dev: the device to register
 217  *
 218  * rtc_device_unregister() must be called when the class device is no
 219  * longer needed.
 220  *
 221  * Returns the pointer to the new struct class device.
 222  */
 223 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 224                                         const struct rtc_class_ops *ops,
 225                                         struct module *owner)
 226 {
 227         struct rtc_device *rtc;
 228         struct rtc_wkalrm alrm;
 229         int id, err;
 230
 231         id = rtc_device_get_id(dev);
 232         if (id < 0) {
 233                 err = id;
 234                 goto exit;
 235         }
 236
 237         rtc = rtc_allocate_device();
 238         if (!rtc) {
 239                 err = -ENOMEM;
 240                 goto exit_ida;
 241         }
 242
 243         rtc->id = id;
 244         rtc->ops = ops;
 245         rtc->owner = owner;
 246         rtc->dev.parent = dev;
 247
 248         dev_set_name(&rtc->dev, "rtc%d", id);
 249
 250         /* Check to see if there is an ALARM already set in hw */
 251         err = __rtc_read_alarm(rtc, &alrm);
 252
 253         if (!err && !rtc_valid_tm(&alrm.time))
 254                 rtc_initialize_alarm(rtc, &alrm);
 255
 256         rtc_dev_prepare(rtc);
 257
 258         err = cdev_device_add(&rtc->char_dev, &rtc->dev);
 259         if (err) {
 260                 dev_warn(&rtc->dev, "%s: failed to add char device %d:%d\n",
 261                          name, MAJOR(rtc->dev.devt), rtc->id);
 262
 263                 /* This will free both memory and the ID */
 264                 put_device(&rtc->dev);
 265                 goto exit;
 266         } else {
 267                 dev_dbg(&rtc->dev, "%s: dev (%d:%d)\n", name,
 268                         MAJOR(rtc->dev.devt), rtc->id);
 269         }
 270
 271         rtc_proc_add_device(rtc);
 272
 273         dev_info(dev, "rtc core: registered %s as %s\n",
 274                         name, dev_name(&rtc->dev));
 275
 276         return rtc;
 277
 278 exit_ida:
 279         ida_simple_remove(&rtc_ida, id);
 280
 281 exit:
 282         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 283                         name, err);
 284         return ERR_PTR(err);
 285 }
 286 EXPORT_SYMBOL_GPL(rtc_device_register);
 287
 288
 289 /**
 290  * rtc_device_unregister - removes the previously registered RTC class device
 291  *
 292  * @rtc: the RTC class device to destroy
 293  */
 294 void rtc_device_unregister(struct rtc_device *rtc)
 295 {
 296         rtc_nvmem_unregister(rtc);
 297
 298         mutex_lock(&rtc->ops_lock);
 299         /*
 300          * Remove innards of this RTC, then disable it, before
 301          * letting any rtc_class_open() users access it again
 302          */
 303         rtc_proc_del_device(rtc);
 304         cdev_device_del(&rtc->char_dev, &rtc->dev);
 305         rtc->ops = NULL;
 306         mutex_unlock(&rtc->ops_lock);
 307         put_device(&rtc->dev);
 308 }
 309 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 310
 311 static void devm_rtc_device_release(struct device *dev, void *res)
 312 {
 313         struct rtc_device *rtc = *(struct rtc_device **)res;
 314
 315         rtc_device_unregister(rtc);
 316 }
 317
 318 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
 319 {
 320         struct rtc **r = res;
 321
 322         return *r == data;
 323 }
 324
 325 /**
 326  * devm_rtc_device_register - resource managed rtc_device_register()
 327  * @dev: the device to register
 328  * @name: the name of the device
 329  * @ops: the rtc operations structure
 330  * @owner: the module owner
 331  *
 332  * @return a struct rtc on success, or an ERR_PTR on error
 333  *
 334  * Managed rtc_device_register(). The rtc_device returned from this function
 335  * are automatically freed on driver detach. See rtc_device_register()
 336  * for more information.
 337  */
 338
 339 struct rtc_device *devm_rtc_device_register(struct device *dev,
 340                                         const char *name,
 341                                         const struct rtc_class_ops *ops,
 342                                         struct module *owner)
 343 {
 344         struct rtc_device **ptr, *rtc;
 345
 346         ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
 347         if (!ptr)
 348                 return ERR_PTR(-ENOMEM);
 349
 350         rtc = rtc_device_register(name, dev, ops, owner);
 351         if (!IS_ERR(rtc)) {
 352                 *ptr = rtc;
 353                 devres_add(dev, ptr);
 354         } else {
 355                 devres_free(ptr);
 356         }
 357
 358         return rtc;
 359 }
 360 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 361
 362 /**
 363  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 364  * @dev: the device to unregister
 365  * @rtc: the RTC class device to unregister
 366  *
 367  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 368  * function will not need to be called and the resource management code will
 369  * ensure that the resource is freed.
 370  */
 371 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
 372 {
 373         int rc;
 374
 375         rc = devres_release(dev, devm_rtc_device_release,
 376                                 devm_rtc_device_match, rtc);
 377         WARN_ON(rc);
 378 }
 379 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
 380
 381 static void devm_rtc_release_device(struct device *dev, void *res)
 382 {
 383         struct rtc_device *rtc = *(struct rtc_device **)res;
 384
 385         if (rtc->registered)
 386                 rtc_device_unregister(rtc);
 387         else
 388                 put_device(&rtc->dev);
 389 }
 390
 391 struct rtc_device *devm_rtc_allocate_device(struct device *dev)
 392 {
 393         struct rtc_device **ptr, *rtc;
 394         int id, err;
 395
 396         id = rtc_device_get_id(dev);
 397         if (id < 0)
 398                 return ERR_PTR(id);
 399
 400         ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
 401         if (!ptr) {
 402                 err = -ENOMEM;
 403                 goto exit_ida;
 404         }
 405
 406         rtc = rtc_allocate_device();
 407         if (!rtc) {
 408                 err = -ENOMEM;
 409                 goto exit_devres;
 410         }
 411
 412         *ptr = rtc;
 413         devres_add(dev, ptr);
 414
 415         rtc->id = id;
 416         rtc->dev.parent = dev;
 417         dev_set_name(&rtc->dev, "rtc%d", id);
 418
 419         return rtc;
 420
 421 exit_devres:
 422         devres_free(ptr);
 423 exit_ida:
 424         ida_simple_remove(&rtc_ida, id);
 425         return ERR_PTR(err);
 426 }
 427 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
 428
 429 int __rtc_register_device(struct module *owner, struct rtc_device *rtc)
 430 {
 431         struct rtc_wkalrm alrm;
 432         int err;
 433
 434         if (!rtc->ops)
 435                 return -EINVAL;
 436
 437         rtc->owner = owner;
 438
 439         /* Check to see if there is an ALARM already set in hw */
 440         err = __rtc_read_alarm(rtc, &alrm);
 441         if (!err && !rtc_valid_tm(&alrm.time))
 442                 rtc_initialize_alarm(rtc, &alrm);
 443
 444         rtc_dev_prepare(rtc);
 445
 446         err = cdev_device_add(&rtc->char_dev, &rtc->dev);
 447         if (err)
 448                 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
 449                          MAJOR(rtc->dev.devt), rtc->id);
 450         else
 451                 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
 452                         MAJOR(rtc->dev.devt), rtc->id);
 453
 454         rtc_proc_add_device(rtc);
 455
 456         rtc_nvmem_register(rtc);
 457
 458         rtc->registered = true;
 459         dev_info(rtc->dev.parent, "registered as %s\n",
 460                  dev_name(&rtc->dev));
 461
 462         return 0;
 463 }
 464 EXPORT_SYMBOL_GPL(__rtc_register_device);
 465
 466 static int __init rtc_init(void)
 467 {
 468         rtc_class = class_create(THIS_MODULE, "rtc");
 469         if (IS_ERR(rtc_class)) {
 470                 pr_err("couldn't create class\n");
 471                 return PTR_ERR(rtc_class);
 472         }
 473         rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 474         rtc_dev_init();
 475         return 0;
 476 }
 477 subsys_initcall(rtc_init);