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         ktime_get_real_ts64(&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         ktime_get_real_ts64(&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         init_waitqueue_head(&rtc->irq_queue);
 176
 177         /* Init timerqueue */
 178         timerqueue_init_head(&rtc->timerqueue);
 179         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 180         /* Init aie timer */
 181         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc);
 182         /* Init uie timer */
 183         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc);
 184         /* Init pie timer */
 185         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 186         rtc->pie_timer.function = rtc_pie_update_irq;
 187         rtc->pie_enabled = 0;
 188
 189         return rtc;
 190 }
 191
 192 static int rtc_device_get_id(struct device *dev)
 193 {
 194         int of_id = -1, id = -1;
 195
 196         if (dev->of_node)
 197                 of_id = of_alias_get_id(dev->of_node, "rtc");
 198         else if (dev->parent && dev->parent->of_node)
 199                 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
 200
 201         if (of_id >= 0) {
 202                 id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
 203                 if (id < 0)
 204                         dev_warn(dev, "/aliases ID %d not available\n", of_id);
 205         }
 206
 207         if (id < 0)
 208                 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 209
 210         return id;
 211 }
 212
 213 static void rtc_device_get_offset(struct rtc_device *rtc)
 214 {
 215         time64_t range_secs;
 216         u32 start_year;
 217         int ret;
 218
 219         /*
 220          * If RTC driver did not implement the range of RTC hardware device,
 221          * then we can not expand the RTC range by adding or subtracting one
 222          * offset.
 223          */
 224         if (rtc->range_min == rtc->range_max)
 225                 return;
 226
 227         ret = device_property_read_u32(rtc->dev.parent, "start-year",
 228                                        &start_year);
 229         if (!ret) {
 230                 rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
 231                 rtc->set_start_time = true;
 232         }
 233
 234         /*
 235          * If user did not implement the start time for RTC driver, then no
 236          * need to expand the RTC range.
 237          */
 238         if (!rtc->set_start_time)
 239                 return;
 240
 241         range_secs = rtc->range_max - rtc->range_min + 1;
 242
 243         /*
 244          * If the start_secs is larger than the maximum seconds (rtc->range_max)
 245          * supported by RTC hardware or the maximum seconds of new expanded
 246          * range (start_secs + rtc->range_max - rtc->range_min) is less than
 247          * rtc->range_min, which means the minimum seconds (rtc->range_min) of
 248          * RTC hardware will be mapped to start_secs by adding one offset, so
 249          * the offset seconds calculation formula should be:
 250          * rtc->offset_secs = rtc->start_secs - rtc->range_min;
 251          *
 252          * If the start_secs is larger than the minimum seconds (rtc->range_min)
 253          * supported by RTC hardware, then there is one region is overlapped
 254          * between the original RTC hardware range and the new expanded range,
 255          * and this overlapped region do not need to be mapped into the new
 256          * expanded range due to it is valid for RTC device. So the minimum
 257          * seconds of RTC hardware (rtc->range_min) should be mapped to
 258          * rtc->range_max + 1, then the offset seconds formula should be:
 259          * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
 260          *
 261          * If the start_secs is less than the minimum seconds (rtc->range_min),
 262          * which is similar to case 2. So the start_secs should be mapped to
 263          * start_secs + rtc->range_max - rtc->range_min + 1, then the
 264          * offset seconds formula should be:
 265          * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
 266          *
 267          * Otherwise the offset seconds should be 0.
 268          */
 269         if (rtc->start_secs > rtc->range_max ||
 270             rtc->start_secs + range_secs - 1 < rtc->range_min)
 271                 rtc->offset_secs = rtc->start_secs - rtc->range_min;
 272         else if (rtc->start_secs > rtc->range_min)
 273                 rtc->offset_secs = range_secs;
 274         else if (rtc->start_secs < rtc->range_min)
 275                 rtc->offset_secs = -range_secs;
 276         else
 277                 rtc->offset_secs = 0;
 278 }
 279
 280 /**
 281  * rtc_device_unregister - removes the previously registered RTC class device
 282  *
 283  * @rtc: the RTC class device to destroy
 284  */
 285 static void rtc_device_unregister(struct rtc_device *rtc)
 286 {
 287         mutex_lock(&rtc->ops_lock);
 288         /*
 289          * Remove innards of this RTC, then disable it, before
 290          * letting any rtc_class_open() users access it again
 291          */
 292         rtc_proc_del_device(rtc);
 293         cdev_device_del(&rtc->char_dev, &rtc->dev);
 294         rtc->ops = NULL;
 295         mutex_unlock(&rtc->ops_lock);
 296         put_device(&rtc->dev);
 297 }
 298
 299 static void devm_rtc_release_device(struct device *dev, void *res)
 300 {
 301         struct rtc_device *rtc = *(struct rtc_device **)res;
 302
 303         rtc_nvmem_unregister(rtc);
 304
 305         if (rtc->registered)
 306                 rtc_device_unregister(rtc);
 307         else
 308                 put_device(&rtc->dev);
 309 }
 310
 311 struct rtc_device *devm_rtc_allocate_device(struct device *dev)
 312 {
 313         struct rtc_device **ptr, *rtc;
 314         int id, err;
 315
 316         id = rtc_device_get_id(dev);
 317         if (id < 0)
 318                 return ERR_PTR(id);
 319
 320         ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
 321         if (!ptr) {
 322                 err = -ENOMEM;
 323                 goto exit_ida;
 324         }
 325
 326         rtc = rtc_allocate_device();
 327         if (!rtc) {
 328                 err = -ENOMEM;
 329                 goto exit_devres;
 330         }
 331
 332         *ptr = rtc;
 333         devres_add(dev, ptr);
 334
 335         rtc->id = id;
 336         rtc->dev.parent = dev;
 337         dev_set_name(&rtc->dev, "rtc%d", id);
 338
 339         return rtc;
 340
 341 exit_devres:
 342         devres_free(ptr);
 343 exit_ida:
 344         ida_simple_remove(&rtc_ida, id);
 345         return ERR_PTR(err);
 346 }
 347 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
 348
 349 int __rtc_register_device(struct module *owner, struct rtc_device *rtc)
 350 {
 351         struct rtc_wkalrm alrm;
 352         int err;
 353
 354         if (!rtc->ops)
 355                 return -EINVAL;
 356
 357         rtc->owner = owner;
 358         rtc_device_get_offset(rtc);
 359
 360         /* Check to see if there is an ALARM already set in hw */
 361         err = __rtc_read_alarm(rtc, &alrm);
 362         if (!err && !rtc_valid_tm(&alrm.time))
 363                 rtc_initialize_alarm(rtc, &alrm);
 364
 365         rtc_dev_prepare(rtc);
 366
 367         err = cdev_device_add(&rtc->char_dev, &rtc->dev);
 368         if (err)
 369                 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
 370                          MAJOR(rtc->dev.devt), rtc->id);
 371         else
 372                 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
 373                         MAJOR(rtc->dev.devt), rtc->id);
 374
 375         rtc_proc_add_device(rtc);
 376
 377         rtc->registered = true;
 378         dev_info(rtc->dev.parent, "registered as %s\n",
 379                  dev_name(&rtc->dev));
 380
 381         return 0;
 382 }
 383 EXPORT_SYMBOL_GPL(__rtc_register_device);
 384
 385 /**
 386  * devm_rtc_device_register - resource managed rtc_device_register()
 387  * @dev: the device to register
 388  * @name: the name of the device (unused)
 389  * @ops: the rtc operations structure
 390  * @owner: the module owner
 391  *
 392  * @return a struct rtc on success, or an ERR_PTR on error
 393  *
 394  * Managed rtc_device_register(). The rtc_device returned from this function
 395  * are automatically freed on driver detach.
 396  * This function is deprecated, use devm_rtc_allocate_device and
 397  * rtc_register_device instead
 398  */
 399 struct rtc_device *devm_rtc_device_register(struct device *dev,
 400                                         const char *name,
 401                                         const struct rtc_class_ops *ops,
 402                                         struct module *owner)
 403 {
 404         struct rtc_device *rtc;
 405         int err;
 406
 407         rtc = devm_rtc_allocate_device(dev);
 408         if (IS_ERR(rtc))
 409                 return rtc;
 410
 411         rtc->ops = ops;
 412
 413         err = __rtc_register_device(owner, rtc);
 414         if (err)
 415                 return ERR_PTR(err);
 416
 417         return rtc;
 418 }
 419 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 420
 421 static int __init rtc_init(void)
 422 {
 423         rtc_class = class_create(THIS_MODULE, "rtc");
 424         if (IS_ERR(rtc_class)) {
 425                 pr_err("couldn't create class\n");
 426                 return PTR_ERR(rtc_class);
 427         }
 428         rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 429         rtc_dev_init();
 430         return 0;
 431 }
 432 subsys_initcall(rtc_init);