root/drivers/rtc/class.c

DEFINITIONS

1. rtc_device_release
2. rtc_suspend
3. rtc_resume
4. rtc_allocate_device
5. rtc_device_get_id
6. rtc_device_get_offset
7. rtc_device_unregister
8. devm_rtc_release_device
9. devm_rtc_allocate_device
10. __rtc_register_device
11. devm_rtc_device_register
12. 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 
  23 static DEFINE_IDA(rtc_ida);
  24 struct class *rtc_class;
  25 
  26 static 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. */
  36 int 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 
  45 static struct timespec64 old_rtc, old_system, old_delta;
  46 
  47 static 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 
  92 static 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 
 142 static 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 */
 149 static 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 
 187 static 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 
 208 static 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  */
 280 static 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 
 294 static 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 
 306 struct 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 
 336 exit_devres:
 337         devres_free(ptr);
 338 exit_ida:
 339         ida_simple_remove(&rtc_ida, id);
 340         return ERR_PTR(err);
 341 }
 342 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
 343 
 344 int __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 }
 380 EXPORT_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  */
 396 struct 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 }
 416 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 417 
 418 static 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 }
 429 subsys_initcall(rtc_init);