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 (has_persistent_clock())
  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 (has_persistent_clock())
 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         if (rtc_valid_tm(&tm) != 0) {
 121                 pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
 122                 return 0;
 123         }
 124         new_rtc.tv_sec = rtc_tm_to_time64(&tm);
 125         new_rtc.tv_nsec = 0;
 126
 127         if (new_rtc.tv_sec < old_rtc.tv_sec) {
 128                 pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
 129                 return 0;
 130         }
 131
 132         /* calculate the RTC time delta (sleep time)*/
 133         sleep_time = timespec64_sub(new_rtc, old_rtc);
 134
 135         /*
 136          * Since these RTC suspend/resume handlers are not called
 137          * at the very end of suspend or the start of resume,
 138          * some run-time may pass on either sides of the sleep time
 139          * so subtract kernel run-time between rtc_suspend to rtc_resume
 140          * to keep things accurate.
 141          */
 142         sleep_time = timespec64_sub(sleep_time,
 143                         timespec64_sub(new_system, old_system));
 144
 145         if (sleep_time.tv_sec >= 0)
 146                 timekeeping_inject_sleeptime64(&sleep_time);
 147         rtc_hctosys_ret = 0;
 148         return 0;
 149 }
 150
 151 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
 152 #define RTC_CLASS_DEV_PM_OPS    (&rtc_class_dev_pm_ops)
 153 #else
 154 #define RTC_CLASS_DEV_PM_OPS    NULL
 155 #endif
 156
 157
 158 /**
 159  * rtc_device_register - register w/ RTC class
 160  * @dev: the device to register
 161  *
 162  * rtc_device_unregister() must be called when the class device is no
 163  * longer needed.
 164  *
 165  * Returns the pointer to the new struct class device.
 166  */
 167 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 168                                         const struct rtc_class_ops *ops,
 169                                         struct module *owner)
 170 {
 171         struct rtc_device *rtc;
 172         struct rtc_wkalrm alrm;
 173         int of_id = -1, id = -1, err;
 174
 175         if (dev->of_node)
 176                 of_id = of_alias_get_id(dev->of_node, "rtc");
 177         else if (dev->parent && dev->parent->of_node)
 178                 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
 179
 180         if (of_id >= 0) {
 181                 id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
 182                                     GFP_KERNEL);
 183                 if (id < 0)
 184                         dev_warn(dev, "/aliases ID %d not available\n",
 185                                     of_id);
 186         }
 187
 188         if (id < 0) {
 189                 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 190                 if (id < 0) {
 191                         err = id;
 192                         goto exit;
 193                 }
 194         }
 195
 196         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 197         if (rtc == NULL) {
 198                 err = -ENOMEM;
 199                 goto exit_ida;
 200         }
 201
 202         rtc->id = id;
 203         rtc->ops = ops;
 204         rtc->owner = owner;
 205         rtc->irq_freq = 1;
 206         rtc->max_user_freq = 64;
 207         rtc->dev.parent = dev;
 208         rtc->dev.class = rtc_class;
 209         rtc->dev.release = rtc_device_release;
 210
 211         mutex_init(&rtc->ops_lock);
 212         spin_lock_init(&rtc->irq_lock);
 213         spin_lock_init(&rtc->irq_task_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, (void *)rtc);
 221         /* Init uie timer */
 222         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)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         /* Check to see if there is an ALARM already set in hw */
 229         err = __rtc_read_alarm(rtc, &alrm);
 230
 231         if (!err && !rtc_valid_tm(&alrm.time))
 232                 rtc_initialize_alarm(rtc, &alrm);
 233
 234         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 235         dev_set_name(&rtc->dev, "rtc%d", id);
 236
 237         rtc_dev_prepare(rtc);
 238
 239         err = device_register(&rtc->dev);
 240         if (err) {
 241                 put_device(&rtc->dev);
 242                 goto exit_kfree;
 243         }
 244
 245         rtc_dev_add_device(rtc);
 246         rtc_sysfs_add_device(rtc);
 247         rtc_proc_add_device(rtc);
 248
 249         dev_info(dev, "rtc core: registered %s as %s\n",
 250                         rtc->name, dev_name(&rtc->dev));
 251
 252         return rtc;
 253
 254 exit_kfree:
 255         kfree(rtc);
 256
 257 exit_ida:
 258         ida_simple_remove(&rtc_ida, id);
 259
 260 exit:
 261         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 262                         name, err);
 263         return ERR_PTR(err);
 264 }
 265 EXPORT_SYMBOL_GPL(rtc_device_register);
 266
 267
 268 /**
 269  * rtc_device_unregister - removes the previously registered RTC class device
 270  *
 271  * @rtc: the RTC class device to destroy
 272  */
 273 void rtc_device_unregister(struct rtc_device *rtc)
 274 {
 275         if (get_device(&rtc->dev) != NULL) {
 276                 mutex_lock(&rtc->ops_lock);
 277                 /* remove innards of this RTC, then disable it, before
 278                  * letting any rtc_class_open() users access it again
 279                  */
 280                 rtc_sysfs_del_device(rtc);
 281                 rtc_dev_del_device(rtc);
 282                 rtc_proc_del_device(rtc);
 283                 device_unregister(&rtc->dev);
 284                 rtc->ops = NULL;
 285                 mutex_unlock(&rtc->ops_lock);
 286                 put_device(&rtc->dev);
 287         }
 288 }
 289 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 290
 291 static void devm_rtc_device_release(struct device *dev, void *res)
 292 {
 293         struct rtc_device *rtc = *(struct rtc_device **)res;
 294
 295         rtc_device_unregister(rtc);
 296 }
 297
 298 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
 299 {
 300         struct rtc **r = res;
 301
 302         return *r == data;
 303 }
 304
 305 /**
 306  * devm_rtc_device_register - resource managed rtc_device_register()
 307  * @dev: the device to register
 308  * @name: the name of the device
 309  * @ops: the rtc operations structure
 310  * @owner: the module owner
 311  *
 312  * @return a struct rtc on success, or an ERR_PTR on error
 313  *
 314  * Managed rtc_device_register(). The rtc_device returned from this function
 315  * are automatically freed on driver detach. See rtc_device_register()
 316  * for more information.
 317  */
 318
 319 struct rtc_device *devm_rtc_device_register(struct device *dev,
 320                                         const char *name,
 321                                         const struct rtc_class_ops *ops,
 322                                         struct module *owner)
 323 {
 324         struct rtc_device **ptr, *rtc;
 325
 326         ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
 327         if (!ptr)
 328                 return ERR_PTR(-ENOMEM);
 329
 330         rtc = rtc_device_register(name, dev, ops, owner);
 331         if (!IS_ERR(rtc)) {
 332                 *ptr = rtc;
 333                 devres_add(dev, ptr);
 334         } else {
 335                 devres_free(ptr);
 336         }
 337
 338         return rtc;
 339 }
 340 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 341
 342 /**
 343  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 344  * @dev: the device to unregister
 345  * @rtc: the RTC class device to unregister
 346  *
 347  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 348  * function will not need to be called and the resource management code will
 349  * ensure that the resource is freed.
 350  */
 351 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
 352 {
 353         int rc;
 354
 355         rc = devres_release(dev, devm_rtc_device_release,
 356                                 devm_rtc_device_match, rtc);
 357         WARN_ON(rc);
 358 }
 359 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
 360
 361 static int __init rtc_init(void)
 362 {
 363         rtc_class = class_create(THIS_MODULE, "rtc");
 364         if (IS_ERR(rtc_class)) {
 365                 pr_err("couldn't create class\n");
 366                 return PTR_ERR(rtc_class);
 367         }
 368         rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 369         rtc_dev_init();
 370         rtc_sysfs_init(rtc_class);
 371         return 0;
 372 }
 373
 374 static void __exit rtc_exit(void)
 375 {
 376         rtc_dev_exit();
 377         class_destroy(rtc_class);
 378         ida_destroy(&rtc_ida);
 379 }
 380
 381 subsys_initcall(rtc_init);
 382 module_exit(rtc_exit);
 383
 384 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 385 MODULE_DESCRIPTION("RTC class support");
 386 MODULE_LICENSE("GPL");