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 timespec 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 timespec         delta, delta_delta;
  56
  57         if (has_persistent_clock())
  58                 return 0;
  59
  60         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  61                 return 0;
  62
  63         /* snapshot the current RTC and system time at suspend*/
  64         rtc_read_time(rtc, &tm);
  65         getnstimeofday(&old_system);
  66         rtc_tm_to_time(&tm, &old_rtc.tv_sec);
  67
  68
  69         /*
  70          * To avoid drift caused by repeated suspend/resumes,
  71          * which each can add ~1 second drift error,
  72          * try to compensate so the difference in system time
  73          * and rtc time stays close to constant.
  74          */
  75         delta = timespec_sub(old_system, old_rtc);
  76         delta_delta = timespec_sub(delta, old_delta);
  77         if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
  78                 /*
  79                  * if delta_delta is too large, assume time correction
  80                  * has occured and set old_delta to the current delta.
  81                  */
  82                 old_delta = delta;
  83         } else {
  84                 /* Otherwise try to adjust old_system to compensate */
  85                 old_system = timespec_sub(old_system, delta_delta);
  86         }
  87
  88         return 0;
  89 }
  90
  91 static int rtc_resume(struct device *dev)
  92 {
  93         struct rtc_device       *rtc = to_rtc_device(dev);
  94         struct rtc_time         tm;
  95         struct timespec         new_system, new_rtc;
  96         struct timespec         sleep_time;
  97
  98         if (has_persistent_clock())
  99                 return 0;
 100
 101         rtc_hctosys_ret = -ENODEV;
 102         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
 103                 return 0;
 104
 105         /* snapshot the current rtc and system time at resume */
 106         getnstimeofday(&new_system);
 107         rtc_read_time(rtc, &tm);
 108         if (rtc_valid_tm(&tm) != 0) {
 109                 pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
 110                 return 0;
 111         }
 112         rtc_tm_to_time(&tm, &new_rtc.tv_sec);
 113         new_rtc.tv_nsec = 0;
 114
 115         if (new_rtc.tv_sec < old_rtc.tv_sec) {
 116                 pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
 117                 return 0;
 118         }
 119
 120         /* calculate the RTC time delta (sleep time)*/
 121         sleep_time = timespec_sub(new_rtc, old_rtc);
 122
 123         /*
 124          * Since these RTC suspend/resume handlers are not called
 125          * at the very end of suspend or the start of resume,
 126          * some run-time may pass on either sides of the sleep time
 127          * so subtract kernel run-time between rtc_suspend to rtc_resume
 128          * to keep things accurate.
 129          */
 130         sleep_time = timespec_sub(sleep_time,
 131                         timespec_sub(new_system, old_system));
 132
 133         if (sleep_time.tv_sec >= 0)
 134                 timekeeping_inject_sleeptime(&sleep_time);
 135         rtc_hctosys_ret = 0;
 136         return 0;
 137 }
 138
 139 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
 140 #define RTC_CLASS_DEV_PM_OPS    (&rtc_class_dev_pm_ops)
 141 #else
 142 #define RTC_CLASS_DEV_PM_OPS    NULL
 143 #endif
 144
 145
 146 /**
 147  * rtc_device_register - register w/ RTC class
 148  * @dev: the device to register
 149  *
 150  * rtc_device_unregister() must be called when the class device is no
 151  * longer needed.
 152  *
 153  * Returns the pointer to the new struct class device.
 154  */
 155 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 156                                         const struct rtc_class_ops *ops,
 157                                         struct module *owner)
 158 {
 159         struct rtc_device *rtc;
 160         struct rtc_wkalrm alrm;
 161         int of_id = -1, id = -1, err;
 162
 163         if (dev->of_node)
 164                 of_id = of_alias_get_id(dev->of_node, "rtc");
 165         else if (dev->parent && dev->parent->of_node)
 166                 of_id = of_alias_get_id(dev->parent->of_node, "rtc");
 167
 168         if (of_id >= 0) {
 169                 id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
 170                                     GFP_KERNEL);
 171                 if (id < 0)
 172                         dev_warn(dev, "/aliases ID %d not available\n",
 173                                     of_id);
 174         }
 175
 176         if (id < 0) {
 177                 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 178                 if (id < 0) {
 179                         err = id;
 180                         goto exit;
 181                 }
 182         }
 183
 184         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 185         if (rtc == NULL) {
 186                 err = -ENOMEM;
 187                 goto exit_ida;
 188         }
 189
 190         rtc->id = id;
 191         rtc->ops = ops;
 192         rtc->owner = owner;
 193         rtc->irq_freq = 1;
 194         rtc->max_user_freq = 64;
 195         rtc->dev.parent = dev;
 196         rtc->dev.class = rtc_class;
 197         rtc->dev.release = rtc_device_release;
 198
 199         mutex_init(&rtc->ops_lock);
 200         spin_lock_init(&rtc->irq_lock);
 201         spin_lock_init(&rtc->irq_task_lock);
 202         init_waitqueue_head(&rtc->irq_queue);
 203
 204         /* Init timerqueue */
 205         timerqueue_init_head(&rtc->timerqueue);
 206         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 207         /* Init aie timer */
 208         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 209         /* Init uie timer */
 210         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 211         /* Init pie timer */
 212         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 213         rtc->pie_timer.function = rtc_pie_update_irq;
 214         rtc->pie_enabled = 0;
 215
 216         /* Check to see if there is an ALARM already set in hw */
 217         err = __rtc_read_alarm(rtc, &alrm);
 218
 219         if (!err && !rtc_valid_tm(&alrm.time))
 220                 rtc_initialize_alarm(rtc, &alrm);
 221
 222         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 223         dev_set_name(&rtc->dev, "rtc%d", id);
 224
 225         rtc_dev_prepare(rtc);
 226
 227         err = device_register(&rtc->dev);
 228         if (err) {
 229                 put_device(&rtc->dev);
 230                 goto exit_kfree;
 231         }
 232
 233         rtc_dev_add_device(rtc);
 234         rtc_sysfs_add_device(rtc);
 235         rtc_proc_add_device(rtc);
 236
 237         dev_info(dev, "rtc core: registered %s as %s\n",
 238                         rtc->name, dev_name(&rtc->dev));
 239
 240         return rtc;
 241
 242 exit_kfree:
 243         kfree(rtc);
 244
 245 exit_ida:
 246         ida_simple_remove(&rtc_ida, id);
 247
 248 exit:
 249         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 250                         name, err);
 251         return ERR_PTR(err);
 252 }
 253 EXPORT_SYMBOL_GPL(rtc_device_register);
 254
 255
 256 /**
 257  * rtc_device_unregister - removes the previously registered RTC class device
 258  *
 259  * @rtc: the RTC class device to destroy
 260  */
 261 void rtc_device_unregister(struct rtc_device *rtc)
 262 {
 263         if (get_device(&rtc->dev) != NULL) {
 264                 mutex_lock(&rtc->ops_lock);
 265                 /* remove innards of this RTC, then disable it, before
 266                  * letting any rtc_class_open() users access it again
 267                  */
 268                 rtc_sysfs_del_device(rtc);
 269                 rtc_dev_del_device(rtc);
 270                 rtc_proc_del_device(rtc);
 271                 device_unregister(&rtc->dev);
 272                 rtc->ops = NULL;
 273                 mutex_unlock(&rtc->ops_lock);
 274                 put_device(&rtc->dev);
 275         }
 276 }
 277 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 278
 279 static void devm_rtc_device_release(struct device *dev, void *res)
 280 {
 281         struct rtc_device *rtc = *(struct rtc_device **)res;
 282
 283         rtc_device_unregister(rtc);
 284 }
 285
 286 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
 287 {
 288         struct rtc **r = res;
 289
 290         return *r == data;
 291 }
 292
 293 /**
 294  * devm_rtc_device_register - resource managed rtc_device_register()
 295  * @dev: the device to register
 296  * @name: the name of the device
 297  * @ops: the rtc operations structure
 298  * @owner: the module owner
 299  *
 300  * @return a struct rtc on success, or an ERR_PTR on error
 301  *
 302  * Managed rtc_device_register(). The rtc_device returned from this function
 303  * are automatically freed on driver detach. See rtc_device_register()
 304  * for more information.
 305  */
 306
 307 struct rtc_device *devm_rtc_device_register(struct device *dev,
 308                                         const char *name,
 309                                         const struct rtc_class_ops *ops,
 310                                         struct module *owner)
 311 {
 312         struct rtc_device **ptr, *rtc;
 313
 314         ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
 315         if (!ptr)
 316                 return ERR_PTR(-ENOMEM);
 317
 318         rtc = rtc_device_register(name, dev, ops, owner);
 319         if (!IS_ERR(rtc)) {
 320                 *ptr = rtc;
 321                 devres_add(dev, ptr);
 322         } else {
 323                 devres_free(ptr);
 324         }
 325
 326         return rtc;
 327 }
 328 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 329
 330 /**
 331  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 332  * @dev: the device to unregister
 333  * @rtc: the RTC class device to unregister
 334  *
 335  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 336  * function will not need to be called and the resource management code will
 337  * ensure that the resource is freed.
 338  */
 339 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
 340 {
 341         int rc;
 342
 343         rc = devres_release(dev, devm_rtc_device_release,
 344                                 devm_rtc_device_match, rtc);
 345         WARN_ON(rc);
 346 }
 347 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
 348
 349 static int __init rtc_init(void)
 350 {
 351         rtc_class = class_create(THIS_MODULE, "rtc");
 352         if (IS_ERR(rtc_class)) {
 353                 pr_err("couldn't create class\n");
 354                 return PTR_ERR(rtc_class);
 355         }
 356         rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 357         rtc_dev_init();
 358         rtc_sysfs_init(rtc_class);
 359         return 0;
 360 }
 361
 362 static void __exit rtc_exit(void)
 363 {
 364         rtc_dev_exit();
 365         class_destroy(rtc_class);
 366         ida_destroy(&rtc_ida);
 367 }
 368
 369 subsys_initcall(rtc_init);
 370 module_exit(rtc_exit);
 371
 372 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 373 MODULE_DESCRIPTION("RTC class support");
 374 MODULE_LICENSE("GPL");