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/rtc.h>
  18 #include <linux/kdev_t.h>
  19 #include <linux/idr.h>
  20 #include <linux/slab.h>
  21 #include <linux/workqueue.h>
  22
  23 #include "rtc-core.h"
  24
  25
  26 static DEFINE_IDA(rtc_ida);
  27 struct class *rtc_class;
  28
  29 static void rtc_device_release(struct device *dev)
  30 {
  31         struct rtc_device *rtc = to_rtc_device(dev);
  32         ida_simple_remove(&rtc_ida, rtc->id);
  33         kfree(rtc);
  34 }
  35
  36 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
  37 /* Result of the last RTC to system clock attempt. */
  38 int rtc_hctosys_ret = -ENODEV;
  39 #endif
  40
  41 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
  42 /*
  43  * On suspend(), measure the delta between one RTC and the
  44  * system's wall clock; restore it on resume().
  45  */
  46
  47 static struct timespec old_rtc, old_system, old_delta;
  48
  49
  50 static int rtc_suspend(struct device *dev)
  51 {
  52         struct rtc_device       *rtc = to_rtc_device(dev);
  53         struct rtc_time         tm;
  54         struct timespec         delta, delta_delta;
  55
  56         if (has_persistent_clock())
  57                 return 0;
  58
  59         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  60                 return 0;
  61
  62         /* snapshot the current RTC and system time at suspend*/
  63         rtc_read_time(rtc, &tm);
  64         getnstimeofday(&old_system);
  65         rtc_tm_to_time(&tm, &old_rtc.tv_sec);
  66
  67
  68         /*
  69          * To avoid drift caused by repeated suspend/resumes,
  70          * which each can add ~1 second drift error,
  71          * try to compensate so the difference in system time
  72          * and rtc time stays close to constant.
  73          */
  74         delta = timespec_sub(old_system, old_rtc);
  75         delta_delta = timespec_sub(delta, old_delta);
  76         if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
  77                 /*
  78                  * if delta_delta is too large, assume time correction
  79                  * has occured and set old_delta to the current delta.
  80                  */
  81                 old_delta = delta;
  82         } else {
  83                 /* Otherwise try to adjust old_system to compensate */
  84                 old_system = timespec_sub(old_system, delta_delta);
  85         }
  86
  87         return 0;
  88 }
  89
  90 static int rtc_resume(struct device *dev)
  91 {
  92         struct rtc_device       *rtc = to_rtc_device(dev);
  93         struct rtc_time         tm;
  94         struct timespec         new_system, new_rtc;
  95         struct timespec         sleep_time;
  96
  97         if (has_persistent_clock())
  98                 return 0;
  99
 100         rtc_hctosys_ret = -ENODEV;
 101         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
 102                 return 0;
 103
 104         /* snapshot the current rtc and system time at resume */
 105         getnstimeofday(&new_system);
 106         rtc_read_time(rtc, &tm);
 107         if (rtc_valid_tm(&tm) != 0) {
 108                 pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
 109                 return 0;
 110         }
 111         rtc_tm_to_time(&tm, &new_rtc.tv_sec);
 112         new_rtc.tv_nsec = 0;
 113
 114         if (new_rtc.tv_sec < old_rtc.tv_sec) {
 115                 pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
 116                 return 0;
 117         }
 118
 119         /* calculate the RTC time delta (sleep time)*/
 120         sleep_time = timespec_sub(new_rtc, old_rtc);
 121
 122         /*
 123          * Since these RTC suspend/resume handlers are not called
 124          * at the very end of suspend or the start of resume,
 125          * some run-time may pass on either sides of the sleep time
 126          * so subtract kernel run-time between rtc_suspend to rtc_resume
 127          * to keep things accurate.
 128          */
 129         sleep_time = timespec_sub(sleep_time,
 130                         timespec_sub(new_system, old_system));
 131
 132         if (sleep_time.tv_sec >= 0)
 133                 timekeeping_inject_sleeptime(&sleep_time);
 134         rtc_hctosys_ret = 0;
 135         return 0;
 136 }
 137
 138 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
 139 #define RTC_CLASS_DEV_PM_OPS    (&rtc_class_dev_pm_ops)
 140 #else
 141 #define RTC_CLASS_DEV_PM_OPS    NULL
 142 #endif
 143
 144
 145 /**
 146  * rtc_device_register - register w/ RTC class
 147  * @dev: the device to register
 148  *
 149  * rtc_device_unregister() must be called when the class device is no
 150  * longer needed.
 151  *
 152  * Returns the pointer to the new struct class device.
 153  */
 154 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 155                                         const struct rtc_class_ops *ops,
 156                                         struct module *owner)
 157 {
 158         struct rtc_device *rtc;
 159         struct rtc_wkalrm alrm;
 160         int id, err;
 161
 162         id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 163         if (id < 0) {
 164                 err = id;
 165                 goto exit;
 166         }
 167
 168         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 169         if (rtc == NULL) {
 170                 err = -ENOMEM;
 171                 goto exit_ida;
 172         }
 173
 174         rtc->id = id;
 175         rtc->ops = ops;
 176         rtc->owner = owner;
 177         rtc->irq_freq = 1;
 178         rtc->max_user_freq = 64;
 179         rtc->dev.parent = dev;
 180         rtc->dev.class = rtc_class;
 181         rtc->dev.release = rtc_device_release;
 182
 183         mutex_init(&rtc->ops_lock);
 184         spin_lock_init(&rtc->irq_lock);
 185         spin_lock_init(&rtc->irq_task_lock);
 186         init_waitqueue_head(&rtc->irq_queue);
 187
 188         /* Init timerqueue */
 189         timerqueue_init_head(&rtc->timerqueue);
 190         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 191         /* Init aie timer */
 192         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 193         /* Init uie timer */
 194         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 195         /* Init pie timer */
 196         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 197         rtc->pie_timer.function = rtc_pie_update_irq;
 198         rtc->pie_enabled = 0;
 199
 200         /* Check to see if there is an ALARM already set in hw */
 201         err = __rtc_read_alarm(rtc, &alrm);
 202
 203         if (!err && !rtc_valid_tm(&alrm.time))
 204                 rtc_initialize_alarm(rtc, &alrm);
 205
 206         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 207         dev_set_name(&rtc->dev, "rtc%d", id);
 208
 209         rtc_dev_prepare(rtc);
 210
 211         err = device_register(&rtc->dev);
 212         if (err) {
 213                 put_device(&rtc->dev);
 214                 goto exit_kfree;
 215         }
 216
 217         rtc_dev_add_device(rtc);
 218         rtc_sysfs_add_device(rtc);
 219         rtc_proc_add_device(rtc);
 220
 221         dev_info(dev, "rtc core: registered %s as %s\n",
 222                         rtc->name, dev_name(&rtc->dev));
 223
 224         return rtc;
 225
 226 exit_kfree:
 227         kfree(rtc);
 228
 229 exit_ida:
 230         ida_simple_remove(&rtc_ida, id);
 231
 232 exit:
 233         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 234                         name, err);
 235         return ERR_PTR(err);
 236 }
 237 EXPORT_SYMBOL_GPL(rtc_device_register);
 238
 239
 240 /**
 241  * rtc_device_unregister - removes the previously registered RTC class device
 242  *
 243  * @rtc: the RTC class device to destroy
 244  */
 245 void rtc_device_unregister(struct rtc_device *rtc)
 246 {
 247         if (get_device(&rtc->dev) != NULL) {
 248                 mutex_lock(&rtc->ops_lock);
 249                 /* remove innards of this RTC, then disable it, before
 250                  * letting any rtc_class_open() users access it again
 251                  */
 252                 rtc_sysfs_del_device(rtc);
 253                 rtc_dev_del_device(rtc);
 254                 rtc_proc_del_device(rtc);
 255                 device_unregister(&rtc->dev);
 256                 rtc->ops = NULL;
 257                 mutex_unlock(&rtc->ops_lock);
 258                 put_device(&rtc->dev);
 259         }
 260 }
 261 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 262
 263 static void devm_rtc_device_release(struct device *dev, void *res)
 264 {
 265         struct rtc_device *rtc = *(struct rtc_device **)res;
 266
 267         rtc_device_unregister(rtc);
 268 }
 269
 270 static int devm_rtc_device_match(struct device *dev, void *res, void *data)
 271 {
 272         struct rtc **r = res;
 273
 274         return *r == data;
 275 }
 276
 277 /**
 278  * devm_rtc_device_register - resource managed rtc_device_register()
 279  * @dev: the device to register
 280  * @name: the name of the device
 281  * @ops: the rtc operations structure
 282  * @owner: the module owner
 283  *
 284  * @return a struct rtc on success, or an ERR_PTR on error
 285  *
 286  * Managed rtc_device_register(). The rtc_device returned from this function
 287  * are automatically freed on driver detach. See rtc_device_register()
 288  * for more information.
 289  */
 290
 291 struct rtc_device *devm_rtc_device_register(struct device *dev,
 292                                         const char *name,
 293                                         const struct rtc_class_ops *ops,
 294                                         struct module *owner)
 295 {
 296         struct rtc_device **ptr, *rtc;
 297
 298         ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
 299         if (!ptr)
 300                 return ERR_PTR(-ENOMEM);
 301
 302         rtc = rtc_device_register(name, dev, ops, owner);
 303         if (!IS_ERR(rtc)) {
 304                 *ptr = rtc;
 305                 devres_add(dev, ptr);
 306         } else {
 307                 devres_free(ptr);
 308         }
 309
 310         return rtc;
 311 }
 312 EXPORT_SYMBOL_GPL(devm_rtc_device_register);
 313
 314 /**
 315  * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 316  * @dev: the device to unregister
 317  * @rtc: the RTC class device to unregister
 318  *
 319  * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 320  * function will not need to be called and the resource management code will
 321  * ensure that the resource is freed.
 322  */
 323 void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
 324 {
 325         int rc;
 326
 327         rc = devres_release(dev, devm_rtc_device_release,
 328                                 devm_rtc_device_match, rtc);
 329         WARN_ON(rc);
 330 }
 331 EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);
 332
 333 static int __init rtc_init(void)
 334 {
 335         rtc_class = class_create(THIS_MODULE, "rtc");
 336         if (IS_ERR(rtc_class)) {
 337                 pr_err("couldn't create class\n");
 338                 return PTR_ERR(rtc_class);
 339         }
 340         rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 341         rtc_dev_init();
 342         rtc_sysfs_init(rtc_class);
 343         return 0;
 344 }
 345
 346 static void __exit rtc_exit(void)
 347 {
 348         rtc_dev_exit();
 349         class_destroy(rtc_class);
 350         ida_destroy(&rtc_ida);
 351 }
 352
 353 subsys_initcall(rtc_init);
 354 module_exit(rtc_exit);
 355
 356 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 357 MODULE_DESCRIPTION("RTC class support");
 358 MODULE_LICENSE("GPL");