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 #include <linux/module.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
  24 static DEFINE_IDA(rtc_ida);
  25 struct class *rtc_class;
  26
  27 static void rtc_device_release(struct device *dev)
  28 {
  29         struct rtc_device *rtc = to_rtc_device(dev);
  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) && 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 timespec old_rtc, old_system, old_delta;
  46
  47
  48 static int rtc_suspend(struct device *dev, pm_message_t mesg)
  49 {
  50         struct rtc_device       *rtc = to_rtc_device(dev);
  51         struct rtc_time         tm;
  52         struct timespec         delta, delta_delta;
  53         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  54                 return 0;
  55
  56         /* snapshot the current RTC and system time at suspend*/
  57         rtc_read_time(rtc, &tm);
  58         getnstimeofday(&old_system);
  59         rtc_tm_to_time(&tm, &old_rtc.tv_sec);
  60
  61
  62         /*
  63          * To avoid drift caused by repeated suspend/resumes,
  64          * which each can add ~1 second drift error,
  65          * try to compensate so the difference in system time
  66          * and rtc time stays close to constant.
  67          */
  68         delta = timespec_sub(old_system, old_rtc);
  69         delta_delta = timespec_sub(delta, old_delta);
  70         if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
  71                 /*
  72                  * if delta_delta is too large, assume time correction
  73                  * has occured and set old_delta to the current delta.
  74                  */
  75                 old_delta = delta;
  76         } else {
  77                 /* Otherwise try to adjust old_system to compensate */
  78                 old_system = timespec_sub(old_system, delta_delta);
  79         }
  80
  81         return 0;
  82 }
  83
  84 static int rtc_resume(struct device *dev)
  85 {
  86         struct rtc_device       *rtc = to_rtc_device(dev);
  87         struct rtc_time         tm;
  88         struct timespec         new_system, new_rtc;
  89         struct timespec         sleep_time;
  90
  91         rtc_hctosys_ret = -ENODEV;
  92         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  93                 return 0;
  94
  95         /* snapshot the current rtc and system time at resume */
  96         getnstimeofday(&new_system);
  97         rtc_read_time(rtc, &tm);
  98         if (rtc_valid_tm(&tm) != 0) {
  99                 pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
 100                 return 0;
 101         }
 102         rtc_tm_to_time(&tm, &new_rtc.tv_sec);
 103         new_rtc.tv_nsec = 0;
 104
 105         if (new_rtc.tv_sec < old_rtc.tv_sec) {
 106                 pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
 107                 return 0;
 108         }
 109
 110         /* calculate the RTC time delta (sleep time)*/
 111         sleep_time = timespec_sub(new_rtc, old_rtc);
 112
 113         /*
 114          * Since these RTC suspend/resume handlers are not called
 115          * at the very end of suspend or the start of resume,
 116          * some run-time may pass on either sides of the sleep time
 117          * so subtract kernel run-time between rtc_suspend to rtc_resume
 118          * to keep things accurate.
 119          */
 120         sleep_time = timespec_sub(sleep_time,
 121                         timespec_sub(new_system, old_system));
 122
 123         if (sleep_time.tv_sec >= 0)
 124                 timekeeping_inject_sleeptime(&sleep_time);
 125         rtc_hctosys_ret = 0;
 126         return 0;
 127 }
 128
 129 #else
 130 #define rtc_suspend     NULL
 131 #define rtc_resume      NULL
 132 #endif
 133
 134
 135 /**
 136  * rtc_device_register - register w/ RTC class
 137  * @dev: the device to register
 138  *
 139  * rtc_device_unregister() must be called when the class device is no
 140  * longer needed.
 141  *
 142  * Returns the pointer to the new struct class device.
 143  */
 144 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 145                                         const struct rtc_class_ops *ops,
 146                                         struct module *owner)
 147 {
 148         struct rtc_device *rtc;
 149         struct rtc_wkalrm alrm;
 150         int id, err;
 151
 152         id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
 153         if (id < 0) {
 154                 err = id;
 155                 goto exit;
 156         }
 157
 158         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 159         if (rtc == NULL) {
 160                 err = -ENOMEM;
 161                 goto exit_ida;
 162         }
 163
 164         rtc->id = id;
 165         rtc->ops = ops;
 166         rtc->owner = owner;
 167         rtc->irq_freq = 1;
 168         rtc->max_user_freq = 64;
 169         rtc->dev.parent = dev;
 170         rtc->dev.class = rtc_class;
 171         rtc->dev.release = rtc_device_release;
 172
 173         mutex_init(&rtc->ops_lock);
 174         spin_lock_init(&rtc->irq_lock);
 175         spin_lock_init(&rtc->irq_task_lock);
 176         init_waitqueue_head(&rtc->irq_queue);
 177
 178         /* Init timerqueue */
 179         timerqueue_init_head(&rtc->timerqueue);
 180         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 181         /* Init aie timer */
 182         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 183         /* Init uie timer */
 184         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 185         /* Init pie timer */
 186         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 187         rtc->pie_timer.function = rtc_pie_update_irq;
 188         rtc->pie_enabled = 0;
 189
 190         /* Check to see if there is an ALARM already set in hw */
 191         err = __rtc_read_alarm(rtc, &alrm);
 192
 193         if (!err && !rtc_valid_tm(&alrm.time))
 194                 rtc_initialize_alarm(rtc, &alrm);
 195
 196         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 197         dev_set_name(&rtc->dev, "rtc%d", id);
 198
 199         rtc_dev_prepare(rtc);
 200
 201         err = device_register(&rtc->dev);
 202         if (err) {
 203                 put_device(&rtc->dev);
 204                 goto exit_kfree;
 205         }
 206
 207         rtc_dev_add_device(rtc);
 208         rtc_sysfs_add_device(rtc);
 209         rtc_proc_add_device(rtc);
 210
 211         dev_info(dev, "rtc core: registered %s as %s\n",
 212                         rtc->name, dev_name(&rtc->dev));
 213
 214         return rtc;
 215
 216 exit_kfree:
 217         kfree(rtc);
 218
 219 exit_ida:
 220         ida_simple_remove(&rtc_ida, id);
 221
 222 exit:
 223         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 224                         name, err);
 225         return ERR_PTR(err);
 226 }
 227 EXPORT_SYMBOL_GPL(rtc_device_register);
 228
 229
 230 /**
 231  * rtc_device_unregister - removes the previously registered RTC class device
 232  *
 233  * @rtc: the RTC class device to destroy
 234  */
 235 void rtc_device_unregister(struct rtc_device *rtc)
 236 {
 237         if (get_device(&rtc->dev) != NULL) {
 238                 mutex_lock(&rtc->ops_lock);
 239                 /* remove innards of this RTC, then disable it, before
 240                  * letting any rtc_class_open() users access it again
 241                  */
 242                 rtc_sysfs_del_device(rtc);
 243                 rtc_dev_del_device(rtc);
 244                 rtc_proc_del_device(rtc);
 245                 device_unregister(&rtc->dev);
 246                 rtc->ops = NULL;
 247                 mutex_unlock(&rtc->ops_lock);
 248                 put_device(&rtc->dev);
 249         }
 250 }
 251 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 252
 253 static int __init rtc_init(void)
 254 {
 255         rtc_class = class_create(THIS_MODULE, "rtc");
 256         if (IS_ERR(rtc_class)) {
 257                 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
 258                 return PTR_ERR(rtc_class);
 259         }
 260         rtc_class->suspend = rtc_suspend;
 261         rtc_class->resume = rtc_resume;
 262         rtc_dev_init();
 263         rtc_sysfs_init(rtc_class);
 264         return 0;
 265 }
 266
 267 static void __exit rtc_exit(void)
 268 {
 269         rtc_dev_exit();
 270         class_destroy(rtc_class);
 271         ida_destroy(&rtc_ida);
 272 }
 273
 274 subsys_initcall(rtc_init);
 275 module_exit(rtc_exit);
 276
 277 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 278 MODULE_DESCRIPTION("RTC class support");
 279 MODULE_LICENSE("GPL");