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_IDR(rtc_idr);
  25 static DEFINE_MUTEX(idr_lock);
  26 struct class *rtc_class;
  27
  28 static void rtc_device_release(struct device *dev)
  29 {
  30         struct rtc_device *rtc = to_rtc_device(dev);
  31         mutex_lock(&idr_lock);
  32         idr_remove(&rtc_idr, rtc->id);
  33         mutex_unlock(&idr_lock);
  34         kfree(rtc);
  35 }
  36
  37 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
  38
  39 /*
  40  * On suspend(), measure the delta between one RTC and the
  41  * system's wall clock; restore it on resume().
  42  */
  43
  44 static struct timespec old_rtc, old_system, old_delta;
  45
  46
  47 static int rtc_suspend(struct device *dev, pm_message_t mesg)
  48 {
  49         struct rtc_device       *rtc = to_rtc_device(dev);
  50         struct rtc_time         tm;
  51         struct timespec         delta, delta_delta;
  52         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  53                 return 0;
  54
  55         /* snapshot the current RTC and system time at suspend*/
  56         rtc_read_time(rtc, &tm);
  57         getnstimeofday(&old_system);
  58         rtc_tm_to_time(&tm, &old_rtc.tv_sec);
  59
  60
  61         /*
  62          * To avoid drift caused by repeated suspend/resumes,
  63          * which each can add ~1 second drift error,
  64          * try to compensate so the difference in system time
  65          * and rtc time stays close to constant.
  66          */
  67         delta = timespec_sub(old_system, old_rtc);
  68         delta_delta = timespec_sub(delta, old_delta);
  69         if (abs(delta_delta.tv_sec)  >= 2) {
  70                 /*
  71                  * if delta_delta is too large, assume time correction
  72                  * has occured and set old_delta to the current delta.
  73                  */
  74                 old_delta = delta;
  75         } else {
  76                 /* Otherwise try to adjust old_system to compensate */
  77                 old_system = timespec_sub(old_system, delta_delta);
  78         }
  79
  80         return 0;
  81 }
  82
  83 static int rtc_resume(struct device *dev)
  84 {
  85         struct rtc_device       *rtc = to_rtc_device(dev);
  86         struct rtc_time         tm;
  87         struct timespec         new_system, new_rtc;
  88         struct timespec         sleep_time;
  89
  90         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  91                 return 0;
  92
  93         /* snapshot the current rtc and system time at resume */
  94         getnstimeofday(&new_system);
  95         rtc_read_time(rtc, &tm);
  96         if (rtc_valid_tm(&tm) != 0) {
  97                 pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
  98                 return 0;
  99         }
 100         rtc_tm_to_time(&tm, &new_rtc.tv_sec);
 101         new_rtc.tv_nsec = 0;
 102
 103         if (new_rtc.tv_sec <= old_rtc.tv_sec) {
 104                 if (new_rtc.tv_sec < old_rtc.tv_sec)
 105                         pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
 106                 return 0;
 107         }
 108
 109         /* calculate the RTC time delta (sleep time)*/
 110         sleep_time = timespec_sub(new_rtc, old_rtc);
 111
 112         /*
 113          * Since these RTC suspend/resume handlers are not called
 114          * at the very end of suspend or the start of resume,
 115          * some run-time may pass on either sides of the sleep time
 116          * so subtract kernel run-time between rtc_suspend to rtc_resume
 117          * to keep things accurate.
 118          */
 119         sleep_time = timespec_sub(sleep_time,
 120                         timespec_sub(new_system, old_system));
 121
 122         timekeeping_inject_sleeptime(&sleep_time);
 123         return 0;
 124 }
 125
 126 #else
 127 #define rtc_suspend     NULL
 128 #define rtc_resume      NULL
 129 #endif
 130
 131
 132 /**
 133  * rtc_device_register - register w/ RTC class
 134  * @dev: the device to register
 135  *
 136  * rtc_device_unregister() must be called when the class device is no
 137  * longer needed.
 138  *
 139  * Returns the pointer to the new struct class device.
 140  */
 141 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 142                                         const struct rtc_class_ops *ops,
 143                                         struct module *owner)
 144 {
 145         struct rtc_device *rtc;
 146         struct rtc_wkalrm alrm;
 147         int id, err;
 148
 149         if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
 150                 err = -ENOMEM;
 151                 goto exit;
 152         }
 153
 154
 155         mutex_lock(&idr_lock);
 156         err = idr_get_new(&rtc_idr, NULL, &id);
 157         mutex_unlock(&idr_lock);
 158
 159         if (err < 0)
 160                 goto exit;
 161
 162         id = id & MAX_ID_MASK;
 163
 164         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 165         if (rtc == NULL) {
 166                 err = -ENOMEM;
 167                 goto exit_idr;
 168         }
 169
 170         rtc->id = id;
 171         rtc->ops = ops;
 172         rtc->owner = owner;
 173         rtc->irq_freq = 1;
 174         rtc->max_user_freq = 64;
 175         rtc->dev.parent = dev;
 176         rtc->dev.class = rtc_class;
 177         rtc->dev.release = rtc_device_release;
 178
 179         mutex_init(&rtc->ops_lock);
 180         spin_lock_init(&rtc->irq_lock);
 181         spin_lock_init(&rtc->irq_task_lock);
 182         init_waitqueue_head(&rtc->irq_queue);
 183
 184         /* Init timerqueue */
 185         timerqueue_init_head(&rtc->timerqueue);
 186         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 187         /* Init aie timer */
 188         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 189         /* Init uie timer */
 190         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 191         /* Init pie timer */
 192         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 193         rtc->pie_timer.function = rtc_pie_update_irq;
 194         rtc->pie_enabled = 0;
 195
 196         /* Check to see if there is an ALARM already set in hw */
 197         err = __rtc_read_alarm(rtc, &alrm);
 198
 199         if (!err && !rtc_valid_tm(&alrm.time))
 200                 rtc_initialize_alarm(rtc, &alrm);
 201
 202         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 203         dev_set_name(&rtc->dev, "rtc%d", id);
 204
 205         rtc_dev_prepare(rtc);
 206
 207         err = device_register(&rtc->dev);
 208         if (err) {
 209                 put_device(&rtc->dev);
 210                 goto exit_kfree;
 211         }
 212
 213         rtc_dev_add_device(rtc);
 214         rtc_sysfs_add_device(rtc);
 215         rtc_proc_add_device(rtc);
 216
 217         dev_info(dev, "rtc core: registered %s as %s\n",
 218                         rtc->name, dev_name(&rtc->dev));
 219
 220         return rtc;
 221
 222 exit_kfree:
 223         kfree(rtc);
 224
 225 exit_idr:
 226         mutex_lock(&idr_lock);
 227         idr_remove(&rtc_idr, id);
 228         mutex_unlock(&idr_lock);
 229
 230 exit:
 231         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 232                         name, err);
 233         return ERR_PTR(err);
 234 }
 235 EXPORT_SYMBOL_GPL(rtc_device_register);
 236
 237
 238 /**
 239  * rtc_device_unregister - removes the previously registered RTC class device
 240  *
 241  * @rtc: the RTC class device to destroy
 242  */
 243 void rtc_device_unregister(struct rtc_device *rtc)
 244 {
 245         if (get_device(&rtc->dev) != NULL) {
 246                 mutex_lock(&rtc->ops_lock);
 247                 /* remove innards of this RTC, then disable it, before
 248                  * letting any rtc_class_open() users access it again
 249                  */
 250                 rtc_sysfs_del_device(rtc);
 251                 rtc_dev_del_device(rtc);
 252                 rtc_proc_del_device(rtc);
 253                 device_unregister(&rtc->dev);
 254                 rtc->ops = NULL;
 255                 mutex_unlock(&rtc->ops_lock);
 256                 put_device(&rtc->dev);
 257         }
 258 }
 259 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 260
 261 static int __init rtc_init(void)
 262 {
 263         rtc_class = class_create(THIS_MODULE, "rtc");
 264         if (IS_ERR(rtc_class)) {
 265                 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
 266                 return PTR_ERR(rtc_class);
 267         }
 268         rtc_class->suspend = rtc_suspend;
 269         rtc_class->resume = rtc_resume;
 270         rtc_dev_init();
 271         rtc_sysfs_init(rtc_class);
 272         return 0;
 273 }
 274
 275 static void __exit rtc_exit(void)
 276 {
 277         rtc_dev_exit();
 278         class_destroy(rtc_class);
 279         idr_destroy(&rtc_idr);
 280 }
 281
 282 subsys_initcall(rtc_init);
 283 module_exit(rtc_exit);
 284
 285 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 286 MODULE_DESCRIPTION("RTC class support");
 287 MODULE_LICENSE("GPL");