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