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  delta;
  45 static time_t           oldtime;
  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         ts = current_kernel_time();
  52
  53         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  54                 return 0;
  55
  56         rtc_read_time(rtc, &tm);
  57         rtc_tm_to_time(&tm, &oldtime);
  58
  59         /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
  60         set_normalized_timespec(&delta,
  61                                 ts.tv_sec - oldtime,
  62                                 ts.tv_nsec - (NSEC_PER_SEC >> 1));
  63
  64         return 0;
  65 }
  66
  67 static int rtc_resume(struct device *dev)
  68 {
  69         struct rtc_device       *rtc = to_rtc_device(dev);
  70         struct rtc_time         tm;
  71         time_t                  newtime;
  72         struct timespec         time;
  73
  74         if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
  75                 return 0;
  76
  77         rtc_read_time(rtc, &tm);
  78         if (rtc_valid_tm(&tm) != 0) {
  79                 pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));
  80                 return 0;
  81         }
  82         rtc_tm_to_time(&tm, &newtime);
  83         if (newtime <= oldtime) {
  84                 if (newtime < oldtime)
  85                         pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
  86                 return 0;
  87         }
  88
  89         /* restore wall clock using delta against this RTC;
  90          * adjust again for avg 1/2 second RTC sampling error
  91          */
  92         set_normalized_timespec(&time,
  93                                 newtime + delta.tv_sec,
  94                                 (NSEC_PER_SEC >> 1) + delta.tv_nsec);
  95         do_settimeofday(&time);
  96
  97         return 0;
  98 }
  99
 100 #else
 101 #define rtc_suspend     NULL
 102 #define rtc_resume      NULL
 103 #endif
 104
 105
 106 /**
 107  * rtc_device_register - register w/ RTC class
 108  * @dev: the device to register
 109  *
 110  * rtc_device_unregister() must be called when the class device is no
 111  * longer needed.
 112  *
 113  * Returns the pointer to the new struct class device.
 114  */
 115 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 116                                         const struct rtc_class_ops *ops,
 117                                         struct module *owner)
 118 {
 119         struct rtc_device *rtc;
 120         int id, err;
 121
 122         if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
 123                 err = -ENOMEM;
 124                 goto exit;
 125         }
 126
 127
 128         mutex_lock(&idr_lock);
 129         err = idr_get_new(&rtc_idr, NULL, &id);
 130         mutex_unlock(&idr_lock);
 131
 132         if (err < 0)
 133                 goto exit;
 134
 135         id = id & MAX_ID_MASK;
 136
 137         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 138         if (rtc == NULL) {
 139                 err = -ENOMEM;
 140                 goto exit_idr;
 141         }
 142
 143         rtc->id = id;
 144         rtc->ops = ops;
 145         rtc->owner = owner;
 146         rtc->max_user_freq = 64;
 147         rtc->dev.parent = dev;
 148         rtc->dev.class = rtc_class;
 149         rtc->dev.release = rtc_device_release;
 150
 151         mutex_init(&rtc->ops_lock);
 152         spin_lock_init(&rtc->irq_lock);
 153         spin_lock_init(&rtc->irq_task_lock);
 154         init_waitqueue_head(&rtc->irq_queue);
 155
 156         /* Init timerqueue */
 157         timerqueue_init_head(&rtc->timerqueue);
 158         INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
 159         /* Init aie timer */
 160         rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
 161         /* Init uie timer */
 162         rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
 163         /* Init pie timer */
 164         hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 165         rtc->pie_timer.function = rtc_pie_update_irq;
 166         rtc->pie_enabled = 0;
 167
 168         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 169         dev_set_name(&rtc->dev, "rtc%d", id);
 170
 171         rtc_dev_prepare(rtc);
 172
 173         err = device_register(&rtc->dev);
 174         if (err) {
 175                 put_device(&rtc->dev);
 176                 goto exit_kfree;
 177         }
 178
 179         rtc_dev_add_device(rtc);
 180         rtc_sysfs_add_device(rtc);
 181         rtc_proc_add_device(rtc);
 182
 183         dev_info(dev, "rtc core: registered %s as %s\n",
 184                         rtc->name, dev_name(&rtc->dev));
 185
 186         return rtc;
 187
 188 exit_kfree:
 189         kfree(rtc);
 190
 191 exit_idr:
 192         mutex_lock(&idr_lock);
 193         idr_remove(&rtc_idr, id);
 194         mutex_unlock(&idr_lock);
 195
 196 exit:
 197         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 198                         name, err);
 199         return ERR_PTR(err);
 200 }
 201 EXPORT_SYMBOL_GPL(rtc_device_register);
 202
 203
 204 /**
 205  * rtc_device_unregister - removes the previously registered RTC class device
 206  *
 207  * @rtc: the RTC class device to destroy
 208  */
 209 void rtc_device_unregister(struct rtc_device *rtc)
 210 {
 211         if (get_device(&rtc->dev) != NULL) {
 212                 mutex_lock(&rtc->ops_lock);
 213                 /* remove innards of this RTC, then disable it, before
 214                  * letting any rtc_class_open() users access it again
 215                  */
 216                 rtc_sysfs_del_device(rtc);
 217                 rtc_dev_del_device(rtc);
 218                 rtc_proc_del_device(rtc);
 219                 device_unregister(&rtc->dev);
 220                 rtc->ops = NULL;
 221                 mutex_unlock(&rtc->ops_lock);
 222                 put_device(&rtc->dev);
 223         }
 224 }
 225 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 226
 227 static int __init rtc_init(void)
 228 {
 229         rtc_class = class_create(THIS_MODULE, "rtc");
 230         if (IS_ERR(rtc_class)) {
 231                 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
 232                 return PTR_ERR(rtc_class);
 233         }
 234         rtc_class->suspend = rtc_suspend;
 235         rtc_class->resume = rtc_resume;
 236         rtc_dev_init();
 237         rtc_sysfs_init(rtc_class);
 238         return 0;
 239 }
 240
 241 static void __exit rtc_exit(void)
 242 {
 243         rtc_dev_exit();
 244         class_destroy(rtc_class);
 245         idr_destroy(&rtc_idr);
 246 }
 247
 248 subsys_initcall(rtc_init);
 249 module_exit(rtc_exit);
 250
 251 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 252 MODULE_DESCRIPTION("RTC class support");
 253 MODULE_LICENSE("GPL");