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
  19 #include "rtc-core.h"
  20
  21
  22 static DEFINE_IDR(rtc_idr);
  23 static DEFINE_MUTEX(idr_lock);
  24 struct class *rtc_class;
  25
  26 static void rtc_device_release(struct device *dev)
  27 {
  28         struct rtc_device *rtc = to_rtc_device(dev);
  29         mutex_lock(&idr_lock);
  30         idr_remove(&rtc_idr, rtc->id);
  31         mutex_unlock(&idr_lock);
  32         kfree(rtc);
  33 }
  34
  35 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
  36
  37 /*
  38  * On suspend(), measure the delta between one RTC and the
  39  * system's wall clock; restore it on resume().
  40  */
  41
  42 static struct timespec  delta;
  43 static time_t           oldtime;
  44
  45 static int rtc_suspend(struct device *dev, pm_message_t mesg)
  46 {
  47         struct rtc_device       *rtc = to_rtc_device(dev);
  48         struct rtc_time         tm;
  49
  50         if (strncmp(rtc->dev.bus_id,
  51                                 CONFIG_RTC_HCTOSYS_DEVICE,
  52                                 BUS_ID_SIZE) != 0)
  53                 return 0;
  54
  55         rtc_read_time(rtc, &tm);
  56         rtc_tm_to_time(&tm, &oldtime);
  57
  58         /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
  59         set_normalized_timespec(&delta,
  60                                 xtime.tv_sec - oldtime,
  61                                 xtime.tv_nsec - (NSEC_PER_SEC >> 1));
  62
  63         return 0;
  64 }
  65
  66 static int rtc_resume(struct device *dev)
  67 {
  68         struct rtc_device       *rtc = to_rtc_device(dev);
  69         struct rtc_time         tm;
  70         time_t                  newtime;
  71         struct timespec         time;
  72
  73         if (strncmp(rtc->dev.bus_id,
  74                                 CONFIG_RTC_HCTOSYS_DEVICE,
  75                                 BUS_ID_SIZE) != 0)
  76                 return 0;
  77
  78         rtc_read_time(rtc, &tm);
  79         if (rtc_valid_tm(&tm) != 0) {
  80                 pr_debug("%s:  bogus resume time\n", rtc->dev.bus_id);
  81                 return 0;
  82         }
  83         rtc_tm_to_time(&tm, &newtime);
  84         if (newtime <= oldtime) {
  85                 if (newtime < oldtime)
  86                         pr_debug("%s:  time travel!\n", rtc->dev.bus_id);
  87                 return 0;
  88         }
  89
  90         /* restore wall clock using delta against this RTC;
  91          * adjust again for avg 1/2 second RTC sampling error
  92          */
  93         set_normalized_timespec(&time,
  94                                 newtime + delta.tv_sec,
  95                                 (NSEC_PER_SEC >> 1) + delta.tv_nsec);
  96         do_settimeofday(&time);
  97
  98         return 0;
  99 }
 100
 101 #else
 102 #define rtc_suspend     NULL
 103 #define rtc_resume      NULL
 104 #endif
 105
 106
 107 /**
 108  * rtc_device_register - register w/ RTC class
 109  * @dev: the device to register
 110  *
 111  * rtc_device_unregister() must be called when the class device is no
 112  * longer needed.
 113  *
 114  * Returns the pointer to the new struct class device.
 115  */
 116 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 117                                         const struct rtc_class_ops *ops,
 118                                         struct module *owner)
 119 {
 120         struct rtc_device *rtc;
 121         int id, err;
 122
 123         if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
 124                 err = -ENOMEM;
 125                 goto exit;
 126         }
 127
 128
 129         mutex_lock(&idr_lock);
 130         err = idr_get_new(&rtc_idr, NULL, &id);
 131         mutex_unlock(&idr_lock);
 132
 133         if (err < 0)
 134                 goto exit;
 135
 136         id = id & MAX_ID_MASK;
 137
 138         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
 139         if (rtc == NULL) {
 140                 err = -ENOMEM;
 141                 goto exit_idr;
 142         }
 143
 144         rtc->id = id;
 145         rtc->ops = ops;
 146         rtc->owner = owner;
 147         rtc->max_user_freq = 64;
 148         rtc->dev.parent = dev;
 149         rtc->dev.class = rtc_class;
 150         rtc->dev.release = rtc_device_release;
 151
 152         mutex_init(&rtc->ops_lock);
 153         spin_lock_init(&rtc->irq_lock);
 154         spin_lock_init(&rtc->irq_task_lock);
 155
 156         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 157         snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id);
 158
 159         rtc_dev_prepare(rtc);
 160
 161         err = device_register(&rtc->dev);
 162         if (err)
 163                 goto exit_kfree;
 164
 165         rtc_dev_add_device(rtc);
 166         rtc_sysfs_add_device(rtc);
 167         rtc_proc_add_device(rtc);
 168
 169         dev_info(dev, "rtc core: registered %s as %s\n",
 170                         rtc->name, rtc->dev.bus_id);
 171
 172         return rtc;
 173
 174 exit_kfree:
 175         kfree(rtc);
 176
 177 exit_idr:
 178         mutex_lock(&idr_lock);
 179         idr_remove(&rtc_idr, id);
 180         mutex_unlock(&idr_lock);
 181
 182 exit:
 183         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 184                         name, err);
 185         return ERR_PTR(err);
 186 }
 187 EXPORT_SYMBOL_GPL(rtc_device_register);
 188
 189
 190 /**
 191  * rtc_device_unregister - removes the previously registered RTC class device
 192  *
 193  * @rtc: the RTC class device to destroy
 194  */
 195 void rtc_device_unregister(struct rtc_device *rtc)
 196 {
 197         if (get_device(&rtc->dev) != NULL) {
 198                 mutex_lock(&rtc->ops_lock);
 199                 /* remove innards of this RTC, then disable it, before
 200                  * letting any rtc_class_open() users access it again
 201                  */
 202                 rtc_sysfs_del_device(rtc);
 203                 rtc_dev_del_device(rtc);
 204                 rtc_proc_del_device(rtc);
 205                 device_unregister(&rtc->dev);
 206                 rtc->ops = NULL;
 207                 mutex_unlock(&rtc->ops_lock);
 208                 put_device(&rtc->dev);
 209         }
 210 }
 211 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 212
 213 static int __init rtc_init(void)
 214 {
 215         rtc_class = class_create(THIS_MODULE, "rtc");
 216         if (IS_ERR(rtc_class)) {
 217                 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
 218                 return PTR_ERR(rtc_class);
 219         }
 220         rtc_class->suspend = rtc_suspend;
 221         rtc_class->resume = rtc_resume;
 222         rtc_dev_init();
 223         rtc_sysfs_init(rtc_class);
 224         return 0;
 225 }
 226
 227 static void __exit rtc_exit(void)
 228 {
 229         rtc_dev_exit();
 230         class_destroy(rtc_class);
 231 }
 232
 233 subsys_initcall(rtc_init);
 234 module_exit(rtc_exit);
 235
 236 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 237 MODULE_DESCRIPTION("RTC class support");
 238 MODULE_LICENSE("GPL");