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