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