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 class_device *class_dev)
  27 {
  28         struct rtc_device *rtc = to_rtc_device(class_dev);
  29         mutex_lock(&idr_lock);
  30         idr_remove(&rtc_idr, rtc->id);
  31         mutex_unlock(&idr_lock);
  32         kfree(rtc);
  33 }
  34
  35 /**
  36  * rtc_device_register - register w/ RTC class
  37  * @dev: the device to register
  38  *
  39  * rtc_device_unregister() must be called when the class device is no
  40  * longer needed.
  41  *
  42  * Returns the pointer to the new struct class device.
  43  */
  44 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
  45                                         const struct rtc_class_ops *ops,
  46                                         struct module *owner)
  47 {
  48         struct rtc_device *rtc;
  49         int id, err;
  50
  51         if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
  52                 err = -ENOMEM;
  53                 goto exit;
  54         }
  55
  56
  57         mutex_lock(&idr_lock);
  58         err = idr_get_new(&rtc_idr, NULL, &id);
  59         mutex_unlock(&idr_lock);
  60
  61         if (err < 0)
  62                 goto exit;
  63
  64         id = id & MAX_ID_MASK;
  65
  66         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
  67         if (rtc == NULL) {
  68                 err = -ENOMEM;
  69                 goto exit_idr;
  70         }
  71
  72         rtc->id = id;
  73         rtc->ops = ops;
  74         rtc->owner = owner;
  75         rtc->max_user_freq = 64;
  76         rtc->class_dev.dev = dev;
  77         rtc->class_dev.class = rtc_class;
  78         rtc->class_dev.release = rtc_device_release;
  79
  80         mutex_init(&rtc->ops_lock);
  81         spin_lock_init(&rtc->irq_lock);
  82         spin_lock_init(&rtc->irq_task_lock);
  83
  84         strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
  85         snprintf(rtc->class_dev.class_id, BUS_ID_SIZE, "rtc%d", id);
  86
  87         err = class_device_register(&rtc->class_dev);
  88         if (err)
  89                 goto exit_kfree;
  90
  91         rtc_dev_add_device(rtc);
  92
  93         dev_info(dev, "rtc core: registered %s as %s\n",
  94                         rtc->name, rtc->class_dev.class_id);
  95
  96         return rtc;
  97
  98 exit_kfree:
  99         kfree(rtc);
 100
 101 exit_idr:
 102         mutex_lock(&idr_lock);
 103         idr_remove(&rtc_idr, id);
 104         mutex_unlock(&idr_lock);
 105
 106 exit:
 107         dev_err(dev, "rtc core: unable to register %s, err = %d\n",
 108                         name, err);
 109         return ERR_PTR(err);
 110 }
 111 EXPORT_SYMBOL_GPL(rtc_device_register);
 112
 113
 114 /**
 115  * rtc_device_unregister - removes the previously registered RTC class device
 116  *
 117  * @rtc: the RTC class device to destroy
 118  */
 119 void rtc_device_unregister(struct rtc_device *rtc)
 120 {
 121         if (class_device_get(&rtc->class_dev) != NULL) {
 122                 mutex_lock(&rtc->ops_lock);
 123                 /* remove innards of this RTC, then disable it, before
 124                  * letting any rtc_class_open() users access it again
 125                  */
 126                 rtc_dev_del_device(rtc);
 127                 class_device_unregister(&rtc->class_dev);
 128                 rtc->ops = NULL;
 129                 mutex_unlock(&rtc->ops_lock);
 130                 class_device_put(&rtc->class_dev);
 131         }
 132 }
 133 EXPORT_SYMBOL_GPL(rtc_device_unregister);
 134
 135 int rtc_interface_register(struct class_interface *intf)
 136 {
 137         intf->class = rtc_class;
 138         return class_interface_register(intf);
 139 }
 140 EXPORT_SYMBOL_GPL(rtc_interface_register);
 141
 142 static int __init rtc_init(void)
 143 {
 144         rtc_class = class_create(THIS_MODULE, "rtc");
 145         if (IS_ERR(rtc_class)) {
 146                 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
 147                 return PTR_ERR(rtc_class);
 148         }
 149         rtc_dev_init();
 150         return 0;
 151 }
 152
 153 static void __exit rtc_exit(void)
 154 {
 155         rtc_dev_exit();
 156         class_destroy(rtc_class);
 157 }
 158
 159 subsys_initcall(rtc_init);
 160 module_exit(rtc_exit);
 161
 162 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 163 MODULE_DESCRIPTION("RTC class support");
 164 MODULE_LICENSE("GPL");