drivers/hwmon/hwmon.c

   1 /*
   2     hwmon.c - part of lm_sensors, Linux kernel modules for hardware monitoring
   3
   4     This file defines the sysfs class "hwmon", for use by sensors drivers.
   5
   6     Copyright (C) 2005 Mark M. Hoffman <mhoffman@lightlink.com>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; version 2 of the License.
  11 */
  12
  13 #include <linux/module.h>
  14 #include <linux/device.h>
  15 #include <linux/err.h>
  16 #include <linux/kdev_t.h>
  17 #include <linux/idr.h>
  18 #include <linux/hwmon.h>
  19
  20 #define HWMON_ID_PREFIX "hwmon"
  21 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
  22
  23 static struct class *hwmon_class;
  24
  25 static DEFINE_IDR(hwmon_idr);
  26
  27 /**
  28  * hwmon_device_register - register w/ hwmon sysfs class
  29  * @dev: the device to register
  30  *
  31  * hwmon_device_unregister() must be called when the class device is no
  32  * longer needed.
  33  *
  34  * Returns the pointer to the new struct class device.
  35  */
  36 struct class_device *hwmon_device_register(struct device *dev)
  37 {
  38         struct class_device *cdev;
  39         int id;
  40
  41         if (idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0)
  42                 return ERR_PTR(-ENOMEM);
  43
  44         if (idr_get_new(&hwmon_idr, NULL, &id) < 0)
  45                 return ERR_PTR(-ENOMEM);
  46
  47         id = id & MAX_ID_MASK;
  48         cdev = class_device_create(hwmon_class, MKDEV(0,0), dev,
  49                                         HWMON_ID_FORMAT, id);
  50
  51         if (IS_ERR(cdev))
  52                 idr_remove(&hwmon_idr, id);
  53
  54         return cdev;
  55 }
  56
  57 /**
  58  * hwmon_device_unregister - removes the previously registered class device
  59  *
  60  * @cdev: the class device to destroy
  61  */
  62 void hwmon_device_unregister(struct class_device *cdev)
  63 {
  64         int id;
  65
  66         if (sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1) {
  67                 class_device_unregister(cdev);
  68                 idr_remove(&hwmon_idr, id);
  69         } else
  70                 dev_dbg(cdev->dev,
  71                         "hwmon_device_unregister() failed: bad class ID!\n");
  72 }
  73
  74 static int __init hwmon_init(void)
  75 {
  76         hwmon_class = class_create(THIS_MODULE, "hwmon");
  77         if (IS_ERR(hwmon_class)) {
  78                 printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");
  79                 return PTR_ERR(hwmon_class);
  80         }
  81         return 0;
  82 }
  83
  84 static void __exit hwmon_exit(void)
  85 {
  86         class_destroy(hwmon_class);
  87 }
  88
  89 module_init(hwmon_init);
  90 module_exit(hwmon_exit);
  91
  92 EXPORT_SYMBOL_GPL(hwmon_device_register);
  93 EXPORT_SYMBOL_GPL(hwmon_device_unregister);
  94
  95 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
  96 MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
  97 MODULE_LICENSE("GPL");
  98