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 #include <linux/gfp.h>
  20
  21 #define HWMON_ID_PREFIX "hwmon"
  22 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
  23
  24 static struct class *hwmon_class;
  25
  26 static DEFINE_IDR(hwmon_idr);
  27
  28 /**
  29  * hwmon_device_register - register w/ hwmon sysfs class
  30  * @dev: the device to register
  31  *
  32  * hwmon_device_unregister() must be called when the class device is no
  33  * longer needed.
  34  *
  35  * Returns the pointer to the new struct class device.
  36  */
  37 struct class_device *hwmon_device_register(struct device *dev)
  38 {
  39         struct class_device *cdev;
  40         int id;
  41
  42         if (idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0)
  43                 return ERR_PTR(-ENOMEM);
  44
  45         if (idr_get_new(&hwmon_idr, NULL, &id) < 0)
  46                 return ERR_PTR(-ENOMEM);
  47
  48         id = id & MAX_ID_MASK;
  49         cdev = class_device_create(hwmon_class, NULL, MKDEV(0,0), dev,
  50                                         HWMON_ID_FORMAT, id);
  51
  52         if (IS_ERR(cdev))
  53                 idr_remove(&hwmon_idr, id);
  54
  55         return cdev;
  56 }
  57
  58 /**
  59  * hwmon_device_unregister - removes the previously registered class device
  60  *
  61  * @cdev: the class device to destroy
  62  */
  63 void hwmon_device_unregister(struct class_device *cdev)
  64 {
  65         int id;
  66
  67         if (sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1) {
  68                 class_device_unregister(cdev);
  69                 idr_remove(&hwmon_idr, id);
  70         } else
  71                 dev_dbg(cdev->dev,
  72                         "hwmon_device_unregister() failed: bad class ID!\n");
  73 }
  74
  75 static int __init hwmon_init(void)
  76 {
  77         hwmon_class = class_create(THIS_MODULE, "hwmon");
  78         if (IS_ERR(hwmon_class)) {
  79                 printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");
  80                 return PTR_ERR(hwmon_class);
  81         }
  82         return 0;
  83 }
  84
  85 static void __exit hwmon_exit(void)
  86 {
  87         class_destroy(hwmon_class);
  88 }
  89
  90 module_init(hwmon_init);
  91 module_exit(hwmon_exit);
  92
  93 EXPORT_SYMBOL_GPL(hwmon_device_register);
  94 EXPORT_SYMBOL_GPL(hwmon_device_unregister);
  95
  96 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
  97 MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
  98 MODULE_LICENSE("GPL");
  99