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 #include <linux/spinlock.h> 21 22 #define HWMON_ID_PREFIX "hwmon" 23 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d" 24 25 static struct class *hwmon_class; 26 27 static DEFINE_IDR(hwmon_idr); 28 static DEFINE_SPINLOCK(idr_lock); 29 30 /** 31 * hwmon_device_register - register w/ hwmon 32 * @dev: the device to register 33 * 34 * hwmon_device_unregister() must be called when the device is no 35 * longer needed. 36 * 37 * Returns the pointer to the new device. 38 */ 39 struct device *hwmon_device_register(struct device *dev) 40 { 41 struct device *hwdev; 42 int id, err; 43 44 again: 45 if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0)) 46 return ERR_PTR(-ENOMEM); 47 48 spin_lock(&idr_lock); 49 err = idr_get_new(&hwmon_idr, NULL, &id); 50 spin_unlock(&idr_lock); 51 52 if (unlikely(err == -EAGAIN)) 53 goto again; 54 else if (unlikely(err)) 55 return ERR_PTR(err); 56 57 id = id & MAX_ID_MASK; 58 hwdev = device_create(hwmon_class, dev, MKDEV(0,0), HWMON_ID_FORMAT, id); 59 60 if (IS_ERR(hwdev)) { 61 spin_lock(&idr_lock); 62 idr_remove(&hwmon_idr, id); 63 spin_unlock(&idr_lock); 64 } 65 66 return hwdev; 67 } 68 69 /** 70 * hwmon_device_unregister - removes the previously registered class device 71 * 72 * @dev: the class device to destroy 73 */ 74 void hwmon_device_unregister(struct device *dev) 75 { 76 int id; 77 78 if (likely(sscanf(dev->bus_id, HWMON_ID_FORMAT, &id) == 1)) { 79 device_unregister(dev); 80 spin_lock(&idr_lock); 81 idr_remove(&hwmon_idr, id); 82 spin_unlock(&idr_lock); 83 } else 84 dev_dbg(dev->parent, 85 "hwmon_device_unregister() failed: bad class ID!\n"); 86 } 87 88 static int __init hwmon_init(void) 89 { 90 hwmon_class = class_create(THIS_MODULE, "hwmon"); 91 if (IS_ERR(hwmon_class)) { 92 printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n"); 93 return PTR_ERR(hwmon_class); 94 } 95 return 0; 96 } 97 98 static void __exit hwmon_exit(void) 99 { 100 class_destroy(hwmon_class); 101 } 102 103 subsys_initcall(hwmon_init); 104 module_exit(hwmon_exit); 105 106 EXPORT_SYMBOL_GPL(hwmon_device_register); 107 EXPORT_SYMBOL_GPL(hwmon_device_unregister); 108 109 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); 110 MODULE_DESCRIPTION("hardware monitoring sysfs/class support"); 111 MODULE_LICENSE("GPL"); 112 113