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 #include <linux/spinlock.h>
  21 #include <linux/pci.h>
  22
  23 #define HWMON_ID_PREFIX "hwmon"
  24 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
  25
  26 static struct class *hwmon_class;
  27
  28 static DEFINE_IDR(hwmon_idr);
  29 static DEFINE_SPINLOCK(idr_lock);
  30
  31 /**
  32  * hwmon_device_register - register w/ hwmon
  33  * @dev: the device to register
  34  *
  35  * hwmon_device_unregister() must be called when the device is no
  36  * longer needed.
  37  *
  38  * Returns the pointer to the new device.
  39  */
  40 struct device *hwmon_device_register(struct device *dev)
  41 {
  42         struct device *hwdev;
  43         int id, err;
  44
  45 again:
  46         if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))
  47                 return ERR_PTR(-ENOMEM);
  48
  49         spin_lock(&idr_lock);
  50         err = idr_get_new(&hwmon_idr, NULL, &id);
  51         spin_unlock(&idr_lock);
  52
  53         if (unlikely(err == -EAGAIN))
  54                 goto again;
  55         else if (unlikely(err))
  56                 return ERR_PTR(err);
  57
  58         id = id & MAX_ID_MASK;
  59         hwdev = device_create(hwmon_class, dev, MKDEV(0, 0), NULL,
  60                               HWMON_ID_FORMAT, id);
  61
  62         if (IS_ERR(hwdev)) {
  63                 spin_lock(&idr_lock);
  64                 idr_remove(&hwmon_idr, id);
  65                 spin_unlock(&idr_lock);
  66         }
  67
  68         return hwdev;
  69 }
  70
  71 /**
  72  * hwmon_device_unregister - removes the previously registered class device
  73  *
  74  * @dev: the class device to destroy
  75  */
  76 void hwmon_device_unregister(struct device *dev)
  77 {
  78         int id;
  79
  80         if (likely(sscanf(dev_name(dev), HWMON_ID_FORMAT, &id) == 1)) {
  81                 device_unregister(dev);
  82                 spin_lock(&idr_lock);
  83                 idr_remove(&hwmon_idr, id);
  84                 spin_unlock(&idr_lock);
  85         } else
  86                 dev_dbg(dev->parent,
  87                         "hwmon_device_unregister() failed: bad class ID!\n");
  88 }
  89
  90 static void __init hwmon_pci_quirks(void)
  91 {
  92 #if defined CONFIG_X86 && defined CONFIG_PCI
  93         struct pci_dev *sb;
  94         u16 base;
  95         u8 enable;
  96
  97         /* Open access to 0x295-0x296 on MSI MS-7031 */
  98         sb = pci_get_device(PCI_VENDOR_ID_ATI, 0x436c, NULL);
  99         if (sb &&
 100             (sb->subsystem_vendor == 0x1462 &&  /* MSI */
 101              sb->subsystem_device == 0x0031)) { /* MS-7031 */
 102
 103                 pci_read_config_byte(sb, 0x48, &enable);
 104                 pci_read_config_word(sb, 0x64, &base);
 105
 106                 if (base == 0 && !(enable & BIT(2))) {
 107                         dev_info(&sb->dev,
 108                                  "Opening wide generic port at 0x295\n");
 109                         pci_write_config_word(sb, 0x64, 0x295);
 110                         pci_write_config_byte(sb, 0x48, enable | BIT(2));
 111                 }
 112         }
 113 #endif
 114 }
 115
 116 static int __init hwmon_init(void)
 117 {
 118         hwmon_pci_quirks();
 119
 120         hwmon_class = class_create(THIS_MODULE, "hwmon");
 121         if (IS_ERR(hwmon_class)) {
 122                 printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");
 123                 return PTR_ERR(hwmon_class);
 124         }
 125         return 0;
 126 }
 127
 128 static void __exit hwmon_exit(void)
 129 {
 130         class_destroy(hwmon_class);
 131 }
 132
 133 subsys_initcall(hwmon_init);
 134 module_exit(hwmon_exit);
 135
 136 EXPORT_SYMBOL_GPL(hwmon_device_register);
 137 EXPORT_SYMBOL_GPL(hwmon_device_unregister);
 138
 139 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
 140 MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
 141 MODULE_LICENSE("GPL");
 142