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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/module.h>
  16 #include <linux/device.h>
  17 #include <linux/err.h>
  18 #include <linux/kdev_t.h>
  19 #include <linux/idr.h>
  20 #include <linux/hwmon.h>
  21 #include <linux/gfp.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/pci.h>
  24
  25 #define HWMON_ID_PREFIX "hwmon"
  26 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
  27
  28 static struct class *hwmon_class;
  29
  30 static DEFINE_IDR(hwmon_idr);
  31 static DEFINE_SPINLOCK(idr_lock);
  32
  33 /**
  34  * hwmon_device_register - register w/ hwmon
  35  * @dev: the device to register
  36  *
  37  * hwmon_device_unregister() must be called when the device is no
  38  * longer needed.
  39  *
  40  * Returns the pointer to the new device.
  41  */
  42 struct device *hwmon_device_register(struct device *dev)
  43 {
  44         struct device *hwdev;
  45         int id, err;
  46
  47 again:
  48         if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))
  49                 return ERR_PTR(-ENOMEM);
  50
  51         spin_lock(&idr_lock);
  52         err = idr_get_new(&hwmon_idr, NULL, &id);
  53         spin_unlock(&idr_lock);
  54
  55         if (unlikely(err == -EAGAIN))
  56                 goto again;
  57         else if (unlikely(err))
  58                 return ERR_PTR(err);
  59
  60         id = id & MAX_ID_MASK;
  61         hwdev = device_create(hwmon_class, dev, MKDEV(0, 0), NULL,
  62                               HWMON_ID_FORMAT, id);
  63
  64         if (IS_ERR(hwdev)) {
  65                 spin_lock(&idr_lock);
  66                 idr_remove(&hwmon_idr, id);
  67                 spin_unlock(&idr_lock);
  68         }
  69
  70         return hwdev;
  71 }
  72
  73 /**
  74  * hwmon_device_unregister - removes the previously registered class device
  75  *
  76  * @dev: the class device to destroy
  77  */
  78 void hwmon_device_unregister(struct device *dev)
  79 {
  80         int id;
  81
  82         if (likely(sscanf(dev_name(dev), HWMON_ID_FORMAT, &id) == 1)) {
  83                 device_unregister(dev);
  84                 spin_lock(&idr_lock);
  85                 idr_remove(&hwmon_idr, id);
  86                 spin_unlock(&idr_lock);
  87         } else
  88                 dev_dbg(dev->parent,
  89                         "hwmon_device_unregister() failed: bad class ID!\n");
  90 }
  91
  92 static void __init hwmon_pci_quirks(void)
  93 {
  94 #if defined CONFIG_X86 && defined CONFIG_PCI
  95         struct pci_dev *sb;
  96         u16 base;
  97         u8 enable;
  98
  99         /* Open access to 0x295-0x296 on MSI MS-7031 */
 100         sb = pci_get_device(PCI_VENDOR_ID_ATI, 0x436c, NULL);
 101         if (sb &&
 102             (sb->subsystem_vendor == 0x1462 &&  /* MSI */
 103              sb->subsystem_device == 0x0031)) { /* MS-7031 */
 104
 105                 pci_read_config_byte(sb, 0x48, &enable);
 106                 pci_read_config_word(sb, 0x64, &base);
 107
 108                 if (base == 0 && !(enable & BIT(2))) {
 109                         dev_info(&sb->dev,
 110                                  "Opening wide generic port at 0x295\n");
 111                         pci_write_config_word(sb, 0x64, 0x295);
 112                         pci_write_config_byte(sb, 0x48, enable | BIT(2));
 113                 }
 114         }
 115 #endif
 116 }
 117
 118 static int __init hwmon_init(void)
 119 {
 120         hwmon_pci_quirks();
 121
 122         hwmon_class = class_create(THIS_MODULE, "hwmon");
 123         if (IS_ERR(hwmon_class)) {
 124                 pr_err("couldn't create sysfs class\n");
 125                 return PTR_ERR(hwmon_class);
 126         }
 127         return 0;
 128 }
 129
 130 static void __exit hwmon_exit(void)
 131 {
 132         class_destroy(hwmon_class);
 133 }
 134
 135 subsys_initcall(hwmon_init);
 136 module_exit(hwmon_exit);
 137
 138 EXPORT_SYMBOL_GPL(hwmon_device_register);
 139 EXPORT_SYMBOL_GPL(hwmon_device_unregister);
 140
 141 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
 142 MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
 143 MODULE_LICENSE("GPL");
 144