/*
      hwmon.c - part of lm_sensors, Linux kernel modules for hardware monitoring
  
      This file defines the sysfs class "hwmon", for use by sensors drivers.
  
      Copyright (C) 2005 Mark M. Hoffman <mhoffman@lightlink.com>
  
      This program is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published by
      the Free Software Foundation; version 2 of the License.
  */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/kdev_t.h>
  #include <linux/idr.h>
  #include <linux/hwmon.h>

  #include <linux/gfp.h>

  #include <linux/spinlock.h>

  #include <linux/pci.h>

  
  #define HWMON_ID_PREFIX "hwmon"
  #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
  
  static struct class *hwmon_class;
  
  static DEFINE_IDR(hwmon_idr);

  static DEFINE_SPINLOCK(idr_lock);

  
  /**

   * hwmon_device_register - register w/ hwmon

   * @dev: the device to register
   *

   * hwmon_device_unregister() must be called when the device is no

   * longer needed.
   *

   * Returns the pointer to the new device.

   */

  struct device *hwmon_device_register(struct device *dev)

  {

  	struct device *hwdev;

  	int id, err;

  again:
  	if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))

  		return ERR_PTR(-ENOMEM);

  	spin_lock(&idr_lock);
  	err = idr_get_new(&hwmon_idr, NULL, &id);
  	spin_unlock(&idr_lock);
  
  	if (unlikely(err == -EAGAIN))
  		goto again;
  	else if (unlikely(err))
  		return ERR_PTR(err);

  
  	id = id & MAX_ID_MASK;

  	hwdev = device_create(hwmon_class, dev, MKDEV(0, 0), NULL,
  			      HWMON_ID_FORMAT, id);

  	if (IS_ERR(hwdev)) {

  		spin_lock(&idr_lock);

  		idr_remove(&hwmon_idr, id);

  		spin_unlock(&idr_lock);
  	}

  	return hwdev;

  }
  
  /**
   * hwmon_device_unregister - removes the previously registered class device
   *

   * @dev: the class device to destroy

   */

  void hwmon_device_unregister(struct device *dev)

  {
  	int id;

  	if (likely(sscanf(dev_name(dev), HWMON_ID_FORMAT, &id) == 1)) {

  		device_unregister(dev);

  		spin_lock(&idr_lock);

  		idr_remove(&hwmon_idr, id);

  		spin_unlock(&idr_lock);

  	} else

  		dev_dbg(dev->parent,

  			"hwmon_device_unregister() failed: bad class ID!
  ");
  }

  static void __init hwmon_pci_quirks(void)
  {
  #if defined CONFIG_X86 && defined CONFIG_PCI
  	struct pci_dev *sb;
  	u16 base;
  	u8 enable;
  
  	/* Open access to 0x295-0x296 on MSI MS-7031 */
  	sb = pci_get_device(PCI_VENDOR_ID_ATI, 0x436c, NULL);
  	if (sb &&
  	    (sb->subsystem_vendor == 0x1462 &&	/* MSI */
  	     sb->subsystem_device == 0x0031)) {	/* MS-7031 */
  
  		pci_read_config_byte(sb, 0x48, &enable);
  		pci_read_config_word(sb, 0x64, &base);
  
  		if (base == 0 && !(enable & BIT(2))) {
  			dev_info(&sb->dev,
  				 "Opening wide generic port at 0x295
  ");
  			pci_write_config_word(sb, 0x64, 0x295);
  			pci_write_config_byte(sb, 0x48, enable | BIT(2));
  		}
  	}
  #endif
  }

  static int __init hwmon_init(void)
  {

  	hwmon_pci_quirks();

  	hwmon_class = class_create(THIS_MODULE, "hwmon");
  	if (IS_ERR(hwmon_class)) {

  		pr_err("couldn't create sysfs class
  ");

  		return PTR_ERR(hwmon_class);
  	}
  	return 0;
  }
  
  static void __exit hwmon_exit(void)
  {
  	class_destroy(hwmon_class);
  }

  subsys_initcall(hwmon_init);

  module_exit(hwmon_exit);
  
  EXPORT_SYMBOL_GPL(hwmon_device_register);
  EXPORT_SYMBOL_GPL(hwmon_device_unregister);
  
  MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
  MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
  MODULE_LICENSE("GPL");