/*
   *  pci_slot.c - ACPI PCI Slot Driver
   *
   *  The code here is heavily leveraged from the acpiphp module.
   *  Thanks to Matthew Wilcox <matthew@wil.cx> for much guidance.
   *  Thanks to Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> for code
   *  review and fixes.
   *

   *  Copyright (C) 2007-2008 Hewlett-Packard Development Company, L.P.
   *  	Alex Chiang <achiang@hp.com>

   *
   *  This program is free software; you can redistribute it and/or modify it
   *  under the terms and conditions of the GNU General Public License,
   *  version 2, as published by the Free Software Foundation.
   *
   *  This program is distributed in the hope that it will be useful, but
   *  WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <linux/types.h>
  #include <linux/pci.h>
  #include <linux/acpi.h>
  #include <acpi/acpi_bus.h>
  #include <acpi/acpi_drivers.h>

  #include <linux/dmi.h>

  static bool debug;

  static int check_sta_before_sun;
  
  #define DRIVER_VERSION 	"0.1"
  #define DRIVER_AUTHOR	"Alex Chiang <achiang@hp.com>"
  #define DRIVER_DESC	"ACPI PCI Slot Detection Driver"
  MODULE_AUTHOR(DRIVER_AUTHOR);
  MODULE_DESCRIPTION(DRIVER_DESC);
  MODULE_LICENSE("GPL");
  MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
  module_param(debug, bool, 0644);
  
  #define _COMPONENT		ACPI_PCI_COMPONENT
  ACPI_MODULE_NAME("pci_slot");
  
  #define MY_NAME "pci_slot"
  #define err(format, arg...) printk(KERN_ERR "%s: " format , MY_NAME , ## arg)
  #define info(format, arg...) printk(KERN_INFO "%s: " format , MY_NAME , ## arg)
  #define dbg(format, arg...)					\
  	do {							\
  		if (debug)					\
  			printk(KERN_DEBUG "%s: " format,	\
  				MY_NAME , ## arg);		\
  	} while (0)

  #define SLOT_NAME_SIZE 21		/* Inspired by #define in acpiphp.h */

  
  struct acpi_pci_slot {
  	acpi_handle root_handle;	/* handle of the root bridge */
  	struct pci_slot *pci_slot;	/* corresponding pci_slot */
  	struct list_head list;		/* node in the list of slots */
  };
  
  static int acpi_pci_slot_add(acpi_handle handle);
  static void acpi_pci_slot_remove(acpi_handle handle);
  
  static LIST_HEAD(slot_list);
  static DEFINE_MUTEX(slot_list_lock);
  static struct acpi_pci_driver acpi_pci_slot_driver = {
  	.add = acpi_pci_slot_add,
  	.remove = acpi_pci_slot_remove,
  };
  
  static int

  check_slot(acpi_handle handle, unsigned long long *sun)

  {

  	int device = -1;

  	unsigned long long adr, sta;

  	acpi_status status;
  	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  
  	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
  	dbg("Checking slot on path: %s
  ", (char *)buffer.pointer);
  
  	if (check_sta_before_sun) {
  		/* If SxFy doesn't have _STA, we just assume it's there */
  		status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);

  		if (ACPI_SUCCESS(status) && !(sta & ACPI_STA_DEVICE_PRESENT))

  			goto out;

  	}
  
  	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
  	if (ACPI_FAILURE(status)) {
  		dbg("_ADR returned %d on %s
  ", status, (char *)buffer.pointer);

  		goto out;
  	}

  	/* No _SUN == not a slot == bail */
  	status = acpi_evaluate_integer(handle, "_SUN", NULL, sun);
  	if (ACPI_FAILURE(status)) {
  		dbg("_SUN returned %d on %s
  ", status, (char *)buffer.pointer);

  		goto out;
  	}

  	device = (adr >> 16) & 0xffff;

  out:
  	kfree(buffer.pointer);

  	return device;

  }
  
  struct callback_args {
  	acpi_walk_callback	user_function;	/* only for walk_p2p_bridge */
  	struct pci_bus		*pci_bus;
  	acpi_handle		root_handle;
  };
  
  /*
   * register_slot
   *
   * Called once for each SxFy object in the namespace. Don't worry about
   * calling pci_create_slot multiple times for the same pci_bus:device,
   * since each subsequent call simply bumps the refcount on the pci_slot.
   *
   * The number of calls to pci_destroy_slot from unregister_slot is
   * symmetrical.
   */
  static acpi_status
  register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
  {
  	int device;

  	unsigned long long sun;

  	char name[SLOT_NAME_SIZE];
  	struct acpi_pci_slot *slot;
  	struct pci_slot *pci_slot;
  	struct callback_args *parent_context = context;
  	struct pci_bus *pci_bus = parent_context->pci_bus;

  	device = check_slot(handle, &sun);
  	if (device < 0)

  		return AE_OK;
  
  	slot = kmalloc(sizeof(*slot), GFP_KERNEL);
  	if (!slot) {
  		err("%s: cannot allocate memory
  ", __func__);
  		return AE_OK;
  	}

  	snprintf(name, sizeof(name), "%llu", sun);

  	pci_slot = pci_create_slot(pci_bus, device, name, NULL);

  	if (IS_ERR(pci_slot)) {
  		err("pci_create_slot returned %ld
  ", PTR_ERR(pci_slot));
  		kfree(slot);

  		return AE_OK;

  	}
  
  	slot->root_handle = parent_context->root_handle;
  	slot->pci_slot = pci_slot;
  	INIT_LIST_HEAD(&slot->list);
  	mutex_lock(&slot_list_lock);
  	list_add(&slot->list, &slot_list);
  	mutex_unlock(&slot_list_lock);

  	get_device(&pci_bus->dev);

  	dbg("pci_slot: %p, pci_bus: %x, device: %d, name: %s
  ",
  		pci_slot, pci_bus->number, device, name);
  
  	return AE_OK;
  }
  
  /*
   * walk_p2p_bridge - discover and walk p2p bridges
   * @handle: points to an acpi_pci_root
   * @context: p2p_bridge_context pointer
   *
   * Note that when we call ourselves recursively, we pass a different
   * value of pci_bus in the child_context.
   */
  static acpi_status
  walk_p2p_bridge(acpi_handle handle, u32 lvl, void *context, void **rv)
  {
  	int device, function;

  	unsigned long long adr;

  	acpi_status status;
  	acpi_handle dummy_handle;
  	acpi_walk_callback user_function;
  
  	struct pci_dev *dev;
  	struct pci_bus *pci_bus;
  	struct callback_args child_context;
  	struct callback_args *parent_context = context;
  
  	pci_bus = parent_context->pci_bus;
  	user_function = parent_context->user_function;
  
  	status = acpi_get_handle(handle, "_ADR", &dummy_handle);
  	if (ACPI_FAILURE(status))
  		return AE_OK;
  
  	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
  	if (ACPI_FAILURE(status))
  		return AE_OK;
  
  	device = (adr >> 16) & 0xffff;
  	function = adr & 0xffff;
  
  	dev = pci_get_slot(pci_bus, PCI_DEVFN(device, function));
  	if (!dev || !dev->subordinate)
  		goto out;
  
  	child_context.pci_bus = dev->subordinate;
  	child_context.user_function = user_function;
  	child_context.root_handle = parent_context->root_handle;
  
  	dbg("p2p bridge walk, pci_bus = %x
  ", dev->subordinate->number);
  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,

  				     user_function, NULL, &child_context, NULL);

  	if (ACPI_FAILURE(status))
  		goto out;
  
  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,

  				     walk_p2p_bridge, NULL, &child_context, NULL);

  out:
  	pci_dev_put(dev);
  	return AE_OK;
  }
  
  /*
   * walk_root_bridge - generic root bridge walker
   * @handle: points to an acpi_pci_root
   * @user_function: user callback for slot objects
   *
   * Call user_function for all objects underneath this root bridge.
   * Walk p2p bridges underneath us and call user_function on those too.
   */
  static int
  walk_root_bridge(acpi_handle handle, acpi_walk_callback user_function)
  {
  	int seg, bus;

  	unsigned long long tmp;

  	acpi_status status;
  	acpi_handle dummy_handle;
  	struct pci_bus *pci_bus;
  	struct callback_args context;
  
  	/* If the bridge doesn't have _STA, we assume it is always there */
  	status = acpi_get_handle(handle, "_STA", &dummy_handle);
  	if (ACPI_SUCCESS(status)) {
  		status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
  		if (ACPI_FAILURE(status)) {
  			info("%s: _STA evaluation failure
  ", __func__);
  			return 0;
  		}
  		if ((tmp & ACPI_STA_DEVICE_FUNCTIONING) == 0)
  			/* don't register this object */
  			return 0;
  	}
  
  	status = acpi_evaluate_integer(handle, "_SEG", NULL, &tmp);
  	seg = ACPI_SUCCESS(status) ? tmp : 0;
  
  	status = acpi_evaluate_integer(handle, "_BBN", NULL, &tmp);
  	bus = ACPI_SUCCESS(status) ? tmp : 0;
  
  	pci_bus = pci_find_bus(seg, bus);
  	if (!pci_bus)
  		return 0;
  
  	context.pci_bus = pci_bus;
  	context.user_function = user_function;
  	context.root_handle = handle;
  
  	dbg("root bridge walk, pci_bus = %x
  ", pci_bus->number);
  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,

  				     user_function, NULL, &context, NULL);

  	if (ACPI_FAILURE(status))
  		return status;
  
  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,

  				     walk_p2p_bridge, NULL, &context, NULL);

  	if (ACPI_FAILURE(status))
  		err("%s: walk_p2p_bridge failure - %d
  ", __func__, status);
  
  	return status;
  }
  
  /*
   * acpi_pci_slot_add
   * @handle: points to an acpi_pci_root
   */
  static int
  acpi_pci_slot_add(acpi_handle handle)
  {
  	acpi_status status;
  
  	status = walk_root_bridge(handle, register_slot);
  	if (ACPI_FAILURE(status))
  		err("%s: register_slot failure - %d
  ", __func__, status);
  
  	return status;
  }
  
  /*
   * acpi_pci_slot_remove
   * @handle: points to an acpi_pci_root
   */
  static void
  acpi_pci_slot_remove(acpi_handle handle)
  {
  	struct acpi_pci_slot *slot, *tmp;

  	struct pci_bus *pbus;

  
  	mutex_lock(&slot_list_lock);
  	list_for_each_entry_safe(slot, tmp, &slot_list, list) {
  		if (slot->root_handle == handle) {
  			list_del(&slot->list);

  			pbus = slot->pci_slot->bus;

  			pci_destroy_slot(slot->pci_slot);

  			put_device(&pbus->dev);

  			kfree(slot);
  		}
  	}
  	mutex_unlock(&slot_list_lock);
  }
  
  static int do_sta_before_sun(const struct dmi_system_id *d)
  {
  	info("%s detected: will evaluate _STA before calling _SUN
  ", d->ident);
  	check_sta_before_sun = 1;
  	return 0;
  }
  
  static struct dmi_system_id acpi_pci_slot_dmi_table[] __initdata = {
  	/*
  	 * Fujitsu Primequest machines will return 1023 to indicate an
  	 * error if the _SUN method is evaluated on SxFy objects that
  	 * are not present (as indicated by _STA), so for those machines,
  	 * we want to check _STA before evaluating _SUN.
  	 */
  	{
  	 .callback = do_sta_before_sun,
  	 .ident = "Fujitsu PRIMEQUEST",
  	 .matches = {
  		DMI_MATCH(DMI_BIOS_VENDOR, "FUJITSU LIMITED"),
  		DMI_MATCH(DMI_BIOS_VERSION, "PRIMEQUEST"),
  		},
  	},
  	{}
  };
  
  static int __init
  acpi_pci_slot_init(void)
  {
  	dmi_check_system(acpi_pci_slot_dmi_table);
  	acpi_pci_register_driver(&acpi_pci_slot_driver);
  	return 0;
  }
  
  static void __exit
  acpi_pci_slot_exit(void)
  {
  	acpi_pci_unregister_driver(&acpi_pci_slot_driver);
  }
  
  module_init(acpi_pci_slot_init);
  module_exit(acpi_pci_slot_exit);