/*
   *  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>
   *
   *  Copyright (C) 2013 Huawei Tech. Co., Ltd.
   *	Jiang Liu <jiang.liu@huawei.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/list.h>
  #include <linux/pci.h>
  #include <linux/acpi.h>
  #include <linux/dmi.h>
  #include <linux/pci-acpi.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...) pr_err("%s: " format , MY_NAME , ## arg)
  #define info(format, arg...) pr_info("%s: " format , MY_NAME , ## arg)
  #define dbg(format, arg...)					\
  	do {							\
  		if (debug)					\
  			pr_debug("%s: " format,	MY_NAME , ## arg); \
  	} while (0)
  
  #define SLOT_NAME_SIZE 21		/* Inspired by #define in acpiphp.h */
  
  struct acpi_pci_slot {
  	struct pci_slot *pci_slot;	/* corresponding pci_slot */
  	struct list_head list;		/* node in the list of slots */
  };
  
  static LIST_HEAD(slot_list);
  static DEFINE_MUTEX(slot_list_lock);
  
  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;
  }
  
  /*
   * Check whether handle has an associated slot and create PCI slot if it has.
   */
  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 pci_bus *pci_bus = context;
  
  	device = check_slot(handle, &sun);
  	if (device < 0)
  		return AE_OK;
  
  	/*
  	 * There may be multiple PCI functions associated with the same slot.
  	 * Check whether PCI slot has already been created for this PCI device.
  	 */
  	list_for_each_entry(slot, &slot_list, list) {
  		pci_slot = slot->pci_slot;
  		if (pci_slot->bus == pci_bus && pci_slot->number == device)
  			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->pci_slot = pci_slot;
  	list_add(&slot->list, &slot_list);
  
  	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;
  }
  
  void acpi_pci_slot_enumerate(struct pci_bus *bus)
  {
  	acpi_handle handle = ACPI_HANDLE(bus->bridge);
  
  	if (handle) {
  		mutex_lock(&slot_list_lock);
  		acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
  				    register_slot, NULL, bus, NULL);
  		mutex_unlock(&slot_list_lock);
  	}
  }
  
  void acpi_pci_slot_remove(struct pci_bus *bus)
  {
  	struct acpi_pci_slot *slot, *tmp;
  
  	mutex_lock(&slot_list_lock);
  	list_for_each_entry_safe(slot, tmp, &slot_list, list) {
  		if (slot->pci_slot->bus == bus) {
  			list_del(&slot->list);
  			pci_destroy_slot(slot->pci_slot);
  			put_device(&bus->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"),
  		},
  	},
  	{}
  };
  
  void __init acpi_pci_slot_init(void)
  {
  	dmi_check_system(acpi_pci_slot_dmi_table);
  }