/*
 * ACPI related functions for PCI Express Hot Plug driver.
 *
 * Copyright (C) 2008 Kenji Kaneshige
 * Copyright (C) 2008 Fujitsu Limited.
 *
 * All rights reserved.
 *
 * 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; either version 2 of the License, or (at
 * your option) any later version.
 *
 * 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, GOOD TITLE or
 * NON INFRINGEMENT.  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/acpi.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/slab.h>
#include <linux/module.h>
#include "pciehp.h"

#define PCIEHP_DETECT_PCIE	(0)
#define PCIEHP_DETECT_ACPI	(1)
#define PCIEHP_DETECT_AUTO	(2)
#define PCIEHP_DETECT_DEFAULT	PCIEHP_DETECT_AUTO

struct dummy_slot {
	u32 number;
	struct list_head list;
};

static int slot_detection_mode;
static char *pciehp_detect_mode;
module_param(pciehp_detect_mode, charp, 0444);
MODULE_PARM_DESC(pciehp_detect_mode,
	 "Slot detection mode: pcie, acpi, auto\n"
	 "  pcie          - Use PCIe based slot detection\n"
	 "  acpi          - Use ACPI for slot detection\n"
	 "  auto(default) - Auto select mode. Use acpi option if duplicate\n"
	 "                  slot ids are found. Otherwise, use pcie option\n");

int pciehp_acpi_slot_detection_check(struct pci_dev *dev)
{
	if (slot_detection_mode != PCIEHP_DETECT_ACPI)
		return 0;
	if (acpi_pci_detect_ejectable(ACPI_HANDLE(&dev->dev)))
		return 0;
	return -ENODEV;
}

static int __init parse_detect_mode(void)
{
	if (!pciehp_detect_mode)
		return PCIEHP_DETECT_DEFAULT;
	if (!strcmp(pciehp_detect_mode, "pcie"))
		return PCIEHP_DETECT_PCIE;
	if (!strcmp(pciehp_detect_mode, "acpi"))
		return PCIEHP_DETECT_ACPI;
	if (!strcmp(pciehp_detect_mode, "auto"))
		return PCIEHP_DETECT_AUTO;
	warn("bad specifier '%s' for pciehp_detect_mode. Use default\n",
	     pciehp_detect_mode);
	return PCIEHP_DETECT_DEFAULT;
}

static int __initdata dup_slot_id;
static int __initdata acpi_slot_detected;
static struct list_head __initdata dummy_slots = LIST_HEAD_INIT(dummy_slots);

/* Dummy driver for duplicate name detection */
static int __init dummy_probe(struct pcie_device *dev)
{
	u32 slot_cap;
	acpi_handle handle;
	struct dummy_slot *slot, *tmp;
	struct pci_dev *pdev = dev->port;

	pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &slot_cap);
	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
	if (!slot)
		return -ENOMEM;
	slot->number = (slot_cap & PCI_EXP_SLTCAP_PSN) >> 19;
	list_for_each_entry(tmp, &dummy_slots, list) {
		if (tmp->number == slot->number)
			dup_slot_id++;
	}
	list_add_tail(&slot->list, &dummy_slots);
	handle = ACPI_HANDLE(&pdev->dev);
	if (!acpi_slot_detected && acpi_pci_detect_ejectable(handle))
		acpi_slot_detected = 1;
	return -ENODEV;         /* dummy driver always returns error */
}

static struct pcie_port_service_driver __initdata dummy_driver = {
	.name		= "pciehp_dummy",
	.port_type	= PCIE_ANY_PORT,
	.service	= PCIE_PORT_SERVICE_HP,
	.probe		= dummy_probe,
};

static int __init select_detection_mode(void)
{
	struct dummy_slot *slot, *tmp;

	if (pcie_port_service_register(&dummy_driver))
		return PCIEHP_DETECT_ACPI;
	pcie_port_service_unregister(&dummy_driver);
	list_for_each_entry_safe(slot, tmp, &dummy_slots, list) {
		list_del(&slot->list);
		kfree(slot);
	}
	if (acpi_slot_detected && dup_slot_id)
		return PCIEHP_DETECT_ACPI;
	return PCIEHP_DETECT_PCIE;
}

void __init pciehp_acpi_slot_detection_init(void)
{
	slot_detection_mode = parse_detect_mode();
	if (slot_detection_mode != PCIEHP_DETECT_AUTO)
		goto out;
	slot_detection_mode = select_detection_mode();
out:
	if (slot_detection_mode == PCIEHP_DETECT_ACPI)
		info("Using ACPI for slot detection.\n");
}