path: root/drivers/pci/hotplug/acpiphp_glue.c

/*
 * ACPI PCI HotPlug glue functions to ACPI CA subsystem
 *
 * Copyright (C) 2002,2003 Takayoshi Kochi (t-kochi@bq.jp.nec.com)
 * Copyright (C) 2002 Hiroshi Aono (h-aono@ap.jp.nec.com)
 * Copyright (C) 2002,2003 NEC Corporation
 * Copyright (C) 2003-2005 Matthew Wilcox (matthew.wilcox@hp.com)
 * Copyright (C) 2003-2005 Hewlett Packard
 * Copyright (C) 2005 Rajesh Shah (rajesh.shah@intel.com)
 * Copyright (C) 2005 Intel Corporation
 *
 * 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.
 *
 * Send feedback to <kristen.c.accardi@intel.com>
 *
 */

/*
 * Lifetime rules for pci_dev:
 *  - The one in acpiphp_bridge has its refcount elevated by pci_get_slot()
 *    when the bridge is scanned and it loses a refcount when the bridge
 *    is removed.
 *  - When a P2P bridge is present, we elevate the refcount on the subordinate
 *    bus. It loses the refcount when the the driver unloads.
 */

#define pr_fmt(fmt) "acpiphp_glue: " fmt

#include <linux/init.h>
#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/pci-acpi.h>
#include <linux/pm_runtime.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/acpi.h>

#include "../pci.h"
#include "acpiphp.h"

static LIST_HEAD(bridge_list);
static DEFINE_MUTEX(bridge_mutex);
static DEFINE_MUTEX(acpiphp_context_lock);

static void handle_hotplug_event(acpi_handle handle, u32 type, void *data);
static void acpiphp_sanitize_bus(struct pci_bus *bus);
static void acpiphp_set_hpp_values(struct pci_bus *bus);
static void hotplug_event(acpi_handle handle, u32 type, void *data);
static void free_bridge(struct kref *kref);

static void acpiphp_context_handler(acpi_handle handle, void *context)
{
	/* Intentionally empty. */
}

/**
 * acpiphp_init_context - Create hotplug context and grab a reference to it.
 * @handle: ACPI object handle to create the context for.
 *
 * Call under acpiphp_context_lock.
 */
static struct acpiphp_context *acpiphp_init_context(acpi_handle handle)
{
	struct acpiphp_context *context;
	acpi_status status;

	context = kzalloc(sizeof(*context), GFP_KERNEL);
	if (!context)
		return NULL;

	context->handle = handle;
	context->refcount = 1;
	status = acpi_attach_data(handle, acpiphp_context_handler, context);
	if (ACPI_FAILURE(status)) {
		kfree(context);
		return NULL;
	}
	return context;
}

/**
 * acpiphp_get_context - Get hotplug context and grab a reference to it.
 * @handle: ACPI object handle to get the context for.
 *
 * Call under acpiphp_context_lock.
 */
static struct acpiphp_context *acpiphp_get_context(acpi_handle handle)
{
	struct acpiphp_context *context = NULL;
	acpi_status status;
	void *data;

	status = acpi_get_data(handle, acpiphp_context_handler, &data);
	if (ACPI_SUCCESS(status)) {
		context = data;
		context->refcount++;
	}
	return context;
}

/**
 * acpiphp_put_context - Drop a reference to ACPI hotplug context.
 * @handle: ACPI object handle to put the context for.
 *
 * The context object is removed if there are no more references to it.
 *
 * Call under acpiphp_context_lock.
 */
static void acpiphp_put_context(struct acpiphp_context *context)
{
	if (--context->refcount)
		return;

	WARN_ON(context->bridge);
	acpi_detach_data(context->handle, acpiphp_context_handler);
	kfree(context);
}

static inline void get_bridge(struct acpiphp_bridge *bridge)
{
	kref_get(&bridge->ref);
}

static inline void put_bridge(struct acpiphp_bridge *bridge)
{
	kref_put(&bridge->ref, free_bridge);
}

static void free_bridge(struct kref *kref)
{
	struct acpiphp_context *context;
	struct acpiphp_bridge *bridge;
	struct acpiphp_slot *slot, *next;
	struct acpiphp_func *func, *tmp;

	mutex_lock(&acpiphp_context_lock);

	bridge = container_of(kref, struct acpiphp_bridge, ref);

	list_for_each_entry_safe(slot, next, &bridge