Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / pci / hotplug / acpiphp_glue.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * 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 (willy@infradead.org)
 * Copyright (C) 2003-2005 Hewlett Packard
 * Copyright (C) 2005 Rajesh Shah (rajesh.shah@intel.com)
 * Copyright (C) 2005 Intel Corporation
 *
 * All rights reserved.
 *
 * 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 driver unloads.
 */

#define pr_fmt(fmt) "acpiphp_glue: " fmt

#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 int acpiphp_hotplug_notify(struct acpi_device *adev, u32 type);
static void acpiphp_post_dock_fixup(struct acpi_device *adev);
static void acpiphp_sanitize_bus(struct pci_bus *bus);
static void hotplug_event(u32 type, struct acpiphp_context *context);
static void free_bridge(struct kref *kref);

/**
 * acpiphp_init_context - Create hotplug context and grab a reference to it.
 * @adev: ACPI device object to create the context for.
 *
 * Call under acpi_hp_context_lock.
 */
static struct acpiphp_context *acpiphp_init_context(struct acpi_device *adev)
{
        struct acpiphp_context *context;

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

        context->refcount = 1;
        context->hp.notify = acpiphp_hotplug_notify;
        context->hp.fixup = acpiphp_post_dock_fixup;
        acpi_set_hp_context(adev, &context->hp);
        return context;
}

/**
 * acpiphp_get_context - Get hotplug context and grab a reference to it.
 * @adev: ACPI device object to get the context for.
 *
 * Call under acpi_hp_context_lock.
 */
static struct acpiphp_context *acpiphp_get_context(struct acpi_device *adev)
{
        struct acpiphp_context *context;

        if (!adev->hp)
                return NULL;

        context = to_acpiphp_context(adev->hp);
        context->refcount++;
        return context;
}

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

        WARN_ON(context->bridge);
        context->hp.self->hp = NULL;
        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 struct acpiphp_context *acpiphp_grab_context(struct acpi_device *adev)
{
        struct acpiphp_context *context;

        acpi_lock_hp_context();

        context = acpiphp_get_context(adev);
        if (!context)
                goto unlock;

        if (context->func.parent->is_going_away) {
                acpiphp_put_context(context);
                context = NULL;
                goto unlock;
        }

        get_bridge(context->func.parent);
        acpiphp_put_context(context);

unlock:
        acpi_unlock_hp_context();
        return context;
}

static void acpiphp_let_context_go(struct acpiphp_context *context)
{
        put_bridge(context->func.parent);
}

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;

        acpi_lock_hp_context();

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

        list_for_each_entry_safe(slot, next, &bridge->slots, node) {
                list_for_each_entry_safe(func, tmp, &slot->funcs, sibling)
                        acpiphp_put_context(func_to_context(func));

                kfree(slot);
        }

        context = bridge->context;
        /* Root bridges will not have hotplug context. */
        if (context) {
                /* Release the reference taken by acpiphp_enumerate_slots(). */
                put_bridge(context->func.parent);
                context->bridge = NULL;
                acpiphp_put_context(context);
        }

        put_device(&bridge->pci_bus->dev);
        pci_dev_put(bridge->pci_dev);
        kfree(bridge);

        acpi_unlock_hp_context();
}

/**
 * acpiphp_post_dock_fixup - Post-dock fixups for PCI devices.
 * @adev: ACPI device object corresponding to a PCI device.
 *
 * TBD - figure out a way to only call fixups for systems that require them.
 */
static void acpiphp_post_dock_fixup(struct acpi_device *adev)
{
        struct acpiphp_context *context = acpiphp_grab_context(adev);
        struct pci_bus *bus;
        u32 buses;

        if (!context)
                return;

        bus = context->func.slot->bus;
        if (!bus->self)
                goto out;

        /* fixup bad _DCK function that rewrites
         * secondary bridge on slot
         */
        pci_read_config_dword(bus->self, PCI_PRIMARY_BUS, &buses);

        if (((buses >> 8) & 0xff) != bus->busn_res.start) {
                buses = (buses & 0xff000000)
                        | ((unsigned int)(bus->primary)     <<  0)
                        | ((unsigned int)(bus->busn_res.start)   <<  8)
                        | ((unsigned int)(bus->busn_res.end) << 16);
                pci_write_config_dword(bus->self, PCI_PRIMARY_BUS, buses);
        }

 out:
        acpiphp_let_context_go(context);
}

/**
 * acpiphp_add_context - Add ACPIPHP context to an ACPI device object.
 * @handle: ACPI handle of the object to add a context to.
 * @lvl: Not used.
 * @data: The object's parent ACPIPHP bridge.
 * @rv: Not used.
 */
static acpi_status acpiphp_add_context(acpi_handle handle, u32 lvl, void *data,
                                       void **rv)
{
        struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
        struct acpiphp_bridge *bridge = data;
        struct acpiphp_context *context;
        struct acpiphp_slot *slot;
        struct acpiphp_func *newfunc;
        acpi_status status = AE_OK;
        unsigned long long adr;
        int device, function;
        struct pci_bus *pbus = bridge->pci_bus;
        struct pci_dev *pdev = bridge->pci_dev;
        u32 val;

        if (!adev)
                return AE_OK;

        status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
        if (ACPI_FAILURE(status)) {
                if (status != AE_NOT_FOUND)
                        acpi_handle_warn(handle,
                                "can't evaluate _ADR (%#x)\n", status);
                return AE_OK;
        }

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

        acpi_lock_hp_context();
        context = acpiphp_init_context(adev);
        if (!context) {
                acpi_unlock_hp_context();
                acpi_handle_err(handle, "No hotplug context\n");
                return AE_NOT_EXIST;
        }
        newfunc = &context->func;
        newfunc->function = function;
        newfunc->parent = bridge;
        acpi_unlock_hp_context();

        /*
         * If this is a dock device, its _EJ0 should be executed by the dock
         * notify handler after calling _DCK.
         */
        if (!is_dock_device(adev) && acpi_has_method(handle, "_EJ0"))
                newfunc->flags = FUNC_HAS_EJ0;

        if (acpi_has_method(handle, "_STA"))
                newfunc->flags |= FUNC_HAS_STA;

        /* search for objects that share the same slot */
        list_for_each_entry(slot, &bridge->slots, node)
                if (slot->device == device)
                        goto slot_found;

        slot = kzalloc(sizeof(struct acpiphp_slot), GFP_KERNEL);
        if (!slot) {
                acpi_lock_hp_context();
                acpiphp_put_context(context);
                acpi_unlock_hp_context();
                return AE_NO_MEMORY;
        }

        slot->bus = bridge->pci_bus;
        slot->device = device;
        INIT_LIST_HEAD(&slot->funcs);

        list_add_tail(&slot->node, &bridge->slots);

        /*
         * Expose slots to user space for functions that have _EJ0 or _RMV or
         * are located in dock stations.  Do not expose them for devices handled
         * by the native PCIe hotplug (PCIeHP) or standard PCI hotplug
         * (SHPCHP), because that code is supposed to expose slots to user
         * space in those cases.
         */
        if ((acpi_pci_check_ejectable(pbus, handle) || is_dock_device(adev))
            && !(pdev && hotplug_is_native(pdev))) {
                unsigned long long sun;
                int retval;

                bridge->nr_slots++;
                status = acpi_evaluate_integer(handle, "_SUN", NULL, &sun);
                if (ACPI_FAILURE(status))
                        sun = bridge->nr_slots;

                pr_debug("found ACPI PCI Hotplug slot %llu at PCI %04x:%02x:%02x\n",
                    sun, pci_domain_nr(pbus), pbus->number, device);

                retval = acpiphp_register_hotplug_slot(slot, sun);
                if (retval) {
                        slot->slot = NULL;
                        bridge->nr_slots--;
                        if (retval == -EBUSY)
                                pr_warn("Slot %llu already registered by another hotplug driver\n", sun);
                        else
                                pr_warn("acpiphp_register_hotplug_slot failed (err code = 0x%x)\n", retval);
                }
                /* Even if the slot registration fails, we can still use it. */
        }

 slot_found:
        newfunc->slot = slot;
        list_add_tail(&newfunc->sibling, &slot->funcs);

        if (pci_bus_read_dev_vendor_id(pbus, PCI_DEVFN(device, function),
                                       &val, 60*1000))
                slot->flags |= SLOT_ENABLED;

        return AE_OK;
}

static void cleanup_bridge(struct acpiphp_bridge *bridge)
{
        struct acpiphp_slot *slot;
        struct acpiphp_func *func;

        list_for_each_entry(slot, &bridge->slots, node) {
                list_for_each_entry(func, &slot->funcs, sibling) {
                        struct acpi_device *adev = func_to_acpi_device(func);

                        acpi_lock_hp_context();
                        adev->hp->notify = NULL;
                        adev->hp->fixup = NULL;
                        acpi_unlock_hp_context();
                }
                slot->flags |= SLOT_IS_GOING_AWAY;
                if (slot->slot)
                        acpiphp_unregister_hotplug_slot(slot);
        }

        mutex_lock(&bridge_mutex);
        list_del(&bridge->list);
        mutex_unlock(&bridge_mutex);

        acpi_lock_hp_context();
        bridge->is_going_away = true;
        acpi_unlock_hp_context();
}

/**
 * acpiphp_max_busnr - return the highest reserved bus number under the given bus.
 * @bus: bus to start search with
 */
static unsigned char acpiphp_max_busnr(struct pci_bus *bus)
{
        struct pci_bus *tmp;
        unsigned char max, n;

        /*
         * pci_bus_max_busnr will return the highest
         * reserved busnr for all these children.
         * that is equivalent to the bus->subordinate
         * value.  We don't want to use the parent's
         * bus->subordinate value because it could have
         * padding in it.
         */
        max = bus->busn_res.start;

        list_for_each_entry(tmp, &bus->children, node) {
                n = pci_bus_max_busnr(tmp);
                if (n > max)
                        max = n;
        }
        return max;
}

static void acpiphp_set_acpi_region(struct acpiphp_slot *slot)
{
        struct acpiphp_func *func;

        list_for_each_entry(func, &slot->funcs, sibling) {
                /* _REG is optional, we don't care about if there is failure */
                acpi_evaluate_reg(func_to_handle(func),
                                  ACPI_ADR_SPACE_PCI_CONFIG,
                                  ACPI_REG_CONNECT);
        }
}

static void check_hotplug_bridge(struct acpiphp_slot *slot, struct pci_dev *dev)
{
        struct acpiphp_func *func;

        /* quirk, or pcie could set it already */
        if (dev->is_hotplug_bridge)
                return;

        /*
         * In the PCIe case, only Root Ports and Downstream Ports are capable of
         * accommodating hotplug devices, so avoid marking Upstream Ports as
         * "hotplug bridges".
         */
        if (pci_is_pcie(dev) && pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM)
                return;

        list_for_each_entry(func, &slot->funcs, sibling) {
                if (PCI_FUNC(dev->devfn) == func->function) {
                        dev->is_hotplug_bridge = 1;
                        break;
                }
        }
}

static int acpiphp_rescan_slot(struct acpiphp_slot *slot)
{
        struct acpiphp_func *func;

        list_for_each_entry(func, &slot->funcs, sibling) {
                struct acpi_device *adev = func_to_acpi_device(func);

                acpi_bus_scan(adev->handle);
                if (acpi_device_enumerated(adev))
                        acpi_device_set_power(adev, ACPI_STATE_D0);
        }
        return pci_scan_slot(slot->bus, PCI_DEVFN(slot->device, 0));
}

static void acpiphp_native_scan_bridge(struct pci_dev *bridge)
{
        struct pci_bus *bus = bridge->subordinate;
        struct pci_dev *dev;
        int max;

        if (!bus)
                return;

        max = bus->busn_res.start;
        /* Scan already configured non-hotplug bridges */
        for_each_pci_bridge(dev, bus) {
                if (!hotplug_is_native(dev))
                        max = pci_scan_bridge(bus, dev, max, 0);
        }

        /* Scan non-hotplug bridges that need to be reconfigured */
        for_each_pci_bridge(dev, bus) {
                if (hotplug_is_native(dev))
                        continue;

                max = pci_scan_bridge(bus, dev, max, 1);
                if (dev->subordinate) {
                        pcibios_resource_survey_bus(dev->subordinate);
                        pci_bus_size_bridges(dev->subordinate);
                        pci_bus_assign_resources(dev->subordinate);
                }
        }
}

/**
 * enable_slot - enable, configure a slot
 * @slot: slot to be enabled
 * @bridge: true if enable is for the whole bridge (not a single slot)
 *
 * This function should be called per *physical slot*,
 * not per each slot object in ACPI namespace.
 */
static void enable_slot(struct acpiphp_slot *slot, bool bridge)
{
        struct pci_dev *dev;
        struct pci_bus *bus = slot->bus;
        struct acpiphp_func *func;

        if (bridge && bus->self && hotplug_is_native(bus->self)) {
                /*
                 * If native hotplug is used, it will take care of hotplug
                 * slot management and resource allocation for hotplug
                 * bridges. However, ACPI hotplug may still be used for
                 * non-hotplug bridges to bring in additional devices such
                 * as a Thunderbolt host controller.
                 */
                for_each_pci_bridge(dev, bus) {
                        if (PCI_SLOT(dev->devfn) == slot->device)
                                acpiphp_native_scan_bridge(dev);
                }
        } else {
                LIST_HEAD(add_list);
                int max, pass;

                acpiphp_rescan_slot(slot);
                max = acpiphp_max_busnr(bus);
                for (pass = 0; pass < 2; pass++) {
                        for_each_pci_bridge(dev, bus) {
                                if (PCI_SLOT(dev->devfn) != slot->device)
                                        continue;

                                max = pci_scan_bridge(bus, dev, max, pass);
                                if (pass && dev->subordinate) {
                                        check_hotplug_bridge(slot, dev);
                                        pcibios_resource_survey_bus(dev->subordinate);
                                        __pci_bus_size_bridges(dev->subordinate,
                                                               &add_list);
                                }
                        }
                }
                __pci_bus_assign_resources(bus, &add_list, NULL);
        }

        acpiphp_sanitize_bus(bus);
        pcie_bus_configure_settings(bus);
        acpiphp_set_acpi_region(slot);

        list_for_each_entry(dev, &bus->devices, bus_list) {
                /* Assume that newly added devices are powered on already. */
                if (!pci_dev_is_added(dev))
                        dev->current_state = PCI_D0;
        }

        pci_bus_add_devices(bus);

        slot->flags |= SLOT_ENABLED;
        list_for_each_entry(func, &slot->funcs, sibling) {
                dev = pci_get_slot(bus, PCI_DEVFN(slot->device,
                                                  func->function));
                if (!dev) {
                        /* Do not set SLOT_ENABLED flag if some funcs
                           are not added. */
                        slot->flags &= ~SLOT_ENABLED;
                        continue;
                }
                pci_dev_put(dev);
        }
}

/**
 * disable_slot - disable a slot
 * @slot: ACPI PHP slot
 */
static void disable_slot(struct acpiphp_slot *slot)
{
        struct pci_bus *bus = slot->bus;
        struct pci_dev *dev, *prev;
        struct acpiphp_func *func;

        /*
         * enable_slot() enumerates all functions in this device via
         * pci_scan_slot(), whether they have associated ACPI hotplug
         * methods (_EJ0, etc.) or not.  Therefore, we remove all functions
         * here.
         */
        list_for_each_entry_safe_reverse(dev, prev, &bus->devices, bus_list)
                if (PCI_SLOT(dev->devfn) == slot->device)
                        pci_stop_and_remove_bus_device(dev);

        list_for_each_entry(func, &slot->funcs, sibling)
                acpi_bus_trim(func_to_acpi_device(func));

        slot->flags &= ~SLOT_ENABLED;
}

static bool slot_no_hotplug(struct acpiphp_slot *slot)
{
        struct pci_bus *bus = slot->bus;
        struct pci_dev *dev;

        list_for_each_entry(dev, &bus->devices, bus_list) {
                if (PCI_SLOT(dev->devfn) == slot->device && dev->ignore_hotplug)
                        return true;
        }
        return false;
}

/**
 * get_slot_status - get ACPI slot status
 * @slot: ACPI PHP slot
 *
 * If a slot has _STA for each function and if any one of them
 * returned non-zero status, return it.
 *
 * If a slot doesn't have _STA and if any one of its functions'
 * configuration space is configured, return 0x0f as a _STA.
 *
 * Otherwise return 0.
 */
static unsigned int get_slot_status(struct acpiphp_slot *slot)
{
        unsigned long long sta = 0;
        struct acpiphp_func *func;
        u32 dvid;

        list_for_each_entry(func, &slot->funcs, sibling) {
                if (func->flags & FUNC_HAS_STA) {
                        acpi_status status;

                        status = acpi_evaluate_integer(func_to_handle(func),
                                                       "_STA", NULL, &sta);
                        if (ACPI_SUCCESS(status) && sta)
                                break;
                } else {
                        if (pci_bus_read_dev_vendor_id(slot->bus,
                                        PCI_DEVFN(slot->device, func->function),
                                        &dvid, 0)) {
                                sta = ACPI_STA_ALL;
                                break;
                        }
                }
        }

        if (!sta) {
                /*
                 * Check for the slot itself since it may be that the
                 * ACPI slot is a device below PCIe upstream port so in
                 * that case it may not even be reachable yet.
                 */
                if (pci_bus_read_dev_vendor_id(slot->bus,
                                PCI_DEVFN(slot->device, 0), &dvid, 0)) {
                        sta = ACPI_STA_ALL;
                }
        }

        return (unsigned int)sta;
}

static inline bool device_status_valid(unsigned int sta)
{
        /*
         * ACPI spec says that _STA may return bit 0 clear with bit 3 set
         * if the device is valid but does not require a device driver to be
         * loaded (Section 6.3.7 of ACPI 5.0A).
         */
        unsigned int mask = ACPI_STA_DEVICE_ENABLED | ACPI_STA_DEVICE_FUNCTIONING;
        return (sta & mask) == mask;
}

/**
 * trim_stale_devices - remove PCI devices that are not responding.
 * @dev: PCI device to start walking the hierarchy from.
 */
static void trim_stale_devices(struct pci_dev *dev)
{
        struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
        struct pci_bus *bus = dev->subordinate;
        bool alive = dev->ignore_hotplug;

        if (adev) {
                acpi_status status;
                unsigned long long sta;

                status = acpi_evaluate_integer(adev->handle, "_STA", NULL, &sta);
                alive = alive || (ACPI_SUCCESS(status) && device_status_valid(sta));
        }
        if (!alive)
                alive = pci_device_is_present(dev);

        if (!alive) {
                pci_dev_set_disconnected(dev, NULL);
                if (pci_has_subordinate(dev))
                        pci_walk_bus(dev->subordinate, pci_dev_set_disconnected,
                                     NULL);

                pci_stop_and_remove_bus_device(dev);
                if (adev)
                        acpi_bus_trim(adev);
        } else if (bus) {
                struct pci_dev *child, *tmp;

                /* The device is a bridge. so check the bus below it. */
                pm_runtime_get_sync(&dev->dev);
                list_for_each_entry_safe_reverse(child, tmp, &bus->devices, bus_list)
                        trim_stale_devices(child);

                pm_runtime_put(&dev->dev);
        }
}

/**
 * acpiphp_check_bridge - re-enumerate devices
 * @bridge: where to begin re-enumeration
 *
 * Iterate over all slots under this bridge and make sure that if a
 * card is present they are enabled, and if not they are disabled.
 */
static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
{
        struct acpiphp_slot *slot;

        /* Bail out if the bridge is going away. */
        if (bridge->is_going_away)
                return;

        if (bridge->pci_dev)
                pm_runtime_get_sync(&bridge->pci_dev->dev);

        list_for_each_entry(slot, &bridge->slots, node) {
                struct pci_bus *bus = slot->bus;
                struct pci_dev *dev, *tmp;

                if (slot_no_hotplug(slot)) {
                        ; /* do nothing */
                } else if (device_status_valid(get_slot_status(slot))) {
                        /* remove stale devices if any */
                        list_for_each_entry_safe_reverse(dev, tmp,
                                                         &bus->devices, bus_list)
                                if (PCI_SLOT(dev->devfn) == slot->device)
                                        trim_stale_devices(dev);

                        /* configure all functions */
                        enable_slot(slot, true);
                } else {
                        disable_slot(slot);
                }
        }

        if (bridge->pci_dev)
                pm_runtime_put(&bridge->pci_dev->dev);
}

/*
 * Remove devices for which we could not assign resources, call
 * arch specific code to fix-up the bus
 */
static void acpiphp_sanitize_bus(struct pci_bus *bus)
{
        struct pci_dev *dev, *tmp;
        int i;
        unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM;

        list_for_each_entry_safe_reverse(dev, tmp, &bus->devices, bus_list) {
                for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) {
                        struct resource *res = &dev->resource[i];
                        if ((res->flags & type_mask) && !res->start &&
                                        res->end) {
                                /* Could not assign a required resources
                                 * for this device, remove it */
                                pci_stop_and_remove_bus_device(dev);
                                break;
                        }
                }
        }
}

/*
 * ACPI event handlers
 */

void acpiphp_check_host_bridge(struct acpi_device *adev)
{
        struct acpiphp_bridge *bridge = NULL;

        acpi_lock_hp_context();
        if (adev->hp) {
                bridge = to_acpiphp_root_context(adev->hp)->root_bridge;
                if (bridge)
                        get_bridge(bridge);
        }
        acpi_unlock_hp_context();
        if (bridge) {
                pci_lock_rescan_remove();

                acpiphp_check_bridge(bridge);

                pci_unlock_rescan_remove();
                put_bridge(bridge);
        }
}

static int acpiphp_disable_and_eject_slot(struct acpiphp_slot *slot);

static void hotplug_event(u32 type, struct acpiphp_context *context)
{
        acpi_handle handle = context->hp.self->handle;
        struct acpiphp_func *func = &context->func;
        struct acpiphp_slot *slot = func->slot;
        struct acpiphp_bridge *bridge;

        acpi_lock_hp_context();
        bridge = context->bridge;
        if (bridge)
                get_bridge(bridge);

        acpi_unlock_hp_context();

        pci_lock_rescan_remove();

        switch (type) {
        case ACPI_NOTIFY_BUS_CHECK:
                /* bus re-enumerate */
                acpi_handle_debug(handle, "Bus check in %s()\n", __func__);
                if (bridge)
                        acpiphp_check_bridge(bridge);
                else if (!(slot->flags & SLOT_IS_GOING_AWAY))
                        enable_slot(slot, false);

                break;

        case ACPI_NOTIFY_DEVICE_CHECK:
                /* device check */
                acpi_handle_debug(handle, "Device check in %s()\n", __func__);
                if (bridge) {
                        acpiphp_check_bridge(bridge);
                } else if (!(slot->flags & SLOT_IS_GOING_AWAY)) {
                        /*
                         * Check if anything has changed in the slot and rescan
                         * from the parent if that's the case.
                         */
                        if (acpiphp_rescan_slot(slot))
                                acpiphp_check_bridge(func->parent);
                }
                break;

        case ACPI_NOTIFY_EJECT_REQUEST:
                /* request device eject */
                acpi_handle_debug(handle, "Eject request in %s()\n", __func__);
                acpiphp_disable_and_eject_slot(slot);
                break;
        }

        pci_unlock_rescan_remove();
        if (bridge)
                put_bridge(bridge);
}

static int acpiphp_hotplug_notify(struct acpi_device *adev, u32 type)
{
        struct acpiphp_context *context;

        context = acpiphp_grab_context(adev);
        if (!context)
                return -ENODATA;

        hotplug_event(type, context);
        acpiphp_let_context_go(context);
        return 0;
}

/**
 * acpiphp_enumerate_slots - Enumerate PCI slots for a given bus.
 * @bus: PCI bus to enumerate the slots for.
 *
 * A "slot" is an object associated with a PCI device number.  All functions
 * (PCI devices) with the same bus and device number belong to the same slot.
 */
void acpiphp_enumerate_slots(struct pci_bus *bus)
{
        struct acpiphp_bridge *bridge;
        struct acpi_device *adev;
        acpi_handle handle;
        acpi_status status;

        if (acpiphp_disabled)
                return;

        adev = ACPI_COMPANION(bus->bridge);
        if (!adev)
                return;

        handle = adev->handle;
        bridge = kzalloc(sizeof(struct acpiphp_bridge), GFP_KERNEL);
        if (!bridge)
                return;

        INIT_LIST_HEAD(&bridge->slots);
        kref_init(&bridge->ref);
        bridge->pci_dev = pci_dev_get(bus->self);
        bridge->pci_bus = bus;

        /*
         * Grab a ref to the subordinate PCI bus in case the bus is
         * removed via PCI core logical hotplug. The ref pins the bus
         * (which we access during module unload).
         */
        get_device(&bus->dev);

        acpi_lock_hp_context();
        if (pci_is_root_bus(bridge->pci_bus)) {
                struct acpiphp_root_context *root_context;

                root_context = kzalloc(sizeof(*root_context), GFP_KERNEL);
                if (!root_context)
                        goto err;

                root_context->root_bridge = bridge;
                acpi_set_hp_context(adev, &root_context->hp);
        } else {
                struct acpiphp_context *context;

                /*
                 * This bridge should have been registered as a hotplug function
                 * under its parent, so the context should be there, unless the
                 * parent is going to be handled by pciehp, in which case this
                 * bridge is not interesting to us either.
                 */
                context = acpiphp_get_context(adev);
                if (!context)
                        goto err;

                bridge->context = context;
                context->bridge = bridge;
                /* Get a reference to the parent bridge. */
                get_bridge(context->func.parent);
        }
        acpi_unlock_hp_context();

        /* Must be added to the list prior to calling acpiphp_add_context(). */
        mutex_lock(&bridge_mutex);
        list_add(&bridge->list, &bridge_list);
        mutex_unlock(&bridge_mutex);

        /* register all slot objects under this bridge */
        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
                                     acpiphp_add_context, NULL, bridge, NULL);
        if (ACPI_FAILURE(status)) {
                acpi_handle_err(handle, "failed to register slots\n");
                cleanup_bridge(bridge);
                put_bridge(bridge);
        }
        return;

 err:
        acpi_unlock_hp_context();
        put_device(&bus->dev);
        pci_dev_put(bridge->pci_dev);
        kfree(bridge);
}

static void acpiphp_drop_bridge(struct acpiphp_bridge *bridge)
{
        if (pci_is_root_bus(bridge->pci_bus)) {
                struct acpiphp_root_context *root_context;
                struct acpi_device *adev;

                acpi_lock_hp_context();
                adev = ACPI_COMPANION(bridge->pci_bus->bridge);
                root_context = to_acpiphp_root_context(adev->hp);
                adev->hp = NULL;
                acpi_unlock_hp_context();
                kfree(root_context);
        }
        cleanup_bridge(bridge);
        put_bridge(bridge);
}

/**
 * acpiphp_remove_slots - Remove slot objects associated with a given bus.
 * @bus: PCI bus to remove the slot objects for.
 */
void acpiphp_remove_slots(struct pci_bus *bus)
{
        struct acpiphp_bridge *bridge;

        if (acpiphp_disabled)
                return;

        mutex_lock(&bridge_mutex);
        list_for_each_entry(bridge, &bridge_list, list)
                if (bridge->pci_bus == bus) {
                        mutex_unlock(&bridge_mutex);
                        acpiphp_drop_bridge(bridge);
                        return;
                }

        mutex_unlock(&bridge_mutex);
}

/**
 * acpiphp_enable_slot - power on slot
 * @slot: ACPI PHP slot
 */
int acpiphp_enable_slot(struct acpiphp_slot *slot)
{
        pci_lock_rescan_remove();

        if (slot->flags & SLOT_IS_GOING_AWAY) {
                pci_unlock_rescan_remove();
                return -ENODEV;
        }

        /* configure all functions */
        if (!(slot->flags & SLOT_ENABLED))
                enable_slot(slot, false);

        pci_unlock_rescan_remove();
        return 0;
}

/**
 * acpiphp_disable_and_eject_slot - power off and eject slot
 * @slot: ACPI PHP slot
 */
static int acpiphp_disable_and_eject_slot(struct acpiphp_slot *slot)
{
        struct acpiphp_func *func;

        if (slot->flags & SLOT_IS_GOING_AWAY)
                return -ENODEV;

        /* unconfigure all functions */
        disable_slot(slot);

        list_for_each_entry(func, &slot->funcs, sibling)
                if (func->flags & FUNC_HAS_EJ0) {
                        acpi_handle handle = func_to_handle(func);

                        if (ACPI_FAILURE(acpi_evaluate_ej0(handle)))
                                acpi_handle_err(handle, "_EJ0 failed\n");

                        break;
                }

        return 0;
}

int acpiphp_disable_slot(struct acpiphp_slot *slot)
{
        int ret;

        /*
         * Acquire acpi_scan_lock to ensure that the execution of _EJ0 in
         * acpiphp_disable_and_eject_slot() will be synchronized properly.
         */
        acpi_scan_lock_acquire();
        pci_lock_rescan_remove();
        ret = acpiphp_disable_and_eject_slot(slot);
        pci_unlock_rescan_remove();
        acpi_scan_lock_release();
        return ret;
}

/*
 * slot enabled:  1
 * slot disabled: 0
 */
u8 acpiphp_get_power_status(struct acpiphp_slot *slot)
{
        return (slot->flags & SLOT_ENABLED);
}

/*
 * latch   open:  1
 * latch closed:  0
 */
u8 acpiphp_get_latch_status(struct acpiphp_slot *slot)
{
        return !(get_slot_status(slot) & ACPI_STA_DEVICE_UI);
}

/*
 * adapter presence : 1
 *          absence : 0
 */
u8 acpiphp_get_adapter_status(struct acpiphp_slot *slot)
{
        return !!get_slot_status(slot);
}