drivers/acpi/pci_root.c - arm/linux-arm-legacy - Git at Google

 /*
  *  pci_root.c - ACPI PCI Root Bridge Driver ($Revision: 40 $)
  *
  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *
  *  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.  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.,
  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/mutex.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/pci.h>
 #include <linux/pci-acpi.h>
 #include <linux/pci-aspm.h>
 #include <linux/acpi.h>
 #include <linux/slab.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 #include <acpi/apei.h>

 #include "internal.h"

 #define PREFIX "ACPI: "

 #define _COMPONENT		ACPI_PCI_COMPONENT
 ACPI_MODULE_NAME("pci_root");
 #define ACPI_PCI_ROOT_CLASS		"pci_bridge"
 #define ACPI_PCI_ROOT_DEVICE_NAME	"PCI Root Bridge"
 static int acpi_pci_root_add(struct acpi_device *device,
 			     const struct acpi_device_id *not_used);
 static void acpi_pci_root_remove(struct acpi_device *device);

 #define ACPI_PCIE_REQ_SUPPORT (OSC_PCI_EXT_CONFIG_SUPPORT \
 				| OSC_PCI_ASPM_SUPPORT \
 				| OSC_PCI_CLOCK_PM_SUPPORT \
 				| OSC_PCI_MSI_SUPPORT)

 static const struct acpi_device_id root_device_ids[] = {
 	{"PNP0A03", 0},
 	{"", 0},
 };

 static struct acpi_scan_handler pci_root_handler = {
 	.ids = root_device_ids,
 	.attach = acpi_pci_root_add,
 	.detach = acpi_pci_root_remove,
 };

 static DEFINE_MUTEX(osc_lock);

 /**
  * acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
  * @handle - the ACPI CA node in question.
  *
  * Note: we could make this API take a struct acpi_device * instead, but
  * for now, it's more convenient to operate on an acpi_handle.
  */
 int acpi_is_root_bridge(acpi_handle handle)
 {
 	int ret;
 	struct acpi_device *device;

 	ret = acpi_bus_get_device(handle, &device);
 	if (ret)
 		return 0;

 	ret = acpi_match_device_ids(device, root_device_ids);
 	if (ret)
 		return 0;
 	else
 		return 1;
 }
 EXPORT_SYMBOL_GPL(acpi_is_root_bridge);

 static acpi_status
 get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
 {
 	struct resource *res = data;
 	struct acpi_resource_address64 address;
 	acpi_status status;

 	status = acpi_resource_to_address64(resource, &address);
 	if (ACPI_FAILURE(status))
 		return AE_OK;

 	if ((address.address_length > 0) &&
 	    (address.resource_type == ACPI_BUS_NUMBER_RANGE)) {
 		res->start = address.minimum;
 		res->end = address.minimum + address.address_length - 1;
 	}

 	return AE_OK;
 }

 static acpi_status try_get_root_bridge_busnr(acpi_handle handle,
 					     struct resource *res)
 {
 	acpi_status status;

 	res->start = -1;
 	status =
 	    acpi_walk_resources(handle, METHOD_NAME__CRS,
 				get_root_bridge_busnr_callback, res);
 	if (ACPI_FAILURE(status))
 		return status;
 	if (res->start == -1)
 		return AE_ERROR;
 	return AE_OK;
 }

 struct pci_osc_bit_struct {
 	u32 bit;
 	char *desc;
 };

 static struct pci_osc_bit_struct pci_osc_support_bit[] = {
 	{ OSC_PCI_EXT_CONFIG_SUPPORT, "ExtendedConfig" },
 	{ OSC_PCI_ASPM_SUPPORT, "ASPM" },
 	{ OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
 	{ OSC_PCI_SEGMENT_GROUPS_SUPPORT, "Segments" },
 	{ OSC_PCI_MSI_SUPPORT, "MSI" },
 };

 static struct pci_osc_bit_struct pci_osc_control_bit[] = {
 	{ OSC_PCI_EXPRESS_NATIVE_HP_CONTROL, "PCIeHotplug" },
 	{ OSC_PCI_SHPC_NATIVE_HP_CONTROL, "SHPCHotplug" },
 	{ OSC_PCI_EXPRESS_PME_CONTROL, "PME" },
 	{ OSC_PCI_EXPRESS_AER_CONTROL, "AER" },
 	{ OSC_PCI_EXPRESS_CAPABILITY_CONTROL, "PCIeCapability" },
 };

 static void decode_osc_bits(struct acpi_pci_root *root, char *msg, u32 word,
 			    struct pci_osc_bit_struct *table, int size)
 {
 	char buf[80];
 	int i, len = 0;
 	struct pci_osc_bit_struct *entry;

 	buf[0] = '\0';
 	for (i = 0, entry = table; i < size; i++, entry++)
 		if (word & entry->bit)
 			len += snprintf(buf + len, sizeof(buf) - len, "%s%s",
 					len ? " " : "", entry->desc);

 	dev_info(&root->device->dev, "_OSC: %s [%s]\n", msg, buf);
 }

 static void decode_osc_support(struct acpi_pci_root *root, char *msg, u32 word)
 {
 	decode_osc_bits(root, msg, word, pci_osc_support_bit,
 			ARRAY_SIZE(pci_osc_support_bit));
 }

 static void decode_osc_control(struct acpi_pci_root *root, char *msg, u32 word)
 {
 	decode_osc_bits(root, msg, word, pci_osc_control_bit,
 			ARRAY_SIZE(pci_osc_control_bit));
 }

 static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766";

 static acpi_status acpi_pci_run_osc(acpi_handle handle,
 				    const u32 *capbuf, u32 *retval)
 {
 	struct acpi_osc_context context = {
 		.uuid_str = pci_osc_uuid_str,
 		.rev = 1,
 		.cap.length = 12,
 		.cap.pointer = (void *)capbuf,
 	};
 	acpi_status status;

 	status = acpi_run_osc(handle, &context);
 	if (ACPI_SUCCESS(status)) {
 		*retval = *((u32 *)(context.ret.pointer + 8));
 		kfree(context.ret.pointer);
 	}
 	return status;
 }

 static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
 					u32 support,
 					u32 *control)
 {
 	acpi_status status;
 	u32 result, capbuf[3];

 	support &= OSC_PCI_SUPPORT_MASKS;
 	support |= root->osc_support_set;

 	capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
 	capbuf[OSC_SUPPORT_DWORD] = support;
 	if (control) {
 		*control &= OSC_PCI_CONTROL_MASKS;
 		capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set;
 	} else {
 		/* Run _OSC query only with existing controls. */
 		capbuf[OSC_CONTROL_DWORD] = root->osc_control_set;
 	}

 	status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
 	if (ACPI_SUCCESS(status)) {
 		root->osc_support_set = support;
 		if (control)
 			*control = result;
 	}
 	return status;
 }

 static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
 {
 	acpi_status status;

 	mutex_lock(&osc_lock);
 	status = acpi_pci_query_osc(root, flags, NULL);
 	mutex_unlock(&osc_lock);
 	return status;
 }

 struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
 {
 	struct acpi_pci_root *root;
 	struct acpi_device *device;

 	if (acpi_bus_get_device(handle, &device) ||
 	    acpi_match_device_ids(device, root_device_ids))
 		return NULL;

 	root = acpi_driver_data(device);

 	return root;
 }
 EXPORT_SYMBOL_GPL(acpi_pci_find_root);

 struct acpi_handle_node {
 	struct list_head node;
 	acpi_handle handle;
 };

 /**
  * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
  * @handle: the handle in question
  *
  * Given an ACPI CA handle, the desired PCI device is located in the
  * list of PCI devices.
  *
  * If the device is found, its reference count is increased and this
  * function returns a pointer to its data structure.  The caller must
  * decrement the reference count by calling pci_dev_put().
  * If no device is found, %NULL is returned.
  */
 struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
 {
 	int dev, fn;
 	unsigned long long adr;
 	acpi_status status;
 	acpi_handle phandle;
 	struct pci_bus *pbus;
 	struct pci_dev *pdev = NULL;
 	struct acpi_handle_node *node, *tmp;
 	struct acpi_pci_root *root;
 	LIST_HEAD(device_list);

 	/*
 	 * Walk up the ACPI CA namespace until we reach a PCI root bridge.
 	 */
 	phandle = handle;
 	while (!acpi_is_root_bridge(phandle)) {
 		node = kzalloc(sizeof(struct acpi_handle_node), GFP_KERNEL);
 		if (!node)
 			goto out;

 		INIT_LIST_HEAD(&node->node);
 		node->handle = phandle;
 		list_add(&node->node, &device_list);

 		status = acpi_get_parent(phandle, &phandle);
 		if (ACPI_FAILURE(status))
 			goto out;
 	}

 	root = acpi_pci_find_root(phandle);
 	if (!root)
 		goto out;

 	pbus = root->bus;

 	/*
 	 * Now, walk back down the PCI device tree until we return to our
 	 * original handle. Assumes that everything between the PCI root
 	 * bridge and the device we're looking for must be a P2P bridge.
 	 */
 	list_for_each_entry(node, &device_list, node) {
 		acpi_handle hnd = node->handle;
 		status = acpi_evaluate_integer(hnd, "_ADR", NULL, &adr);
 		if (ACPI_FAILURE(status))
 			goto out;
 		dev = (adr >> 16) & 0xffff;
 		fn  = adr & 0xffff;

 		pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
 		if (!pdev || hnd == handle)
 			break;

 		pbus = pdev->subordinate;
 		pci_dev_put(pdev);

 		/*
 		 * This function may be called for a non-PCI device that has a
 		 * PCI parent (eg. a disk under a PCI SATA controller).  In that
 		 * case pdev->subordinate will be NULL for the parent.
 		 */
 		if (!pbus) {
 			dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
 			pdev = NULL;
 			break;
 		}
 	}
 out:
 	list_for_each_entry_safe(node, tmp, &device_list, node)
 		kfree(node);

 	return pdev;
 }
 EXPORT_SYMBOL_GPL(acpi_get_pci_dev);

 /**
  * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
  * @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
  * @mask: Mask of _OSC bits to request control of, place to store control mask.
  * @req: Mask of _OSC bits the control of is essential to the caller.
  *
  * Run _OSC query for @mask and if that is successful, compare the returned
  * mask of control bits with @req.  If all of the @req bits are set in the
  * returned mask, run _OSC request for it.
  *
  * The variable at the @mask address may be modified regardless of whether or
  * not the function returns success.  On success it will contain the mask of
  * _OSC bits the BIOS has granted control of, but its contents are meaningless
  * on failure.
  **/
 acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
 {
 	struct acpi_pci_root *root;
 	acpi_status status = AE_OK;
 	u32 ctrl, capbuf[3];

 	if (!mask)
 		return AE_BAD_PARAMETER;

 	ctrl = *mask & OSC_PCI_CONTROL_MASKS;
 	if ((ctrl & req) != req)
 		return AE_TYPE;

 	root = acpi_pci_find_root(handle);
 	if (!root)
 		return AE_NOT_EXIST;

 	mutex_lock(&osc_lock);

 	*mask = ctrl | root->osc_control_set;
 	/* No need to evaluate _OSC if the control was already granted. */
 	if ((root->osc_control_set & ctrl) == ctrl)
 		goto out;

 	/* Need to check the available controls bits before requesting them. */
 	while (*mask) {
 		status = acpi_pci_query_osc(root, root->osc_support_set, mask);
 		if (ACPI_FAILURE(status))
 			goto out;
 		if (ctrl == *mask)
 			break;
 		decode_osc_control(root, "platform does not support",
 				   ctrl & ~(*mask));
 		ctrl = *mask;
 	}

 	if ((ctrl & req) != req) {
 		decode_osc_control(root, "not requesting control; platform does not support",
 				   req & ~(ctrl));
 		status = AE_SUPPORT;
 		goto out;
 	}

 	capbuf[OSC_QUERY_DWORD] = 0;
 	capbuf[OSC_SUPPORT_DWORD] = root->osc_support_set;
 	capbuf[OSC_CONTROL_DWORD] = ctrl;
 	status = acpi_pci_run_osc(handle, capbuf, mask);
 	if (ACPI_SUCCESS(status))
 		root->osc_control_set = *mask;
 out:
 	mutex_unlock(&osc_lock);
 	return status;
 }
 EXPORT_SYMBOL(acpi_pci_osc_control_set);

 static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
 				 int *clear_aspm)
 {
 	u32 support, control, requested;
 	acpi_status status;
 	struct acpi_device *device = root->device;
 	acpi_handle handle = device->handle;

 	/*
 	 * All supported architectures that use ACPI have support for
 	 * PCI domains, so we indicate this in _OSC support capabilities.
 	 */
 	support = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 	if (pci_ext_cfg_avail())
 		support |= OSC_PCI_EXT_CONFIG_SUPPORT;
 	if (pcie_aspm_support_enabled())
 		support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT;
 	if (pci_msi_enabled())
 		support |= OSC_PCI_MSI_SUPPORT;

 	decode_osc_support(root, "OS supports", support);
 	status = acpi_pci_osc_support(root, support);
 	if (ACPI_FAILURE(status)) {
 		dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
 			 acpi_format_exception(status));
 		*no_aspm = 1;
 		return;
 	}

 	if (pcie_ports_disabled) {
 		dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n");
 		return;
 	}

 	if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
 		decode_osc_support(root, "not requesting OS control; OS requires",
 				   ACPI_PCIE_REQ_SUPPORT);
 		return;
 	}

 	control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
 		| OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
 		| OSC_PCI_EXPRESS_PME_CONTROL;

 	if (pci_aer_available()) {
 		if (aer_acpi_firmware_first())
 			dev_info(&device->dev,
 				 "PCIe AER handled by firmware\n");
 		else
 			control |= OSC_PCI_EXPRESS_AER_CONTROL;
 	}

 	requested = control;
 	status = acpi_pci_osc_control_set(handle, &control,
 					  OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
 	if (ACPI_SUCCESS(status)) {
 		decode_osc_control(root, "OS now controls", control);
 		if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
 			/*
 			 * We have ASPM control, but the FADT indicates
 			 * that it's unsupported. Clear it.
 			 */
 			*clear_aspm = 1;
 		}
 	} else {
 		decode_osc_control(root, "OS requested", requested);
 		decode_osc_control(root, "platform willing to grant", control);
 		dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
 			acpi_format_exception(status));

 		/*
 		 * We want to disable ASPM here, but aspm_disabled
 		 * needs to remain in its state from boot so that we
 		 * properly handle PCIe 1.1 devices.  So we set this
 		 * flag here, to defer the action until after the ACPI
 		 * root scan.
 		 */
 		*no_aspm = 1;
 	}
 }

 static int acpi_pci_root_add(struct acpi_device *device,
 			     const struct acpi_device_id *not_used)
 {
 	unsigned long long segment, bus;
 	acpi_status status;
 	int result;
 	struct acpi_pci_root *root;
 	acpi_handle handle = device->handle;
 	int no_aspm = 0, clear_aspm = 0;

 	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 	if (!root)
 		return -ENOMEM;

 	segment = 0;
 	status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL,
 				       &segment);
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 		dev_err(&device->dev,  "can't evaluate _SEG\n");
 		result = -ENODEV;
 		goto end;
 	}

 	/* Check _CRS first, then _BBN.  If no _BBN, default to zero. */
 	root->secondary.flags = IORESOURCE_BUS;
 	status = try_get_root_bridge_busnr(handle, &root->secondary);
 	if (ACPI_FAILURE(status)) {
 		/*
 		 * We need both the start and end of the downstream bus range
 		 * to interpret _CBA (MMCONFIG base address), so it really is
 		 * supposed to be in _CRS.  If we don't find it there, all we
 		 * can do is assume [_BBN-0xFF] or [0-0xFF].
 		 */
 		root->secondary.end = 0xFF;
 		dev_warn(&device->dev,
 			 FW_BUG "no secondary bus range in _CRS\n");
 		status = acpi_evaluate_integer(handle, METHOD_NAME__BBN,
 					       NULL, &bus);
 		if (ACPI_SUCCESS(status))
 			root->secondary.start = bus;
 		else if (status == AE_NOT_FOUND)
 			root->secondary.start = 0;
 		else {
 			dev_err(&device->dev, "can't evaluate _BBN\n");
 			result = -ENODEV;
 			goto end;
 		}
 	}

 	root->device = device;
 	root->segment = segment & 0xFFFF;
 	strcpy(acpi_device_name(device), ACPI_PCI_ROOT_DEVICE_NAME);
 	strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
 	device->driver_data = root;

 	pr_info(PREFIX "%s [%s] (domain %04x %pR)\n",
 	       acpi_device_name(device), acpi_device_bid(device),
 	       root->segment, &root->secondary);

 	root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle);

 	negotiate_os_control(root, &no_aspm, &clear_aspm);

 	/*
 	 * TBD: Need PCI interface for enumeration/configuration of roots.
 	 */

 	/*
 	 * Scan the Root Bridge
 	 * --------------------
 	 * Must do this prior to any attempt to bind the root device, as the
 	 * PCI namespace does not get created until this call is made (and
 	 * thus the root bridge's pci_dev does not exist).
 	 */
 	root->bus = pci_acpi_scan_root(root);
 	if (!root->bus) {
 		dev_err(&device->dev,
 			"Bus %04x:%02x not present in PCI namespace\n",
 			root->segment, (unsigned int)root->secondary.start);
 		device->driver_data = NULL;
 		result = -ENODEV;
 		goto end;
 	}

 	if (clear_aspm) {
 		dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
 		pcie_clear_aspm(root->bus);
 	}
 	if (no_aspm)
 		pcie_no_aspm();

 	pci_acpi_add_bus_pm_notifier(device, root->bus);
 	if (device->wakeup.flags.run_wake)
 		device_set_run_wake(root->bus->bridge, true);

 	if (system_state != SYSTEM_BOOTING) {
 		pcibios_resource_survey_bus(root->bus);
 		pci_assign_unassigned_root_bus_resources(root->bus);
 	}

 	pci_bus_add_devices(root->bus);
 	return 1;

 end:
 	kfree(root);
 	return result;
 }

 static void acpi_pci_root_remove(struct acpi_device *device)
 {
 	struct acpi_pci_root *root = acpi_driver_data(device);

 	pci_stop_root_bus(root->bus);

 	device_set_run_wake(root->bus->bridge, false);
 	pci_acpi_remove_bus_pm_notifier(device);

 	pci_remove_root_bus(root->bus);

 	kfree(root);
 }

 void __init acpi_pci_root_init(void)
 {
 	acpi_hest_init();

 	if (!acpi_pci_disabled) {
 		pci_acpi_crs_quirks();
 		acpi_scan_add_handler(&pci_root_handler);
 	}
 }
 /* Support root bridge hotplug */

 static void handle_root_bridge_insertion(acpi_handle handle)
 {
 	struct acpi_device *device;

 	if (!acpi_bus_get_device(handle, &device)) {
 		dev_printk(KERN_DEBUG, &device->dev,
 			   "acpi device already exists; ignoring notify\n");
 		return;
 	}

 	if (acpi_bus_scan(handle))
 		acpi_handle_err(handle, "cannot add bridge to acpi list\n");
 }

 static void hotplug_event_root(void *data, u32 type)
 {
 	acpi_handle handle = data;
 	struct acpi_pci_root *root;

 	acpi_scan_lock_acquire();

 	root = acpi_pci_find_root(handle);

 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		/* bus enumerate */
 		acpi_handle_printk(KERN_DEBUG, handle,
 				   "Bus check notify on %s\n", __func__);
 		if (root)
 			acpiphp_check_host_bridge(handle);
 		else
 			handle_root_bridge_insertion(handle);

 		break;

 	case ACPI_NOTIFY_DEVICE_CHECK:
 		/* device check */
 		acpi_handle_printk(KERN_DEBUG, handle,
 				   "Device check notify on %s\n", __func__);
 		if (!root)
 			handle_root_bridge_insertion(handle);
 		break;

 	case ACPI_NOTIFY_EJECT_REQUEST:
 		/* request device eject */
 		acpi_handle_printk(KERN_DEBUG, handle,
 				   "Device eject notify on %s\n", __func__);
 		if (!root)
 			break;

 		get_device(&root->device->dev);

 		acpi_scan_lock_release();

 		acpi_bus_device_eject(root->device, ACPI_NOTIFY_EJECT_REQUEST);
 		return;
 	default:
 		acpi_handle_warn(handle,
 				 "notify_handler: unknown event type 0x%x\n",
 				 type);
 		break;
 	}

 	acpi_scan_lock_release();
 }

 static void handle_hotplug_event_root(acpi_handle handle, u32 type,
 					void *context)
 {
 	acpi_hotplug_execute(hotplug_event_root, handle, type);
 }

 static acpi_status __init
 find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
 {
 	acpi_status status;
 	int *count = (int *)context;

 	if (!acpi_is_root_bridge(handle))
 		return AE_OK;

 	(*count)++;

 	status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
 					handle_hotplug_event_root, NULL);
 	if (ACPI_FAILURE(status))
 		acpi_handle_printk(KERN_DEBUG, handle,
 			"notify handler is not installed, exit status: %u\n",
 			 (unsigned int)status);
 	else
 		acpi_handle_printk(KERN_DEBUG, handle,
 				   "notify handler is installed\n");

 	return AE_OK;
 }

 void __init acpi_pci_root_hp_init(void)
 {
 	int num = 0;

 	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 		ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);

 	printk(KERN_DEBUG "Found %d acpi root devices\n", num);
 }
	/*
	* pci_root.c - ACPI PCI Root Bridge Driver ($Revision: 40 $)
	*
	* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
	* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
	*
	* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	*
	* 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. 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.,
	* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
	*
	* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/types.h>
	#include <linux/mutex.h>
	#include <linux/pm.h>
	#include <linux/pm_runtime.h>
	#include <linux/pci.h>
	#include <linux/pci-acpi.h>
	#include <linux/pci-aspm.h>
	#include <linux/acpi.h>
	#include <linux/slab.h>
	#include <acpi/acpi_bus.h>
	#include <acpi/acpi_drivers.h>
	#include <acpi/apei.h>

	#include "internal.h"

	#define PREFIX "ACPI: "

	#define _COMPONENT ACPI_PCI_COMPONENT
	ACPI_MODULE_NAME("pci_root");
	#define ACPI_PCI_ROOT_CLASS "pci_bridge"
	#define ACPI_PCI_ROOT_DEVICE_NAME "PCI Root Bridge"
	static int acpi_pci_root_add(struct acpi_device *device,
	const struct acpi_device_id *not_used);
	static void acpi_pci_root_remove(struct acpi_device *device);

	#define ACPI_PCIE_REQ_SUPPORT (OSC_PCI_EXT_CONFIG_SUPPORT \
	\| OSC_PCI_ASPM_SUPPORT \
	\| OSC_PCI_CLOCK_PM_SUPPORT \
	\| OSC_PCI_MSI_SUPPORT)

	static const struct acpi_device_id root_device_ids[] = {
	{"PNP0A03", 0},
	{"", 0},
	};

	static struct acpi_scan_handler pci_root_handler = {
	.ids = root_device_ids,
	.attach = acpi_pci_root_add,
	.detach = acpi_pci_root_remove,
	};

	static DEFINE_MUTEX(osc_lock);

	/**
	* acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
	* @handle - the ACPI CA node in question.
	*
	* Note: we could make this API take a struct acpi_device * instead, but
	* for now, it's more convenient to operate on an acpi_handle.
	*/
	int acpi_is_root_bridge(acpi_handle handle)
	{
	int ret;
	struct acpi_device *device;

	ret = acpi_bus_get_device(handle, &device);
	if (ret)
	return 0;

	ret = acpi_match_device_ids(device, root_device_ids);
	if (ret)
	return 0;
	else
	return 1;
	}
	EXPORT_SYMBOL_GPL(acpi_is_root_bridge);

	static acpi_status
	get_root_bridge_busnr_callback(struct acpi_resource resource, void data)
	{
	struct resource *res = data;
	struct acpi_resource_address64 address;
	acpi_status status;

	status = acpi_resource_to_address64(resource, &address);
	if (ACPI_FAILURE(status))
	return AE_OK;

	if ((address.address_length > 0) &&
	(address.resource_type == ACPI_BUS_NUMBER_RANGE)) {
	res->start = address.minimum;
	res->end = address.minimum + address.address_length - 1;
	}

	return AE_OK;
	}

	static acpi_status try_get_root_bridge_busnr(acpi_handle handle,
	struct resource *res)
	{
	acpi_status status;

	res->start = -1;
	status =
	acpi_walk_resources(handle, METHOD_NAME__CRS,
	get_root_bridge_busnr_callback, res);
	if (ACPI_FAILURE(status))
	return status;
	if (res->start == -1)
	return AE_ERROR;
	return AE_OK;
	}

	struct pci_osc_bit_struct {
	u32 bit;
	char *desc;
	};

	static struct pci_osc_bit_struct pci_osc_support_bit[] = {
	{ OSC_PCI_EXT_CONFIG_SUPPORT, "ExtendedConfig" },
	{ OSC_PCI_ASPM_SUPPORT, "ASPM" },
	{ OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
	{ OSC_PCI_SEGMENT_GROUPS_SUPPORT, "Segments" },
	{ OSC_PCI_MSI_SUPPORT, "MSI" },
	};

	static struct pci_osc_bit_struct pci_osc_control_bit[] = {
	{ OSC_PCI_EXPRESS_NATIVE_HP_CONTROL, "PCIeHotplug" },
	{ OSC_PCI_SHPC_NATIVE_HP_CONTROL, "SHPCHotplug" },
	{ OSC_PCI_EXPRESS_PME_CONTROL, "PME" },
	{ OSC_PCI_EXPRESS_AER_CONTROL, "AER" },
	{ OSC_PCI_EXPRESS_CAPABILITY_CONTROL, "PCIeCapability" },
	};

	static void decode_osc_bits(struct acpi_pci_root root, char msg, u32 word,
	struct pci_osc_bit_struct *table, int size)
	{
	char buf[80];
	int i, len = 0;
	struct pci_osc_bit_struct *entry;

	buf[0] = '\0';
	for (i = 0, entry = table; i < size; i++, entry++)
	if (word & entry->bit)
	len += snprintf(buf + len, sizeof(buf) - len, "%s%s",
	len ? " " : "", entry->desc);

	dev_info(&root->device->dev, "_OSC: %s [%s]\n", msg, buf);
	}

	static void decode_osc_support(struct acpi_pci_root root, char msg, u32 word)
	{
	decode_osc_bits(root, msg, word, pci_osc_support_bit,
	ARRAY_SIZE(pci_osc_support_bit));
	}

	static void decode_osc_control(struct acpi_pci_root root, char msg, u32 word)
	{
	decode_osc_bits(root, msg, word, pci_osc_control_bit,
	ARRAY_SIZE(pci_osc_control_bit));
	}

	static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766";

	static acpi_status acpi_pci_run_osc(acpi_handle handle,
	const u32 capbuf, u32 retval)
	{
	struct acpi_osc_context context = {
	.uuid_str = pci_osc_uuid_str,
	.rev = 1,
	.cap.length = 12,
	.cap.pointer = (void *)capbuf,
	};
	acpi_status status;

	status = acpi_run_osc(handle, &context);
	if (ACPI_SUCCESS(status)) {
	retval = ((u32 *)(context.ret.pointer + 8));
	kfree(context.ret.pointer);
	}
	return status;
	}

	static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
	u32 support,
	u32 *control)
	{
	acpi_status status;
	u32 result, capbuf[3];

	support &= OSC_PCI_SUPPORT_MASKS;
	support \|= root->osc_support_set;

	capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
	capbuf[OSC_SUPPORT_DWORD] = support;
	if (control) {
	*control &= OSC_PCI_CONTROL_MASKS;
	capbuf[OSC_CONTROL_DWORD] = *control \| root->osc_control_set;
	} else {
	/* Run _OSC query only with existing controls. */
	capbuf[OSC_CONTROL_DWORD] = root->osc_control_set;
	}

	status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
	if (ACPI_SUCCESS(status)) {
	root->osc_support_set = support;
	if (control)
	*control = result;
	}
	return status;
	}

	static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
	{
	acpi_status status;

	mutex_lock(&osc_lock);
	status = acpi_pci_query_osc(root, flags, NULL);
	mutex_unlock(&osc_lock);
	return status;
	}

	struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
	{
	struct acpi_pci_root *root;
	struct acpi_device *device;

	if (acpi_bus_get_device(handle, &device) \|\|
	acpi_match_device_ids(device, root_device_ids))
	return NULL;

	root = acpi_driver_data(device);

	return root;
	}
	EXPORT_SYMBOL_GPL(acpi_pci_find_root);

	struct acpi_handle_node {
	struct list_head node;
	acpi_handle handle;
	};

	/**
	* acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
	* @handle: the handle in question
	*
	* Given an ACPI CA handle, the desired PCI device is located in the
	* list of PCI devices.
	*
	* If the device is found, its reference count is increased and this
	* function returns a pointer to its data structure. The caller must
	* decrement the reference count by calling pci_dev_put().
	* If no device is found, %NULL is returned.
	*/
	struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
	{
	int dev, fn;
	unsigned long long adr;
	acpi_status status;
	acpi_handle phandle;
	struct pci_bus *pbus;
	struct pci_dev *pdev = NULL;
	struct acpi_handle_node node, tmp;
	struct acpi_pci_root *root;
	LIST_HEAD(device_list);

	/*
	* Walk up the ACPI CA namespace until we reach a PCI root bridge.
	*/
	phandle = handle;
	while (!acpi_is_root_bridge(phandle)) {
	node = kzalloc(sizeof(struct acpi_handle_node), GFP_KERNEL);
	if (!node)
	goto out;

	INIT_LIST_HEAD(&node->node);
	node->handle = phandle;
	list_add(&node->node, &device_list);

	status = acpi_get_parent(phandle, &phandle);
	if (ACPI_FAILURE(status))
	goto out;
	}

	root = acpi_pci_find_root(phandle);
	if (!root)
	goto out;

	pbus = root->bus;

	/*
	* Now, walk back down the PCI device tree until we return to our
	* original handle. Assumes that everything between the PCI root
	* bridge and the device we're looking for must be a P2P bridge.
	*/
	list_for_each_entry(node, &device_list, node) {
	acpi_handle hnd = node->handle;
	status = acpi_evaluate_integer(hnd, "_ADR", NULL, &adr);
	if (ACPI_FAILURE(status))
	goto out;
	dev = (adr >> 16) & 0xffff;
	fn = adr & 0xffff;

	pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
	if (!pdev \|\| hnd == handle)
	break;

	pbus = pdev->subordinate;
	pci_dev_put(pdev);

	/*
	* This function may be called for a non-PCI device that has a
	* PCI parent (eg. a disk under a PCI SATA controller). In that
	* case pdev->subordinate will be NULL for the parent.
	*/
	if (!pbus) {
	dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
	pdev = NULL;
	break;
	}
	}
	out:
	list_for_each_entry_safe(node, tmp, &device_list, node)
	kfree(node);

	return pdev;
	}
	EXPORT_SYMBOL_GPL(acpi_get_pci_dev);

	/**
	* acpi_pci_osc_control_set - Request control of PCI root _OSC features.
	* @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
	* @mask: Mask of _OSC bits to request control of, place to store control mask.
	* @req: Mask of _OSC bits the control of is essential to the caller.
	*
	* Run _OSC query for @mask and if that is successful, compare the returned
	* mask of control bits with @req. If all of the @req bits are set in the
	* returned mask, run _OSC request for it.
	*
	* The variable at the @mask address may be modified regardless of whether or
	* not the function returns success. On success it will contain the mask of
	* _OSC bits the BIOS has granted control of, but its contents are meaningless
	* on failure.
	**/
	acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
	{
	struct acpi_pci_root *root;
	acpi_status status = AE_OK;
	u32 ctrl, capbuf[3];

	if (!mask)
	return AE_BAD_PARAMETER;

	ctrl = *mask & OSC_PCI_CONTROL_MASKS;
	if ((ctrl & req) != req)
	return AE_TYPE;

	root = acpi_pci_find_root(handle);
	if (!root)
	return AE_NOT_EXIST;

	mutex_lock(&osc_lock);

	*mask = ctrl \| root->osc_control_set;
	/* No need to evaluate _OSC if the control was already granted. */
	if ((root->osc_control_set & ctrl) == ctrl)
	goto out;

	/* Need to check the available controls bits before requesting them. */
	while (*mask) {
	status = acpi_pci_query_osc(root, root->osc_support_set, mask);
	if (ACPI_FAILURE(status))
	goto out;
	if (ctrl == *mask)
	break;
	decode_osc_control(root, "platform does not support",
	ctrl & ~(*mask));
	ctrl = *mask;
	}

	if ((ctrl & req) != req) {
	decode_osc_control(root, "not requesting control; platform does not support",
	req & ~(ctrl));
	status = AE_SUPPORT;
	goto out;
	}

	capbuf[OSC_QUERY_DWORD] = 0;
	capbuf[OSC_SUPPORT_DWORD] = root->osc_support_set;
	capbuf[OSC_CONTROL_DWORD] = ctrl;
	status = acpi_pci_run_osc(handle, capbuf, mask);
	if (ACPI_SUCCESS(status))
	root->osc_control_set = *mask;
	out:
	mutex_unlock(&osc_lock);
	return status;
	}
	EXPORT_SYMBOL(acpi_pci_osc_control_set);

	static void negotiate_os_control(struct acpi_pci_root root, int no_aspm,
	int *clear_aspm)
	{
	u32 support, control, requested;
	acpi_status status;
	struct acpi_device *device = root->device;
	acpi_handle handle = device->handle;

	/*
	* All supported architectures that use ACPI have support for
	* PCI domains, so we indicate this in _OSC support capabilities.
	*/
	support = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
	if (pci_ext_cfg_avail())
	support \|= OSC_PCI_EXT_CONFIG_SUPPORT;
	if (pcie_aspm_support_enabled())
	support \|= OSC_PCI_ASPM_SUPPORT \| OSC_PCI_CLOCK_PM_SUPPORT;
	if (pci_msi_enabled())
	support \|= OSC_PCI_MSI_SUPPORT;

	decode_osc_support(root, "OS supports", support);
	status = acpi_pci_osc_support(root, support);
	if (ACPI_FAILURE(status)) {
	dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
	acpi_format_exception(status));
	*no_aspm = 1;
	return;
	}

	if (pcie_ports_disabled) {
	dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n");
	return;
	}

	if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
	decode_osc_support(root, "not requesting OS control; OS requires",
	ACPI_PCIE_REQ_SUPPORT);
	return;
	}

	control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
	\| OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
	\| OSC_PCI_EXPRESS_PME_CONTROL;

	if (pci_aer_available()) {
	if (aer_acpi_firmware_first())
	dev_info(&device->dev,
	"PCIe AER handled by firmware\n");
	else
	control \|= OSC_PCI_EXPRESS_AER_CONTROL;
	}

	requested = control;
	status = acpi_pci_osc_control_set(handle, &control,
	OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
	if (ACPI_SUCCESS(status)) {
	decode_osc_control(root, "OS now controls", control);
	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
	/*
	* We have ASPM control, but the FADT indicates
	* that it's unsupported. Clear it.
	*/
	*clear_aspm = 1;
	}
	} else {
	decode_osc_control(root, "OS requested", requested);
	decode_osc_control(root, "platform willing to grant", control);
	dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
	acpi_format_exception(status));

	/*
	* We want to disable ASPM here, but aspm_disabled
	* needs to remain in its state from boot so that we
	* properly handle PCIe 1.1 devices. So we set this
	* flag here, to defer the action until after the ACPI
	* root scan.
	*/
	*no_aspm = 1;
	}
	}

	static int acpi_pci_root_add(struct acpi_device *device,
	const struct acpi_device_id *not_used)
	{
	unsigned long long segment, bus;
	acpi_status status;
	int result;
	struct acpi_pci_root *root;
	acpi_handle handle = device->handle;
	int no_aspm = 0, clear_aspm = 0;

	root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
	if (!root)
	return -ENOMEM;

	segment = 0;
	status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL,
	&segment);
	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
	dev_err(&device->dev, "can't evaluate _SEG\n");
	result = -ENODEV;
	goto end;
	}

	/* Check _CRS first, then _BBN. If no _BBN, default to zero. */
	root->secondary.flags = IORESOURCE_BUS;
	status = try_get_root_bridge_busnr(handle, &root->secondary);
	if (ACPI_FAILURE(status)) {
	/*
	* We need both the start and end of the downstream bus range
	* to interpret _CBA (MMCONFIG base address), so it really is
	* supposed to be in _CRS. If we don't find it there, all we
	* can do is assume [_BBN-0xFF] or [0-0xFF].
	*/
	root->secondary.end = 0xFF;
	dev_warn(&device->dev,
	FW_BUG "no secondary bus range in _CRS\n");
	status = acpi_evaluate_integer(handle, METHOD_NAME__BBN,
	NULL, &bus);
	if (ACPI_SUCCESS(status))
	root->secondary.start = bus;
	else if (status == AE_NOT_FOUND)
	root->secondary.start = 0;
	else {
	dev_err(&device->dev, "can't evaluate _BBN\n");
	result = -ENODEV;
	goto end;
	}
	}

	root->device = device;
	root->segment = segment & 0xFFFF;
	strcpy(acpi_device_name(device), ACPI_PCI_ROOT_DEVICE_NAME);
	strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
	device->driver_data = root;

	pr_info(PREFIX "%s [%s] (domain %04x %pR)\n",
	acpi_device_name(device), acpi_device_bid(device),
	root->segment, &root->secondary);

	root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle);

	negotiate_os_control(root, &no_aspm, &clear_aspm);

	/*
	* TBD: Need PCI interface for enumeration/configuration of roots.
	*/

	/*
	* Scan the Root Bridge
	* --------------------
	* Must do this prior to any attempt to bind the root device, as the
	* PCI namespace does not get created until this call is made (and
	* thus the root bridge's pci_dev does not exist).
	*/
	root->bus = pci_acpi_scan_root(root);
	if (!root->bus) {
	dev_err(&device->dev,
	"Bus %04x:%02x not present in PCI namespace\n",
	root->segment, (unsigned int)root->secondary.start);
	device->driver_data = NULL;
	result = -ENODEV;
	goto end;
	}

	if (clear_aspm) {
	dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
	pcie_clear_aspm(root->bus);
	}
	if (no_aspm)
	pcie_no_aspm();

	pci_acpi_add_bus_pm_notifier(device, root->bus);
	if (device->wakeup.flags.run_wake)
	device_set_run_wake(root->bus->bridge, true);

	if (system_state != SYSTEM_BOOTING) {
	pcibios_resource_survey_bus(root->bus);
	pci_assign_unassigned_root_bus_resources(root->bus);
	}

	pci_bus_add_devices(root->bus);
	return 1;

	end:
	kfree(root);
	return result;
	}

	static void acpi_pci_root_remove(struct acpi_device *device)
	{
	struct acpi_pci_root *root = acpi_driver_data(device);

	pci_stop_root_bus(root->bus);

	device_set_run_wake(root->bus->bridge, false);
	pci_acpi_remove_bus_pm_notifier(device);

	pci_remove_root_bus(root->bus);

	kfree(root);
	}

	void __init acpi_pci_root_init(void)
	{
	acpi_hest_init();

	if (!acpi_pci_disabled) {
	pci_acpi_crs_quirks();
	acpi_scan_add_handler(&pci_root_handler);
	}
	}
	/* Support root bridge hotplug */

	static void handle_root_bridge_insertion(acpi_handle handle)
	{
	struct acpi_device *device;

	if (!acpi_bus_get_device(handle, &device)) {
	dev_printk(KERN_DEBUG, &device->dev,
	"acpi device already exists; ignoring notify\n");
	return;
	}

	if (acpi_bus_scan(handle))
	acpi_handle_err(handle, "cannot add bridge to acpi list\n");
	}

	static void hotplug_event_root(void *data, u32 type)
	{
	acpi_handle handle = data;
	struct acpi_pci_root *root;

	acpi_scan_lock_acquire();

	root = acpi_pci_find_root(handle);

	switch (type) {
	case ACPI_NOTIFY_BUS_CHECK:
	/* bus enumerate */
	acpi_handle_printk(KERN_DEBUG, handle,
	"Bus check notify on %s\n", __func__);
	if (root)
	acpiphp_check_host_bridge(handle);
	else
	handle_root_bridge_insertion(handle);

	break;

	case ACPI_NOTIFY_DEVICE_CHECK:
	/* device check */
	acpi_handle_printk(KERN_DEBUG, handle,
	"Device check notify on %s\n", __func__);
	if (!root)
	handle_root_bridge_insertion(handle);
	break;

	case ACPI_NOTIFY_EJECT_REQUEST:
	/* request device eject */
	acpi_handle_printk(KERN_DEBUG, handle,
	"Device eject notify on %s\n", __func__);
	if (!root)
	break;

	get_device(&root->device->dev);

	acpi_scan_lock_release();

	acpi_bus_device_eject(root->device, ACPI_NOTIFY_EJECT_REQUEST);
	return;
	default:
	acpi_handle_warn(handle,
	"notify_handler: unknown event type 0x%x\n",
	type);
	break;
	}

	acpi_scan_lock_release();
	}

	static void handle_hotplug_event_root(acpi_handle handle, u32 type,
	void *context)
	{
	acpi_hotplug_execute(hotplug_event_root, handle, type);
	}

	static acpi_status __init
	find_root_bridges(acpi_handle handle, u32 lvl, void context, void *rv)
	{
	acpi_status status;
	int count = (int )context;

	if (!acpi_is_root_bridge(handle))
	return AE_OK;

	(*count)++;

	status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
	handle_hotplug_event_root, NULL);
	if (ACPI_FAILURE(status))
	acpi_handle_printk(KERN_DEBUG, handle,
	"notify handler is not installed, exit status: %u\n",
	(unsigned int)status);
	else
	acpi_handle_printk(KERN_DEBUG, handle,
	"notify handler is installed\n");

	return AE_OK;
	}

	void __init acpi_pci_root_hp_init(void)
	{
	int num = 0;

	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);

	printk(KERN_DEBUG "Found %d acpi root devices\n", num);
	}