drivers/acpi/pci_root.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *  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>

 #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_EXT_PCI_CONFIG_SUPPORT \
 				| OSC_ACTIVE_STATE_PWR_SUPPORT \
 				| OSC_CLOCK_PWR_CAPABILITY_SUPPORT \
 				| OSC_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,
 };

 /* Lock to protect both acpi_pci_roots lists */
 static DEFINE_MUTEX(acpi_pci_root_lock);
 static LIST_HEAD(acpi_pci_roots);

 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;

 	if (resource->type != ACPI_RESOURCE_TYPE_ADDRESS16 &&
 	    resource->type != ACPI_RESOURCE_TYPE_ADDRESS32 &&
 	    resource->type != ACPI_RESOURCE_TYPE_ADDRESS64)
 		return AE_OK;

 	acpi_resource_to_address64(resource, &address);
 	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;
 }

 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_TYPE] = OSC_QUERY_ENABLE;
 	capbuf[OSC_SUPPORT_TYPE] = support;
 	if (control) {
 		*control &= OSC_PCI_CONTROL_MASKS;
 		capbuf[OSC_CONTROL_TYPE] = *control | root->osc_control_set;
 	} else {
 		/* Run _OSC query for all possible controls. */
 		capbuf[OSC_CONTROL_TYPE] = OSC_PCI_CONTROL_MASKS;
 	}

 	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;
 	acpi_handle tmp;

 	status = acpi_get_handle(root->device->handle, "_OSC", &tmp);
 	if (ACPI_FAILURE(status))
 		return 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;
 	u32 ctrl, capbuf[3];
 	acpi_handle tmp;

 	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;

 	status = acpi_get_handle(handle, "_OSC", &tmp);
 	if (ACPI_FAILURE(status))
 		return status;

 	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;
 		ctrl = *mask;
 	}

 	if ((ctrl & req) != req) {
 		status = AE_SUPPORT;
 		goto out;
 	}

 	capbuf[OSC_QUERY_TYPE] = 0;
 	capbuf[OSC_SUPPORT_TYPE] = root->osc_support_set;
 	capbuf[OSC_CONTROL_TYPE] = 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 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;
 	u32 flags, base_flags;

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

 	segment = 0;
 	status = acpi_evaluate_integer(device->handle, METHOD_NAME__SEG, NULL,
 				       &segment);
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 		printk(KERN_ERR PREFIX "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(device->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;
 		printk(KERN_WARNING FW_BUG PREFIX
 		       "no secondary bus range in _CRS\n");
 		status = acpi_evaluate_integer(device->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 {
 			printk(KERN_ERR PREFIX "can't evaluate _BBN\n");
 			result = -ENODEV;
 			goto end;
 		}
 	}

 	INIT_LIST_HEAD(&root->node);
 	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;

 	printk(KERN_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(device->handle);

 	/*
 	 * All supported architectures that use ACPI have support for
 	 * PCI domains, so we indicate this in _OSC support capabilities.
 	 */
 	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 	acpi_pci_osc_support(root, flags);

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

 	mutex_lock(&acpi_pci_root_lock);
 	list_add_tail(&root->node, &acpi_pci_roots);
 	mutex_unlock(&acpi_pci_root_lock);

 	/*
 	 * 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) {
 		printk(KERN_ERR PREFIX
 			    "Bus %04x:%02x not present in PCI namespace\n",
 			    root->segment, (unsigned int)root->secondary.start);
 		result = -ENODEV;
 		goto out_del_root;
 	}

 	/* Indicate support for various _OSC capabilities. */
 	if (pci_ext_cfg_avail())
 		flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
 	if (pcie_aspm_support_enabled()) {
 		flags |= OSC_ACTIVE_STATE_PWR_SUPPORT |
 		OSC_CLOCK_PWR_CAPABILITY_SUPPORT;
 	}
 	if (pci_msi_enabled())
 		flags |= OSC_MSI_SUPPORT;
 	if (flags != base_flags) {
 		status = acpi_pci_osc_support(root, flags);
 		if (ACPI_FAILURE(status)) {
 			dev_info(&device->dev, "ACPI _OSC support "
 				"notification failed, disabling PCIe ASPM\n");
 			pcie_no_aspm();
 			flags = base_flags;
 		}
 	}

 	if (!pcie_ports_disabled
 	    && (flags & ACPI_PCIE_REQ_SUPPORT) == ACPI_PCIE_REQ_SUPPORT) {
 		flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL
 			| OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
 			| OSC_PCI_EXPRESS_PME_CONTROL;

 		if (pci_aer_available()) {
 			if (aer_acpi_firmware_first())
 				dev_dbg(&device->dev,
 					"PCIe errors handled by BIOS.\n");
 			else
 				flags |= OSC_PCI_EXPRESS_AER_CONTROL;
 		}

 		dev_info(&device->dev,
 			"Requesting ACPI _OSC control (0x%02x)\n", flags);

 		status = acpi_pci_osc_control_set(device->handle, &flags,
 				       OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
 		if (ACPI_SUCCESS(status)) {
 			dev_info(&device->dev,
 				"ACPI _OSC control (0x%02x) granted\n", flags);
 			if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
 				/*
 				 * We have ASPM control, but the FADT indicates
 				 * that it's unsupported. Clear it.
 				 */
 				pcie_clear_aspm(root->bus);
 			}
 		} else {
 			dev_info(&device->dev,
 				"ACPI _OSC request failed (%s), "
 				"returned control mask: 0x%02x\n",
 				acpi_format_exception(status), flags);
 			pr_info("ACPI _OSC control for PCIe not granted, "
 				"disabling ASPM\n");
 			pcie_no_aspm();
 		}
 	} else {
 		dev_info(&device->dev,
 			 "Unable to request _OSC control "
 			 "(_OSC support mask: 0x%02x)\n", flags);
 	}

 	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_bus_resources(root->bus);
 	}

 	/* need to after hot-added ioapic is registered */
 	if (system_state != SYSTEM_BOOTING)
 		pci_enable_bridges(root->bus);

 	pci_bus_add_devices(root->bus);
 	return 1;

 out_del_root:
 	mutex_lock(&acpi_pci_root_lock);
 	list_del(&root->node);
 	mutex_unlock(&acpi_pci_root_lock);

 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);

 	mutex_lock(&acpi_pci_root_lock);
 	list_del(&root->node);
 	mutex_unlock(&acpi_pci_root_lock);
 	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)) {
 		printk(KERN_DEBUG "acpi device exists...\n");
 		return;
 	}

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

 static void handle_root_bridge_removal(struct acpi_device *device)
 {
 	acpi_status status;
 	struct acpi_eject_event *ej_event;

 	ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
 	if (!ej_event) {
 		/* Inform firmware the hot-remove operation has error */
 		(void) acpi_evaluate_hotplug_ost(device->handle,
 					ACPI_NOTIFY_EJECT_REQUEST,
 					ACPI_OST_SC_NON_SPECIFIC_FAILURE,
 					NULL);
 		return;
 	}

 	ej_event->device = device;
 	ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;

 	status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device, ej_event);
 	if (ACPI_FAILURE(status))
 		kfree(ej_event);
 }

 static void _handle_hotplug_event_root(struct work_struct *work)
 {
 	struct acpi_pci_root *root;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER };
 	struct acpi_hp_work *hp_work;
 	acpi_handle handle;
 	u32 type;

 	hp_work = container_of(work, struct acpi_hp_work, work);
 	handle = hp_work->handle;
 	type = hp_work->type;

 	acpi_scan_lock_acquire();

 	root = acpi_pci_find_root(handle);
 	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);

 	switch (type) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		/* bus enumerate */
 		printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
 				 (char *)buffer.pointer);
 		if (!root)
 			handle_root_bridge_insertion(handle);

 		break;

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

 	case ACPI_NOTIFY_EJECT_REQUEST:
 		/* request device eject */
 		printk(KERN_DEBUG "%s: Device eject notify on %s\n", __func__,
 				 (char *)buffer.pointer);
 		if (root)
 			handle_root_bridge_removal(root->device);
 		break;
 	default:
 		printk(KERN_WARNING "notify_handler: unknown event type 0x%x for %s\n",
 				 type, (char *)buffer.pointer);
 		break;
 	}

 	acpi_scan_lock_release();
 	kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
 	kfree(buffer.pointer);
 }

 static void handle_hotplug_event_root(acpi_handle handle, u32 type,
 					void *context)
 {
 	alloc_acpi_hp_work(handle, type, context,
 				_handle_hotplug_event_root);
 }

 static acpi_status __init
 find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
 {
 	acpi_status status;
 	char objname[64];
 	struct acpi_buffer buffer = { .length = sizeof(objname),
 				      .pointer = objname };
 	int *count = (int *)context;

 	if (!acpi_is_root_bridge(handle))
 		return AE_OK;

 	(*count)++;

 	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);

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

 	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>

	#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_EXT_PCI_CONFIG_SUPPORT \
	\| OSC_ACTIVE_STATE_PWR_SUPPORT \
	\| OSC_CLOCK_PWR_CAPABILITY_SUPPORT \
	\| OSC_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,
	};

	/* Lock to protect both acpi_pci_roots lists */
	static DEFINE_MUTEX(acpi_pci_root_lock);
	static LIST_HEAD(acpi_pci_roots);

	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;

	if (resource->type != ACPI_RESOURCE_TYPE_ADDRESS16 &&
	resource->type != ACPI_RESOURCE_TYPE_ADDRESS32 &&
	resource->type != ACPI_RESOURCE_TYPE_ADDRESS64)
	return AE_OK;

	acpi_resource_to_address64(resource, &address);
	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;
	}

	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_TYPE] = OSC_QUERY_ENABLE;
	capbuf[OSC_SUPPORT_TYPE] = support;
	if (control) {
	*control &= OSC_PCI_CONTROL_MASKS;
	capbuf[OSC_CONTROL_TYPE] = *control \| root->osc_control_set;
	} else {
	/* Run _OSC query for all possible controls. */
	capbuf[OSC_CONTROL_TYPE] = OSC_PCI_CONTROL_MASKS;
	}

	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;
	acpi_handle tmp;

	status = acpi_get_handle(root->device->handle, "_OSC", &tmp);
	if (ACPI_FAILURE(status))
	return 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;
	u32 ctrl, capbuf[3];
	acpi_handle tmp;

	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;

	status = acpi_get_handle(handle, "_OSC", &tmp);
	if (ACPI_FAILURE(status))
	return status;

	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;
	ctrl = *mask;
	}

	if ((ctrl & req) != req) {
	status = AE_SUPPORT;
	goto out;
	}

	capbuf[OSC_QUERY_TYPE] = 0;
	capbuf[OSC_SUPPORT_TYPE] = root->osc_support_set;
	capbuf[OSC_CONTROL_TYPE] = 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 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;
	u32 flags, base_flags;

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

	segment = 0;
	status = acpi_evaluate_integer(device->handle, METHOD_NAME__SEG, NULL,
	&segment);
	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
	printk(KERN_ERR PREFIX "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(device->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;
	printk(KERN_WARNING FW_BUG PREFIX
	"no secondary bus range in _CRS\n");
	status = acpi_evaluate_integer(device->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 {
	printk(KERN_ERR PREFIX "can't evaluate _BBN\n");
	result = -ENODEV;
	goto end;
	}
	}

	INIT_LIST_HEAD(&root->node);
	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;

	printk(KERN_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(device->handle);

	/*
	* All supported architectures that use ACPI have support for
	* PCI domains, so we indicate this in _OSC support capabilities.
	*/
	flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
	acpi_pci_osc_support(root, flags);

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

	mutex_lock(&acpi_pci_root_lock);
	list_add_tail(&root->node, &acpi_pci_roots);
	mutex_unlock(&acpi_pci_root_lock);

	/*
	* 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) {
	printk(KERN_ERR PREFIX
	"Bus %04x:%02x not present in PCI namespace\n",
	root->segment, (unsigned int)root->secondary.start);
	result = -ENODEV;
	goto out_del_root;
	}

	/* Indicate support for various _OSC capabilities. */
	if (pci_ext_cfg_avail())
	flags \|= OSC_EXT_PCI_CONFIG_SUPPORT;
	if (pcie_aspm_support_enabled()) {
	flags \|= OSC_ACTIVE_STATE_PWR_SUPPORT \|
	OSC_CLOCK_PWR_CAPABILITY_SUPPORT;
	}
	if (pci_msi_enabled())
	flags \|= OSC_MSI_SUPPORT;
	if (flags != base_flags) {
	status = acpi_pci_osc_support(root, flags);
	if (ACPI_FAILURE(status)) {
	dev_info(&device->dev, "ACPI _OSC support "
	"notification failed, disabling PCIe ASPM\n");
	pcie_no_aspm();
	flags = base_flags;
	}
	}

	if (!pcie_ports_disabled
	&& (flags & ACPI_PCIE_REQ_SUPPORT) == ACPI_PCIE_REQ_SUPPORT) {
	flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL
	\| OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
	\| OSC_PCI_EXPRESS_PME_CONTROL;

	if (pci_aer_available()) {
	if (aer_acpi_firmware_first())
	dev_dbg(&device->dev,
	"PCIe errors handled by BIOS.\n");
	else
	flags \|= OSC_PCI_EXPRESS_AER_CONTROL;
	}

	dev_info(&device->dev,
	"Requesting ACPI _OSC control (0x%02x)\n", flags);

	status = acpi_pci_osc_control_set(device->handle, &flags,
	OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
	if (ACPI_SUCCESS(status)) {
	dev_info(&device->dev,
	"ACPI _OSC control (0x%02x) granted\n", flags);
	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
	/*
	* We have ASPM control, but the FADT indicates
	* that it's unsupported. Clear it.
	*/
	pcie_clear_aspm(root->bus);
	}
	} else {
	dev_info(&device->dev,
	"ACPI _OSC request failed (%s), "
	"returned control mask: 0x%02x\n",
	acpi_format_exception(status), flags);
	pr_info("ACPI _OSC control for PCIe not granted, "
	"disabling ASPM\n");
	pcie_no_aspm();
	}
	} else {
	dev_info(&device->dev,
	"Unable to request _OSC control "
	"(_OSC support mask: 0x%02x)\n", flags);
	}

	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_bus_resources(root->bus);
	}

	/* need to after hot-added ioapic is registered */
	if (system_state != SYSTEM_BOOTING)
	pci_enable_bridges(root->bus);

	pci_bus_add_devices(root->bus);
	return 1;

	out_del_root:
	mutex_lock(&acpi_pci_root_lock);
	list_del(&root->node);
	mutex_unlock(&acpi_pci_root_lock);

	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);

	mutex_lock(&acpi_pci_root_lock);
	list_del(&root->node);
	mutex_unlock(&acpi_pci_root_lock);
	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)) {
	printk(KERN_DEBUG "acpi device exists...\n");
	return;
	}

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

	static void handle_root_bridge_removal(struct acpi_device *device)
	{
	acpi_status status;
	struct acpi_eject_event *ej_event;

	ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
	if (!ej_event) {
	/* Inform firmware the hot-remove operation has error */
	(void) acpi_evaluate_hotplug_ost(device->handle,
	ACPI_NOTIFY_EJECT_REQUEST,
	ACPI_OST_SC_NON_SPECIFIC_FAILURE,
	NULL);
	return;
	}

	ej_event->device = device;
	ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;

	status = acpi_os_hotplug_execute(acpi_bus_hot_remove_device, ej_event);
	if (ACPI_FAILURE(status))
	kfree(ej_event);
	}

	static void _handle_hotplug_event_root(struct work_struct *work)
	{
	struct acpi_pci_root *root;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER };
	struct acpi_hp_work *hp_work;
	acpi_handle handle;
	u32 type;

	hp_work = container_of(work, struct acpi_hp_work, work);
	handle = hp_work->handle;
	type = hp_work->type;

	acpi_scan_lock_acquire();

	root = acpi_pci_find_root(handle);
	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);

	switch (type) {
	case ACPI_NOTIFY_BUS_CHECK:
	/* bus enumerate */
	printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
	(char *)buffer.pointer);
	if (!root)
	handle_root_bridge_insertion(handle);

	break;

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

	case ACPI_NOTIFY_EJECT_REQUEST:
	/* request device eject */
	printk(KERN_DEBUG "%s: Device eject notify on %s\n", __func__,
	(char *)buffer.pointer);
	if (root)
	handle_root_bridge_removal(root->device);
	break;
	default:
	printk(KERN_WARNING "notify_handler: unknown event type 0x%x for %s\n",
	type, (char *)buffer.pointer);
	break;
	}

	acpi_scan_lock_release();
	kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
	kfree(buffer.pointer);
	}

	static void handle_hotplug_event_root(acpi_handle handle, u32 type,
	void *context)
	{
	alloc_acpi_hp_work(handle, type, context,
	_handle_hotplug_event_root);
	}

	static acpi_status __init
	find_root_bridges(acpi_handle handle, u32 lvl, void context, void *rv)
	{
	acpi_status status;
	char objname[64];
	struct acpi_buffer buffer = { .length = sizeof(objname),
	.pointer = objname };
	int count = (int )context;

	if (!acpi_is_root_bridge(handle))
	return AE_OK;

	(*count)++;

	acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);

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

	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);
	}