drivers/acpi/acpi_memhotplug.c - linux - Git at Google

 /*
  * Copyright (C) 2004 Intel Corporation <naveen.b.s@intel.com>
  *
  * All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or (at
  * your option) any later version.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  * NON INFRINGEMENT.  See the GNU General Public License for more
  * details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  *
  *
  * ACPI based HotPlug driver that supports Memory Hotplug
  * This driver fields notifications from firmware for memory add
  * and remove operations and alerts the VM of the affected memory
  * ranges.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/memory_hotplug.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <acpi/acpi_drivers.h>

 #define ACPI_MEMORY_DEVICE_CLASS		"memory"
 #define ACPI_MEMORY_DEVICE_HID			"PNP0C80"
 #define ACPI_MEMORY_DEVICE_NAME			"Hotplug Mem Device"

 #define _COMPONENT		ACPI_MEMORY_DEVICE_COMPONENT

 #undef PREFIX
 #define 	PREFIX		"ACPI:memory_hp:"

 ACPI_MODULE_NAME("acpi_memhotplug");
 MODULE_AUTHOR("Naveen B S <naveen.b.s@intel.com>");
 MODULE_DESCRIPTION("Hotplug Mem Driver");
 MODULE_LICENSE("GPL");

 /* Memory Device States */
 #define MEMORY_INVALID_STATE	0
 #define MEMORY_POWER_ON_STATE	1
 #define MEMORY_POWER_OFF_STATE	2

 static int acpi_memory_device_add(struct acpi_device *device);
 static int acpi_memory_device_remove(struct acpi_device *device);

 static const struct acpi_device_id memory_device_ids[] = {
 	{ACPI_MEMORY_DEVICE_HID, 0},
 	{"", 0},
 };
 MODULE_DEVICE_TABLE(acpi, memory_device_ids);

 static struct acpi_driver acpi_memory_device_driver = {
 	.name = "acpi_memhotplug",
 	.class = ACPI_MEMORY_DEVICE_CLASS,
 	.ids = memory_device_ids,
 	.ops = {
 		.add = acpi_memory_device_add,
 		.remove = acpi_memory_device_remove,
 		},
 };

 struct acpi_memory_info {
 	struct list_head list;
 	u64 start_addr;		/* Memory Range start physical addr */
 	u64 length;		/* Memory Range length */
 	unsigned short caching;	/* memory cache attribute */
 	unsigned short write_protect;	/* memory read/write attribute */
 	unsigned int enabled:1;
 	unsigned int failed:1;
 };

 struct acpi_memory_device {
 	struct acpi_device * device;
 	unsigned int state;	/* State of the memory device */
 	struct list_head res_list;
 };

 static acpi_status
 acpi_memory_get_resource(struct acpi_resource *resource, void *context)
 {
 	struct acpi_memory_device *mem_device = context;
 	struct acpi_resource_address64 address64;
 	struct acpi_memory_info *info, *new;
 	acpi_status status;

 	status = acpi_resource_to_address64(resource, &address64);
 	if (ACPI_FAILURE(status) ||
 	    (address64.resource_type != ACPI_MEMORY_RANGE))
 		return AE_OK;

 	list_for_each_entry(info, &mem_device->res_list, list) {
 		/* Can we combine the resource range information? */
 		if ((info->caching == address64.info.mem.caching) &&
 		    (info->write_protect == address64.info.mem.write_protect) &&
 		    (info->start_addr + info->length == address64.minimum)) {
 			info->length += address64.address_length;
 			return AE_OK;
 		}
 	}

 	new = kzalloc(sizeof(struct acpi_memory_info), GFP_KERNEL);
 	if (!new)
 		return AE_ERROR;

 	INIT_LIST_HEAD(&new->list);
 	new->caching = address64.info.mem.caching;
 	new->write_protect = address64.info.mem.write_protect;
 	new->start_addr = address64.minimum;
 	new->length = address64.address_length;
 	list_add_tail(&new->list, &mem_device->res_list);

 	return AE_OK;
 }

 static void
 acpi_memory_free_device_resources(struct acpi_memory_device *mem_device)
 {
 	struct acpi_memory_info *info, *n;

 	list_for_each_entry_safe(info, n, &mem_device->res_list, list)
 		kfree(info);
 	INIT_LIST_HEAD(&mem_device->res_list);
 }

 static int
 acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
 {
 	acpi_status status;

 	if (!list_empty(&mem_device->res_list))
 		return 0;

 	status = acpi_walk_resources(mem_device->device->handle, METHOD_NAME__CRS,
 				     acpi_memory_get_resource, mem_device);
 	if (ACPI_FAILURE(status)) {
 		acpi_memory_free_device_resources(mem_device);
 		return -EINVAL;
 	}

 	return 0;
 }

 static int
 acpi_memory_get_device(acpi_handle handle,
 		       struct acpi_memory_device **mem_device)
 {
 	struct acpi_device *device = NULL;
 	int result;

 	if (!acpi_bus_get_device(handle, &device) && device)
 		goto end;

 	/*
 	 * Now add the notified device.  This creates the acpi_device
 	 * and invokes .add function
 	 */
 	result = acpi_bus_scan(handle);
 	if (result) {
 		acpi_handle_warn(handle, "Cannot add acpi bus\n");
 		return -EINVAL;
 	}
 	result = acpi_bus_get_device(handle, &device);
 	if (result) {
 		acpi_handle_warn(handle, "Missing device object\n");
 		return -EINVAL;
 	}

       end:
 	*mem_device = acpi_driver_data(device);
 	if (!(*mem_device)) {
 		dev_err(&device->dev, "driver data not found\n");
 		return -ENODEV;
 	}

 	return 0;
 }

 static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
 {
 	unsigned long long current_status;

 	/* Get device present/absent information from the _STA */
 	if (ACPI_FAILURE(acpi_evaluate_integer(mem_device->device->handle, "_STA",
 					       NULL, &current_status)))
 		return -ENODEV;
 	/*
 	 * Check for device status. Device should be
 	 * present/enabled/functioning.
 	 */
 	if (!((current_status & ACPI_STA_DEVICE_PRESENT)
 	      && (current_status & ACPI_STA_DEVICE_ENABLED)
 	      && (current_status & ACPI_STA_DEVICE_FUNCTIONING)))
 		return -ENODEV;

 	return 0;
 }

 static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 {
 	int result, num_enabled = 0;
 	struct acpi_memory_info *info;
 	int node;

 	node = acpi_get_node(mem_device->device->handle);
 	/*
 	 * Tell the VM there is more memory here...
 	 * Note: Assume that this function returns zero on success
 	 * We don't have memory-hot-add rollback function,now.
 	 * (i.e. memory-hot-remove function)
 	 */
 	list_for_each_entry(info, &mem_device->res_list, list) {
 		if (info->enabled) { /* just sanity check...*/
 			num_enabled++;
 			continue;
 		}
 		/*
 		 * If the memory block size is zero, please ignore it.
 		 * Don't try to do the following memory hotplug flowchart.
 		 */
 		if (!info->length)
 			continue;
 		if (node < 0)
 			node = memory_add_physaddr_to_nid(info->start_addr);

 		result = add_memory(node, info->start_addr, info->length);

 		/*
 		 * If the memory block has been used by the kernel, add_memory()
 		 * returns -EEXIST. If add_memory() returns the other error, it
 		 * means that this memory block is not used by the kernel.
 		 */
 		if (result && result != -EEXIST) {
 			info->failed = 1;
 			continue;
 		}

 		if (!result)
 			info->enabled = 1;
 		/*
 		 * Add num_enable even if add_memory() returns -EEXIST, so the
 		 * device is bound to this driver.
 		 */
 		num_enabled++;
 	}
 	if (!num_enabled) {
 		dev_err(&mem_device->device->dev, "add_memory failed\n");
 		mem_device->state = MEMORY_INVALID_STATE;
 		return -EINVAL;
 	}
 	/*
 	 * Sometimes the memory device will contain several memory blocks.
 	 * When one memory block is hot-added to the system memory, it will
 	 * be regarded as a success.
 	 * Otherwise if the last memory block can't be hot-added to the system
 	 * memory, it will be failure and the memory device can't be bound with
 	 * driver.
 	 */
 	return 0;
 }

 static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
 	int result = 0;
 	struct acpi_memory_info *info, *n;

 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (info->failed)
 			/* The kernel does not use this memory block */
 			continue;

 		if (!info->enabled)
 			/*
 			 * The kernel uses this memory block, but it may be not
 			 * managed by us.
 			 */
 			return -EBUSY;

 		result = remove_memory(info->start_addr, info->length);
 		if (result)
 			return result;

 		list_del(&info->list);
 		kfree(info);
 	}

 	return result;
 }

 static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
 {
 	struct acpi_memory_device *mem_device;
 	struct acpi_device *device;
 	struct acpi_eject_event *ej_event = NULL;
 	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */

 	switch (event) {
 	case ACPI_NOTIFY_BUS_CHECK:
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 				  "\nReceived BUS CHECK notification for device\n"));
 		/* Fall Through */
 	case ACPI_NOTIFY_DEVICE_CHECK:
 		if (event == ACPI_NOTIFY_DEVICE_CHECK)
 			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 					  "\nReceived DEVICE CHECK notification for device\n"));
 		if (acpi_memory_get_device(handle, &mem_device)) {
 			acpi_handle_err(handle, "Cannot find driver data\n");
 			break;
 		}

 		ost_code = ACPI_OST_SC_SUCCESS;
 		break;

 	case ACPI_NOTIFY_EJECT_REQUEST:
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 				  "\nReceived EJECT REQUEST notification for device\n"));

 		if (acpi_bus_get_device(handle, &device)) {
 			acpi_handle_err(handle, "Device doesn't exist\n");
 			break;
 		}
 		mem_device = acpi_driver_data(device);
 		if (!mem_device) {
 			acpi_handle_err(handle, "Driver Data is NULL\n");
 			break;
 		}

 		ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
 		if (!ej_event) {
 			pr_err(PREFIX "No memory, dropping EJECT\n");
 			break;
 		}

 		ej_event->device = device;
 		ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
 		acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
 					(void *)ej_event);

 		/* eject is performed asynchronously */
 		return;
 	default:
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 				  "Unsupported event [0x%x]\n", event));

 		/* non-hotplug event; possibly handled by other handler */
 		return;
 	}

 	/* Inform firmware that the hotplug operation has completed */
 	(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
 	return;
 }

 static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
 {
 	if (!mem_device)
 		return;

 	acpi_memory_free_device_resources(mem_device);
 	kfree(mem_device);
 }

 static int acpi_memory_device_add(struct acpi_device *device)
 {
 	int result;
 	struct acpi_memory_device *mem_device = NULL;


 	if (!device)
 		return -EINVAL;

 	mem_device = kzalloc(sizeof(struct acpi_memory_device), GFP_KERNEL);
 	if (!mem_device)
 		return -ENOMEM;

 	INIT_LIST_HEAD(&mem_device->res_list);
 	mem_device->device = device;
 	sprintf(acpi_device_name(device), "%s", ACPI_MEMORY_DEVICE_NAME);
 	sprintf(acpi_device_class(device), "%s", ACPI_MEMORY_DEVICE_CLASS);
 	device->driver_data = mem_device;

 	/* Get the range from the _CRS */
 	result = acpi_memory_get_device_resources(mem_device);
 	if (result) {
 		kfree(mem_device);
 		return result;
 	}

 	/* Set the device state */
 	mem_device->state = MEMORY_POWER_ON_STATE;

 	pr_debug("%s\n", acpi_device_name(device));

 	if (!acpi_memory_check_device(mem_device)) {
 		/* call add_memory func */
 		result = acpi_memory_enable_device(mem_device);
 		if (result) {
 			dev_err(&device->dev,
 				"Error in acpi_memory_enable_device\n");
 			acpi_memory_device_free(mem_device);
 		}
 	}
 	return result;
 }

 static int acpi_memory_device_remove(struct acpi_device *device)
 {
 	struct acpi_memory_device *mem_device = NULL;
 	int result;

 	if (!device || !acpi_driver_data(device))
 		return -EINVAL;

 	mem_device = acpi_driver_data(device);

 	result = acpi_memory_remove_memory(mem_device);
 	if (result)
 		return result;

 	acpi_memory_device_free(mem_device);

 	return 0;
 }

 /*
  * Helper function to check for memory device
  */
 static acpi_status is_memory_device(acpi_handle handle)
 {
 	char *hardware_id;
 	acpi_status status;
 	struct acpi_device_info *info;

 	status = acpi_get_object_info(handle, &info);
 	if (ACPI_FAILURE(status))
 		return status;

 	if (!(info->valid & ACPI_VALID_HID)) {
 		kfree(info);
 		return AE_ERROR;
 	}

 	hardware_id = info->hardware_id.string;
 	if ((hardware_id == NULL) ||
 	    (strcmp(hardware_id, ACPI_MEMORY_DEVICE_HID)))
 		status = AE_ERROR;

 	kfree(info);
 	return status;
 }

 static acpi_status
 acpi_memory_register_notify_handler(acpi_handle handle,
 				    u32 level, void *ctxt, void **retv)
 {
 	acpi_status status;


 	status = is_memory_device(handle);
 	if (ACPI_FAILURE(status))
 		return AE_OK;	/* continue */

 	status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
 					     acpi_memory_device_notify, NULL);
 	/* continue */
 	return AE_OK;
 }

 static acpi_status
 acpi_memory_deregister_notify_handler(acpi_handle handle,
 				      u32 level, void *ctxt, void **retv)
 {
 	acpi_status status;


 	status = is_memory_device(handle);
 	if (ACPI_FAILURE(status))
 		return AE_OK;	/* continue */

 	status = acpi_remove_notify_handler(handle,
 					    ACPI_SYSTEM_NOTIFY,
 					    acpi_memory_device_notify);

 	return AE_OK;	/* continue */
 }

 static int __init acpi_memory_device_init(void)
 {
 	int result;
 	acpi_status status;


 	result = acpi_bus_register_driver(&acpi_memory_device_driver);

 	if (result < 0)
 		return -ENODEV;

 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX,
 				     acpi_memory_register_notify_handler, NULL,
 				     NULL, NULL);

 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "walk_namespace failed"));
 		acpi_bus_unregister_driver(&acpi_memory_device_driver);
 		return -ENODEV;
 	}

 	return 0;
 }

 static void __exit acpi_memory_device_exit(void)
 {
 	acpi_status status;


 	/*
 	 * Adding this to un-install notification handlers for all the device
 	 * handles.
 	 */
 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				     ACPI_UINT32_MAX,
 				     acpi_memory_deregister_notify_handler, NULL,
 				     NULL, NULL);

 	if (ACPI_FAILURE(status))
 		ACPI_EXCEPTION((AE_INFO, status, "walk_namespace failed"));

 	acpi_bus_unregister_driver(&acpi_memory_device_driver);

 	return;
 }

 module_init(acpi_memory_device_init);
 module_exit(acpi_memory_device_exit);
	/*
	* Copyright (C) 2004 Intel Corporation <naveen.b.s@intel.com>
	*
	* All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or (at
	* your option) any later version.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	* NON INFRINGEMENT. See the GNU General Public License for more
	* details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*
	*
	* ACPI based HotPlug driver that supports Memory Hotplug
	* This driver fields notifications from firmware for memory add
	* and remove operations and alerts the VM of the affected memory
	* ranges.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/types.h>
	#include <linux/memory_hotplug.h>
	#include <linux/slab.h>
	#include <linux/acpi.h>
	#include <acpi/acpi_drivers.h>

	#define ACPI_MEMORY_DEVICE_CLASS "memory"
	#define ACPI_MEMORY_DEVICE_HID "PNP0C80"
	#define ACPI_MEMORY_DEVICE_NAME "Hotplug Mem Device"

	#define _COMPONENT ACPI_MEMORY_DEVICE_COMPONENT

	#undef PREFIX
	#define PREFIX "ACPI:memory_hp:"

	ACPI_MODULE_NAME("acpi_memhotplug");
	MODULE_AUTHOR("Naveen B S <naveen.b.s@intel.com>");
	MODULE_DESCRIPTION("Hotplug Mem Driver");
	MODULE_LICENSE("GPL");

	/* Memory Device States */
	#define MEMORY_INVALID_STATE 0
	#define MEMORY_POWER_ON_STATE 1
	#define MEMORY_POWER_OFF_STATE 2

	static int acpi_memory_device_add(struct acpi_device *device);
	static int acpi_memory_device_remove(struct acpi_device *device);

	static const struct acpi_device_id memory_device_ids[] = {
	{ACPI_MEMORY_DEVICE_HID, 0},
	{"", 0},
	};
	MODULE_DEVICE_TABLE(acpi, memory_device_ids);

	static struct acpi_driver acpi_memory_device_driver = {
	.name = "acpi_memhotplug",
	.class = ACPI_MEMORY_DEVICE_CLASS,
	.ids = memory_device_ids,
	.ops = {
	.add = acpi_memory_device_add,
	.remove = acpi_memory_device_remove,
	},
	};

	struct acpi_memory_info {
	struct list_head list;
	u64 start_addr; /* Memory Range start physical addr */
	u64 length; /* Memory Range length */
	unsigned short caching; /* memory cache attribute */
	unsigned short write_protect; /* memory read/write attribute */
	unsigned int enabled:1;
	unsigned int failed:1;
	};

	struct acpi_memory_device {
	struct acpi_device * device;
	unsigned int state; /* State of the memory device */
	struct list_head res_list;
	};

	static acpi_status
	acpi_memory_get_resource(struct acpi_resource resource, void context)
	{
	struct acpi_memory_device *mem_device = context;
	struct acpi_resource_address64 address64;
	struct acpi_memory_info info, new;
	acpi_status status;

	status = acpi_resource_to_address64(resource, &address64);
	if (ACPI_FAILURE(status) \|\|
	(address64.resource_type != ACPI_MEMORY_RANGE))
	return AE_OK;

	list_for_each_entry(info, &mem_device->res_list, list) {
	/* Can we combine the resource range information? */
	if ((info->caching == address64.info.mem.caching) &&
	(info->write_protect == address64.info.mem.write_protect) &&
	(info->start_addr + info->length == address64.minimum)) {
	info->length += address64.address_length;
	return AE_OK;
	}
	}

	new = kzalloc(sizeof(struct acpi_memory_info), GFP_KERNEL);
	if (!new)
	return AE_ERROR;

	INIT_LIST_HEAD(&new->list);
	new->caching = address64.info.mem.caching;
	new->write_protect = address64.info.mem.write_protect;
	new->start_addr = address64.minimum;
	new->length = address64.address_length;
	list_add_tail(&new->list, &mem_device->res_list);

	return AE_OK;
	}

	static void
	acpi_memory_free_device_resources(struct acpi_memory_device *mem_device)
	{
	struct acpi_memory_info info, n;

	list_for_each_entry_safe(info, n, &mem_device->res_list, list)
	kfree(info);
	INIT_LIST_HEAD(&mem_device->res_list);
	}

	static int
	acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
	{
	acpi_status status;

	if (!list_empty(&mem_device->res_list))
	return 0;

	status = acpi_walk_resources(mem_device->device->handle, METHOD_NAME__CRS,
	acpi_memory_get_resource, mem_device);
	if (ACPI_FAILURE(status)) {
	acpi_memory_free_device_resources(mem_device);
	return -EINVAL;
	}

	return 0;
	}

	static int
	acpi_memory_get_device(acpi_handle handle,
	struct acpi_memory_device **mem_device)
	{
	struct acpi_device *device = NULL;
	int result;

	if (!acpi_bus_get_device(handle, &device) && device)
	goto end;

	/*
	* Now add the notified device. This creates the acpi_device
	* and invokes .add function
	*/
	result = acpi_bus_scan(handle);
	if (result) {
	acpi_handle_warn(handle, "Cannot add acpi bus\n");
	return -EINVAL;
	}
	result = acpi_bus_get_device(handle, &device);
	if (result) {
	acpi_handle_warn(handle, "Missing device object\n");
	return -EINVAL;
	}

	end:
	*mem_device = acpi_driver_data(device);
	if (!(*mem_device)) {
	dev_err(&device->dev, "driver data not found\n");
	return -ENODEV;
	}

	return 0;
	}

	static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
	{
	unsigned long long current_status;

	/* Get device present/absent information from the _STA */
	if (ACPI_FAILURE(acpi_evaluate_integer(mem_device->device->handle, "_STA",
	NULL, &current_status)))
	return -ENODEV;
	/*
	* Check for device status. Device should be
	* present/enabled/functioning.
	*/
	if (!((current_status & ACPI_STA_DEVICE_PRESENT)
	&& (current_status & ACPI_STA_DEVICE_ENABLED)
	&& (current_status & ACPI_STA_DEVICE_FUNCTIONING)))
	return -ENODEV;

	return 0;
	}

	static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
	{
	int result, num_enabled = 0;
	struct acpi_memory_info *info;
	int node;

	node = acpi_get_node(mem_device->device->handle);
	/*
	* Tell the VM there is more memory here...
	* Note: Assume that this function returns zero on success
	* We don't have memory-hot-add rollback function,now.
	* (i.e. memory-hot-remove function)
	*/
	list_for_each_entry(info, &mem_device->res_list, list) {
	if (info->enabled) { /* just sanity check...*/
	num_enabled++;
	continue;
	}
	/*
	* If the memory block size is zero, please ignore it.
	* Don't try to do the following memory hotplug flowchart.
	*/
	if (!info->length)
	continue;
	if (node < 0)
	node = memory_add_physaddr_to_nid(info->start_addr);

	result = add_memory(node, info->start_addr, info->length);

	/*
	* If the memory block has been used by the kernel, add_memory()
	* returns -EEXIST. If add_memory() returns the other error, it
	* means that this memory block is not used by the kernel.
	*/
	if (result && result != -EEXIST) {
	info->failed = 1;
	continue;
	}

	if (!result)
	info->enabled = 1;
	/*
	* Add num_enable even if add_memory() returns -EEXIST, so the
	* device is bound to this driver.
	*/
	num_enabled++;
	}
	if (!num_enabled) {
	dev_err(&mem_device->device->dev, "add_memory failed\n");
	mem_device->state = MEMORY_INVALID_STATE;
	return -EINVAL;
	}
	/*
	* Sometimes the memory device will contain several memory blocks.
	* When one memory block is hot-added to the system memory, it will
	* be regarded as a success.
	* Otherwise if the last memory block can't be hot-added to the system
	* memory, it will be failure and the memory device can't be bound with
	* driver.
	*/
	return 0;
	}

	static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
	{
	int result = 0;
	struct acpi_memory_info info, n;

	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
	if (info->failed)
	/* The kernel does not use this memory block */
	continue;

	if (!info->enabled)
	/*
	* The kernel uses this memory block, but it may be not
	* managed by us.
	*/
	return -EBUSY;

	result = remove_memory(info->start_addr, info->length);
	if (result)
	return result;

	list_del(&info->list);
	kfree(info);
	}

	return result;
	}

	static void acpi_memory_device_notify(acpi_handle handle, u32 event, void *data)
	{
	struct acpi_memory_device *mem_device;
	struct acpi_device *device;
	struct acpi_eject_event *ej_event = NULL;
	u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE; /* default */

	switch (event) {
	case ACPI_NOTIFY_BUS_CHECK:
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	"\nReceived BUS CHECK notification for device\n"));
	/* Fall Through */
	case ACPI_NOTIFY_DEVICE_CHECK:
	if (event == ACPI_NOTIFY_DEVICE_CHECK)
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	"\nReceived DEVICE CHECK notification for device\n"));
	if (acpi_memory_get_device(handle, &mem_device)) {
	acpi_handle_err(handle, "Cannot find driver data\n");
	break;
	}

	ost_code = ACPI_OST_SC_SUCCESS;
	break;

	case ACPI_NOTIFY_EJECT_REQUEST:
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	"\nReceived EJECT REQUEST notification for device\n"));

	if (acpi_bus_get_device(handle, &device)) {
	acpi_handle_err(handle, "Device doesn't exist\n");
	break;
	}
	mem_device = acpi_driver_data(device);
	if (!mem_device) {
	acpi_handle_err(handle, "Driver Data is NULL\n");
	break;
	}

	ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
	if (!ej_event) {
	pr_err(PREFIX "No memory, dropping EJECT\n");
	break;
	}

	ej_event->device = device;
	ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
	acpi_os_hotplug_execute(acpi_bus_hot_remove_device,
	(void *)ej_event);

	/* eject is performed asynchronously */
	return;
	default:
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	"Unsupported event [0x%x]\n", event));

	/* non-hotplug event; possibly handled by other handler */
	return;
	}

	/* Inform firmware that the hotplug operation has completed */
	(void) acpi_evaluate_hotplug_ost(handle, event, ost_code, NULL);
	return;
	}

	static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
	{
	if (!mem_device)
	return;

	acpi_memory_free_device_resources(mem_device);
	kfree(mem_device);
	}

	static int acpi_memory_device_add(struct acpi_device *device)
	{
	int result;
	struct acpi_memory_device *mem_device = NULL;


	if (!device)
	return -EINVAL;

	mem_device = kzalloc(sizeof(struct acpi_memory_device), GFP_KERNEL);
	if (!mem_device)
	return -ENOMEM;

	INIT_LIST_HEAD(&mem_device->res_list);
	mem_device->device = device;
	sprintf(acpi_device_name(device), "%s", ACPI_MEMORY_DEVICE_NAME);
	sprintf(acpi_device_class(device), "%s", ACPI_MEMORY_DEVICE_CLASS);
	device->driver_data = mem_device;

	/* Get the range from the _CRS */
	result = acpi_memory_get_device_resources(mem_device);
	if (result) {
	kfree(mem_device);
	return result;
	}

	/* Set the device state */
	mem_device->state = MEMORY_POWER_ON_STATE;

	pr_debug("%s\n", acpi_device_name(device));

	if (!acpi_memory_check_device(mem_device)) {
	/* call add_memory func */
	result = acpi_memory_enable_device(mem_device);
	if (result) {
	dev_err(&device->dev,
	"Error in acpi_memory_enable_device\n");
	acpi_memory_device_free(mem_device);
	}
	}
	return result;
	}

	static int acpi_memory_device_remove(struct acpi_device *device)
	{
	struct acpi_memory_device *mem_device = NULL;
	int result;

	if (!device \|\| !acpi_driver_data(device))
	return -EINVAL;

	mem_device = acpi_driver_data(device);

	result = acpi_memory_remove_memory(mem_device);
	if (result)
	return result;

	acpi_memory_device_free(mem_device);

	return 0;
	}

	/*
	* Helper function to check for memory device
	*/
	static acpi_status is_memory_device(acpi_handle handle)
	{
	char *hardware_id;
	acpi_status status;
	struct acpi_device_info *info;

	status = acpi_get_object_info(handle, &info);
	if (ACPI_FAILURE(status))
	return status;

	if (!(info->valid & ACPI_VALID_HID)) {
	kfree(info);
	return AE_ERROR;
	}

	hardware_id = info->hardware_id.string;
	if ((hardware_id == NULL) \|\|
	(strcmp(hardware_id, ACPI_MEMORY_DEVICE_HID)))
	status = AE_ERROR;

	kfree(info);
	return status;
	}

	static acpi_status
	acpi_memory_register_notify_handler(acpi_handle handle,
	u32 level, void ctxt, void *retv)
	{
	acpi_status status;


	status = is_memory_device(handle);
	if (ACPI_FAILURE(status))
	return AE_OK; /* continue */

	status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
	acpi_memory_device_notify, NULL);
	/* continue */
	return AE_OK;
	}

	static acpi_status
	acpi_memory_deregister_notify_handler(acpi_handle handle,
	u32 level, void ctxt, void *retv)
	{
	acpi_status status;


	status = is_memory_device(handle);
	if (ACPI_FAILURE(status))
	return AE_OK; /* continue */

	status = acpi_remove_notify_handler(handle,
	ACPI_SYSTEM_NOTIFY,
	acpi_memory_device_notify);

	return AE_OK; /* continue */
	}

	static int __init acpi_memory_device_init(void)
	{
	int result;
	acpi_status status;


	result = acpi_bus_register_driver(&acpi_memory_device_driver);

	if (result < 0)
	return -ENODEV;

	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX,
	acpi_memory_register_notify_handler, NULL,
	NULL, NULL);

	if (ACPI_FAILURE(status)) {
	ACPI_EXCEPTION((AE_INFO, status, "walk_namespace failed"));
	acpi_bus_unregister_driver(&acpi_memory_device_driver);
	return -ENODEV;
	}

	return 0;
	}

	static void __exit acpi_memory_device_exit(void)
	{
	acpi_status status;


	/*
	* Adding this to un-install notification handlers for all the device
	* handles.
	*/
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX,
	acpi_memory_deregister_notify_handler, NULL,
	NULL, NULL);

	if (ACPI_FAILURE(status))
	ACPI_EXCEPTION((AE_INFO, status, "walk_namespace failed"));

	acpi_bus_unregister_driver(&acpi_memory_device_driver);

	return;
	}

	module_init(acpi_memory_device_init);
	module_exit(acpi_memory_device_exit);