drivers/acpi/acpi_memhotplug.c - kernel/msm - Gitiles

 /*
  * 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 firmare 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 <acpi/acpi_drivers.h>

 #define ACPI_MEMORY_DEVICE_COMPONENT		0x08000000UL
 #define ACPI_MEMORY_DEVICE_CLASS		"memory"
 #define ACPI_MEMORY_DEVICE_HID			"PNP0C80"
 #define ACPI_MEMORY_DEVICE_DRIVER_NAME		"Hotplug Mem Driver"
 #define ACPI_MEMORY_DEVICE_NAME			"Hotplug Mem Device"

 #define _COMPONENT		ACPI_MEMORY_DEVICE_COMPONENT

 ACPI_MODULE_NAME("acpi_memory")
     MODULE_AUTHOR("Naveen B S <naveen.b.s@intel.com>");
 MODULE_DESCRIPTION(ACPI_MEMORY_DEVICE_DRIVER_NAME);
 MODULE_LICENSE("GPL");

 /* ACPI _STA method values */
 #define ACPI_MEMORY_STA_PRESENT		(0x00000001UL)
 #define ACPI_MEMORY_STA_ENABLED		(0x00000002UL)
 #define ACPI_MEMORY_STA_FUNCTIONAL	(0x00000008UL)

 /* 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, int type);
 static int acpi_memory_device_start(struct acpi_device *device);

 static struct acpi_driver acpi_memory_device_driver = {
 	.name = ACPI_MEMORY_DEVICE_DRIVER_NAME,
 	.class = ACPI_MEMORY_DEVICE_CLASS,
 	.ids = ACPI_MEMORY_DEVICE_HID,
 	.ops = {
 		.add = acpi_memory_device_add,
 		.remove = acpi_memory_device_remove,
 		.start = acpi_memory_device_start,
 		},
 };

 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;
 };

 struct acpi_memory_device {
 	acpi_handle handle;
 	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 int
 acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
 {
 	acpi_status status;
 	struct acpi_memory_info *info, *n;


 	status = acpi_walk_resources(mem_device->handle, METHOD_NAME__CRS,
 				     acpi_memory_get_resource, mem_device);
 	if (ACPI_FAILURE(status)) {
 		list_for_each_entry_safe(info, n, &mem_device->res_list, list)
 			kfree(info);
 		return -EINVAL;
 	}

 	return 0;
 }

 static int
 acpi_memory_get_device(acpi_handle handle,
 		       struct acpi_memory_device **mem_device)
 {
 	acpi_status status;
 	acpi_handle phandle;
 	struct acpi_device *device = NULL;
 	struct acpi_device *pdevice = NULL;


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

 	status = acpi_get_parent(handle, &phandle);
 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "Cannot find acpi parent"));
 		return -EINVAL;
 	}

 	/* Get the parent device */
 	status = acpi_bus_get_device(phandle, &pdevice);
 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "Cannot get acpi bus device"));
 		return -EINVAL;
 	}

 	/*
 	 * Now add the notified device.  This creates the acpi_device
 	 * and invokes .add function
 	 */
 	status = acpi_bus_add(&device, pdevice, handle, ACPI_BUS_TYPE_DEVICE);
 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "Cannot add acpi bus"));
 		return -EINVAL;
 	}

       end:
 	*mem_device = acpi_driver_data(device);
 	if (!(*mem_device)) {
 		printk(KERN_ERR "\n driver data not found");
 		return -ENODEV;
 	}

 	return 0;
 }

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


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


 	/* Get the range from the _CRS */
 	result = acpi_memory_get_device_resources(mem_device);
 	if (result) {
 		printk(KERN_ERR PREFIX "get_device_resources failed\n");
 		mem_device->state = MEMORY_INVALID_STATE;
 		return result;
 	}

 	node = acpi_get_node(mem_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) {
 		u64 start_pfn, end_pfn;

 		start_pfn = info->start_addr >> PAGE_SHIFT;
 		end_pfn = (info->start_addr + info->length - 1) >> PAGE_SHIFT;

 		if (pfn_valid(start_pfn) || pfn_valid(end_pfn)) {
 			/* already enabled. try next area */
 			num_enabled++;
 			continue;
 		}

 		result = add_memory(node, info->start_addr, info->length);
 		if (result)
 			continue;
 		info->enabled = 1;
 		num_enabled++;
 	}
 	if (!num_enabled) {
 		printk(KERN_ERR PREFIX "add_memory failed\n");
 		mem_device->state = MEMORY_INVALID_STATE;
 		return -EINVAL;
 	}

 	return result;
 }

 static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
 {
 	acpi_status status;
 	struct acpi_object_list arg_list;
 	union acpi_object arg;
 	unsigned long current_status;


 	/* Issue the _EJ0 command */
 	arg_list.count = 1;
 	arg_list.pointer = &arg;
 	arg.type = ACPI_TYPE_INTEGER;
 	arg.integer.value = 1;
 	status = acpi_evaluate_object(mem_device->handle,
 				      "_EJ0", &arg_list, NULL);
 	/* Return on _EJ0 failure */
 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "_EJ0 failed"));
 		return -ENODEV;
 	}

 	/* Evalute _STA to check if the device is disabled */
 	status = acpi_evaluate_integer(mem_device->handle, "_STA",
 				       NULL, &current_status);
 	if (ACPI_FAILURE(status))
 		return -ENODEV;

 	/* Check for device status.  Device should be disabled */
 	if (current_status & ACPI_MEMORY_STA_ENABLED)
 		return -EINVAL;

 	return 0;
 }

 static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
 {
 	int result;
 	struct acpi_memory_info *info, *n;


 	/*
 	 * Ask the VM to offline this memory range.
 	 * Note: Assume that this function returns zero on success
 	 */
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (info->enabled) {
 			result = remove_memory(info->start_addr, info->length);
 			if (result)
 				return result;
 		}
 		kfree(info);
 	}

 	/* Power-off and eject the device */
 	result = acpi_memory_powerdown_device(mem_device);
 	if (result) {
 		/* Set the status of the device to invalid */
 		mem_device->state = MEMORY_INVALID_STATE;
 		return result;
 	}

 	mem_device->state = MEMORY_POWER_OFF_STATE;
 	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;


 	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)) {
 			printk(KERN_ERR PREFIX "Cannot find driver data\n");
 			return;
 		}

 		if (!acpi_memory_check_device(mem_device)) {
 			if (acpi_memory_enable_device(mem_device))
 				printk(KERN_ERR PREFIX
 					    "Cannot enable memory device\n");
 		}
 		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)) {
 			printk(KERN_ERR PREFIX "Device doesn't exist\n");
 			break;
 		}
 		mem_device = acpi_driver_data(device);
 		if (!mem_device) {
 			printk(KERN_ERR PREFIX "Driver Data is NULL\n");
 			break;
 		}

 		/*
 		 * Currently disabling memory device from kernel mode
 		 * TBD: Can also be disabled from user mode scripts
 		 * TBD: Can also be disabled by Callback registration
 		 *      with generic sysfs driver
 		 */
 		if (acpi_memory_disable_device(mem_device))
 			printk(KERN_ERR PREFIX
 				    "Disable memory device\n");
 		/*
 		 * TBD: Invoke acpi_bus_remove to cleanup data structures
 		 */
 		break;
 	default:
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 				  "Unsupported event [0x%x]\n", event));
 		break;
 	}

 	return;
 }

 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 = kmalloc(sizeof(struct acpi_memory_device), GFP_KERNEL);
 	if (!mem_device)
 		return -ENOMEM;
 	memset(mem_device, 0, sizeof(struct acpi_memory_device));

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

 	printk(KERN_INFO "%s \n", acpi_device_name(device));

 	return result;
 }

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


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

 	mem_device = (struct acpi_memory_device *)acpi_driver_data(device);
 	kfree(mem_device);

 	return 0;
 }

 static int acpi_memory_device_start (struct acpi_device *device)
 {
 	struct acpi_memory_device *mem_device;
 	int result = 0;

 	mem_device = acpi_driver_data(device);

 	if (!acpi_memory_check_device(mem_device)) {
 		/* call add_memory func */
 		result = acpi_memory_enable_device(mem_device);
 		if (result)
 			ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
 				"Error in acpi_memory_enable_device\n"));
 	}
 	return result;
 }

 /*
  * Helper function to check for memory device
  */
 static acpi_status is_memory_device(acpi_handle handle)
 {
 	char *hardware_id;
 	acpi_status status;
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	struct acpi_device_info *info;


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

 	info = buffer.pointer;
 	if (!(info->valid & ACPI_VALID_HID)) {
 		acpi_os_free(buffer.pointer);
 		return AE_ERROR;
 	}

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

 	acpi_os_free(buffer.pointer);
 	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)){
 		ACPI_EXCEPTION((AE_INFO, status, "handle is no memory device"));
 		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)){
 		ACPI_EXCEPTION((AE_INFO, status, "handle is no memory device"));
 		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);

 	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);

 	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 firmare 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 <acpi/acpi_drivers.h>

	#define ACPI_MEMORY_DEVICE_COMPONENT 0x08000000UL
	#define ACPI_MEMORY_DEVICE_CLASS "memory"
	#define ACPI_MEMORY_DEVICE_HID "PNP0C80"
	#define ACPI_MEMORY_DEVICE_DRIVER_NAME "Hotplug Mem Driver"
	#define ACPI_MEMORY_DEVICE_NAME "Hotplug Mem Device"

	#define _COMPONENT ACPI_MEMORY_DEVICE_COMPONENT

	ACPI_MODULE_NAME("acpi_memory")
	MODULE_AUTHOR("Naveen B S <naveen.b.s@intel.com>");
	MODULE_DESCRIPTION(ACPI_MEMORY_DEVICE_DRIVER_NAME);
	MODULE_LICENSE("GPL");

	/* ACPI _STA method values */
	#define ACPI_MEMORY_STA_PRESENT (0x00000001UL)
	#define ACPI_MEMORY_STA_ENABLED (0x00000002UL)
	#define ACPI_MEMORY_STA_FUNCTIONAL (0x00000008UL)

	/* 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, int type);
	static int acpi_memory_device_start(struct acpi_device *device);

	static struct acpi_driver acpi_memory_device_driver = {
	.name = ACPI_MEMORY_DEVICE_DRIVER_NAME,
	.class = ACPI_MEMORY_DEVICE_CLASS,
	.ids = ACPI_MEMORY_DEVICE_HID,
	.ops = {
	.add = acpi_memory_device_add,
	.remove = acpi_memory_device_remove,
	.start = acpi_memory_device_start,
	},
	};

	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;
	};

	struct acpi_memory_device {
	acpi_handle handle;
	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 int
	acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
	{
	acpi_status status;
	struct acpi_memory_info info, n;


	status = acpi_walk_resources(mem_device->handle, METHOD_NAME__CRS,
	acpi_memory_get_resource, mem_device);
	if (ACPI_FAILURE(status)) {
	list_for_each_entry_safe(info, n, &mem_device->res_list, list)
	kfree(info);
	return -EINVAL;
	}

	return 0;
	}

	static int
	acpi_memory_get_device(acpi_handle handle,
	struct acpi_memory_device **mem_device)
	{
	acpi_status status;
	acpi_handle phandle;
	struct acpi_device *device = NULL;
	struct acpi_device *pdevice = NULL;


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

	status = acpi_get_parent(handle, &phandle);
	if (ACPI_FAILURE(status)) {
	ACPI_EXCEPTION((AE_INFO, status, "Cannot find acpi parent"));
	return -EINVAL;
	}

	/* Get the parent device */
	status = acpi_bus_get_device(phandle, &pdevice);
	if (ACPI_FAILURE(status)) {
	ACPI_EXCEPTION((AE_INFO, status, "Cannot get acpi bus device"));
	return -EINVAL;
	}

	/*
	* Now add the notified device. This creates the acpi_device
	* and invokes .add function
	*/
	status = acpi_bus_add(&device, pdevice, handle, ACPI_BUS_TYPE_DEVICE);
	if (ACPI_FAILURE(status)) {
	ACPI_EXCEPTION((AE_INFO, status, "Cannot add acpi bus"));
	return -EINVAL;
	}

	end:
	*mem_device = acpi_driver_data(device);
	if (!(*mem_device)) {
	printk(KERN_ERR "\n driver data not found");
	return -ENODEV;
	}

	return 0;
	}

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


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


	/* Get the range from the _CRS */
	result = acpi_memory_get_device_resources(mem_device);
	if (result) {
	printk(KERN_ERR PREFIX "get_device_resources failed\n");
	mem_device->state = MEMORY_INVALID_STATE;
	return result;
	}

	node = acpi_get_node(mem_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) {
	u64 start_pfn, end_pfn;

	start_pfn = info->start_addr >> PAGE_SHIFT;
	end_pfn = (info->start_addr + info->length - 1) >> PAGE_SHIFT;

	if (pfn_valid(start_pfn) \|\| pfn_valid(end_pfn)) {
	/* already enabled. try next area */
	num_enabled++;
	continue;
	}

	result = add_memory(node, info->start_addr, info->length);
	if (result)
	continue;
	info->enabled = 1;
	num_enabled++;
	}
	if (!num_enabled) {
	printk(KERN_ERR PREFIX "add_memory failed\n");
	mem_device->state = MEMORY_INVALID_STATE;
	return -EINVAL;
	}

	return result;
	}

	static int acpi_memory_powerdown_device(struct acpi_memory_device *mem_device)
	{
	acpi_status status;
	struct acpi_object_list arg_list;
	union acpi_object arg;
	unsigned long current_status;


	/* Issue the _EJ0 command */
	arg_list.count = 1;
	arg_list.pointer = &arg;
	arg.type = ACPI_TYPE_INTEGER;
	arg.integer.value = 1;
	status = acpi_evaluate_object(mem_device->handle,
	"_EJ0", &arg_list, NULL);
	/* Return on _EJ0 failure */
	if (ACPI_FAILURE(status)) {
	ACPI_EXCEPTION((AE_INFO, status, "_EJ0 failed"));
	return -ENODEV;
	}

	/* Evalute _STA to check if the device is disabled */
	status = acpi_evaluate_integer(mem_device->handle, "_STA",
	NULL, &current_status);
	if (ACPI_FAILURE(status))
	return -ENODEV;

	/* Check for device status. Device should be disabled */
	if (current_status & ACPI_MEMORY_STA_ENABLED)
	return -EINVAL;

	return 0;
	}

	static int acpi_memory_disable_device(struct acpi_memory_device *mem_device)
	{
	int result;
	struct acpi_memory_info info, n;


	/*
	* Ask the VM to offline this memory range.
	* Note: Assume that this function returns zero on success
	*/
	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
	if (info->enabled) {
	result = remove_memory(info->start_addr, info->length);
	if (result)
	return result;
	}
	kfree(info);
	}

	/* Power-off and eject the device */
	result = acpi_memory_powerdown_device(mem_device);
	if (result) {
	/* Set the status of the device to invalid */
	mem_device->state = MEMORY_INVALID_STATE;
	return result;
	}

	mem_device->state = MEMORY_POWER_OFF_STATE;
	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;


	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)) {
	printk(KERN_ERR PREFIX "Cannot find driver data\n");
	return;
	}

	if (!acpi_memory_check_device(mem_device)) {
	if (acpi_memory_enable_device(mem_device))
	printk(KERN_ERR PREFIX
	"Cannot enable memory device\n");
	}
	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)) {
	printk(KERN_ERR PREFIX "Device doesn't exist\n");
	break;
	}
	mem_device = acpi_driver_data(device);
	if (!mem_device) {
	printk(KERN_ERR PREFIX "Driver Data is NULL\n");
	break;
	}

	/*
	* Currently disabling memory device from kernel mode
	* TBD: Can also be disabled from user mode scripts
	* TBD: Can also be disabled by Callback registration
	* with generic sysfs driver
	*/
	if (acpi_memory_disable_device(mem_device))
	printk(KERN_ERR PREFIX
	"Disable memory device\n");
	/*
	* TBD: Invoke acpi_bus_remove to cleanup data structures
	*/
	break;
	default:
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	"Unsupported event [0x%x]\n", event));
	break;
	}

	return;
	}

	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 = kmalloc(sizeof(struct acpi_memory_device), GFP_KERNEL);
	if (!mem_device)
	return -ENOMEM;
	memset(mem_device, 0, sizeof(struct acpi_memory_device));

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

	printk(KERN_INFO "%s \n", acpi_device_name(device));

	return result;
	}

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


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

	mem_device = (struct acpi_memory_device *)acpi_driver_data(device);
	kfree(mem_device);

	return 0;
	}

	static int acpi_memory_device_start (struct acpi_device *device)
	{
	struct acpi_memory_device *mem_device;
	int result = 0;

	mem_device = acpi_driver_data(device);

	if (!acpi_memory_check_device(mem_device)) {
	/* call add_memory func */
	result = acpi_memory_enable_device(mem_device);
	if (result)
	ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
	"Error in acpi_memory_enable_device\n"));
	}
	return result;
	}

	/*
	* Helper function to check for memory device
	*/
	static acpi_status is_memory_device(acpi_handle handle)
	{
	char *hardware_id;
	acpi_status status;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	struct acpi_device_info *info;


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

	info = buffer.pointer;
	if (!(info->valid & ACPI_VALID_HID)) {
	acpi_os_free(buffer.pointer);
	return AE_ERROR;
	}

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

	acpi_os_free(buffer.pointer);
	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)){
	ACPI_EXCEPTION((AE_INFO, status, "handle is no memory device"));
	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)){
	ACPI_EXCEPTION((AE_INFO, status, "handle is no memory device"));
	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);

	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);

	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);