/*

   * Copyright (C) 2004, 2013 Intel Corporation
   * Author: Naveen B S <naveen.b.s@intel.com>
   * Author: Rafael J. Wysocki <rafael.j.wysocki@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.
   *

   * 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/acpi.h>

  #include <linux/memory.h>

  #include <linux/memory_hotplug.h>
  
  #include "internal.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");

  static const struct acpi_device_id memory_device_ids[] = {
  	{ACPI_MEMORY_DEVICE_HID, 0},
  	{"", 0},
  };
  
  #ifdef CONFIG_ACPI_HOTPLUG_MEMORY

  /* 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,
  				  const struct acpi_device_id *not_used);
  static void acpi_memory_device_remove(struct acpi_device *device);

  static struct acpi_scan_handler memory_device_handler = {

  	.ids = memory_device_ids,

  	.attach = acpi_memory_device_add,
  	.detach = acpi_memory_device_remove,
  	.hotplug = {
  		.enabled = true,
  	},

  };

  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 {

  	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.address.minimum)) {
  			info->length += address64.address.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.address.minimum;
  	new->length = address64.address.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_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,
  					       METHOD_NAME__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 unsigned long acpi_meminfo_start_pfn(struct acpi_memory_info *info)
  {
  	return PFN_DOWN(info->start_addr);
  }
  
  static unsigned long acpi_meminfo_end_pfn(struct acpi_memory_info *info)
  {
  	return PFN_UP(info->start_addr + info->length-1);
  }
  
  static int acpi_bind_memblk(struct memory_block *mem, void *arg)
  {

  	return acpi_bind_one(&mem->dev, arg);

  }
  
  static int acpi_bind_memory_blocks(struct acpi_memory_info *info,

  				   struct acpi_device *adev)

  {
  	return walk_memory_range(acpi_meminfo_start_pfn(info),

  				 acpi_meminfo_end_pfn(info), adev,

  				 acpi_bind_memblk);
  }
  
  static int acpi_unbind_memblk(struct memory_block *mem, void *arg)
  {
  	acpi_unbind_one(&mem->dev);
  	return 0;
  }

  static void acpi_unbind_memory_blocks(struct acpi_memory_info *info)

  {
  	walk_memory_range(acpi_meminfo_start_pfn(info),
  			  acpi_meminfo_end_pfn(info), NULL, acpi_unbind_memblk);
  }

  static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)

  {

  	acpi_handle handle = mem_device->device->handle;

  	int result, num_enabled = 0;
  	struct acpi_memory_info *info;

  	int node;

  	node = acpi_get_node(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)

  			continue;

  		result = acpi_bind_memory_blocks(info, mem_device->device);

  		if (result) {

  			acpi_unbind_memory_blocks(info);

  			return -ENODEV;
  		}

  		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
  ");

  		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 void acpi_memory_remove_memory(struct acpi_memory_device *mem_device)

  {

  	acpi_handle handle = mem_device->device->handle;

  	struct acpi_memory_info *info, *n;

  	int nid = acpi_get_node(handle);

  	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {

  		if (!info->enabled)

  			continue;

  		if (nid == NUMA_NO_NODE)

  			nid = memory_add_physaddr_to_nid(info->start_addr);

  		acpi_unbind_memory_blocks(info);

  		remove_memory(nid, info->start_addr, info->length);

  		list_del(&info->list);

  		kfree(info);

  	}

  }

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

  	mem_device->device->driver_data = NULL;

  	kfree(mem_device);
  }

  static int acpi_memory_device_add(struct acpi_device *device,
  				  const struct acpi_device_id *not_used)

  {

  	struct acpi_memory_device *mem_device;

  	int result;

  
  	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) {

  		device->driver_data = NULL;

  		kfree(mem_device);

  		return result;

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

  	result = acpi_memory_check_device(mem_device);
  	if (result) {
  		acpi_memory_device_free(mem_device);
  		return 0;
  	}

  	result = acpi_memory_enable_device(mem_device);
  	if (result) {
  		dev_err(&device->dev, "acpi_memory_enable_device() error
  ");
  		acpi_memory_device_free(mem_device);

  		return result;

  	}

  
  	dev_dbg(&device->dev, "Memory device configured by ACPI
  ");
  	return 1;

  }

  static void acpi_memory_device_remove(struct acpi_device *device)

  {

  	struct acpi_memory_device *mem_device;

  
  	if (!device || !acpi_driver_data(device))

  		return;

  
  	mem_device = acpi_driver_data(device);

  	acpi_memory_remove_memory(mem_device);

  	acpi_memory_device_free(mem_device);

  }

  static bool __initdata acpi_no_memhotplug;

  void __init acpi_memory_hotplug_init(void)

  {

  	if (acpi_no_memhotplug) {
  		memory_device_handler.attach = NULL;
  		acpi_scan_add_handler(&memory_device_handler);

  		return;

  	}

  	acpi_scan_add_handler_with_hotplug(&memory_device_handler, "memory");

  }

  
  static int __init disable_acpi_memory_hotplug(char *str)
  {
  	acpi_no_memhotplug = true;
  	return 1;
  }
  __setup("acpi_no_memhotplug", disable_acpi_memory_hotplug);

  
  #else
  
  static struct acpi_scan_handler memory_device_handler = {
  	.ids = memory_device_ids,
  };
  
  void __init acpi_memory_hotplug_init(void)
  {
  	acpi_scan_add_handler(&memory_device_handler);
  }
  
  #endif /* CONFIG_ACPI_HOTPLUG_MEMORY */