/*
 * 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 <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, int type);

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;
};

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

static int acpi_hotmem_initialized;

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;


        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)) {
                list_for_each_entry_safe(info, n, &mem_device->res_list, list)
                        kfree(info);
                INIT_LIST_HEAD(&mem_device->res_list);
                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;
        int result;


        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 */
        result = acpi_bus_get_device(phandle, &pdevice);
        if (result) {
                printk(KERN_WARNING PREFIX "Cannot get acpi bus device");
                return -EINVAL;
        }

        /*
         * Now add the notified device.  This creates the acpi_device
         * and invokes .add function
         */
        result = acpi_bus_add(&device, pdevice, handle, ACPI_BUS_TYPE_DEVICE);
        if (result) {
                printk(KERN_WARNING PREFIX "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 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;


        /* 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->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 (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;
        }
        /*
         * 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_powerdown_device(struct acpi_memory_device *mem_device)
{
        acpi_status status;
        struct acpi_object_list arg_list;
        union acpi_object arg;
        unsigned long 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->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->device->handle, "_STA",
                                       NULL, &current_status);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        /* Check for device status.  Device should be disabled */
        if (current_status & ACPI_STA_DEVICE_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 = 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;

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

        /*
         * Early boot code has recognized memory area by EFI/E820.
         * If DSDT shows these memory devices on boot, hotplug is not necessary
         * for them. So, it just returns until completion of this driver's
         * start up.
         */
        if (!acpi_hotmem_initialized)
                return 0;

        if (!acpi_memory_check_device(mem_device)) {
                /* call add_memory func */
                result = acpi_memory_enable_device(mem_device);
                if (result)
                        printk(KERN_ERR PREFIX
                                "Error in acpi_memory_enable_device\n");
        }
        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 = acpi_driver_data(device);
        kfree(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;
        }

        acpi_hotmem_initialized = 1;
        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);