/*
 *  acpi_ipmi.c - ACPI IPMI opregion
 *
 *  Copyright (C) 2010 Intel Corporation
 *  Copyright (C) 2010 Zhao Yakui <yakui.zhao@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/delay.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <linux/ipmi.h>
#include <linux/device.h>
#include <linux/pnp.h>

MODULE_AUTHOR("Zhao Yakui");
MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
MODULE_LICENSE("GPL");

#define IPMI_FLAGS_HANDLER_INSTALL      0

#define ACPI_IPMI_OK                    0
#define ACPI_IPMI_TIMEOUT               0x10
#define ACPI_IPMI_UNKNOWN               0x07
/* the IPMI timeout is 5s */
#define IPMI_TIMEOUT                    (5 * HZ)

struct acpi_ipmi_device {
        /* the device list attached to driver_data.ipmi_devices */
        struct list_head head;
        /* the IPMI request message list */
        struct list_head tx_msg_list;
        struct mutex    tx_msg_lock;
        acpi_handle handle;
        struct pnp_dev *pnp_dev;
        ipmi_user_t     user_interface;
        int ipmi_ifnum; /* IPMI interface number */
        long curr_msgid;
        unsigned long flags;
        struct ipmi_smi_info smi_data;
};

struct ipmi_driver_data {
        struct list_head        ipmi_devices;
        struct ipmi_smi_watcher bmc_events;
        struct ipmi_user_hndl   ipmi_hndlrs;
        struct mutex            ipmi_lock;
};

struct acpi_ipmi_msg {
        struct list_head head;
        /*
         * General speaking the addr type should be SI_ADDR_TYPE. And
         * the addr channel should be BMC.
         * In fact it can also be IPMB type. But we will have to
         * parse it from the Netfn command buffer. It is so complex
         * that it is skipped.
         */
        struct ipmi_addr addr;
        long tx_msgid;
        /* it is used to track whether the IPMI message is finished */
        struct completion tx_complete;
        struct kernel_ipmi_msg tx_message;
        int     msg_done;
        /* tx data . And copy it from ACPI object buffer */
        u8      tx_data[64];
        int     tx_len;
        u8      rx_data[64];
        int     rx_len;
        struct acpi_ipmi_device *device;
};

/* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
struct acpi_ipmi_buffer {
        u8 status;
        u8 length;
        u8 data[64];
};

static void ipmi_register_bmc(int iface, struct device *dev);
static void ipmi_bmc_gone(int iface);
static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device);
static void acpi_remove_ipmi_device(struct acpi_ipmi_device *ipmi_device);

static struct ipmi_driver_data driver_data = {
        .ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
        .bmc_events = {
                .owner = THIS_MODULE,
                .new_smi = ipmi_register_bmc,
                .smi_gone = ipmi_bmc_gone,
        },
        .ipmi_hndlrs = {
                .ipmi_recv_hndl = ipmi_msg_handler,
        },
};

static struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi)
{
        struct acpi_ipmi_msg *ipmi_msg;
        struct pnp_dev *pnp_dev = ipmi->pnp_dev;

        ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
        if (!ipmi_msg)  {
                dev_warn(&pnp_dev->dev, "Can't allocate memory for ipmi_msg\n");
                return NULL;
        }
        init_completion(&ipmi_msg->tx_complete);
        INIT_LIST_HEAD(&ipmi_msg->head);
        ipmi_msg->device = ipmi;
        return ipmi_msg;
}

#define         IPMI_OP_RGN_NETFN(offset)       ((offset >> 8) & 0xff)
#define         IPMI_OP_RGN_CMD(offset)         (offset & 0xff)
static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
                                acpi_physical_address address,
                                acpi_integer *value)
{
        struct kernel_ipmi_msg *msg;
        struct acpi_ipmi_buffer *buffer;
        struct acpi_ipmi_device *device;

        msg = &tx_msg->tx_message;
        /*
         * IPMI network function and command are encoded in the address
         * within the IPMI OpRegion; see ACPI 4.0, sec 5.5.2.4.3.
         */
        msg->netfn = IPMI_OP_RGN_NETFN(address);
        msg->cmd = IPMI_OP_RGN_CMD(address);
        msg->data = tx_msg->tx_data;
        /*
         * value is the parameter passed by the IPMI opregion space handler.
         * It points to the IPMI request message buffer
         */
        buffer = (struct acpi_ipmi_buffer *)value;
        /* copy the tx message data */
        msg->data_len = buffer->length;
        memcpy(tx_msg->tx_data, buffer->data, msg->data_len);
        /*
         * now the default type is SYSTEM_INTERFACE and channel type is BMC.
         * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
         * the addr type should be changed to IPMB. Then we will have to parse
         * the IPMI request message buffer to get the IPMB address.
         * If so, please fix me.
         */
        tx_msg->addr.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
        tx_msg->addr.channel = IPMI_BMC_CHANNEL;
        tx_msg->addr.data[0] = 0;

        /* Get the msgid */
        device = tx_msg->device;
        mutex_lock(&device->tx_msg_lock);
        device->curr_msgid++;
        tx_msg->tx_msgid = device->curr_msgid;
        mutex_unlock(&device->tx_msg_lock);
}

static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
                acpi_integer *value, int rem_time)
{
        struct acpi_ipmi_buffer *buffer;

        /*
         * value is also used as output parameter. It represents the response
         * IPMI message returned by IPMI command.
         */
        buffer = (struct acpi_ipmi_buffer *)value;
        if (!rem_time && !msg->msg_done) {
                buffer->status = ACPI_IPMI_TIMEOUT;
                return;
        }
        /*
         * If the flag of msg_done is not set or the recv length is zero, it
         * means that the IPMI command is not executed correctly.
         * The status code will be ACPI_IPMI_UNKNOWN.
         */
        if (!msg->msg_done || !msg->rx_len) {
                buffer->status = ACPI_IPMI_UNKNOWN;
                return;
        }
        /*
         * If the IPMI response message is obtained correctly, the status code
         * will be ACPI_IPMI_OK
         */
        buffer->status = ACPI_IPMI_OK;
        buffer->length = msg->rx_len;
        memcpy(buffer->data, msg->rx_data, msg->rx_len);
}

static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
{
        struct acpi_ipmi_msg *tx_msg, *temp;
        int count = HZ / 10;
        struct pnp_dev *pnp_dev = ipmi->pnp_dev;

        list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
                /* wake up the sleep thread on the Tx msg */
                complete(&tx_msg->tx_complete);
        }

        /* wait for about 100ms to flush the tx message list */
        while (count--) {
                if (list_empty(&ipmi->tx_msg_list))
                        break;
                schedule_timeout(1);
        }
        if (!list_empty(&ipmi->tx_msg_list))
                dev_warn(&pnp_dev->dev, "tx msg list is not NULL\n");
}

static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
{
        struct acpi_ipmi_device *ipmi_device = user_msg_data;
        int msg_found = 0;
        struct acpi_ipmi_msg *tx_msg;
        struct pnp_dev *pnp_dev = ipmi_device->pnp_dev;

        if (msg->user != ipmi_device->user_interface) {
                dev_warn(&pnp_dev->dev, "Unexpected response is returned. "
                        "returned user %p, expected user %p\n",
                        msg->user, ipmi_device->user_interface);
                ipmi_free_recv_msg(msg);
                return;
        }
        mutex_lock(&ipmi_device->tx_msg_lock);
        list_for_each_entry(tx_msg, &ipmi_device->tx_msg_list, head) {
                if (msg->msgid == tx_msg->tx_msgid) {
                        msg_found = 1;
                        break;
                }
        }

        mutex_unlock(&ipmi_device->tx_msg_lock);
        if (!msg_found) {
                dev_warn(&pnp_dev->dev, "Unexpected response (msg id %ld) is "
                        "returned.\n", msg->msgid);
                ipmi_free_recv_msg(msg);
                return;
        }

        if (msg->msg.data_len) {
                /* copy the response data to Rx_data buffer */
                memcpy(tx_msg->rx_data, msg->msg_data, msg->msg.data_len);
                tx_msg->rx_len = msg->msg.data_len;
                tx_msg->msg_done = 1;
        }
        complete(&tx_msg->tx_complete);
        ipmi_free_recv_msg(msg);
};

static void ipmi_register_bmc(int iface, struct device *dev)
{
        struct acpi_ipmi_device *ipmi_device, *temp;
        struct pnp_dev *pnp_dev;
        ipmi_user_t             user;
        int err;
        struct ipmi_smi_info smi_data;
        acpi_handle handle;

        err = ipmi_get_smi_info(iface, &smi_data);

        if (err)
                return;

        if (smi_data.addr_src != SI_ACPI) {
                put_device(smi_data.dev);
                return;
        }

        handle = smi_data.addr_info.acpi_info.acpi_handle;

        mutex_lock(&driver_data.ipmi_lock);
        list_for_each_entry(temp, &driver_data.ipmi_devices, head) {
                /*
                 * if the corresponding ACPI handle is already added
                 * to the device list, don't add it again.
                 */
                if (temp->handle == handle)
                        goto out;
        }

        ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);

        if (!ipmi_device)
                goto out;

        pnp_dev = to_pnp_dev(smi_data.dev);
        ipmi_device->handle = handle;
        ipmi_device->pnp_dev = pnp_dev;

        err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
                                        ipmi_device, &user);
        if (err) {
                dev_warn(&pnp_dev->dev, "Can't create IPMI user interface\n");
                kfree(ipmi_device);
                goto out;
        }
        acpi_add_ipmi_device(ipmi_device);
        ipmi_device->user_interface = user;
        ipmi_device->ipmi_ifnum = iface;
        mutex_unlock(&driver_data.ipmi_lock);
        memcpy(&ipmi_device->smi_data, &smi_data, sizeof(struct ipmi_smi_info));
        return;

out:
        mutex_unlock(&driver_data.ipmi_lock);
        put_device(smi_data.dev);
        return;
}

static void ipmi_bmc_gone(int iface)
{
        struct acpi_ipmi_device *ipmi_device, *temp;

        mutex_lock(&driver_data.ipmi_lock);
        list_for_each_entry_safe(ipmi_device, temp,
                                &driver_data.ipmi_devices, head) {
                if (ipmi_device->ipmi_ifnum != iface)
                        continue;

                acpi_remove_ipmi_device(ipmi_device);
                put_device(ipmi_device->smi_data.dev);
                kfree(ipmi_device);
                break;
        }
        mutex_unlock(&driver_data.ipmi_lock);
}
/* --------------------------------------------------------------------------
 *                      Address Space Management
 * -------------------------------------------------------------------------- */
/*
 * This is the IPMI opregion space handler.
 * @function: indicates the read/write. In fact as the IPMI message is driven
 * by command, only write is meaningful.
 * @address: This contains the netfn/command of IPMI request message.
 * @bits   : not used.
 * @value  : it is an in/out parameter. It points to the IPMI message buffer.
 *           Before the IPMI message is sent, it represents the actual request
 *           IPMI message. After the IPMI message is finished, it represents
 *           the response IPMI message returned by IPMI command.
 * @handler_context: IPMI device context.
 */

static acpi_status
acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
                      u32 bits, acpi_integer *value,
                      void *handler_context, void *region_context)
{
        struct acpi_ipmi_msg *tx_msg;
        struct acpi_ipmi_device *ipmi_device = handler_context;
        int err, rem_time;
        acpi_status status;
        /*
         * IPMI opregion message.
         * IPMI message is firstly written to the BMC and system software
         * can get the respsonse. So it is unmeaningful for the read access
         * of IPMI opregion.
         */
        if ((function & ACPI_IO_MASK) == ACPI_READ)
                return AE_TYPE;

        if (!ipmi_device->user_interface)
                return AE_NOT_EXIST;

        tx_msg = acpi_alloc_ipmi_msg(ipmi_device);
        if (!tx_msg)
                return AE_NO_MEMORY;

        acpi_format_ipmi_msg(tx_msg, address, value);
        mutex_lock(&ipmi_device->tx_msg_lock);
        list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
        mutex_unlock(&ipmi_device->tx_msg_lock);
        err = ipmi_request_settime(ipmi_device->user_interface,
                                        &tx_msg->addr,
                                        tx_msg->tx_msgid,
                                        &tx_msg->tx_message,
                                        NULL, 0, 0, 0);
        if (err) {
                status = AE_ERROR;
                goto end_label;
        }
        rem_time = wait_for_completion_timeout(&tx_msg->tx_complete,
                                        IPMI_TIMEOUT);
        acpi_format_ipmi_response(tx_msg, value, rem_time);
        status = AE_OK;

end_label:
        mutex_lock(&ipmi_device->tx_msg_lock);
        list_del(&tx_msg->head);
        mutex_unlock(&ipmi_device->tx_msg_lock);
        kfree(tx_msg);
        return status;
}

static void ipmi_remove_space_handler(struct acpi_ipmi_device *ipmi)
{
        if (!test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
                return;

        acpi_remove_address_space_handler(ipmi->handle,
                                ACPI_ADR_SPACE_IPMI, &acpi_ipmi_space_handler);

        clear_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
}

static int ipmi_install_space_handler(struct acpi_ipmi_device *ipmi)
{
        acpi_status status;

        if (test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
                return 0;

        status = acpi_install_address_space_handler(ipmi->handle,
                                                    ACPI_ADR_SPACE_IPMI,
                                                    &acpi_ipmi_space_handler,
                                                    NULL, ipmi);
        if (ACPI_FAILURE(status)) {
                struct pnp_dev *pnp_dev = ipmi->pnp_dev;
                dev_warn(&pnp_dev->dev, "Can't register IPMI opregion space "
                        "handle\n");
                return -EINVAL;
        }
        set_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
        return 0;
}

static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device)
{

        INIT_LIST_HEAD(&ipmi_device->head);

        mutex_init(&ipmi_device->tx_msg_lock);
        INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
        ipmi_install_space_handler(ipmi_device);

        list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
}

static void acpi_remove_ipmi_device(struct acpi_ipmi_device *ipmi_device)
{
        /*
         * If the IPMI user interface is created, it should be
         * destroyed.
         */
        if (ipmi_device->user_interface) {
                ipmi_destroy_user(ipmi_device->user_interface);
                ipmi_device->user_interface = NULL;
        }
        /* flush the Tx_msg list */
        if (!list_empty(&ipmi_device->tx_msg_list))
                ipmi_flush_tx_msg(ipmi_device);

        list_del(&ipmi_device->head);
        ipmi_remove_space_handler(ipmi_device);
}

static int __init acpi_ipmi_init(void)
{
        int result = 0;

        if (acpi_disabled)
                return result;

        mutex_init(&driver_data.ipmi_lock);

        result = ipmi_smi_watcher_register(&driver_data.bmc_events);

        return result;
}

static void __exit acpi_ipmi_exit(void)
{
        struct acpi_ipmi_device *ipmi_device, *temp;

        if (acpi_disabled)
                return;

        ipmi_smi_watcher_unregister(&driver_data.bmc_events);

        /*
         * When one smi_watcher is unregistered, it is only deleted
         * from the smi_watcher list. But the smi_gone callback function
         * is not called. So explicitly uninstall the ACPI IPMI oregion
         * handler and free it.
         */
        mutex_lock(&driver_data.ipmi_lock);
        list_for_each_entry_safe(ipmi_device, temp,
                                &driver_data.ipmi_devices, head) {
                acpi_remove_ipmi_device(ipmi_device);
                put_device(ipmi_device->smi_data.dev);
                kfree(ipmi_device);
        }
        mutex_unlock(&driver_data.ipmi_lock);
}

module_init(acpi_ipmi_init);
module_exit(acpi_ipmi_exit);