/*
 *
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2003-2012, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/aio.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/uuid.h>
#include <linux/jiffies.h>
#include <linux/uaccess.h>

#include <linux/mei.h>

#include "mei_dev.h"
#include "hbm.h"
#include "hw-me.h"
#include "client.h"

const uuid_le mei_amthif_guid  = UUID_LE(0x12f80028, 0xb4b7, 0x4b2d,
                                         0xac, 0xa8, 0x46, 0xe0,
                                         0xff, 0x65, 0x81, 0x4c);

/**
 * mei_amthif_reset_params - initializes mei device iamthif
 *
 * @dev: the device structure
 */
void mei_amthif_reset_params(struct mei_device *dev)
{
        /* reset iamthif parameters. */
        dev->iamthif_current_cb = NULL;
        dev->iamthif_msg_buf_size = 0;
        dev->iamthif_msg_buf_index = 0;
        dev->iamthif_canceled = false;
        dev->iamthif_ioctl = false;
        dev->iamthif_state = MEI_IAMTHIF_IDLE;
        dev->iamthif_timer = 0;
}

/**
 * mei_amthif_host_init - mei initialization amthif client.
 *
 * @dev: the device structure
 *
 */
int mei_amthif_host_init(struct mei_device *dev)
{
        struct mei_cl *cl = &dev->iamthif_cl;
        unsigned char *msg_buf;
        int ret, i;

        dev->iamthif_state = MEI_IAMTHIF_IDLE;

        mei_cl_init(cl, dev);

        i = mei_me_cl_by_uuid(dev, &mei_amthif_guid);
        if (i < 0) {
                dev_info(&dev->pdev->dev, "amthif: failed to find the client\n");
                return -ENOENT;
        }

        cl->me_client_id = dev->me_clients[i].client_id;

        /* Assign iamthif_mtu to the value received from ME  */

        dev->iamthif_mtu = dev->me_clients[i].props.max_msg_length;
        dev_dbg(&dev->pdev->dev, "IAMTHIF_MTU = %d\n",
                        dev->me_clients[i].props.max_msg_length);

        kfree(dev->iamthif_msg_buf);
        dev->iamthif_msg_buf = NULL;

        /* allocate storage for ME message buffer */
        msg_buf = kcalloc(dev->iamthif_mtu,
                        sizeof(unsigned char), GFP_KERNEL);
        if (!msg_buf) {
                dev_err(&dev->pdev->dev, "amthif: memory allocation for ME message buffer failed.\n");
                return -ENOMEM;
        }

        dev->iamthif_msg_buf = msg_buf;

        ret = mei_cl_link(cl, MEI_IAMTHIF_HOST_CLIENT_ID);

        if (ret < 0) {
                dev_err(&dev->pdev->dev, "amthif: failed link client\n");
                return -ENOENT;
        }

        cl->state = MEI_FILE_CONNECTING;

        if (mei_hbm_cl_connect_req(dev, cl)) {
                dev_dbg(&dev->pdev->dev, "amthif: Failed to connect to ME client\n");
                cl->state = MEI_FILE_DISCONNECTED;
                cl->host_client_id = 0;
        } else {
                cl->timer_count = MEI_CONNECT_TIMEOUT;
        }
        return 0;
}

/**
 * mei_amthif_find_read_list_entry - finds a amthilist entry for current file
 *
 * @dev: the device structure
 * @file: pointer to file object
 *
 * returns   returned a list entry on success, NULL on failure.
 */
struct mei_cl_cb *mei_amthif_find_read_list_entry(struct mei_device *dev,
                                                struct file *file)
{
        struct mei_cl_cb *pos = NULL;
        struct mei_cl_cb *next = NULL;

        list_for_each_entry_safe(pos, next,
                                &dev->amthif_rd_complete_list.list, list) {
                if (pos->cl && pos->cl == &dev->iamthif_cl &&
                        pos->file_object == file)
                        return pos;
        }
        return NULL;
}


/**
 * mei_amthif_read - read data from AMTHIF client
 *
 * @dev: the device structure
 * @if_num:  minor number
 * @file: pointer to file object
 * @*ubuf: pointer to user data in user space
 * @length: data length to read
 * @offset: data read offset
 *
 * Locking: called under "dev->device_lock" lock
 *
 * returns
 *  returned data length on success,
 *  zero if no data to read,
 *  negative on failure.
 */
int mei_amthif_read(struct mei_device *dev, struct file *file,
               char __user *ubuf, size_t length, loff_t *offset)
{
        int rets;
        int wait_ret;
        struct mei_cl_cb *cb = NULL;
        struct mei_cl *cl = file->private_data;
        unsigned long timeout;
        int i;

        /* Only Posible if we are in timeout */
        if (!cl || cl != &dev->iamthif_cl) {
                dev_dbg(&dev->pdev->dev, "bad file ext.\n");
                return -ETIMEDOUT;
        }

        i = mei_me_cl_by_id(dev, dev->iamthif_cl.me_client_id);

        if (i < 0) {
                dev_dbg(&dev->pdev->dev, "amthif client not found.\n");
                return -ENODEV;
        }
        dev_dbg(&dev->pdev->dev, "checking amthif data\n");
        cb = mei_amthif_find_read_list_entry(dev, file);

        /* Check for if we can block or not*/
        if (cb == NULL && file->f_flags & O_NONBLOCK)
                return -EAGAIN;


        dev_dbg(&dev->pdev->dev, "waiting for amthif data\n");
        while (cb == NULL) {
                /* unlock the Mutex */
                mutex_unlock(&dev->device_lock);

                wait_ret = wait_event_interruptible(dev->iamthif_cl.wait,
                        (cb = mei_amthif_find_read_list_entry(dev, file)));

                /* Locking again the Mutex */
                mutex_lock(&dev->device_lock);

                if (wait_ret)
                        return -ERESTARTSYS;

                dev_dbg(&dev->pdev->dev, "woke up from sleep\n");
        }


        dev_dbg(&dev->pdev->dev, "Got amthif data\n");
        dev->iamthif_timer = 0;

        if (cb) {
                timeout = cb->read_time +
                        mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);
                dev_dbg(&dev->pdev->dev, "amthif timeout = %lud\n",
                                timeout);

                if  (time_after(jiffies, timeout)) {
                        dev_dbg(&dev->pdev->dev, "amthif Time out\n");
                        /* 15 sec for the message has expired */
                        list_del(&cb->list);
                        rets = -ETIMEDOUT;
                        goto free;
                }
        }
        /* if the whole message will fit remove it from the list */
        if (cb->buf_idx >= *offset && length >= (cb->buf_idx - *offset))
                list_del(&cb->list);
        else if (cb->buf_idx > 0 && cb->buf_idx <= *offset) {
                /* end of the message has been reached */
                list_del(&cb->list);
                rets = 0;
                goto free;
        }
                /* else means that not full buffer will be read and do not
                 * remove message from deletion list
                 */

        dev_dbg(&dev->pdev->dev, "amthif cb->response_buffer size - %d\n",
            cb->response_buffer.size);
        dev_dbg(&dev->pdev->dev, "amthif cb->buf_idx - %lu\n", cb->buf_idx);

        /* length is being turncated to PAGE_SIZE, however,
         * the buf_idx may point beyond */
        length = min_t(size_t, length, (cb->buf_idx - *offset));

        if (copy_to_user(ubuf, cb->response_buffer.data + *offset, length))
                rets = -EFAULT;
        else {
                rets = length;
                if ((*offset + length) < cb->buf_idx) {
                        *offset += length;
                        goto out;
                }
        }
free:
        dev_dbg(&dev->pdev->dev, "free amthif cb memory.\n");
        *offset = 0;
        mei_io_cb_free(cb);
out:
        return rets;
}

/**
 * mei_amthif_send_cmd - send amthif command to the ME
 *
 * @dev: the device structure
 * @cb: mei call back struct
 *
 * returns 0 on success, <0 on failure.
 *
 */
static int mei_amthif_send_cmd(struct mei_device *dev, struct mei_cl_cb *cb)
{
        struct mei_msg_hdr mei_hdr;
        int ret;

        if (!dev || !cb)
                return -ENODEV;

        dev_dbg(&dev->pdev->dev, "write data to amthif client.\n");

        dev->iamthif_state = MEI_IAMTHIF_WRITING;
        dev->iamthif_current_cb = cb;
        dev->iamthif_file_object = cb->file_object;
        dev->iamthif_canceled = false;
        dev->iamthif_ioctl = true;
        dev->iamthif_msg_buf_size = cb->request_buffer.size;
        memcpy(dev->iamthif_msg_buf, cb->request_buffer.data,
               cb->request_buffer.size);

        ret = mei_cl_flow_ctrl_creds(&dev->iamthif_cl);
        if (ret < 0)
                return ret;

        if (ret && dev->hbuf_is_ready) {
                ret = 0;
                dev->hbuf_is_ready = false;
                if (cb->request_buffer.size > mei_hbuf_max_len(dev)) {
                        mei_hdr.length = mei_hbuf_max_len(dev);
                        mei_hdr.msg_complete = 0;
                } else {
                        mei_hdr.length = cb->request_buffer.size;
                        mei_hdr.msg_complete = 1;
                }

                mei_hdr.host_addr = dev->iamthif_cl.host_client_id;
                mei_hdr.me_addr = dev->iamthif_cl.me_client_id;
                mei_hdr.reserved = 0;
                dev->iamthif_msg_buf_index += mei_hdr.length;
                if (mei_write_message(dev, &mei_hdr,
                                        (unsigned char *)dev->iamthif_msg_buf))
                        return -ENODEV;

                if (mei_hdr.msg_complete) {
                        if (mei_cl_flow_ctrl_reduce(&dev->iamthif_cl))
                                return -ENODEV;
                        dev->iamthif_flow_control_pending = true;
                        dev->iamthif_state = MEI_IAMTHIF_FLOW_CONTROL;
                        dev_dbg(&dev->pdev->dev, "add amthif cb to write waiting list\n");
                        dev->iamthif_current_cb = cb;
                        dev->iamthif_file_object = cb->file_object;
                        list_add_tail(&cb->list, &dev->write_waiting_list.list);
                } else {
                        dev_dbg(&dev->pdev->dev, "message does not complete, so add amthif cb to write list.\n");
                        list_add_tail(&cb->list, &dev->write_list.list);
                }
        } else {
                if (!dev->hbuf_is_ready)
                        dev_dbg(&dev->pdev->dev, "host buffer is not empty");

                dev_dbg(&dev->pdev->dev, "No flow control credentials, so add iamthif cb to write list.\n");
                list_add_tail(&cb->list, &dev->write_list.list);
        }
        return 0;
}

/**
 * mei_amthif_write - write amthif data to amthif client
 *
 * @dev: the device structure
 * @cb: mei call back struct
 *
 * returns 0 on success, <0 on failure.
 *
 */
int mei_amthif_write(struct mei_device *dev, struct mei_cl_cb *cb)
{
        int ret;

        if (!dev || !cb)
                return -ENODEV;

        ret = mei_io_cb_alloc_resp_buf(cb, dev->iamthif_mtu);
        if (ret)
                return ret;

        cb->fop_type = MEI_FOP_IOCTL;

        if (!list_empty(&dev->amthif_cmd_list.list) ||
            dev->iamthif_state != MEI_IAMTHIF_IDLE) {
                dev_dbg(&dev->pdev->dev,
                        "amthif state = %d\n", dev->iamthif_state);
                dev_dbg(&dev->pdev->dev, "AMTHIF: add cb to the wait list\n");
                list_add_tail(&cb->list, &dev->amthif_cmd_list.list);
                return 0;
        }
        return mei_amthif_send_cmd(dev, cb);
}
/**
 * mei_amthif_run_next_cmd
 *
 * @dev: the device structure
 *
 * returns 0 on success, <0 on failure.
 */
void mei_amthif_run_next_cmd(struct mei_device *dev)
{
        struct mei_cl_cb *pos = NULL;
        struct mei_cl_cb *next = NULL;
        int status;

        if (!dev)
                return;

        dev->iamthif_msg_buf_size = 0;
        dev->iamthif_msg_buf_index = 0;
        dev->iamthif_canceled = false;
        dev->iamthif_ioctl = true;
        dev->iamthif_state = MEI_IAMTHIF_IDLE;
        dev->iamthif_timer = 0;
        dev->iamthif_file_object = NULL;

        dev_dbg(&dev->pdev->dev, "complete amthif cmd_list cb.\n");

        list_for_each_entry_safe(pos, next, &dev->amthif_cmd_list.list, list) {
                list_del(&pos->list);

                if (pos->cl && pos->cl == &dev->iamthif_cl) {
                        status = mei_amthif_send_cmd(dev, pos);
                        if (status) {
                                dev_dbg(&dev->pdev->dev,
                                        "amthif write failed status = %d\n",
                                                status);
                                return;
                        }
                        break;
                }
        }
}


unsigned int mei_amthif_poll(struct mei_device *dev,
                struct file *file, poll_table *wait)
{
        unsigned int mask = 0;
        mutex_unlock(&dev->device_lock);
        poll_wait(file, &dev->iamthif_cl.wait, wait);
        mutex_lock(&dev->device_lock);
        if (dev->iamthif_state == MEI_IAMTHIF_READ_COMPLETE &&
                dev->iamthif_file_object == file) {
                mask |= (POLLIN | POLLRDNORM);
                dev_dbg(&dev->pdev->dev, "run next amthif cb\n");
                mei_amthif_run_next_cmd(dev);
        }
        return mask;
}



/**
 * mei_amthif_irq_write_completed - processes completed iamthif operation.
 *
 * @dev: the device structure.
 * @slots: free slots.
 * @cb_pos: callback block.
 * @cl: private data of the file object.
 * @cmpl_list: complete list.
 *
 * returns 0, OK; otherwise, error.
 */
int mei_amthif_irq_write_complete(struct mei_device *dev, s32 *slots,
                        struct mei_cl_cb *cb, struct mei_cl_cb *cmpl_list)
{
        struct mei_msg_hdr mei_hdr;
        struct mei_cl *cl = cb->cl;
        size_t len = dev->iamthif_msg_buf_size - dev->iamthif_msg_buf_index;
        u32 msg_slots = mei_data2slots(len);

        mei_hdr.host_addr = cl->host_client_id;
        mei_hdr.me_addr = cl->me_client_id;
        mei_hdr.reserved = 0;

        if (*slots >= msg_slots) {
                mei_hdr.length = len;
                mei_hdr.msg_complete = 1;
        /* Split the message only if we can write the whole host buffer */
        } else if (*slots == dev->hbuf_depth) {
                msg_slots = *slots;
                len = (*slots * sizeof(u32)) - sizeof(struct mei_msg_hdr);
                mei_hdr.length = len;
                mei_hdr.msg_complete = 0;
        } else {
                /* wait for next time the host buffer is empty */
                return 0;
        }

        dev_dbg(&dev->pdev->dev, MEI_HDR_FMT,  MEI_HDR_PRM(&mei_hdr));

        *slots -=  msg_slots;
        if (mei_write_message(dev, &mei_hdr,
                dev->iamthif_msg_buf + dev->iamthif_msg_buf_index)) {
                        dev->iamthif_state = MEI_IAMTHIF_IDLE;
                        cl->status = -ENODEV;
                        list_del(&cb->list);
                        return -ENODEV;
        }

        if (mei_cl_flow_ctrl_reduce(cl))
                return -ENODEV;

        dev->iamthif_msg_buf_index += mei_hdr.length;
        cl->status = 0;

        if (mei_hdr.msg_complete) {
                dev->iamthif_state = MEI_IAMTHIF_FLOW_CONTROL;
                dev->iamthif_flow_control_pending = true;

                /* save iamthif cb sent to amthif client */
                cb->buf_idx = dev->iamthif_msg_buf_index;
                dev->iamthif_current_cb = cb;

                list_move_tail(&cb->list, &dev->write_waiting_list.list);
        }


        return 0;
}

/**
 * mei_amthif_irq_read_message - read routine after ISR to
 *                      handle the read amthif message
 *
 * @dev: the device structure
 * @mei_hdr: header of amthif message
 * @complete_list: An instance of our list structure
 *
 * returns 0 on success, <0 on failure.
 */
int mei_amthif_irq_read_msg(struct mei_device *dev,
                            struct mei_msg_hdr *mei_hdr,
                            struct mei_cl_cb *complete_list)
{
        struct mei_cl_cb *cb;
        unsigned char *buffer;

        BUG_ON(mei_hdr->me_addr != dev->iamthif_cl.me_client_id);
        BUG_ON(dev->iamthif_state != MEI_IAMTHIF_READING);

        buffer = dev->iamthif_msg_buf + dev->iamthif_msg_buf_index;
        BUG_ON(dev->iamthif_mtu < dev->iamthif_msg_buf_index + mei_hdr->length);

        mei_read_slots(dev, buffer, mei_hdr->length);

        dev->iamthif_msg_buf_index += mei_hdr->length;

        if (!mei_hdr->msg_complete)
                return 0;

        dev_dbg(&dev->pdev->dev, "amthif_message_buffer_index =%d\n",
                        mei_hdr->length);

        dev_dbg(&dev->pdev->dev, "completed amthif read.\n ");
        if (!dev->iamthif_current_cb)
                return -ENODEV;

        cb = dev->iamthif_current_cb;
        dev->iamthif_current_cb = NULL;

        if (!cb->cl)
                return -ENODEV;

        dev->iamthif_stall_timer = 0;
        cb->buf_idx = dev->iamthif_msg_buf_index;
        cb->read_time = jiffies;
        if (dev->iamthif_ioctl && cb->cl == &dev->iamthif_cl) {
                /* found the iamthif cb */
                dev_dbg(&dev->pdev->dev, "complete the amthif read cb.\n ");
                dev_dbg(&dev->pdev->dev, "add the amthif read cb to complete.\n ");
                list_add_tail(&cb->list, &complete_list->list);
        }
        return 0;
}

/**
 * mei_amthif_irq_read - prepares to read amthif data.
 *
 * @dev: the device structure.
 * @slots: free slots.
 *
 * returns 0, OK; otherwise, error.
 */
int mei_amthif_irq_read(struct mei_device *dev, s32 *slots)
{
        u32 msg_slots = mei_data2slots(sizeof(struct hbm_flow_control));

        if (*slots < msg_slots)
                return -EMSGSIZE;

        *slots -= msg_slots;

        if (mei_hbm_cl_flow_control_req(dev, &dev->iamthif_cl)) {
                dev_dbg(&dev->pdev->dev, "iamthif flow control failed\n");
                return -EIO;
        }

        dev_dbg(&dev->pdev->dev, "iamthif flow control success\n");
        dev->iamthif_state = MEI_IAMTHIF_READING;
        dev->iamthif_flow_control_pending = false;
        dev->iamthif_msg_buf_index = 0;
        dev->iamthif_msg_buf_size = 0;
        dev->iamthif_stall_timer = MEI_IAMTHIF_STALL_TIMER;
        dev->hbuf_is_ready = mei_hbuf_is_ready(dev);
        return 0;
}

/**
 * mei_amthif_complete - complete amthif callback.
 *
 * @dev: the device structure.
 * @cb_pos: callback block.
 */
void mei_amthif_complete(struct mei_device *dev, struct mei_cl_cb *cb)
{
        if (dev->iamthif_canceled != 1) {
                dev->iamthif_state = MEI_IAMTHIF_READ_COMPLETE;
                dev->iamthif_stall_timer = 0;
                memcpy(cb->response_buffer.data,
                                dev->iamthif_msg_buf,
                                dev->iamthif_msg_buf_index);
                list_add_tail(&cb->list, &dev->amthif_rd_complete_list.list);
                dev_dbg(&dev->pdev->dev, "amthif read completed\n");
                dev->iamthif_timer = jiffies;
                dev_dbg(&dev->pdev->dev, "dev->iamthif_timer = %ld\n",
                                dev->iamthif_timer);
        } else {
                mei_amthif_run_next_cmd(dev);
        }

        dev_dbg(&dev->pdev->dev, "completing amthif call back.\n");
        wake_up_interruptible(&dev->iamthif_cl.wait);
}

/**
 * mei_clear_list - removes all callbacks associated with file
 *              from mei_cb_list
 *
 * @dev: device structure.
 * @file: file structure
 * @mei_cb_list: callbacks list
 *
 * mei_clear_list is called to clear resources associated with file
 * when application calls close function or Ctrl-C was pressed
 *
 * returns true if callback removed from the list, false otherwise
 */
static bool mei_clear_list(struct mei_device *dev,
                const struct file *file, struct list_head *mei_cb_list)
{
        struct mei_cl_cb *cb_pos = NULL;
        struct mei_cl_cb *cb_next = NULL;
        bool removed = false;

        /* list all list member */
        list_for_each_entry_safe(cb_pos, cb_next, mei_cb_list, list) {
                /* check if list member associated with a file */
                if (file == cb_pos->file_object) {
                        /* remove member from the list */
                        list_del(&cb_pos->list);
                        /* check if cb equal to current iamthif cb */
                        if (dev->iamthif_current_cb == cb_pos) {
                                dev->iamthif_current_cb = NULL;
                                /* send flow control to iamthif client */
                                mei_hbm_cl_flow_control_req(dev,
                                                        &dev->iamthif_cl);
                        }
                        /* free all allocated buffers */
                        mei_io_cb_free(cb_pos);
                        cb_pos = NULL;
                        removed = true;
                }
        }
        return removed;
}

/**
 * mei_clear_lists - removes all callbacks associated with file
 *
 * @dev: device structure
 * @file: file structure
 *
 * mei_clear_lists is called to clear resources associated with file
 * when application calls close function or Ctrl-C was pressed
 *
 * returns true if callback removed from the list, false otherwise
 */
static bool mei_clear_lists(struct mei_device *dev, struct file *file)
{
        bool removed = false;

        /* remove callbacks associated with a file */
        mei_clear_list(dev, file, &dev->amthif_cmd_list.list);
        if (mei_clear_list(dev, file, &dev->amthif_rd_complete_list.list))
                removed = true;

        mei_clear_list(dev, file, &dev->ctrl_rd_list.list);

        if (mei_clear_list(dev, file, &dev->ctrl_wr_list.list))
                removed = true;

        if (mei_clear_list(dev, file, &dev->write_waiting_list.list))
                removed = true;

        if (mei_clear_list(dev, file, &dev->write_list.list))
                removed = true;

        /* check if iamthif_current_cb not NULL */
        if (dev->iamthif_current_cb && !removed) {
                /* check file and iamthif current cb association */
                if (dev->iamthif_current_cb->file_object == file) {
                        /* remove cb */
                        mei_io_cb_free(dev->iamthif_current_cb);
                        dev->iamthif_current_cb = NULL;
                        removed = true;
                }
        }
        return removed;
}

/**
* mei_amthif_release - the release function
*
*  @dev: device structure
*  @file: pointer to file structure
*
*  returns 0 on success, <0 on error
*/
int mei_amthif_release(struct mei_device *dev, struct file *file)
{
        if (dev->open_handle_count > 0)
                dev->open_handle_count--;

        if (dev->iamthif_file_object == file &&
            dev->iamthif_state != MEI_IAMTHIF_IDLE) {

                dev_dbg(&dev->pdev->dev, "amthif canceled iamthif state %d\n",
                    dev->iamthif_state);
                dev->iamthif_canceled = true;
                if (dev->iamthif_state == MEI_IAMTHIF_READ_COMPLETE) {
                        dev_dbg(&dev->pdev->dev, "run next amthif iamthif cb\n");
                        mei_amthif_run_next_cmd(dev);
                }
        }

        if (mei_clear_lists(dev, file))
                dev->iamthif_state = MEI_IAMTHIF_IDLE;

        return 0;
}