/*
 *
 * 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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/device.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/poll.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <linux/uuid.h>
#include <linux/compat.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>
#include <linux/miscdevice.h>

#include <linux/mei.h>

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

/**
 * mei_open - the open function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 e
 * returns 0 on success, <0 on error
 */
static int mei_open(struct inode *inode, struct file *file)
{
        struct miscdevice *misc = file->private_data;
        struct pci_dev *pdev;
        struct mei_cl *cl;
        struct mei_device *dev;

        int err;

        err = -ENODEV;
        if (!misc->parent)
                goto out;

        pdev = container_of(misc->parent, struct pci_dev, dev);

        dev = pci_get_drvdata(pdev);
        if (!dev)
                goto out;

        mutex_lock(&dev->device_lock);
        err = -ENOMEM;
        cl = mei_cl_allocate(dev);
        if (!cl)
                goto out_unlock;

        err = -ENODEV;
        if (dev->dev_state != MEI_DEV_ENABLED) {
                dev_dbg(&dev->pdev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
                    mei_dev_state_str(dev->dev_state));
                goto out_unlock;
        }
        err = -EMFILE;
        if (dev->open_handle_count >= MEI_MAX_OPEN_HANDLE_COUNT) {
                dev_err(&dev->pdev->dev, "open_handle_count exceded %d",
                        MEI_MAX_OPEN_HANDLE_COUNT);
                goto out_unlock;
        }

        err = mei_cl_link(cl, MEI_HOST_CLIENT_ID_ANY);
        if (err)
                goto out_unlock;

        file->private_data = cl;
        mutex_unlock(&dev->device_lock);

        return nonseekable_open(inode, file);

out_unlock:
        mutex_unlock(&dev->device_lock);
        kfree(cl);
out:
        return err;
}

/**
 * mei_release - the release function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * returns 0 on success, <0 on error
 */
static int mei_release(struct inode *inode, struct file *file)
{
        struct mei_cl *cl = file->private_data;
        struct mei_cl_cb *cb;
        struct mei_device *dev;
        int rets = 0;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        mutex_lock(&dev->device_lock);
        if (cl == &dev->iamthif_cl) {
                rets = mei_amthif_release(dev, file);
                goto out;
        }
        if (cl->state == MEI_FILE_CONNECTED) {
                cl->state = MEI_FILE_DISCONNECTING;
                dev_dbg(&dev->pdev->dev,
                        "disconnecting client host client = %d, "
                    "ME client = %d\n",
                    cl->host_client_id,
                    cl->me_client_id);
                rets = mei_cl_disconnect(cl);
        }
        mei_cl_flush_queues(cl);
        dev_dbg(&dev->pdev->dev, "remove client host client = %d, ME client = %d\n",
            cl->host_client_id,
            cl->me_client_id);

        if (dev->open_handle_count > 0) {
                clear_bit(cl->host_client_id, dev->host_clients_map);
                dev->open_handle_count--;
        }
        mei_cl_unlink(cl);


        /* free read cb */
        cb = NULL;
        if (cl->read_cb) {
                cb = mei_cl_find_read_cb(cl);
                /* Remove entry from read list */
                if (cb)
                        list_del(&cb->list);

                cb = cl->read_cb;
                cl->read_cb = NULL;
        }

        file->private_data = NULL;

        if (cb) {
                mei_io_cb_free(cb);
                cb = NULL;
        }

        kfree(cl);
out:
        mutex_unlock(&dev->device_lock);
        return rets;
}


/**
 * mei_read - the read function.
 *
 * @file: pointer to file structure
 * @ubuf: pointer to user buffer
 * @length: buffer length
 * @offset: data offset in buffer
 *
 * returns >=0 data length on success , <0 on error
 */
static ssize_t mei_read(struct file *file, char __user *ubuf,
                        size_t length, loff_t *offset)
{
        struct mei_cl *cl = file->private_data;
        struct mei_cl_cb *cb_pos = NULL;
        struct mei_cl_cb *cb = NULL;
        struct mei_device *dev;
        int rets;
        int err;


        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        mutex_lock(&dev->device_lock);
        if (dev->dev_state != MEI_DEV_ENABLED) {
                rets = -ENODEV;
                goto out;
        }

        if (cl == &dev->iamthif_cl) {
                rets = mei_amthif_read(dev, file, ubuf, length, offset);
                goto out;
        }

        if (cl->read_cb) {
                cb = cl->read_cb;
                /* read what left */
                if (cb->buf_idx > *offset)
                        goto copy_buffer;
                /* offset is beyond buf_idx we have no more data return 0 */
                if (cb->buf_idx > 0 && cb->buf_idx <= *offset) {
                        rets = 0;
                        goto free;
                }
                /* Offset needs to be cleaned for contiguous reads*/
                if (cb->buf_idx == 0 && *offset > 0)
                        *offset = 0;
        } else if (*offset > 0) {
                *offset = 0;
        }

        err = mei_cl_read_start(cl, length);
        if (err && err != -EBUSY) {
                dev_dbg(&dev->pdev->dev,
                        "mei start read failure with status = %d\n", err);
                rets = err;
                goto out;
        }

        if (MEI_READ_COMPLETE != cl->reading_state &&
                        !waitqueue_active(&cl->rx_wait)) {
                if (file->f_flags & O_NONBLOCK) {
                        rets = -EAGAIN;
                        goto out;
                }

                mutex_unlock(&dev->device_lock);

                if (wait_event_interruptible(cl->rx_wait,
                                MEI_READ_COMPLETE == cl->reading_state ||
                                mei_cl_is_transitioning(cl))) {

                        if (signal_pending(current))
                                return -EINTR;
                        return -ERESTARTSYS;
                }

                mutex_lock(&dev->device_lock);
                if (mei_cl_is_transitioning(cl)) {
                        rets = -EBUSY;
                        goto out;
                }
        }

        cb = cl->read_cb;

        if (!cb) {
                rets = -ENODEV;
                goto out;
        }
        if (cl->reading_state != MEI_READ_COMPLETE) {
                rets = 0;
                goto out;
        }
        /* now copy the data to user space */
copy_buffer:
        dev_dbg(&dev->pdev->dev, "buf.size = %d buf.idx= %ld\n",
            cb->response_buffer.size, cb->buf_idx);
        if (length == 0 || ubuf == NULL || *offset > cb->buf_idx) {
                rets = -EMSGSIZE;
                goto free;
        }

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

        if (copy_to_user(ubuf, cb->response_buffer.data + *offset, length)) {
                rets = -EFAULT;
                goto free;
        }

        rets = length;
        *offset += length;
        if ((unsigned long)*offset < cb->buf_idx)
                goto out;

free:
        cb_pos = mei_cl_find_read_cb(cl);
        /* Remove entry from read list */
        if (cb_pos)
                list_del(&cb_pos->list);
        mei_io_cb_free(cb);
        cl->reading_state = MEI_IDLE;
        cl->read_cb = NULL;
out:
        dev_dbg(&dev->pdev->dev, "end mei read rets= %d\n", rets);
        mutex_unlock(&dev->device_lock);
        return rets;
}
/**
 * mei_write - the write function.
 *
 * @file: pointer to file structure
 * @ubuf: pointer to user buffer
 * @length: buffer length
 * @offset: data offset in buffer
 *
 * returns >=0 data length on success , <0 on error
 */
static ssize_t mei_write(struct file *file, const char __user *ubuf,
                         size_t length, loff_t *offset)
{
        struct mei_cl *cl = file->private_data;
        struct mei_cl_cb *write_cb = NULL;
        struct mei_device *dev;
        unsigned long timeout = 0;
        int rets;
        int id;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        mutex_lock(&dev->device_lock);

        if (dev->dev_state != MEI_DEV_ENABLED) {
                rets = -ENODEV;
                goto out;
        }

        id = mei_me_cl_by_id(dev, cl->me_client_id);
        if (id < 0) {
                rets = -ENODEV;
                goto out;
        }
        if (length > dev->me_clients[id].props.max_msg_length || length <= 0) {
                rets = -EMSGSIZE;
                goto out;
        }

        if (cl->state != MEI_FILE_CONNECTED) {
                dev_err(&dev->pdev->dev, "host client = %d,  is not connected to ME client = %d",
                        cl->host_client_id, cl->me_client_id);
                rets = -ENODEV;
                goto out;
        }
        if (cl == &dev->iamthif_cl) {
                write_cb = mei_amthif_find_read_list_entry(dev, file);

                if (write_cb) {
                        timeout = write_cb->read_time +
                                mei_secs_to_jiffies(MEI_IAMTHIF_READ_TIMER);

                        if (time_after(jiffies, timeout) ||
                            cl->reading_state == MEI_READ_COMPLETE) {
                                *offset = 0;
                                list_del(&write_cb->list);
                                mei_io_cb_free(write_cb);
                                write_cb = NULL;
                        }
                }
        }

        /* free entry used in read */
        if (cl->reading_state == MEI_READ_COMPLETE) {
                *offset = 0;
                write_cb = mei_cl_find_read_cb(cl);
                if (write_cb) {
                        list_del(&write_cb->list);
                        mei_io_cb_free(write_cb);
                        write_cb = NULL;
                        cl->reading_state = MEI_IDLE;
                        cl->read_cb = NULL;
                }
        } else if (cl->reading_state == MEI_IDLE)
                *offset = 0;


        write_cb = mei_io_cb_init(cl, file);
        if (!write_cb) {
                dev_err(&dev->pdev->dev, "write cb allocation failed\n");
                rets = -ENOMEM;
                goto out;
        }
        rets = mei_io_cb_alloc_req_buf(write_cb, length);
        if (rets)
                goto out;

        rets = copy_from_user(write_cb->request_buffer.data, ubuf, length);
        if (rets)
                goto out;

        if (cl == &dev->iamthif_cl) {
                rets = mei_amthif_write(dev, write_cb);

                if (rets) {
                        dev_err(&dev->pdev->dev,
                                "amthif write failed with status = %d\n", rets);
                        goto out;
                }
                mutex_unlock(&dev->device_lock);
                return length;
        }

        rets = mei_cl_write(cl, write_cb, false);
out:
        mutex_unlock(&dev->device_lock);
        if (rets < 0)
                mei_io_cb_free(write_cb);
        return rets;
}

/**
 * mei_ioctl_connect_client - the connect to fw client IOCTL function
 *
 * @dev: the device structure
 * @data: IOCTL connect data, input and output parameters
 * @file: private data of the file object
 *
 * Locking: called under "dev->device_lock" lock
 *
 * returns 0 on success, <0 on failure.
 */
static int mei_ioctl_connect_client(struct file *file,
                        struct mei_connect_client_data *data)
{
        struct mei_device *dev;
        struct mei_client *client;
        struct mei_cl *cl;
        int i;
        int rets;

        cl = file->private_data;
        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        if (dev->dev_state != MEI_DEV_ENABLED) {
                rets = -ENODEV;
                goto end;
        }

        if (cl->state != MEI_FILE_INITIALIZING &&
            cl->state != MEI_FILE_DISCONNECTED) {
                rets = -EBUSY;
                goto end;
        }

        /* find ME client we're trying to connect to */
        i = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
        if (i < 0 || dev->me_clients[i].props.fixed_address) {
                dev_dbg(&dev->pdev->dev, "Cannot connect to FW Client UUID = %pUl\n",
                                &data->in_client_uuid);
                rets = -ENODEV;
                goto end;
        }

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

        dev_dbg(&dev->pdev->dev, "Connect to FW Client ID = %d\n",
                        cl->me_client_id);
        dev_dbg(&dev->pdev->dev, "FW Client - Protocol Version = %d\n",
                        dev->me_clients[i].props.protocol_version);
        dev_dbg(&dev->pdev->dev, "FW Client - Max Msg Len = %d\n",
                        dev->me_clients[i].props.max_msg_length);

        /* if we're connecting to amthif client then we will use the
         * existing connection
         */
        if (uuid_le_cmp(data->in_client_uuid, mei_amthif_guid) == 0) {
                dev_dbg(&dev->pdev->dev, "FW Client is amthi\n");
                if (dev->iamthif_cl.state != MEI_FILE_CONNECTED) {
                        rets = -ENODEV;
                        goto end;
                }
                clear_bit(cl->host_client_id, dev->host_clients_map);
                mei_cl_unlink(cl);

                kfree(cl);
                cl = NULL;
                file->private_data = &dev->iamthif_cl;

                client = &data->out_client_properties;
                client->max_msg_length =
                        dev->me_clients[i].props.max_msg_length;
                client->protocol_version =
                        dev->me_clients[i].props.protocol_version;
                rets = dev->iamthif_cl.status;

                goto end;
        }


        /* prepare the output buffer */
        client = &data->out_client_properties;
        client->max_msg_length = dev->me_clients[i].props.max_msg_length;
        client->protocol_version = dev->me_clients[i].props.protocol_version;
        dev_dbg(&dev->pdev->dev, "Can connect?\n");


        rets = mei_cl_connect(cl, file);

end:
        return rets;
}


/**
 * mei_ioctl - the IOCTL function
 *
 * @file: pointer to file structure
 * @cmd: ioctl command
 * @data: pointer to mei message structure
 *
 * returns 0 on success , <0 on error
 */
static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
{
        struct mei_device *dev;
        struct mei_cl *cl = file->private_data;
        struct mei_connect_client_data *connect_data = NULL;
        int rets;

        if (cmd != IOCTL_MEI_CONNECT_CLIENT)
                return -EINVAL;

        if (WARN_ON(!cl || !cl->dev))
                return -ENODEV;

        dev = cl->dev;

        dev_dbg(&dev->pdev->dev, "IOCTL cmd = 0x%x", cmd);

        mutex_lock(&dev->device_lock);
        if (dev->dev_state != MEI_DEV_ENABLED) {
                rets = -ENODEV;
                goto out;
        }

        dev_dbg(&dev->pdev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");

        connect_data = kzalloc(sizeof(struct mei_connect_client_data),
                                                        GFP_KERNEL);
        if (!connect_data) {
                rets = -ENOMEM;
                goto out;
        }
        dev_dbg(&dev->pdev->dev, "copy connect data from user\n");
        if (copy_from_user(connect_data, (char __user *)data,
                                sizeof(struct mei_connect_client_data))) {
                dev_dbg(&dev->pdev->dev, "failed to copy data from userland\n");
                rets = -EFAULT;
                goto out;
        }

        rets = mei_ioctl_connect_client(file, connect_data);

        /* if all is ok, copying the data back to user. */
        if (rets)
                goto out;

        dev_dbg(&dev->pdev->dev, "copy connect data to user\n");
        if (copy_to_user((char __user *)data, connect_data,
                                sizeof(struct mei_connect_client_data))) {
                dev_dbg(&dev->pdev->dev, "failed to copy data to userland\n");
                rets = -EFAULT;
                goto out;
        }

out:
        kfree(connect_data);
        mutex_unlock(&dev->device_lock);
        return rets;
}

/**
 * mei_compat_ioctl - the compat IOCTL function
 *
 * @file: pointer to file structure
 * @cmd: ioctl command
 * @data: pointer to mei message structure
 *
 * returns 0 on success , <0 on error
 */
#ifdef CONFIG_COMPAT
static long mei_compat_ioctl(struct file *file,
                        unsigned int cmd, unsigned long data)
{
        return mei_ioctl(file, cmd, (unsigned long)compat_ptr(data));
}
#endif


/**
 * mei_poll - the poll function
 *
 * @file: pointer to file structure
 * @wait: pointer to poll_table structure
 *
 * returns poll mask
 */
static unsigned int mei_poll(struct file *file, poll_table *wait)
{
        struct mei_cl *cl = file->private_data;
        struct mei_device *dev;
        unsigned int mask = 0;

        if (WARN_ON(!cl || !cl->dev))
                return POLLERR;

        dev = cl->dev;

        mutex_lock(&dev->device_lock);

        if (!mei_cl_is_connected(cl)) {
                mask = POLLERR;
                goto out;
        }

        mutex_unlock(&dev->device_lock);


        if (cl == &dev->iamthif_cl)
                return mei_amthif_poll(dev, file, wait);

        poll_wait(file, &cl->tx_wait, wait);

        mutex_lock(&dev->device_lock);

        if (!mei_cl_is_connected(cl)) {
                mask = POLLERR;
                goto out;
        }

        if (MEI_WRITE_COMPLETE == cl->writing_state)
                mask |= (POLLIN | POLLRDNORM);

out:
        mutex_unlock(&dev->device_lock);
        return mask;
}

/*
 * file operations structure will be used for mei char device.
 */
static const struct file_operations mei_fops = {
        .owner = THIS_MODULE,
        .read = mei_read,
        .unlocked_ioctl = mei_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl = mei_compat_ioctl,
#endif
        .open = mei_open,
        .release = mei_release,
        .write = mei_write,
        .poll = mei_poll,
        .llseek = no_llseek
};

/*
 * Misc Device Struct
 */
static struct miscdevice  mei_misc_device = {
                .name = "mei",
                .fops = &mei_fops,
                .minor = MISC_DYNAMIC_MINOR,
};


int mei_register(struct mei_device *dev)
{
        int ret;
        mei_misc_device.parent = &dev->pdev->dev;
        ret = misc_register(&mei_misc_device);
        if (ret)
                return ret;

        if (mei_dbgfs_register(dev, mei_misc_device.name))
                dev_err(&dev->pdev->dev, "cannot register debugfs\n");

        return 0;
}
EXPORT_SYMBOL_GPL(mei_register);

void mei_deregister(struct mei_device *dev)
{
        mei_dbgfs_deregister(dev);
        misc_deregister(&mei_misc_device);
        mei_misc_device.parent = NULL;
}
EXPORT_SYMBOL_GPL(mei_deregister);

static int __init mei_init(void)
{
        return mei_cl_bus_init();
}

static void __exit mei_exit(void)
{
        mei_cl_bus_exit();
}

module_init(mei_init);
module_exit(mei_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
MODULE_LICENSE("GPL v2");