/*
 *
 * 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/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.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/mei.h>

#include "mei_dev.h"
#include "client.h"

/**
 * mei_open - the open function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * Return: 0 on success, <0 on error
 */
static int mei_open(struct inode *inode, struct file *file)
{
        struct mei_device *dev;
        struct mei_cl *cl;

        int err;

        dev = container_of(inode->i_cdev, struct mei_device, cdev);
        if (!dev)
                return -ENODEV;

        mutex_lock(&dev->device_lock);

        if (dev->dev_state != MEI_DEV_ENABLED) {
                dev_dbg(dev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
                    mei_dev_state_str(dev->dev_state));
                err = -ENODEV;
                goto err_unlock;
        }

        cl = mei_cl_alloc_linked(dev, MEI_HOST_CLIENT_ID_ANY);
        if (IS_ERR(cl)) {
                err = PTR_ERR(cl);
                goto err_unlock;
        }

        file->private_data = cl;

        mutex_unlock(&dev->device_lock);

        return nonseekable_open(inode, file);

err_unlock:
        mutex_unlock(&dev->device_lock);
        return err;
}

/**
 * mei_release - the release function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * Return: 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_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 (mei_cl_is_connected(cl)) {
                cl->state = MEI_FILE_DISCONNECTING;
                cl_dbg(dev, cl, "disconnecting\n");
                rets = mei_cl_disconnect(cl);
        }
        mei_cl_flush_queues(cl, file);
        cl_dbg(dev, cl, "removing\n");

        mei_cl_unlink(cl);

        file->private_data = 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
 *
 * Return: >=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_device *dev;
        struct mei_cl_cb *cb = NULL;
        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 (length == 0) {
                rets = 0;
                goto out;
        }

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

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

        if (list_empty(&cl->rd_completed) && !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,
                                (!list_empty(&cl->rd_completed)) ||
                                (!mei_cl_is_connected(cl)))) {

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

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

        cb = mei_cl_read_cb(cl, file);
        if (!cb) {
                rets = 0;
                goto out;
        }

copy_buffer:
        /* now copy the data to user space */
        if (cb->status) {
                rets = cb->status;
                dev_dbg(dev->dev, "read operation failed %d\n", rets);
                goto free;
        }

        dev_dbg(dev->dev, "buf.size = %d buf.idx= %ld\n",
            cb->buf.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->buf.data + *offset, length)) {
                dev_dbg(dev->dev, "failed to copy data to userland\n");
                rets = -EFAULT;
                goto free;
        }

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

free:
        mei_io_cb_free(cb);

out:
        dev_dbg(dev->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
 *
 * Return: >=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_me_client *me_cl = NULL;
        struct mei_cl_cb *write_cb = NULL;
        struct mei_device *dev;
        unsigned long timeout = 0;
        int rets;

        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;
        }

        me_cl = mei_me_cl_by_uuid_id(dev, &cl->cl_uuid, cl->me_client_id);
        if (!me_cl) {
                rets = -ENOTTY;
                goto out;
        }

        if (length == 0) {
                rets = 0;
                goto out;
        }

        if (length > me_cl->props.max_msg_length) {
                rets = -EFBIG;
                goto out;
        }

        if (!mei_cl_is_connected(cl)) {
                cl_err(dev, cl, "is not connected");
                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)) {
                                *offset = 0;
                                mei_io_cb_free(write_cb);
                                write_cb = NULL;
                        }
                }
        }

        *offset = 0;
        write_cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, file);
        if (!write_cb) {
                rets = -ENOMEM;
                goto out;
        }

        rets = copy_from_user(write_cb->buf.data, ubuf, length);
        if (rets) {
                dev_dbg(dev->dev, "failed to copy data from userland\n");
                rets = -EFAULT;
                goto out;
        }

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

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

        rets = mei_cl_write(cl, write_cb, false);
out:
        mei_me_cl_put(me_cl);
        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
 *
 * @file: private data of the file object
 * @data: IOCTL connect data, input and output parameters
 *
 * Locking: called under "dev->device_lock" lock
 *
 * Return: 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_me_client *me_cl;
        struct mei_cl *cl;
        int rets;

        cl = file->private_data;
        dev = cl->dev;

        if (dev->dev_state != MEI_DEV_ENABLED)
                return -ENODEV;

        if (cl->state != MEI_FILE_INITIALIZING &&
            cl->state != MEI_FILE_DISCONNECTED)
                return  -EBUSY;

        /* find ME client we're trying to connect to */
        me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
        if (!me_cl || me_cl->props.fixed_address) {
                dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
                                &data->in_client_uuid);
                return  -ENOTTY;
        }

        cl->me_client_id = me_cl->client_id;
        cl->cl_uuid = me_cl->props.protocol_name;

        dev_dbg(dev->dev, "Connect to FW Client ID = %d\n",
                        cl->me_client_id);
        dev_dbg(dev->dev, "FW Client - Protocol Version = %d\n",
                        me_cl->props.protocol_version);
        dev_dbg(dev->dev, "FW Client - Max Msg Len = %d\n",
                        me_cl->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->dev, "FW Client is amthi\n");
                if (!mei_cl_is_connected(&dev->iamthif_cl)) {
                        rets = -ENODEV;
                        goto end;
                }
                mei_cl_unlink(cl);

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

                client = &data->out_client_properties;
                client->max_msg_length = me_cl->props.max_msg_length;
                client->protocol_version = me_cl->props.protocol_version;
                rets = dev->iamthif_cl.status;

                goto end;
        }

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

        rets = mei_cl_connect(cl, file);

end:
        mei_me_cl_put(me_cl);
        return rets;
}

/**
 * mei_ioctl - the IOCTL function
 *
 * @file: pointer to file structure
 * @cmd: ioctl command
 * @data: pointer to mei message structure
 *
 * Return: 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;
        int rets;


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

        dev = cl->dev;

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

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

        switch (cmd) {
        case IOCTL_MEI_CONNECT_CLIENT:
                dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
                if (copy_from_user(&connect_data, (char __user *)data,
                                sizeof(struct mei_connect_client_data))) {
                        dev_dbg(dev->dev, "failed to copy data from userland\n");
                        rets = -EFAULT;
                        goto out;
                }

                rets = mei_ioctl_connect_client(file, &connect_data);
                if (rets)
                        goto out;

                /* if all is ok, copying the data back to user. */
                if (copy_to_user((char __user *)data, &connect_data,
                                sizeof(struct mei_connect_client_data))) {
                        dev_dbg(dev->dev, "failed to copy data to userland\n");
                        rets = -EFAULT;
                        goto out;
                }

                break;

        default:
                dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
                rets = -ENOIOCTLCMD;
        }

out:
        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
 *
 * Return: 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
 *
 * Return: poll mask
 */
static unsigned int mei_poll(struct file *file, poll_table *wait)
{
        unsigned long req_events = poll_requested_events(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 (dev->dev_state != MEI_DEV_ENABLED ||
            !mei_cl_is_connected(cl)) {
                mask = POLLERR;
                goto out;
        }

        if (cl == &dev->iamthif_cl) {
                mask = mei_amthif_poll(dev, file, wait);
                goto out;
        }

        if (req_events & (POLLIN | POLLRDNORM)) {
                poll_wait(file, &cl->rx_wait, wait);

                if (!list_empty(&cl->rd_completed))
                        mask |= POLLIN | POLLRDNORM;
                else
                        mei_cl_read_start(cl, 0, file);
        }

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

/**
 * fw_status_show - mei device attribute show method
 *
 * @device: device pointer
 * @attr: attribute pointer
 * @buf:  char out buffer
 *
 * Return: number of the bytes printed into buf or error
 */
static ssize_t fw_status_show(struct device *device,
                struct device_attribute *attr, char *buf)
{
        struct mei_device *dev = dev_get_drvdata(device);
        struct mei_fw_status fw_status;
        int err, i;
        ssize_t cnt = 0;

        mutex_lock(&dev->device_lock);
        err = mei_fw_status(dev, &fw_status);
        mutex_unlock(&dev->device_lock);
        if (err) {
                dev_err(device, "read fw_status error = %d\n", err);
                return err;
        }

        for (i = 0; i < fw_status.count; i++)
                cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%08X\n",
                                fw_status.status[i]);
        return cnt;
}
static DEVICE_ATTR_RO(fw_status);

static struct attribute *mei_attrs[] = {
        &dev_attr_fw_status.attr,
        NULL
};
ATTRIBUTE_GROUPS(mei);

/*
 * 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
};

static struct class *mei_class;
static dev_t mei_devt;
#define MEI_MAX_DEVS  MINORMASK
static DEFINE_MUTEX(mei_minor_lock);
static DEFINE_IDR(mei_idr);

/**
 * mei_minor_get - obtain next free device minor number
 *
 * @dev:  device pointer
 *
 * Return: allocated minor, or -ENOSPC if no free minor left
 */
static int mei_minor_get(struct mei_device *dev)
{
        int ret;

        mutex_lock(&mei_minor_lock);
        ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
        if (ret >= 0)
                dev->minor = ret;
        else if (ret == -ENOSPC)
                dev_err(dev->dev, "too many mei devices\n");

        mutex_unlock(&mei_minor_lock);
        return ret;
}

/**
 * mei_minor_free - mark device minor number as free
 *
 * @dev:  device pointer
 */
static void mei_minor_free(struct mei_device *dev)
{
        mutex_lock(&mei_minor_lock);
        idr_remove(&mei_idr, dev->minor);
        mutex_unlock(&mei_minor_lock);
}

int mei_register(struct mei_device *dev, struct device *parent)
{
        struct device *clsdev; /* class device */
        int ret, devno;

        ret = mei_minor_get(dev);
        if (ret < 0)
                return ret;

        /* Fill in the data structures */
        devno = MKDEV(MAJOR(mei_devt), dev->minor);
        cdev_init(&dev->cdev, &mei_fops);
        dev->cdev.owner = mei_fops.owner;

        /* Add the device */
        ret = cdev_add(&dev->cdev, devno, 1);
        if (ret) {
                dev_err(parent, "unable to add device %d:%d\n",
                        MAJOR(mei_devt), dev->minor);
                goto err_dev_add;
        }

        clsdev = device_create_with_groups(mei_class, parent, devno,
                                           dev, mei_groups,
                                           "mei%d", dev->minor);

        if (IS_ERR(clsdev)) {
                dev_err(parent, "unable to create device %d:%d\n",
                        MAJOR(mei_devt), dev->minor);
                ret = PTR_ERR(clsdev);
                goto err_dev_create;
        }

        ret = mei_dbgfs_register(dev, dev_name(clsdev));
        if (ret) {
                dev_err(clsdev, "cannot register debugfs ret = %d\n", ret);
                goto err_dev_dbgfs;
        }

        return 0;

err_dev_dbgfs:
        device_destroy(mei_class, devno);
err_dev_create:
        cdev_del(&dev->cdev);
err_dev_add:
        mei_minor_free(dev);
        return ret;
}
EXPORT_SYMBOL_GPL(mei_register);

void mei_deregister(struct mei_device *dev)
{
        int devno;

        devno = dev->cdev.dev;
        cdev_del(&dev->cdev);

        mei_dbgfs_deregister(dev);

        device_destroy(mei_class, devno);

        mei_minor_free(dev);
}
EXPORT_SYMBOL_GPL(mei_deregister);

static int __init mei_init(void)
{
        int ret;

        mei_class = class_create(THIS_MODULE, "mei");
        if (IS_ERR(mei_class)) {
                pr_err("couldn't create class\n");
                ret = PTR_ERR(mei_class);
                goto err;
        }

        ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
        if (ret < 0) {
                pr_err("unable to allocate char dev region\n");
                goto err_class;
        }

        ret = mei_cl_bus_init();
        if (ret < 0) {
                pr_err("unable to initialize bus\n");
                goto err_chrdev;
        }

        return 0;

err_chrdev:
        unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
err_class:
        class_destroy(mei_class);
err:
        return ret;
}

static void __exit mei_exit(void)
{
        unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
        class_destroy(mei_class);
        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");