/*
 *
 * handshake_client.c
 * Description:
 * handshake mrpc client driver
 *
 *
 * GPL LICENSE SUMMARY
 *
 *  Copyright(c) 2016 Intel Corporation.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of version 2 of the GNU General Public License as
 *  published by the Free Software Foundation.
 *
 *  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., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *  The full GNU General Public License is included in this distribution
 *  in the file called LICENSE.GPL.
 *
 *  Contact Information:
 *  Intel Corporation
 *  2200 Mission College Blvd.
 *  Santa Clara, CA  97052
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s:%d " fmt "\n", __func__, __LINE__

/************************************************/
/**                    Includes                 */
/************************************************/
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/byteorder/generic.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/err.h>
#include <linux/netdevice.h>
#include <linux/mrpc.h>

#ifdef DEBUG
#define DBG(fmt, ...) pr_err(fmt, ##__VA_ARGS__)
#else
#define DBG(fmt, ...) pr_debug(fmt, ##__VA_ARGS__)
#endif

#define HANDSHAKE_CLIENT_NAME "handshake_client"

/* driver private database */
struct handshake_private {
    struct platform_device *pdev;   /* platform device */
    struct mrpc_client *mrpc;       /* mrpc client handle */
};

static struct handshake_private *this;

static inline int handshake_mrpc_poll(void)
{
    struct handshake_private *priv = this;
    int status, ret, errcode;

    if (!priv) {
        pr_err("ERROR: mrpc handshake not initialized");
        return -1;
    }

    ret = mrpc_call(priv->mrpc, 0, NULL, 0, &status, sizeof(status), 0, &errcode);

    if (ret || errcode) {
        pr_err("ERROR: ret=%d, errcode=%d", ret, errcode);
        return -2;
    }

    return ntohl(status);
}

static ssize_t status_show(struct device *dev,
                           struct device_attribute *attr, char *buf)
{
    struct handshake_private *priv = dev_get_drvdata(dev);
    int ret;

    if (!priv)
        return -EINVAL;
    ret = handshake_mrpc_poll();
    return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
}

static DEVICE_ATTR(status, S_IRUGO, status_show, NULL);

static struct attribute *handshake_attrs[] = {
    &dev_attr_status.attr,
    NULL
};

static struct attribute_group handshake_attrs_group = {
    .attrs = handshake_attrs,
};

/**
 * handshake_mrpc_probe
 *
 * @param pdev   platform device
 *
 * @return 0 for success, error code otherwise
 */
static int handshake_mrpc_probe(struct platform_device *pdev)
{
    struct handshake_private *priv;
    int ret;

    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
    if (!priv) {
        pr_err("memory allocation failed");
        return -ENOMEM;
    }

    dev_set_drvdata(&pdev->dev, priv);
    priv->pdev = pdev;

    ret = sysfs_create_group(&priv->pdev->dev.kobj, &handshake_attrs_group);
    if (ret) {
        pr_err("sysfs_create_group failed (ret=%d)", ret);
        return ret;
    }

    priv->mrpc = mrpc_client_register(MRPC_RESERVED_ID_HANDSHAKE, HANDSHAKE_CLIENT_NAME);
    if (!priv->mrpc) {
        pr_err("failed to register handshake");
        ret = -ENODEV;
        goto out_remove_group;
    }

    this = priv;
    return 0;

out_remove_group:
    sysfs_remove_group(&priv->pdev->dev.kobj, &handshake_attrs_group);
    return 0;
}

/**
 * handshake_mrpc_remove
 *
 * This function is called when the handshake mrpc driver is
 * removed.
 *
 * @param pdev   platform device
 *
 * @return 0 for success, error code otherwise
 */
static int handshake_mrpc_remove(struct platform_device *pdev)
{
    struct handshake_private *priv = platform_get_drvdata(pdev);
    mrpc_client_unregister(priv->mrpc);
    sysfs_remove_group(&priv->pdev->dev.kobj, &handshake_attrs_group);
    dev_set_drvdata(&pdev->dev, NULL);
    this = NULL;

    return 0;
}

static struct platform_driver handshake_driver = {
    .driver = {
        .name   = HANDSHAKE_CLIENT_NAME,
    },
    .probe = handshake_mrpc_probe,
    .remove = handshake_mrpc_remove,
};

static struct platform_device *handshake_device;

static int handshake_mrpc_init(void)
{
    int ret;

    ret = platform_driver_register(&handshake_driver);
    if (ret < 0) {
        pr_err("Failed to register handshake platform driver: %d\n", ret);
        return ret;
    }

    pr_debug("handshake client platform driver is registered");

    handshake_device = platform_device_register_simple(HANDSHAKE_CLIENT_NAME, -1, NULL, 0);
    if (IS_ERR(handshake_device)) {
        ret = PTR_ERR(handshake_device);
        pr_err("Failed to register handshake platform device: %d\n", ret);
        platform_driver_unregister(&handshake_driver);
        return ret;
    }

    dev_info(&handshake_device->dev, "platform device is registered\n");

    return 0;
}

static void __exit handshake_mrpc_exit(void)
{
    platform_device_unregister(handshake_device);
    platform_driver_unregister(&handshake_driver);
}

/******************************************************/
/**    Module Declarations                           **/
/******************************************************/
static_notifier_module_init(mrpc_ready, handshake_mrpc_init);
module_exit(handshake_mrpc_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_AUTHOR("Tzviel Lemberger tzviel.lemberger@intel.com");
MODULE_DESCRIPTION("handshake mrpc client");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.0");