/*
 * TIMA Uevent Support
 *
 */
#include <asm/uaccess.h>
#include <linux/list.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/syscalls.h>

#include "tima_uevent.h"

// Forward declaration
struct inode;

// Global declaration
static DEFINE_MUTEX(tima_uevent_mutex);

static struct class *tima_uevent_class;
struct device *tima_uevent_dev;
EXPORT_SYMBOL_GPL(tima_uevent_dev);

static LIST_HEAD(tima_uevent_list);
static DEFINE_SPINLOCK(tima_uevent_list_lock);

static ssize_t show_tima_uevent(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    if (!dev)
        return -ENODEV;

    // TODO: extract TIMA uevent from the uevent list
    return sprintf(buf, "%s\n", "TIMA uevent data");
}

static DEVICE_ATTR(name, S_IRUGO, show_tima_uevent, NULL);

static int
tima_uevent_release(struct inode *inode, struct file *file)
{
    printk(KERN_WARNING
            "%s TIMA uevent driver is released.",
            __func__);
    module_put(THIS_MODULE);
    return 0;
}

static bool
tima_uevent_validate(void)
{
    printk(KERN_ERR
            "Validate caller (%s)",
            current->comm);
    return true;
}

static ssize_t
tima_uevent_read(struct file *filp, char __user *buff,
        size_t len, loff_t * offset)
{
    char tima_uevent[80] = "TIMA uevent read";
    char *data;
    int size = strlen(tima_uevent);
    int retval = 0;

    if ( !tima_uevent_validate() ) {
        printk(KERN_ERR
                "%s invalid request.\n",
                __func__);
        return -EPERM;
    }

    data = kzalloc(sizeof(tima_uevent), GFP_KERNEL);
    if (!data) {
        printk(KERN_ERR
                "%s out of memory.\n",
                __func__);
        return -ENOMEM;
    }

    spin_lock(&tima_uevent_list_lock);
    snprintf(data, size, "%c%s", size - 2, tima_uevent);
    if ( copy_to_user(buff, data, size) ) {
        retval = -EFAULT;
        goto out;
    }

out:
    spin_unlock(&tima_uevent_list_lock);
    kfree(data);
	if (retval) {
		return retval;
	} else {
		return size;
	}
}

static ssize_t
tima_uevent_write(struct file *filp, const char __user *buff,
        size_t len, loff_t * off)
{
    int retval = 0;
    char *req;

    if ( !tima_uevent_validate() ) {
        printk(KERN_ERR
                "%s invalid request.\n",
                __func__);
        return -EPERM;
    }

    req = kzalloc(256, GFP_KERNEL);
    if (!req) {
        printk(KERN_ERR
                "%s out of memory.\n",
                __func__);
        return -ENOMEM;
    }

    /* Copy from user with truncation. */
    if ( copy_from_user(req, buff, min((size_t)256, len)) ) {
        printk(KERN_ERR
                "%s copy_from_user failed.\n",
                __func__);
        retval = -EFAULT;
        goto out;
    }

    /* Terminate the request string if it has been truncated. */
    if (len > 255)
        req[255] = '\0';

    printk(KERN_DEBUG "%s TIMA uevent request (%s).\n", __func__, req);

out:
    kfree(req);
    return retval;
}

static struct file_operations tima_uevent_fops = {
    .owner = THIS_MODULE,
    .read = tima_uevent_read,
    .write = tima_uevent_write,
    .release = tima_uevent_release
};

struct miscdevice tima_uevent_mdev = {
    .minor = MISC_DYNAMIC_MINOR,
    .name = TIMA_UEVENT_DEV,
    .fops = &tima_uevent_fops,
};

static int __init tima_uevent_init(void)
{
    int retval = 0;

    retval = misc_register(&tima_uevent_mdev);
    if (retval)
        goto out;

    printk(KERN_ALERT "%s\n", __func__);
    tima_uevent_class = class_create(THIS_MODULE, "tima");
    if (IS_ERR(tima_uevent_class)) {
        retval = PTR_ERR(tima_uevent_class);
        goto error;
    }

    tima_uevent_dev = device_create(tima_uevent_class,
            NULL /* parent */, 0 /* dev_t */, NULL /* drvdata */,
            TIMA_UEVENT_DEV);
    if (IS_ERR(tima_uevent_dev)) {
        retval = PTR_ERR(tima_uevent_dev);
        goto error_destroy;
    }

    /* register this tima device with the driver core */
    retval = device_create_file(tima_uevent_dev, &dev_attr_name);
    if (retval)
        goto error_destroy;

    printk(KERN_DEBUG "TIMA uevent driver (%s) is initialized.\n", TIMA_UEVENT_DEV);
    return 0;

error_destroy:
    kfree(tima_uevent_dev);
    device_destroy(tima_uevent_class, 0);
error:
    misc_deregister(&tima_uevent_mdev);
out:
    printk(KERN_ERR "%s: TIMA uevent driver initialization failed\n", __FILE__);
    return retval;
}

static void __exit tima_uevent_exit (void)
{
    class_destroy(tima_uevent_class);
    printk(KERN_ALERT "%s\n", __func__);
}

MODULE_AUTHOR("Ken Chen, geng.c@sta.samsung.com");
MODULE_DESCRIPTION("TIMA uevent driver");
MODULE_VERSION("0.1");

module_init(tima_uevent_init);
module_exit(tima_uevent_exit);

/* char *envp[2]; */
/* env[0] = data */
/* env[1] = NULL */
/* kobject_uevent_env(&tima_uevent_dev->kobj, KOBJ_CHANGE, envp); */