/*
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *
 * This program is free software and is provided to you under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation, and any use by you of this program is subject to the terms of such GNU licence.
 *
 * A copy of the licence is included with the program, and can also be obtained from Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/gfp.h>
#include <linux/wait.h>
#include <linux/jiffies.h>
#include <asm/current.h>
#include <linux/sched.h>

#include "slp_global_lock.h"

#if MALI_INTERNAL_TIMELINE_PROFILING_ENABLED
#include "mali_osk.h"
#include "mali_osk_profiling.h"
#endif

#define SGL_WARN(x, y...)	printk(KERN_INFO "[SGL_WARN(%d,%d)](%s):%d " x " \n" , current->tgid, current->pid, __FUNCTION__, __LINE__, ##y)
#define SGL_INFO(x, y...)	printk(KERN_INFO "[SGL_INFO] " x , ##y)

#if 0 /* LOG */

#define SGL_LOG(x, y...)	printk(KERN_INFO "[SGL_LOG(%d,%d)](%s):%d " x " \n" , current->tgid, current->pid, __FUNCTION__, __LINE__, ##y);
#define SGL_DEBUG(x, y...)	printk(KERN_INFO "[SGL_DEBUG(%d,%d)](%s):%d " x " \n" , current->tgid, current->pid, __FUNCTION__, __LINE__, ##y);

#else

#define SGL_LOG(x, y...)
#define SGL_DEBUG(x, y...)

#endif

static struct sgl_global {
	int major;
	struct class		*class;
	struct device		*device;
	void				*locks;			/* global lock table */
	int					refcnt;			/* ref count of sgl_global */
	struct mutex		mutex;
} sgl_global;

struct sgl_session_data {
	void				*inited_locks;	/* per session initialized locks */
	void				*locked_locks;	/* per session locked locks */
};

struct sgl_lock {
	unsigned int		key;			/* key of this lock */
	unsigned int		timeout_ms;		/* timeout in ms */
	unsigned int		refcnt;			/* ref count of initialization */
	wait_queue_head_t	waiting_queue;	/* waiting queue */
	struct list_head	waiting_list;	/* waiting list */
	struct mutex		waiting_list_mutex;
	unsigned int		locked;			/* flag if this lock is locked */
	unsigned int		owner;			/* session data */

	struct mutex		data_mutex;
	unsigned int		user_data1;
	unsigned int		user_data2;

	pid_t			owner_pid;
	pid_t			owner_tid;
};

/**************** hash code start ***************/
#define SGL_HASH_BITS		4
#define SGL_HASH_ENTRIES	(1 << SGL_HASH_BITS)

struct sgl_hash_head {
	struct hlist_head	head;			/* hash_head */
	struct mutex		mutex;
};

struct sgl_hash_node {
	unsigned int		key;			/* key for lock. must be same as lock->key */
	struct sgl_lock		*lock;			/* lock object */
	struct hlist_node	node;			/* hash node */
};

static const char sgl_dev_name[] = "slp_global_lock";

/* find the sgl_lock object with key in the hash table */
static struct sgl_hash_node *sgl_hash_get_node(struct sgl_hash_head *hash, unsigned int key)
{
	struct sgl_hash_head *hash_head = &hash[hash_32(key, SGL_HASH_BITS)];
	struct sgl_hash_node *hash_node = NULL;
	struct sgl_hash_node *found = NULL;

	struct hlist_head *head = &hash_head->head;

	SGL_LOG("key %d", key);

	mutex_lock(&hash_head->mutex);
	hlist_for_each_entry(hash_node, head, node) {
		if (hash_node->key == key) {
			found = hash_node;
			break;
		}
	}
	mutex_unlock(&hash_head->mutex);

	SGL_LOG("hash_node: %p", hash_node);

	return found;
}

/* insert the hash entry */
static struct sgl_hash_node *sgl_hash_insert_node(struct sgl_hash_head *hash, unsigned int key)
{
	struct sgl_hash_head *hash_head = &hash[hash_32(key, SGL_HASH_BITS)];
	struct sgl_hash_node *hash_node;

	struct hlist_head *head = &hash_head->head;

	SGL_LOG("key %d", key);

	hash_node = kzalloc(sizeof(struct sgl_hash_node), GFP_KERNEL);
	if (hash_node == NULL)
		return NULL;

	INIT_HLIST_NODE(&hash_node->node);
	mutex_lock(&hash_head->mutex);
	hlist_add_head(&hash_node->node, head);
	mutex_unlock(&hash_head->mutex);

	hash_node->key = key;

	SGL_LOG();

	return hash_node;
}

/* remove the hash entry */
static int sgl_hash_remove_node(struct sgl_hash_head *hash, unsigned int key)
{
	struct sgl_hash_head *hash_head = &hash[hash_32(key, SGL_HASH_BITS)];
	struct sgl_hash_node *hash_node;

	struct hlist_head *head = &hash_head->head;

	int err = -ENOENT;

	SGL_LOG("key %d", key);

	mutex_lock(&hash_head->mutex);
	hlist_for_each_entry(hash_node, head, node) {
		if (hash_node->key == key) {
			hlist_del(&hash_node->node);
			kfree(hash_node);
			err = 0;
			break;
		}
	}
	mutex_unlock(&hash_head->mutex);

	SGL_LOG();

	return err;
}

static int sgl_hash_cleanup_nodes(struct sgl_hash_head *hash, int (*lock_cleanup_func)(struct sgl_lock *))
{
	struct sgl_hash_node *hash_node;

	struct hlist_head *head;

	int i;
	int err = 0;

	SGL_LOG();

	for (i = 0; i < SGL_HASH_ENTRIES; i++) {
		head = &hash[i].head;
		mutex_lock(&hash->mutex);
		while (!hlist_empty(head)) {
			hash_node = hlist_entry(head->first, struct sgl_hash_node, node);
			if (lock_cleanup_func(hash_node->lock) < 0)
				err = -EBADRQC;
			hlist_del(&hash_node->node);
			kfree(hash_node);
		}
		mutex_unlock(&hash->mutex);
	}

	SGL_LOG();

	return err;
}

/* allocate the hash table */
static struct sgl_hash_head *sgl_hash_create_table(void)
{
	struct sgl_hash_head *hash;

	int i;

	SGL_LOG();

	hash = kzalloc(sizeof(struct sgl_hash_head) * SGL_HASH_ENTRIES, GFP_KERNEL);
	if (hash == NULL)
		return NULL;

	for (i = 0; i < SGL_HASH_ENTRIES; i++) {
		INIT_HLIST_HEAD(&hash[i].head);
		mutex_init(&hash[i].mutex);
	}

	SGL_LOG();

	return hash;
}

/* release the hash table */
static void sgl_hash_destroy_table(struct sgl_hash_head *hash)
{
	SGL_LOG();

	kfree(hash);

	SGL_LOG();

	return;
}

/**************** hash code end ***************/

static struct sgl_lock *sgl_get_lock(void *locks, unsigned int key)
{
	struct sgl_hash_node *hash_node;

	hash_node = sgl_hash_get_node((struct sgl_hash_head *)locks, key);
	if (hash_node == NULL) {
		return NULL;
	}

	return hash_node->lock;
}

static int sgl_insert_lock(void *locks, struct sgl_lock *lock)
{
	struct sgl_hash_node *hash_node;

	hash_node = sgl_hash_insert_node((struct sgl_hash_head *)locks, lock->key);
	if (hash_node == NULL)
		return -ENOMEM;
	hash_node->lock = lock;

	return 0;
}

static int sgl_remove_lock(void *locks, unsigned int key)
{
	int err;

	err = sgl_hash_remove_node((struct sgl_hash_head *)locks, key);

	return err;
}

static int sgl_cleanup_locks(void *locks, int (*lock_cleanup_func)(struct sgl_lock *))
{
	int err = 0;

	err = sgl_hash_cleanup_nodes((struct sgl_hash_head *)locks, lock_cleanup_func);

	return err;
}

static void *sgl_create_locks(void)
{
	return (void *)sgl_hash_create_table();
}

static void sgl_destroy_locks(void *locks)
{
	sgl_hash_destroy_table((struct sgl_hash_head *)locks);
	return;
}
/********** lock - hash glue code end *********/


static int sgl_lock_lock(struct sgl_session_data *session_data, unsigned int key)
{
	struct sgl_lock *lock;

	struct list_head waiting_entry;

	unsigned long jiffies;
	long ret = 0;

	SGL_LOG("key: %d", key);

	mutex_lock(&sgl_global.mutex);
	lock = sgl_get_lock(sgl_global.locks, key);
	if (lock == NULL) {
		if (sgl_get_lock(session_data->inited_locks, key))
			sgl_remove_lock(session_data->inited_locks, key);

		if (sgl_get_lock(session_data->locked_locks, key))
			sgl_remove_lock(session_data->locked_locks, key);
		mutex_unlock(&sgl_global.mutex);
		SGL_WARN("lock is not in the global locks");
		return -ENOENT;
	}

	lock = sgl_get_lock(session_data->inited_locks, key);
	if (lock == NULL) {
		mutex_unlock(&sgl_global.mutex);
		SGL_WARN("lock is not in the inited locks");
		return -ENOENT;
	}
	mutex_unlock(&sgl_global.mutex);

	INIT_LIST_HEAD(&waiting_entry);
	mutex_lock(&lock->data_mutex);
	lock->refcnt++;
	mutex_unlock(&lock->data_mutex);
	mutex_lock(&lock->waiting_list_mutex);
	list_add_tail(&waiting_entry, &lock->waiting_list);
	mutex_unlock(&lock->waiting_list_mutex);

	jiffies = msecs_to_jiffies(lock->timeout_ms);

#if MALI_INTERNAL_TIMELINE_PROFILING_ENABLED
    _mali_osk_profiling_add_event( MALI_PROFILING_EVENT_TYPE_SINGLE |
                               MALI_PROFILING_EVENT_CHANNEL_SOFTWARE |
                               MALI_PROFILING_EVENT_REASON_SINGLE_SW_GLOBAL_TRY_LOCK,
                               _mali_osk_get_pid(), _mali_osk_get_tid(), key, 0, 0);
#endif

	SGL_LOG();

	ret = wait_event_timeout(lock->waiting_queue,
			((lock->locked == 0)
			&& lock->waiting_list.next == &waiting_entry),
			jiffies);
	if (ret == 0) {
		SGL_WARN("timed out, key: %d, owner(%d, %d)",
				key, lock->owner_pid, lock->owner_tid);
		mutex_lock(&lock->data_mutex);
		lock->refcnt--;
		mutex_unlock(&lock->data_mutex);
		mutex_lock(&lock->waiting_list_mutex);
		list_del(&waiting_entry);
		mutex_unlock(&lock->waiting_list_mutex);
		return -ETIMEDOUT;
	}

	SGL_LOG();

	mutex_lock(&lock->data_mutex);
	lock->owner = (unsigned int)session_data;
	lock->locked = 1;
	lock->owner_pid = current->tgid;
	lock->owner_tid = current->pid;
	mutex_unlock(&lock->data_mutex);

	mutex_lock(&lock->waiting_list_mutex);
	list_del(&waiting_entry);
	mutex_unlock(&lock->waiting_list_mutex);

	/* add to the locked lock */
	sgl_insert_lock(session_data->locked_locks, lock);

#if MALI_INTERNAL_TIMELINE_PROFILING_ENABLED
    _mali_osk_profiling_add_event( MALI_PROFILING_EVENT_TYPE_SINGLE |
                               MALI_PROFILING_EVENT_CHANNEL_SOFTWARE |
                               MALI_PROFILING_EVENT_REASON_SINGLE_SW_GLOBAL_LOCK,
                               _mali_osk_get_pid(), _mali_osk_get_tid(), key, 0, 0);
#endif

	SGL_LOG();

	return 0;
}

static int _sgl_unlock_lock(struct sgl_lock *lock)
{
	SGL_LOG();

	if (lock == NULL) {
		SGL_WARN("lock == NULL");
		return -EBADRQC;
	}
	mutex_lock(&lock->data_mutex);

	if (lock->locked == 0) {
		mutex_unlock(&lock->data_mutex);
		SGL_WARN("tried to unlock not-locked lock");
		return -EBADRQC;
	}

	lock->owner = 0;
	lock->locked = 0;
	lock->owner_pid = 0;
	lock->owner_tid = 0;
	lock->refcnt--;

	if (waitqueue_active(&lock->waiting_queue)) {
		wake_up(&lock->waiting_queue);
	}
	mutex_unlock(&lock->data_mutex);

	SGL_LOG();

	return 0;
}

static int sgl_unlock_lock(struct sgl_session_data *session_data, unsigned int key)
{
	struct sgl_lock *lock;

	int err = -ENOENT;

	SGL_LOG("key: %d", key);

	mutex_lock(&sgl_global.mutex);
	lock = sgl_get_lock(sgl_global.locks, key);
	if (lock == NULL) {
		if (sgl_get_lock(session_data->inited_locks, key))
			sgl_remove_lock(session_data->inited_locks, key);

		if (sgl_get_lock(session_data->locked_locks, key))
			sgl_remove_lock(session_data->locked_locks, key);
		mutex_unlock(&sgl_global.mutex);
		SGL_WARN("lock is not in the global locks");
		return -ENOENT;
	}

	lock = sgl_get_lock(session_data->inited_locks, key);
	if (lock == NULL) {
		mutex_unlock(&sgl_global.mutex);
		SGL_WARN("lock is not in the inited locks");
		return -ENOENT;
	}
	mutex_unlock(&sgl_global.mutex);

	mutex_lock(&lock->data_mutex);
	if (lock->owner != (unsigned int)session_data) {
		mutex_unlock(&lock->data_mutex);
		SGL_WARN("tried to unlock the lock not-owned by calling session");
		return -EBADRQC;
	}
	mutex_unlock(&lock->data_mutex);
	sgl_remove_lock(session_data->locked_locks, key);
	err = _sgl_unlock_lock(lock);
	if (err < 0)
		SGL_WARN("_sgl_unlock_lock() failed");

#if MALI_INTERNAL_TIMELINE_PROFILING_ENABLED
    _mali_osk_profiling_add_event( MALI_PROFILING_EVENT_TYPE_SINGLE |
                               MALI_PROFILING_EVENT_CHANNEL_SOFTWARE |
                               MALI_PROFILING_EVENT_REASON_SINGLE_SW_GLOBAL_UNLOCK,
                               _mali_osk_get_pid(), _mali_osk_get_tid(), key, 0, 0);
#endif


	if (err < 0)
		SGL_WARN("sgl_remove_lock() failed");

	SGL_LOG();

	return err;
}

static int sgl_init_lock(struct sgl_session_data *session_data, struct sgl_attribute *attr)
{
	struct sgl_lock *lock;

	int err = 0;

	SGL_LOG("key: %d", attr->key);

	mutex_lock(&sgl_global.mutex);

	lock = sgl_get_lock(sgl_global.locks, attr->key);
	if (lock == NULL) {
		/* allocate and add to the global table if this is the first initialization */
		lock = kzalloc(sizeof(struct sgl_lock), GFP_KERNEL);
		if (lock == NULL) {
			err = -ENOMEM;
			goto out_unlock;
		}

		lock->key = attr->key;

		err = sgl_insert_lock(sgl_global.locks, lock);
		if (err < 0)
			goto out_unlock;

		/* default timeout value is 16ms */
		lock->timeout_ms = attr->timeout_ms ? attr->timeout_ms : 16;

		init_waitqueue_head(&lock->waiting_queue);
		INIT_LIST_HEAD(&lock->waiting_list);
		mutex_init(&lock->waiting_list_mutex);
		mutex_init(&lock->data_mutex);
	}
	mutex_lock(&lock->data_mutex);
	lock->refcnt++;
	mutex_unlock(&lock->data_mutex);

	/* add to the inited locks */
	err = sgl_insert_lock(session_data->inited_locks, lock);

out_unlock:

	mutex_unlock(&sgl_global.mutex);

	SGL_LOG();

	return err;
}

static int _sgl_destroy_lock(struct sgl_lock *lock)
{
	int err = 0;

	SGL_LOG();

	if (lock == NULL) {
		SGL_WARN("lock == NULL");
		return -EBADRQC;
	}

	mutex_lock(&lock->data_mutex);
	lock->refcnt--;
	if (lock->refcnt == 0) {
		mutex_unlock(&lock->data_mutex);
		err = sgl_remove_lock(sgl_global.locks, lock->key);
		if (err < 0)
			return err;

		kfree(lock);
	} else
		mutex_unlock(&lock->data_mutex);

	SGL_LOG();

	return err;
}

static int sgl_destroy_lock(struct sgl_session_data *session_data, unsigned int key)
{
	struct sgl_lock *lock;

	int err = 0;

	SGL_LOG();

	mutex_lock(&sgl_global.mutex);

	lock = sgl_get_lock(sgl_global.locks, key);
	if (lock == NULL) {
		SGL_WARN("lock is not in the global locks");
		err = -ENOENT;
		goto out_unlock;
	}
	if (!sgl_get_lock(session_data->inited_locks, key)) {
		SGL_WARN("lock is not in the inited locks");
		err = -ENOENT;
		goto out_unlock;
	}

	/* check if lock is still locked */
	if (sgl_get_lock(session_data->locked_locks, key)) {
		SGL_WARN("destroy failed. lock is still locked");
		err = -EBUSY;
		goto out_unlock;
	}

	err = _sgl_destroy_lock(lock);
	if (err < 0)
		goto out_unlock;

	/* remove from the inited lock */
	err = sgl_remove_lock(session_data->inited_locks, key);
	if (err < 0)
		goto out_unlock;

out_unlock:

	mutex_unlock(&sgl_global.mutex);

	SGL_LOG();

	return err;
}

static int sgl_set_data(struct sgl_session_data *session_data, struct sgl_user_data *user_data)
{
	struct sgl_lock *lock;
	int ret = 0;
	unsigned int key = user_data->key;

	SGL_LOG("key: %d", key);

	mutex_lock(&sgl_global.mutex);

	lock = sgl_get_lock(sgl_global.locks, key);
	if (lock == NULL) {
		SGL_WARN("lock is not in the inited locks");
		mutex_unlock(&sgl_global.mutex);
		return -ENOENT;
	}
	mutex_lock(&lock->data_mutex);
	lock->user_data1 = user_data->data1;
	lock->user_data2 = user_data->data2;
	user_data->locked = lock->locked;
	mutex_unlock(&lock->data_mutex);
	mutex_unlock(&sgl_global.mutex);

	SGL_LOG();

	return ret;
}

static int sgl_get_data(struct sgl_session_data *session_data, struct sgl_user_data *user_data)
{
	struct sgl_lock *lock;
	int ret = 0;
	unsigned int key = user_data->key;

	SGL_LOG("key: %d", key);
	mutex_lock(&sgl_global.mutex);

	lock = sgl_get_lock(sgl_global.locks, key);
	if (lock == NULL) {
		SGL_WARN("lock is not in the inited locks");
		mutex_unlock(&sgl_global.mutex);
		return -ENOENT;
	}
	mutex_lock(&lock->data_mutex);
	user_data->data1 = lock->user_data1;
	user_data->data2 = lock->user_data2;
	user_data->locked = lock->locked;
	mutex_unlock(&lock->data_mutex);
	mutex_unlock(&sgl_global.mutex);

	SGL_LOG();

	return ret;
}

static void sgl_dump_locks(void)
{
	int i;
	SGL_INFO("SLP_GLOBAL_LOCK DUMP START\n");
	mutex_lock(&sgl_global.mutex);
	for (i = 0; i < SGL_HASH_ENTRIES; i++) {
		struct sgl_hash_head *shead;
		struct sgl_hash_node *snode;
		struct hlist_head *hhead;

		shead = &((struct sgl_hash_head *)sgl_global.locks)[i];
		if (!shead)
			continue;
		mutex_lock(&shead->mutex);
		hhead = &shead->head;
		hlist_for_each_entry(snode, hhead, node) {
			struct sgl_lock *lock = snode->lock;
			mutex_lock(&lock->data_mutex);
			SGL_INFO("lock key: %d, refcnt: %d, owner_pid: %d, owner_tid: %d\n",
					lock->key, lock->refcnt, lock->owner_pid, lock->owner_tid);
			mutex_unlock(&lock->data_mutex);
		}
		mutex_unlock(&shead->mutex);
	}
	mutex_unlock(&sgl_global.mutex);
	SGL_INFO("SLP_GLOBAL_LOCK DUMP END\n");
}

#ifdef HAVE_UNLOCKED_IOCTL
static long sgl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
#else
static int sgl_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
#endif
{
	struct sgl_session_data *session_data = (struct sgl_session_data *)file->private_data;

	int err = 0;

	SGL_LOG();

	switch (cmd) {
	case SGL_IOC_INIT_LOCK:
		/* destroy lock with attribute */
		err = sgl_init_lock(session_data, (struct sgl_attribute *)arg);
		break;
	case SGL_IOC_DESTROY_LOCK:
		/* destroy lock with id(=arg) */
		err = sgl_destroy_lock(session_data, (unsigned int)arg);
		break;
	case SGL_IOC_LOCK_LOCK:
		/* lock lock with id(=arg) */
		err = sgl_lock_lock(session_data, (unsigned int)arg);
		break;
	case SGL_IOC_UNLOCK_LOCK:
		/* unlock lock with id(=arg) */
		err = sgl_unlock_lock(session_data, (unsigned int)arg);
		break;
	case SGL_IOC_SET_DATA:
		err = sgl_set_data(session_data, (struct sgl_user_data *)arg);
		break;
	case SGL_IOC_GET_DATA:
		err = sgl_get_data(session_data, (struct sgl_user_data *)arg);
		break;
	case SGL_IOC_DUMP_LOCKS:
		sgl_dump_locks();
		break;
	default:
			SGL_WARN("unknown type of ioctl command");
		break;
	}

	SGL_LOG();

    return err;
}

static int sgl_open(struct inode *inode, struct file *file)
{
	struct sgl_session_data *session_data;

	SGL_LOG();

	/* init per thread data using file->private_data*/
	session_data = kzalloc(sizeof(struct sgl_session_data), GFP_KERNEL);
	if (session_data == NULL)
		goto err_session_data;

	session_data->inited_locks = sgl_create_locks();
	if (session_data->inited_locks == NULL) {
		goto err_inited_locks;
	}

	session_data->locked_locks = sgl_create_locks();
	if (session_data->locked_locks == NULL) {
		goto err_locked_locks;
	}

	file->private_data = (void *)session_data;

	sgl_global.refcnt++;

	SGL_LOG();

    return 0;

err_locked_locks:
	sgl_destroy_locks(session_data->inited_locks);
err_inited_locks:
	kfree(session_data);
err_session_data:
	SGL_WARN();
	return -ENOMEM;
}

static int sgl_release(struct inode *inode, struct file *file)
{
	struct sgl_session_data *session_data = file->private_data;

	int err = 0;

	SGL_LOG();

	mutex_lock(&sgl_global.mutex);

	/* clean up the locked locks */
	if (sgl_cleanup_locks(session_data->locked_locks, _sgl_unlock_lock))
		SGL_WARN("clean-up locked locks failed");

	/* clean up the inited locks */
	if (sgl_cleanup_locks(session_data->inited_locks, _sgl_destroy_lock))
		SGL_WARN("clean-up inited locks failed");

	/* clean up per thread data */
	file->private_data = NULL;

	sgl_destroy_locks(session_data->locked_locks);
	sgl_destroy_locks(session_data->inited_locks);

	kfree(session_data);

	mutex_unlock(&sgl_global.mutex);
	sgl_global.refcnt--;
	if (sgl_global.refcnt == 0) {
		/* destroy global lock table */
		sgl_destroy_locks(sgl_global.locks);

	    device_destroy(sgl_global.class, MKDEV(sgl_global.major, 0));
	    class_destroy(sgl_global.class);
	    unregister_chrdev(sgl_global.major, sgl_dev_name);
	}

	SGL_LOG();

    return err;
}

static const struct file_operations sgl_ops = {
	.owner = THIS_MODULE,
    .open = sgl_open,
    .release = sgl_release,
#ifdef HAVE_UNLOCKED_IOCTL
	.unlocked_ioctl = sgl_ioctl,
#else
	.ioctl = sgl_ioctl,
#endif
};

static int __init sgl_init(void)
{
	int err = 0;

	SGL_LOG();

	memset(&sgl_global, 0, sizeof(struct sgl_global));

	sgl_global.major = SGL_MAJOR;
	err = register_chrdev(sgl_global.major, sgl_dev_name, &sgl_ops);
	if (err < 0)
		goto err_register_chrdev;

    sgl_global.class = class_create(THIS_MODULE, sgl_dev_name);
	if (IS_ERR(sgl_global.class)) {
		err = PTR_ERR(sgl_global.class);
		goto err_class_create;
	}

    sgl_global.device = device_create(sgl_global.class, NULL, MKDEV(sgl_global.major, 0), NULL, sgl_dev_name);
	if (IS_ERR(sgl_global.device)) {
		err = PTR_ERR(sgl_global.device);
		goto err_device_create;
	}

	/* create the global lock table */
	sgl_global.locks = sgl_create_locks();
	if (sgl_global.locks == NULL) {
		err = -ENOMEM;
		goto err_create_locks;
	}

	mutex_init(&sgl_global.mutex);

	sgl_global.refcnt++;

	SGL_LOG();

    return 0;

err_create_locks:
err_device_create:
    class_unregister(sgl_global.class);
err_class_create:
    unregister_chrdev(sgl_global.major, sgl_dev_name);
err_register_chrdev:
	SGL_WARN();
	return err;
}

void sgl_exit(void)
{
	SGL_LOG();

	sgl_global.refcnt--;
	if (sgl_global.refcnt == 0) {
		mutex_destroy(&sgl_global.mutex);

		/* destroy global lock table */
		sgl_destroy_locks(sgl_global.locks);

	    device_destroy(sgl_global.class, MKDEV(sgl_global.major, 0));
	    class_destroy(sgl_global.class);
	    unregister_chrdev(sgl_global.major, sgl_dev_name);
	}

	SGL_LOG();

    return;
}

module_init(sgl_init);
module_exit(sgl_exit);

MODULE_LICENSE("GPL");