/*
 * Copyright (C) 2010-2012 ARM Limited. All rights reserved.
 * 
 * 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.
 */

/**
 * @file mali_osk_notification.c
 * Implementation of the OS abstraction layer for the kernel device driver
 */

#include "mali_osk.h"
#include "mali_kernel_common.h"

/* needed to detect kernel version specific code */
#include <linux/version.h>

#include <linux/sched.h>
#include <linux/slab.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
#include <linux/semaphore.h>
#else /* pre 2.6.26 the file was in the arch specific location */
#include <asm/semaphore.h>
#endif

/**
 * Declaration of the notification queue object type
 * Contains a linked list of notification pending delivery to user space.
 * It also contains a wait queue of exclusive waiters blocked in the ioctl
 * When a new notification is posted a single thread is resumed.
 */
struct _mali_osk_notification_queue_t_struct
{
	struct semaphore mutex; /**< Mutex protecting the list */
	wait_queue_head_t receive_queue; /**< Threads waiting for new entries to the queue */
	struct list_head head; /**< List of notifications waiting to be picked up */
};

typedef struct _mali_osk_notification_wrapper_t_struct
{
    struct list_head list;           /**< Internal linked list variable */
    _mali_osk_notification_t data;   /**< Notification data */
} _mali_osk_notification_wrapper_t;

_mali_osk_notification_queue_t *_mali_osk_notification_queue_init( void )
{
	_mali_osk_notification_queue_t *	result;

	result = (_mali_osk_notification_queue_t *)kmalloc(sizeof(_mali_osk_notification_queue_t), GFP_KERNEL);
	if (NULL == result) return NULL;

	sema_init(&result->mutex, 1);
	init_waitqueue_head(&result->receive_queue);
	INIT_LIST_HEAD(&result->head);

	return result;
}

_mali_osk_notification_t *_mali_osk_notification_create( u32 type, u32 size )
{
	/* OPT Recycling of notification objects */
    _mali_osk_notification_wrapper_t *notification;

	notification = (_mali_osk_notification_wrapper_t *)kmalloc( sizeof(_mali_osk_notification_wrapper_t) + size, GFP_KERNEL );
    if (NULL == notification)
    {
		MALI_DEBUG_PRINT(1, ("Failed to create a notification object\n"));
		return NULL;
    }

	/* Init the list */
	INIT_LIST_HEAD(&notification->list);

	if (0 != size)
	{
		notification->data.result_buffer = ((u8*)notification) + sizeof(_mali_osk_notification_wrapper_t);
	}
	else
	{
		notification->data.result_buffer = NULL;
	}

	/* set up the non-allocating fields */
	notification->data.notification_type = type;
	notification->data.result_buffer_size = size;

	/* all ok */
    return &(notification->data);
}

void _mali_osk_notification_delete( _mali_osk_notification_t *object )
{
	_mali_osk_notification_wrapper_t *notification;
	MALI_DEBUG_ASSERT_POINTER( object );

    notification = container_of( object, _mali_osk_notification_wrapper_t, data );

	/* Remove from the list */
	list_del(&notification->list);
	/* Free the container */
	kfree(notification);
}

void _mali_osk_notification_queue_term( _mali_osk_notification_queue_t *queue )
{
	MALI_DEBUG_ASSERT_POINTER( queue );

	/* not much to do, just free the memory */
	kfree(queue);
}

void _mali_osk_notification_queue_send( _mali_osk_notification_queue_t *queue, _mali_osk_notification_t *object )
{
	_mali_osk_notification_wrapper_t *notification;
	MALI_DEBUG_ASSERT_POINTER( queue );
	MALI_DEBUG_ASSERT_POINTER( object );

    notification = container_of( object, _mali_osk_notification_wrapper_t, data );

	/* lock queue access */
	down(&queue->mutex);
	/* add to list */
	list_add_tail(&notification->list, &queue->head);
	/* unlock the queue */
	up(&queue->mutex);

	/* and wake up one possible exclusive waiter */
	wake_up(&queue->receive_queue);
}

static int _mali_notification_queue_is_empty( _mali_osk_notification_queue_t *queue )
{
	int ret;

	down(&queue->mutex);
	ret = list_empty(&queue->head);
	up(&queue->mutex);
	return ret;
}

#if MALI_STATE_TRACKING
mali_bool _mali_osk_notification_queue_is_empty( _mali_osk_notification_queue_t *queue )
{
	return _mali_notification_queue_is_empty(queue) ? MALI_TRUE : MALI_FALSE;
}
#endif

_mali_osk_errcode_t _mali_osk_notification_queue_dequeue( _mali_osk_notification_queue_t *queue, _mali_osk_notification_t **result )
{
	_mali_osk_errcode_t ret = _MALI_OSK_ERR_ITEM_NOT_FOUND;
	_mali_osk_notification_wrapper_t *wrapper_object;

	down(&queue->mutex);

	if (!list_empty(&queue->head))
	{
		wrapper_object = list_entry(queue->head.next, _mali_osk_notification_wrapper_t, list);
		*result = &(wrapper_object->data);
		list_del_init(&wrapper_object->list);
		ret = _MALI_OSK_ERR_OK;
	}

	up(&queue->mutex);

	return ret;
}

_mali_osk_errcode_t _mali_osk_notification_queue_receive( _mali_osk_notification_queue_t *queue, _mali_osk_notification_t **result )
{
    /* check input */
	MALI_DEBUG_ASSERT_POINTER( queue );
	MALI_DEBUG_ASSERT_POINTER( result );

    /* default result */
	*result = NULL;

	while (_MALI_OSK_ERR_OK != _mali_osk_notification_queue_dequeue(queue, result))
	{
		if (wait_event_interruptible(queue->receive_queue, !_mali_notification_queue_is_empty(queue)))
		{
			return _MALI_OSK_ERR_RESTARTSYSCALL;
		}
	}

	return _MALI_OSK_ERR_OK; /* all ok */
}
