/*
 * Copyright (C) 2010-2015 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"

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

/**
 * 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 {
        spinlock_t 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;

        spin_lock_init(&result->mutex);
        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 | __GFP_HIGH | __GFP_REPEAT);
        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);

        /* Free the container */
        kfree(notification);
}

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

        while (_MALI_OSK_ERR_OK == _mali_osk_notification_queue_dequeue(queue, &result)) {
                _mali_osk_notification_delete(result);
        }

        /* 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)
{
#if defined(MALI_UPPER_HALF_SCHEDULING)
        unsigned long irq_flags;
#endif

        _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);

#if defined(MALI_UPPER_HALF_SCHEDULING)
        spin_lock_irqsave(&queue->mutex, irq_flags);
#else
        spin_lock(&queue->mutex);
#endif

        list_add_tail(&notification->list, &queue->head);

#if defined(MALI_UPPER_HALF_SCHEDULING)
        spin_unlock_irqrestore(&queue->mutex, irq_flags);
#else
        spin_unlock(&queue->mutex);
#endif

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

_mali_osk_errcode_t _mali_osk_notification_queue_dequeue(_mali_osk_notification_queue_t *queue, _mali_osk_notification_t **result)
{
#if defined(MALI_UPPER_HALF_SCHEDULING)
        unsigned long irq_flags;
#endif

        _mali_osk_errcode_t ret = _MALI_OSK_ERR_ITEM_NOT_FOUND;
        _mali_osk_notification_wrapper_t *wrapper_object;

#if defined(MALI_UPPER_HALF_SCHEDULING)
        spin_lock_irqsave(&queue->mutex, irq_flags);
#else
        spin_lock(&queue->mutex);
#endif

        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;
        }

#if defined(MALI_UPPER_HALF_SCHEDULING)
        spin_unlock_irqrestore(&queue->mutex, irq_flags);
#else
        spin_unlock(&queue->mutex);
#endif

        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;

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

        return _MALI_OSK_ERR_OK; /* all ok */
}