/* i915_mem.c -- Simple agp/fb memory manager for i915 -*- linux-c -*-
 */
/*
 * Copyright 2003 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
 * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include "drmP.h"
#include "drm.h"
#include "i915_drm.h"
#include "i915_drv.h"

/* This memory manager is integrated into the global/local lru
 * mechanisms used by the clients.  Specifically, it operates by
 * setting the 'in_use' fields of the global LRU to indicate whether
 * this region is privately allocated to a client.
 *
 * This does require the client to actually respect that field.
 *
 * Currently no effort is made to allocate 'private' memory in any
 * clever way - the LRU information isn't used to determine which
 * block to allocate, and the ring is drained prior to allocations --
 * in other words allocation is expensive.
 */
static void mark_block(struct drm_device * dev, struct mem_block *p, int in_use)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        struct drm_i915_master_private *master_priv = dev->primary->master->driver_priv;
        drm_i915_sarea_t *sarea_priv = master_priv->sarea_priv;
        struct drm_tex_region *list;
        unsigned shift, nr;
        unsigned start;
        unsigned end;
        unsigned i;
        int age;

        shift = dev_priv->tex_lru_log_granularity;
        nr = I915_NR_TEX_REGIONS;

        start = p->start >> shift;
        end = (p->start + p->size - 1) >> shift;

        age = ++sarea_priv->texAge;
        list = sarea_priv->texList;

        /* Mark the regions with the new flag and update their age.  Move
         * them to head of list to preserve LRU semantics.
         */
        for (i = start; i <= end; i++) {
                list[i].in_use = in_use;
                list[i].age = age;

                /* remove_from_list(i)
                 */
                list[(unsigned)list[i].next].prev = list[i].prev;
                list[(unsigned)list[i].prev].next = list[i].next;

                /* insert_at_head(list, i)
                 */
                list[i].prev = nr;
                list[i].next = list[nr].next;
                list[(unsigned)list[nr].next].prev = i;
                list[nr].next = i;
        }
}

/* Very simple allocator for agp memory, working on a static range
 * already mapped into each client's address space.
 */

static struct mem_block *split_block(struct mem_block *p, int start, int size,
                                     struct drm_file *file_priv)
{
        /* Maybe cut off the start of an existing block */
        if (start > p->start) {
                struct mem_block *newblock = kmalloc(sizeof(*newblock),
                                                     GFP_KERNEL);
                if (!newblock)
                        goto out;
                newblock->start = start;
                newblock->size = p->size - (start - p->start);
                newblock->file_priv = NULL;
                newblock->next = p->next;
                newblock->prev = p;
                p->next->prev = newblock;
                p->next = newblock;
                p->size -= newblock->size;
                p = newblock;
        }

        /* Maybe cut off the end of an existing block */
        if (size < p->size) {
                struct mem_block *newblock = kmalloc(sizeof(*newblock),
                                                     GFP_KERNEL);
                if (!newblock)
                        goto out;
                newblock->start = start + size;
                newblock->size = p->size - size;
                newblock->file_priv = NULL;
                newblock->next = p->next;
                newblock->prev = p;
                p->next->prev = newblock;
                p->next = newblock;
                p->size = size;
        }

      out:
        /* Our block is in the middle */
        p->file_priv = file_priv;
        return p;
}

static struct mem_block *alloc_block(struct mem_block *heap, int size,
                                     int align2, struct drm_file *file_priv)
{
        struct mem_block *p;
        int mask = (1 << align2) - 1;

        for (p = heap->next; p != heap; p = p->next) {
                int start = (p->start + mask) & ~mask;
                if (p->file_priv == NULL && start + size <= p->start + p->size)
                        return split_block(p, start, size, file_priv);
        }

        return NULL;
}

static struct mem_block *find_block(struct mem_block *heap, int start)
{
        struct mem_block *p;

        for (p = heap->next; p != heap; p = p->next)
                if (p->start == start)
                        return p;

        return NULL;
}

static void free_block(struct mem_block *p)
{
        p->file_priv = NULL;

        /* Assumes a single contiguous range.  Needs a special file_priv in
         * 'heap' to stop it being subsumed.
         */
        if (p->next->file_priv == NULL) {
                struct mem_block *q = p->next;
                p->size += q->size;
                p->next = q->next;
                p->next->prev = p;
                kfree(q);
        }

        if (p->prev->file_priv == NULL) {
                struct mem_block *q = p->prev;
                q->size += p->size;
                q->next = p->next;
                q->next->prev = q;
                kfree(p);
        }
}

/* Initialize.  How to check for an uninitialized heap?
 */
static int init_heap(struct mem_block **heap, int start, int size)
{
        struct mem_block *blocks = kmalloc(sizeof(*blocks), GFP_KERNEL);

        if (!blocks)
                return -ENOMEM;

        *heap = kmalloc(sizeof(**heap), GFP_KERNEL);
        if (!*heap) {
                kfree(blocks);
                return -ENOMEM;
        }

        blocks->start = start;
        blocks->size = size;
        blocks->file_priv = NULL;
        blocks->next = blocks->prev = *heap;

        memset(*heap, 0, sizeof(**heap));
        (*heap)->file_priv = (struct drm_file *) - 1;
        (*heap)->next = (*heap)->prev = blocks;
        return 0;
}

/* Free all blocks associated with the releasing file.
 */
void i915_mem_release(struct drm_device * dev, struct drm_file *file_priv,
                      struct mem_block *heap)
{
        struct mem_block *p;

        if (!heap || !heap->next)
                return;

        for (p = heap->next; p != heap; p = p->next) {
                if (p->file_priv == file_priv) {
                        p->file_priv = NULL;
                        mark_block(dev, p, 0);
                }
        }

        /* Assumes a single contiguous range.  Needs a special file_priv in
         * 'heap' to stop it being subsumed.
         */
        for (p = heap->next; p != heap; p = p->next) {
                while (p->file_priv == NULL && p->next->file_priv == NULL) {
                        struct mem_block *q = p->next;
                        p->size += q->size;
                        p->next = q->next;
                        p->next->prev = p;
                        kfree(q);
                }
        }
}

/* Shutdown.
 */
void i915_mem_takedown(struct mem_block **heap)
{
        struct mem_block *p;

        if (!*heap)
                return;

        for (p = (*heap)->next; p != *heap;) {
                struct mem_block *q = p;
                p = p->next;
                kfree(q);
        }

        kfree(*heap);
        *heap = NULL;
}

static struct mem_block **get_heap(drm_i915_private_t * dev_priv, int region)
{
        switch (region) {
        case I915_MEM_REGION_AGP:
                return &dev_priv->agp_heap;
        default:
                return NULL;
        }
}

/* IOCTL HANDLERS */

int i915_mem_alloc(struct drm_device *dev, void *data,
                   struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        drm_i915_mem_alloc_t *alloc = data;
        struct mem_block *block, **heap;

        if (!dev_priv) {
                DRM_ERROR("called with no initialization\n");
                return -EINVAL;
        }

        heap = get_heap(dev_priv, alloc->region);
        if (!heap || !*heap)
                return -EFAULT;

        /* Make things easier on ourselves: all allocations at least
         * 4k aligned.
         */
        if (alloc->alignment < 12)
                alloc->alignment = 12;

        block = alloc_block(*heap, alloc->size, alloc->alignment, file_priv);

        if (!block)
                return -ENOMEM;

        mark_block(dev, block, 1);

        if (DRM_COPY_TO_USER(alloc->region_offset, &block->start,
                             sizeof(int))) {
                DRM_ERROR("copy_to_user\n");
                return -EFAULT;
        }

        return 0;
}

int i915_mem_free(struct drm_device *dev, void *data,
                  struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        drm_i915_mem_free_t *memfree = data;
        struct mem_block *block, **heap;

        if (!dev_priv) {
                DRM_ERROR("called with no initialization\n");
                return -EINVAL;
        }

        heap = get_heap(dev_priv, memfree->region);
        if (!heap || !*heap)
                return -EFAULT;

        block = find_block(*heap, memfree->region_offset);
        if (!block)
                return -EFAULT;

        if (block->file_priv != file_priv)
                return -EPERM;

        mark_block(dev, block, 0);
        free_block(block);
        return 0;
}

int i915_mem_init_heap(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        drm_i915_mem_init_heap_t *initheap = data;
        struct mem_block **heap;

        if (!dev_priv) {
                DRM_ERROR("called with no initialization\n");
                return -EINVAL;
        }

        heap = get_heap(dev_priv, initheap->region);
        if (!heap)
                return -EFAULT;

        if (*heap) {
                DRM_ERROR("heap already initialized?");
                return -EFAULT;
        }

        return init_heap(heap, initheap->start, initheap->size);
}

int i915_mem_destroy_heap( struct drm_device *dev, void *data,
                           struct drm_file *file_priv )
{
        drm_i915_private_t *dev_priv = dev->dev_private;
        drm_i915_mem_destroy_heap_t *destroyheap = data;
        struct mem_block **heap;

        if ( !dev_priv ) {
                DRM_ERROR( "called with no initialization\n" );
                return -EINVAL;
        }

        heap = get_heap( dev_priv, destroyheap->region );
        if (!heap) {
                DRM_ERROR("get_heap failed");
                return -EFAULT;
        }

        if (!*heap) {
                DRM_ERROR("heap not initialized?");
                return -EFAULT;
        }

        i915_mem_takedown( heap );
        return 0;
}