/* i915_mem.c -- Simple agp/fb memory manager for i915 -*- linux-c -*-
 */
/**************************************************************************
 * 
 * Copyright 2003 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 * 
 **************************************************************************/

#include "i915.h"
#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( drm_device_t *dev, struct mem_block *p,
			int in_use )
{
   drm_i915_private_t *dev_priv = dev->dev_private;
   drm_i915_sarea_t *sarea_priv = dev_priv->sarea_priv;
   drm_tex_region_t *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,
				     DRMFILE filp )
{
	/* Maybe cut off the start of an existing block */
	if (start > p->start) {
		struct mem_block *newblock = DRM_MALLOC(sizeof(*newblock));
		if (!newblock) 
			goto out;
		newblock->start = start;
		newblock->size = p->size - (start - p->start);
		newblock->filp = 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 = DRM_MALLOC(sizeof(*newblock));
		if (!newblock)
			goto out;
		newblock->start = start + size;
		newblock->size = p->size - size;
		newblock->filp = 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->filp = filp;
	return p;
}

static struct mem_block *alloc_block( struct mem_block *heap, int size, 
				      int align2, DRMFILE filp )
{
	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->filp == NULL && start + size <= p->start + p->size)
			return split_block( p, start, size, filp );
	}

	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->filp = NULL;

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

	if (p->prev->filp == NULL) {
		struct mem_block *q = p->prev;
		q->size += p->size;
		q->next = p->next;
		q->next->prev = q;
		DRM_FREE(p, sizeof(*q));
	}
}

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

	if (!blocks) 
		return -ENOMEM;
	
	*heap = DRM_MALLOC(sizeof(**heap));
	if (!*heap) {
		DRM_FREE( blocks, sizeof(*blocks) );
		return -ENOMEM;
	}

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

	memset( *heap, 0, sizeof(**heap) );
	(*heap)->filp = (DRMFILE) -1;
	(*heap)->next = (*heap)->prev = blocks;
	return 0;
}


/* Free all blocks associated with the releasing file.
 */
void i915_mem_release( drm_device_t *dev, 
		       DRMFILE filp, struct mem_block *heap )
{
	struct mem_block *p;

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

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

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

	DRM_FREE( *heap, sizeof(**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( DRM_IOCTL_ARGS )
{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_alloc_t alloc;
	struct mem_block *block, **heap;

	if ( !dev_priv ) {
		DRM_ERROR( "%s called with no initialization\n", __FUNCTION__ );
		return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL( alloc, (drm_i915_mem_alloc_t __user *)data,
				  sizeof(alloc) );

	heap = get_heap( dev_priv, alloc.region );
	if (!heap || !*heap)
		return DRM_ERR(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,
			     filp );

	if (!block) 
		return DRM_ERR(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 DRM_ERR(EFAULT);
	}
	
	return 0;
}



int i915_mem_free( DRM_IOCTL_ARGS )
{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_free_t memfree;
	struct mem_block *block, **heap;

	if ( !dev_priv ) {
		DRM_ERROR( "%s called with no initialization\n", __FUNCTION__ );
		return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL( memfree, (drm_i915_mem_free_t __user *)data,
				  sizeof(memfree) );

	heap = get_heap( dev_priv, memfree.region );
	if (!heap || !*heap)
		return DRM_ERR(EFAULT);
	
	block = find_block( *heap, memfree.region_offset );
	if (!block)
		return DRM_ERR(EFAULT);

	if (block->filp != filp)
		return DRM_ERR(EPERM);

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

int i915_mem_init_heap( DRM_IOCTL_ARGS )
{
	DRM_DEVICE;
	drm_i915_private_t *dev_priv = dev->dev_private;
	drm_i915_mem_init_heap_t initheap;
	struct mem_block **heap;

	if ( !dev_priv ) {
		DRM_ERROR( "%s called with no initialization\n", __FUNCTION__ );
		return DRM_ERR(EINVAL);
	}

	DRM_COPY_FROM_USER_IOCTL( initheap, (drm_i915_mem_init_heap_t __user *)data,
				  sizeof(initheap) );

	heap = get_heap( dev_priv, initheap.region );
	if (!heap) 
		return DRM_ERR(EFAULT);
	
	if (*heap) {
		DRM_ERROR("heap already initialized?");
		return DRM_ERR(EFAULT);
	}
		
	return init_heap( heap, initheap.start, initheap.size );
}