/**************************************************************************
*
* Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
* 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
* THE COPYRIGHT HOLDERS, AUTHORS 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.
*
*
**************************************************************************/
/*
* Generic simple memory manager implementation. Intended to be used as a base
* class implementation for more advanced memory managers.
*
* Note that the algorithm used is quite simple and there might be substantial
* performance gains if a smarter free list is implemented. Currently it is just an
* unordered stack of free regions. This could easily be improved if an RB-tree
* is used instead. At least if we expect heavy fragmentation.
*
* Aligned allocations can also see improvement.
*
* Authors:
* Thomas Hellström <thomas-at-tungstengraphics-dot-com>
*/
#include <drm/drmP.h>
#include <drm/drm_mm.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/export.h>
/**
* DOC: Overview
*
* drm_mm provides a simple range allocator. The drivers are free to use the
* resource allocator from the linux core if it suits them, the upside of drm_mm
* is that it's in the DRM core. Which means that it's easier to extend for
* some of the crazier special purpose needs of gpus.
*
* The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
* Drivers are free to embed either of them into their own suitable
* datastructures. drm_mm itself will not do any allocations of its own, so if
* drivers choose not to embed nodes they need to still allocate them
* themselves.
*
* The range allocator also supports reservation of preallocated blocks. This is
* useful for taking over initial mode setting configurations from the firmware,
* where an object needs to be created which exactly matches the firmware's
* scanout target. As long as the range is still free it can be inserted anytime
* after the allocator is initialized, which helps with avoiding looped
* depencies in the driver load sequence.
*
* drm_mm maintains a stack of most recently freed holes, which of all
* simplistic datastructures seems to be a fairly decent approach to clustering
* allocations and avoiding too much fragmentation. This means free space
* searches are O(num_holes). Given that all the fancy features drm_mm supports
* something better would be fairly complex and since gfx thrashing is a fairly
* steep cliff not a real concern. Removing a node again is O(1).
*
* drm_mm supports a few features: Alignment and range restrictions can be
* supplied. Further more every &drm_mm_node has a color value (which is just an
* opaqua unsigned long) which in conjunction with a driver callback can be used
* to implement sophisticated placement restrictions. The i915 DRM driver uses
* this to implement guard pages between incompatible caching domains in the
* graphics TT.
*
* Two behaviors are supported for searching and allocating: bottom-up and top-down.
* The default is bottom-up. Top-down allocation can be used if the memory area
* has different restrictions, or just to reduce fragmentation.
*
* Finally iteration helpers to walk all nodes and all holes are provided as are
* some basic allocator dumpers for debugging.
*/
static struct drm_mm_node *drm_mm_search_free_generic(const struct drm_mm *mm,
unsigned long size,
unsigned alignment,
unsigned long color,
enum drm_mm_search_flags flags);
static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
unsigned long size,
unsigned alignment,
unsigned long color,
unsigned long start,
unsigned long end,
enum drm_mm_search_flags flags);
static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
struct drm_mm_node *node,
unsigned long size, unsigned alignment,
unsigned long color,
enum drm_mm_allocator_flags flags)
{
struct drm_mm *mm = hole_node->mm;
unsigned long hole_start = drm_mm_hole_node_start(hole_node);
unsigned long hole_end = drm_mm_hole_node_end(hole_node);
unsigned long adj_start = hole_start;
unsigned long adj_end = hole_end;
BUG_ON(node->allocated);
if (mm->color_adjust)
mm->color_adjust(hole_node, color, &adj_start, &adj_end);
if (flags & DRM_MM_CREATE_TOP)
adj_start = adj_end - size;
if (alignment) {
unsigned tmp = adj_start % alignment;
if (tmp) {
if (flags & DRM_MM_CREATE_TOP)
adj_start -= tmp;
else
adj_start += alignment - tmp;
}
}
BUG_ON(adj_start < hole_start);
BUG_ON(adj_end > hole_end);
if (adj_start == hole_start) {
hole_node->hole_follows = 0;
list_del(&hole_node->hole_stack);
}
node->start = adj_start;
node->size = size;
node->mm = mm;
node->color = color;
node->allocated = 1;
INIT_LIST_HEAD(&node->hole_stack);
list_add(&node->node_list, &hole_node->node_list);
BUG_ON(node->start + node->size > adj_end);
node->hole_follows = 0;
if (__drm_mm_hole_node_start(node) < hole_end) {
list_add(&node->hole_stack, &mm->hole_stack);
node->hole_follows = 1;
}
}
/**
* drm_mm_reserve_node - insert an pre-initialized node
* @mm: drm_mm allocator to insert @node into
* @node: drm_mm_node to insert
*
* This functions inserts an already set-up drm_mm_node into the allocator,
* meaning that start, size and color must be set by the caller. This is useful
* to initialize the allocator with preallocated objects which must be set-up
* before the range allocator can be set-up, e.g. when taking over a firmware
* framebuffer.
*
* Returns:
* 0 on success, -ENOSPC if there's no hole where @node is.
*/
int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
{
struct drm_mm_node *hole;
unsigned long end = node->start + node->size;
unsigned long hole_start;
unsigned long hole_end;
BUG_ON(node == NULL);
/* Find the relevant hole to add our node to */
drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
if (hole_start > node->start || hole_end < end)
continue;
node->mm = mm;
node->allocated = 1;
INIT_LIST_HEAD(&node->hole_stack);
list_add(&node->node_list, &hole->node_list);
if (node->start == hole_start) {
hole->hole_follows = 0;
list_del_init(&hole->hole_stack);
}
node->hole_follows = 0;
if (end != hole_end) {
list_add(&node->hole_stack, &mm->hole_stack);
node->hole_follows = 1;
}
return 0;
}
return -ENOSPC;
}
EXPORT_SYMBOL(drm_mm_reserve_node);
/**
* drm_mm_insert_node_generic - search for space and insert @node
* @mm: drm_mm to allocate from
* @node: preallocate node to insert
* @size: size of the allocation
* @alignment: alignment of the allocation
* @color: opaque tag value to use for this node
* @sflags: flags to fine-tune the allocation search
* @aflags: flags to fine-tune the allocation behavior
*
* The preallocated node must be cleared to 0.
*
* Return