drivers/gpu/drm/i915/i915_gem_stolen.c - nest-hello/linux-3.10 - Git at Google

 /*
  * Copyright © 2008-2012 Intel Corporation
  *
  * 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, sublicense,
  * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS 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.
  *
  * Authors:
  *    Eric Anholt <eric@anholt.net>
  *    Chris Wilson <chris@chris-wilson.co.uk>
  *
  */

 #include <drm/drmP.h>
 #include <drm/i915_drm.h>
 #include "i915_drv.h"

 /*
  * The BIOS typically reserves some of the system's memory for the exclusive
  * use of the integrated graphics. This memory is no longer available for
  * use by the OS and so the user finds that his system has less memory
  * available than he put in. We refer to this memory as stolen.
  *
  * The BIOS will allocate its framebuffer from the stolen memory. Our
  * goal is try to reuse that object for our own fbcon which must always
  * be available for panics. Anything else we can reuse the stolen memory
  * for is a boon.
  */

 static unsigned long i915_stolen_to_physical(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct pci_dev *pdev = dev_priv->bridge_dev;
 	u32 base;

 	/* On the machines I have tested the Graphics Base of Stolen Memory
 	 * is unreliable, so on those compute the base by subtracting the
 	 * stolen memory from the Top of Low Usable DRAM which is where the
 	 * BIOS places the graphics stolen memory.
 	 *
 	 * On gen2, the layout is slightly different with the Graphics Segment
 	 * immediately following Top of Memory (or Top of Usable DRAM). Note
 	 * it appears that TOUD is only reported by 865g, so we just use the
 	 * top of memory as determined by the e820 probe.
 	 *
 	 * XXX gen2 requires an unavailable symbol and 945gm fails with
 	 * its value of TOLUD.
 	 */
 	base = 0;
 	if (INTEL_INFO(dev)->gen >= 6) {
 		/* Read Base Data of Stolen Memory Register (BDSM) directly.
 		 * Note that there is also a MCHBAR miror at 0x1080c0 or
 		 * we could use device 2:0x5c instead.
 		*/
 		pci_read_config_dword(pdev, 0xB0, &base);
 		base &= ~4095; /* lower bits used for locking register */
 	} else if (INTEL_INFO(dev)->gen > 3 || IS_G33(dev)) {
 		/* Read Graphics Base of Stolen Memory directly */
 		pci_read_config_dword(pdev, 0xA4, &base);
 #if 0
 	} else if (IS_GEN3(dev)) {
 		u8 val;
 		/* Stolen is immediately below Top of Low Usable DRAM */
 		pci_read_config_byte(pdev, 0x9c, &val);
 		base = val >> 3 << 27;
 		base -= dev_priv->mm.gtt->stolen_size;
 	} else {
 		/* Stolen is immediately above Top of Memory */
 		base = max_low_pfn_mapped << PAGE_SHIFT;
 #endif
 	}

 	return base;
 }

 static int i915_setup_compression(struct drm_device *dev, int size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_mm_node *compressed_fb, *uninitialized_var(compressed_llb);

 	/* Try to over-allocate to reduce reallocations and fragmentation */
 	compressed_fb = drm_mm_search_free(&dev_priv->mm.stolen,
 					   size <<= 1, 4096, 0);
 	if (!compressed_fb)
 		compressed_fb = drm_mm_search_free(&dev_priv->mm.stolen,
 						   size >>= 1, 4096, 0);
 	if (compressed_fb)
 		compressed_fb = drm_mm_get_block(compressed_fb, size, 4096);
 	if (!compressed_fb)
 		goto err;

 	if (HAS_PCH_SPLIT(dev))
 		I915_WRITE(ILK_DPFC_CB_BASE, compressed_fb->start);
 	else if (IS_GM45(dev)) {
 		I915_WRITE(DPFC_CB_BASE, compressed_fb->start);
 	} else {
 		compressed_llb = drm_mm_search_free(&dev_priv->mm.stolen,
 						    4096, 4096, 0);
 		if (compressed_llb)
 			compressed_llb = drm_mm_get_block(compressed_llb,
 							  4096, 4096);
 		if (!compressed_llb)
 			goto err_fb;

 		dev_priv->compressed_llb = compressed_llb;

 		I915_WRITE(FBC_CFB_BASE,
 			   dev_priv->mm.stolen_base + compressed_fb->start);
 		I915_WRITE(FBC_LL_BASE,
 			   dev_priv->mm.stolen_base + compressed_llb->start);
 	}

 	dev_priv->compressed_fb = compressed_fb;
 	dev_priv->cfb_size = size;

 	DRM_DEBUG_KMS("reserved %d bytes of contiguous stolen space for FBC\n",
 		      size);

 	return 0;

 err_fb:
 	drm_mm_put_block(compressed_fb);
 err:
 	return -ENOSPC;
 }

 int i915_gem_stolen_setup_compression(struct drm_device *dev, int size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;

 	if (dev_priv->mm.stolen_base == 0)
 		return -ENODEV;

 	if (size < dev_priv->cfb_size)
 		return 0;

 	/* Release any current block */
 	i915_gem_stolen_cleanup_compression(dev);

 	return i915_setup_compression(dev, size);
 }

 void i915_gem_stolen_cleanup_compression(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;

 	if (dev_priv->cfb_size == 0)
 		return;

 	if (dev_priv->compressed_fb)
 		drm_mm_put_block(dev_priv->compressed_fb);

 	if (dev_priv->compressed_llb)
 		drm_mm_put_block(dev_priv->compressed_llb);

 	dev_priv->cfb_size = 0;
 }

 void i915_gem_cleanup_stolen(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;

 	i915_gem_stolen_cleanup_compression(dev);
 	drm_mm_takedown(&dev_priv->mm.stolen);
 }

 int i915_gem_init_stolen(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;

 	dev_priv->mm.stolen_base = i915_stolen_to_physical(dev);
 	if (dev_priv->mm.stolen_base == 0)
 		return 0;

 	DRM_DEBUG_KMS("found %zd bytes of stolen memory at %08lx\n",
 		      dev_priv->gtt.stolen_size, dev_priv->mm.stolen_base);

 	/* Basic memrange allocator for stolen space */
 	drm_mm_init(&dev_priv->mm.stolen, 0, dev_priv->gtt.stolen_size);

 	return 0;
 }

 static struct sg_table *
 i915_pages_create_for_stolen(struct drm_device *dev,
 			     u32 offset, u32 size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct sg_table *st;
 	struct scatterlist *sg;

 	DRM_DEBUG_DRIVER("offset=0x%x, size=%d\n", offset, size);
 	BUG_ON(offset > dev_priv->gtt.stolen_size - size);

 	/* We hide that we have no struct page backing our stolen object
 	 * by wrapping the contiguous physical allocation with a fake
 	 * dma mapping in a single scatterlist.
 	 */

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

 	if (sg_alloc_table(st, 1, GFP_KERNEL)) {
 		kfree(st);
 		return NULL;
 	}

 	sg = st->sgl;
 	sg->offset = 0;
 	sg->length = size;

 	sg_dma_address(sg) = (dma_addr_t)dev_priv->mm.stolen_base + offset;
 	sg_dma_len(sg) = size;

 	return st;
 }

 static int i915_gem_object_get_pages_stolen(struct drm_i915_gem_object *obj)
 {
 	BUG();
 	return -EINVAL;
 }

 static void i915_gem_object_put_pages_stolen(struct drm_i915_gem_object *obj)
 {
 	/* Should only be called during free */
 	sg_free_table(obj->pages);
 	kfree(obj->pages);
 }

 static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
 	.get_pages = i915_gem_object_get_pages_stolen,
 	.put_pages = i915_gem_object_put_pages_stolen,
 };

 static struct drm_i915_gem_object *
 _i915_gem_object_create_stolen(struct drm_device *dev,
 			       struct drm_mm_node *stolen)
 {
 	struct drm_i915_gem_object *obj;

 	obj = i915_gem_object_alloc(dev);
 	if (obj == NULL)
 		return NULL;

 	if (drm_gem_private_object_init(dev, &obj->base, stolen->size))
 		goto cleanup;

 	i915_gem_object_init(obj, &i915_gem_object_stolen_ops);

 	obj->pages = i915_pages_create_for_stolen(dev,
 						  stolen->start, stolen->size);
 	if (obj->pages == NULL)
 		goto cleanup;

 	obj->has_dma_mapping = true;
 	obj->pages_pin_count = 1;
 	obj->stolen = stolen;

 	obj->base.write_domain = I915_GEM_DOMAIN_GTT;
 	obj->base.read_domains = I915_GEM_DOMAIN_GTT;
 	obj->cache_level = I915_CACHE_NONE;

 	return obj;

 cleanup:
 	i915_gem_object_free(obj);
 	return NULL;
 }

 struct drm_i915_gem_object *
 i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
 	struct drm_mm_node *stolen;

 	if (dev_priv->mm.stolen_base == 0)
 		return NULL;

 	DRM_DEBUG_KMS("creating stolen object: size=%x\n", size);
 	if (size == 0)
 		return NULL;

 	stolen = drm_mm_search_free(&dev_priv->mm.stolen, size, 4096, 0);
 	if (stolen)
 		stolen = drm_mm_get_block(stolen, size, 4096);
 	if (stolen == NULL)
 		return NULL;

 	obj = _i915_gem_object_create_stolen(dev, stolen);
 	if (obj)
 		return obj;

 	drm_mm_put_block(stolen);
 	return NULL;
 }

 struct drm_i915_gem_object *
 i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 					       u32 stolen_offset,
 					       u32 gtt_offset,
 					       u32 size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
 	struct drm_mm_node *stolen;

 	if (dev_priv->mm.stolen_base == 0)
 		return NULL;

 	DRM_DEBUG_KMS("creating preallocated stolen object: stolen_offset=%x, gtt_offset=%x, size=%x\n",
 			stolen_offset, gtt_offset, size);

 	/* KISS and expect everything to be page-aligned */
 	BUG_ON(stolen_offset & 4095);
 	BUG_ON(gtt_offset & 4095);
 	BUG_ON(size & 4095);

 	if (WARN_ON(size == 0))
 		return NULL;

 	stolen = drm_mm_create_block(&dev_priv->mm.stolen,
 				     stolen_offset, size,
 				     false);
 	if (stolen == NULL) {
 		DRM_DEBUG_KMS("failed to allocate stolen space\n");
 		return NULL;
 	}

 	obj = _i915_gem_object_create_stolen(dev, stolen);
 	if (obj == NULL) {
 		DRM_DEBUG_KMS("failed to allocate stolen object\n");
 		drm_mm_put_block(stolen);
 		return NULL;
 	}

 	/* To simplify the initialisation sequence between KMS and GTT,
 	 * we allow construction of the stolen object prior to
 	 * setting up the GTT space. The actual reservation will occur
 	 * later.
 	 */
 	if (drm_mm_initialized(&dev_priv->mm.gtt_space)) {
 		obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
 						     gtt_offset, size,
 						     false);
 		if (obj->gtt_space == NULL) {
 			DRM_DEBUG_KMS("failed to allocate stolen GTT space\n");
 			drm_gem_object_unreference(&obj->base);
 			return NULL;
 		}
 	} else
 		obj->gtt_space = I915_GTT_RESERVED;

 	obj->gtt_offset = gtt_offset;
 	obj->has_global_gtt_mapping = 1;

 	list_add_tail(&obj->gtt_list, &dev_priv->mm.bound_list);
 	list_add_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

 	return obj;
 }

 void
 i915_gem_object_release_stolen(struct drm_i915_gem_object *obj)
 {
 	if (obj->stolen) {
 		drm_mm_put_block(obj->stolen);
 		obj->stolen = NULL;
 	}
 }
	/*
	* Copyright © 2008-2012 Intel Corporation
	*
	* 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, sublicense,
	* 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 NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS 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.
	*
	* Authors:
	* Eric Anholt <eric@anholt.net>
	* Chris Wilson <chris@chris-wilson.co.uk>
	*
	*/

	#include <drm/drmP.h>
	#include <drm/i915_drm.h>
	#include "i915_drv.h"

	/*
	* The BIOS typically reserves some of the system's memory for the exclusive
	* use of the integrated graphics. This memory is no longer available for
	* use by the OS and so the user finds that his system has less memory
	* available than he put in. We refer to this memory as stolen.
	*
	* The BIOS will allocate its framebuffer from the stolen memory. Our
	* goal is try to reuse that object for our own fbcon which must always
	* be available for panics. Anything else we can reuse the stolen memory
	* for is a boon.
	*/

	static unsigned long i915_stolen_to_physical(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct pci_dev *pdev = dev_priv->bridge_dev;
	u32 base;

	/* On the machines I have tested the Graphics Base of Stolen Memory
	* is unreliable, so on those compute the base by subtracting the
	* stolen memory from the Top of Low Usable DRAM which is where the
	* BIOS places the graphics stolen memory.
	*
	* On gen2, the layout is slightly different with the Graphics Segment
	* immediately following Top of Memory (or Top of Usable DRAM). Note
	* it appears that TOUD is only reported by 865g, so we just use the
	* top of memory as determined by the e820 probe.
	*
	* XXX gen2 requires an unavailable symbol and 945gm fails with
	* its value of TOLUD.
	*/
	base = 0;
	if (INTEL_INFO(dev)->gen >= 6) {
	/* Read Base Data of Stolen Memory Register (BDSM) directly.
	* Note that there is also a MCHBAR miror at 0x1080c0 or
	* we could use device 2:0x5c instead.
	*/
	pci_read_config_dword(pdev, 0xB0, &base);
	base &= ~4095; /* lower bits used for locking register */
	} else if (INTEL_INFO(dev)->gen > 3 \|\| IS_G33(dev)) {
	/* Read Graphics Base of Stolen Memory directly */
	pci_read_config_dword(pdev, 0xA4, &base);
	#if 0
	} else if (IS_GEN3(dev)) {
	u8 val;
	/* Stolen is immediately below Top of Low Usable DRAM */
	pci_read_config_byte(pdev, 0x9c, &val);
	base = val >> 3 << 27;
	base -= dev_priv->mm.gtt->stolen_size;
	} else {
	/* Stolen is immediately above Top of Memory */
	base = max_low_pfn_mapped << PAGE_SHIFT;
	#endif
	}

	return base;
	}

	static int i915_setup_compression(struct drm_device *dev, int size)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct drm_mm_node compressed_fb, uninitialized_var(compressed_llb);

	/* Try to over-allocate to reduce reallocations and fragmentation */
	compressed_fb = drm_mm_search_free(&dev_priv->mm.stolen,
	size <<= 1, 4096, 0);
	if (!compressed_fb)
	compressed_fb = drm_mm_search_free(&dev_priv->mm.stolen,
	size >>= 1, 4096, 0);
	if (compressed_fb)
	compressed_fb = drm_mm_get_block(compressed_fb, size, 4096);
	if (!compressed_fb)
	goto err;

	if (HAS_PCH_SPLIT(dev))
	I915_WRITE(ILK_DPFC_CB_BASE, compressed_fb->start);
	else if (IS_GM45(dev)) {
	I915_WRITE(DPFC_CB_BASE, compressed_fb->start);
	} else {
	compressed_llb = drm_mm_search_free(&dev_priv->mm.stolen,
	4096, 4096, 0);
	if (compressed_llb)
	compressed_llb = drm_mm_get_block(compressed_llb,
	4096, 4096);
	if (!compressed_llb)
	goto err_fb;

	dev_priv->compressed_llb = compressed_llb;

	I915_WRITE(FBC_CFB_BASE,
	dev_priv->mm.stolen_base + compressed_fb->start);
	I915_WRITE(FBC_LL_BASE,
	dev_priv->mm.stolen_base + compressed_llb->start);
	}

	dev_priv->compressed_fb = compressed_fb;
	dev_priv->cfb_size = size;

	DRM_DEBUG_KMS("reserved %d bytes of contiguous stolen space for FBC\n",
	size);

	return 0;

	err_fb:
	drm_mm_put_block(compressed_fb);
	err:
	return -ENOSPC;
	}

	int i915_gem_stolen_setup_compression(struct drm_device *dev, int size)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;

	if (dev_priv->mm.stolen_base == 0)
	return -ENODEV;

	if (size < dev_priv->cfb_size)
	return 0;

	/* Release any current block */
	i915_gem_stolen_cleanup_compression(dev);

	return i915_setup_compression(dev, size);
	}

	void i915_gem_stolen_cleanup_compression(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;

	if (dev_priv->cfb_size == 0)
	return;

	if (dev_priv->compressed_fb)
	drm_mm_put_block(dev_priv->compressed_fb);

	if (dev_priv->compressed_llb)
	drm_mm_put_block(dev_priv->compressed_llb);

	dev_priv->cfb_size = 0;
	}

	void i915_gem_cleanup_stolen(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;

	i915_gem_stolen_cleanup_compression(dev);
	drm_mm_takedown(&dev_priv->mm.stolen);
	}

	int i915_gem_init_stolen(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;

	dev_priv->mm.stolen_base = i915_stolen_to_physical(dev);
	if (dev_priv->mm.stolen_base == 0)
	return 0;

	DRM_DEBUG_KMS("found %zd bytes of stolen memory at %08lx\n",
	dev_priv->gtt.stolen_size, dev_priv->mm.stolen_base);

	/* Basic memrange allocator for stolen space */
	drm_mm_init(&dev_priv->mm.stolen, 0, dev_priv->gtt.stolen_size);

	return 0;
	}

	static struct sg_table *
	i915_pages_create_for_stolen(struct drm_device *dev,
	u32 offset, u32 size)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct sg_table *st;
	struct scatterlist *sg;

	DRM_DEBUG_DRIVER("offset=0x%x, size=%d\n", offset, size);
	BUG_ON(offset > dev_priv->gtt.stolen_size - size);

	/* We hide that we have no struct page backing our stolen object
	* by wrapping the contiguous physical allocation with a fake
	* dma mapping in a single scatterlist.
	*/

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

	if (sg_alloc_table(st, 1, GFP_KERNEL)) {
	kfree(st);
	return NULL;
	}

	sg = st->sgl;
	sg->offset = 0;
	sg->length = size;

	sg_dma_address(sg) = (dma_addr_t)dev_priv->mm.stolen_base + offset;
	sg_dma_len(sg) = size;

	return st;
	}

	static int i915_gem_object_get_pages_stolen(struct drm_i915_gem_object *obj)
	{
	BUG();
	return -EINVAL;
	}

	static void i915_gem_object_put_pages_stolen(struct drm_i915_gem_object *obj)
	{
	/* Should only be called during free */
	sg_free_table(obj->pages);
	kfree(obj->pages);
	}

	static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
	.get_pages = i915_gem_object_get_pages_stolen,
	.put_pages = i915_gem_object_put_pages_stolen,
	};

	static struct drm_i915_gem_object *
	_i915_gem_object_create_stolen(struct drm_device *dev,
	struct drm_mm_node *stolen)
	{
	struct drm_i915_gem_object *obj;

	obj = i915_gem_object_alloc(dev);
	if (obj == NULL)
	return NULL;

	if (drm_gem_private_object_init(dev, &obj->base, stolen->size))
	goto cleanup;

	i915_gem_object_init(obj, &i915_gem_object_stolen_ops);

	obj->pages = i915_pages_create_for_stolen(dev,
	stolen->start, stolen->size);
	if (obj->pages == NULL)
	goto cleanup;

	obj->has_dma_mapping = true;
	obj->pages_pin_count = 1;
	obj->stolen = stolen;

	obj->base.write_domain = I915_GEM_DOMAIN_GTT;
	obj->base.read_domains = I915_GEM_DOMAIN_GTT;
	obj->cache_level = I915_CACHE_NONE;

	return obj;

	cleanup:
	i915_gem_object_free(obj);
	return NULL;
	}

	struct drm_i915_gem_object *
	i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct drm_i915_gem_object *obj;
	struct drm_mm_node *stolen;

	if (dev_priv->mm.stolen_base == 0)
	return NULL;

	DRM_DEBUG_KMS("creating stolen object: size=%x\n", size);
	if (size == 0)
	return NULL;

	stolen = drm_mm_search_free(&dev_priv->mm.stolen, size, 4096, 0);
	if (stolen)
	stolen = drm_mm_get_block(stolen, size, 4096);
	if (stolen == NULL)
	return NULL;

	obj = _i915_gem_object_create_stolen(dev, stolen);
	if (obj)
	return obj;

	drm_mm_put_block(stolen);
	return NULL;
	}

	struct drm_i915_gem_object *
	i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
	u32 stolen_offset,
	u32 gtt_offset,
	u32 size)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct drm_i915_gem_object *obj;
	struct drm_mm_node *stolen;

	if (dev_priv->mm.stolen_base == 0)
	return NULL;

	DRM_DEBUG_KMS("creating preallocated stolen object: stolen_offset=%x, gtt_offset=%x, size=%x\n",
	stolen_offset, gtt_offset, size);

	/* KISS and expect everything to be page-aligned */
	BUG_ON(stolen_offset & 4095);
	BUG_ON(gtt_offset & 4095);
	BUG_ON(size & 4095);

	if (WARN_ON(size == 0))
	return NULL;

	stolen = drm_mm_create_block(&dev_priv->mm.stolen,
	stolen_offset, size,
	false);
	if (stolen == NULL) {
	DRM_DEBUG_KMS("failed to allocate stolen space\n");
	return NULL;
	}

	obj = _i915_gem_object_create_stolen(dev, stolen);
	if (obj == NULL) {
	DRM_DEBUG_KMS("failed to allocate stolen object\n");
	drm_mm_put_block(stolen);
	return NULL;
	}

	/* To simplify the initialisation sequence between KMS and GTT,
	* we allow construction of the stolen object prior to
	* setting up the GTT space. The actual reservation will occur
	* later.
	*/
	if (drm_mm_initialized(&dev_priv->mm.gtt_space)) {
	obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
	gtt_offset, size,
	false);
	if (obj->gtt_space == NULL) {
	DRM_DEBUG_KMS("failed to allocate stolen GTT space\n");
	drm_gem_object_unreference(&obj->base);
	return NULL;
	}
	} else
	obj->gtt_space = I915_GTT_RESERVED;

	obj->gtt_offset = gtt_offset;
	obj->has_global_gtt_mapping = 1;

	list_add_tail(&obj->gtt_list, &dev_priv->mm.bound_list);
	list_add_tail(&obj->mm_list, &dev_priv->mm.inactive_list);

	return obj;
	}

	void
	i915_gem_object_release_stolen(struct drm_i915_gem_object *obj)
	{
	if (obj->stolen) {
	drm_mm_put_block(obj->stolen);
	obj->stolen = NULL;
	}
	}