drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c - kernel/bruno - Git at Google

 /*
  * Copyright 2008 Advanced Micro Devices, Inc.
  * Copyright 2008 Red Hat Inc.
  * Copyright 2009 Jerome Glisse.
  *
  * 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 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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: Dave Airlie
  *          Alex Deucher
  *          Jerome Glisse
  */
 #include <drm/drmP.h>
 #include <drm/amdgpu_drm.h>
 #include "amdgpu.h"

 /*
  * GART
  * The GART (Graphics Aperture Remapping Table) is an aperture
  * in the GPU's address space.  System pages can be mapped into
  * the aperture and look like contiguous pages from the GPU's
  * perspective.  A page table maps the pages in the aperture
  * to the actual backing pages in system memory.
  *
  * Radeon GPUs support both an internal GART, as described above,
  * and AGP.  AGP works similarly, but the GART table is configured
  * and maintained by the northbridge rather than the driver.
  * Radeon hw has a separate AGP aperture that is programmed to
  * point to the AGP aperture provided by the northbridge and the
  * requests are passed through to the northbridge aperture.
  * Both AGP and internal GART can be used at the same time, however
  * that is not currently supported by the driver.
  *
  * This file handles the common internal GART management.
  */

 /*
  * Common GART table functions.
  */
 /**
  * amdgpu_gart_table_ram_alloc - allocate system ram for gart page table
  *
  * @adev: amdgpu_device pointer
  *
  * Allocate system memory for GART page table
  * (r1xx-r3xx, non-pcie r4xx, rs400).  These asics require the
  * gart table to be in system memory.
  * Returns 0 for success, -ENOMEM for failure.
  */
 int amdgpu_gart_table_ram_alloc(struct amdgpu_device *adev)
 {
 	void *ptr;

 	ptr = pci_alloc_consistent(adev->pdev, adev->gart.table_size,
 				   &adev->gart.table_addr);
 	if (ptr == NULL) {
 		return -ENOMEM;
 	}
 #ifdef CONFIG_X86
 	if (0) {
 		set_memory_uc((unsigned long)ptr,
 			      adev->gart.table_size >> PAGE_SHIFT);
 	}
 #endif
 	adev->gart.ptr = ptr;
 	memset((void *)adev->gart.ptr, 0, adev->gart.table_size);
 	return 0;
 }

 /**
  * amdgpu_gart_table_ram_free - free system ram for gart page table
  *
  * @adev: amdgpu_device pointer
  *
  * Free system memory for GART page table
  * (r1xx-r3xx, non-pcie r4xx, rs400).  These asics require the
  * gart table to be in system memory.
  */
 void amdgpu_gart_table_ram_free(struct amdgpu_device *adev)
 {
 	if (adev->gart.ptr == NULL) {
 		return;
 	}
 #ifdef CONFIG_X86
 	if (0) {
 		set_memory_wb((unsigned long)adev->gart.ptr,
 			      adev->gart.table_size >> PAGE_SHIFT);
 	}
 #endif
 	pci_free_consistent(adev->pdev, adev->gart.table_size,
 			    (void *)adev->gart.ptr,
 			    adev->gart.table_addr);
 	adev->gart.ptr = NULL;
 	adev->gart.table_addr = 0;
 }

 /**
  * amdgpu_gart_table_vram_alloc - allocate vram for gart page table
  *
  * @adev: amdgpu_device pointer
  *
  * Allocate video memory for GART page table
  * (pcie r4xx, r5xx+).  These asics require the
  * gart table to be in video memory.
  * Returns 0 for success, error for failure.
  */
 int amdgpu_gart_table_vram_alloc(struct amdgpu_device *adev)
 {
 	int r;

 	if (adev->gart.robj == NULL) {
 		r = amdgpu_bo_create(adev, adev->gart.table_size,
 				     PAGE_SIZE, true, AMDGPU_GEM_DOMAIN_VRAM,
 				     AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED,
 				     NULL, NULL, &adev->gart.robj);
 		if (r) {
 			return r;
 		}
 	}
 	return 0;
 }

 /**
  * amdgpu_gart_table_vram_pin - pin gart page table in vram
  *
  * @adev: amdgpu_device pointer
  *
  * Pin the GART page table in vram so it will not be moved
  * by the memory manager (pcie r4xx, r5xx+).  These asics require the
  * gart table to be in video memory.
  * Returns 0 for success, error for failure.
  */
 int amdgpu_gart_table_vram_pin(struct amdgpu_device *adev)
 {
 	uint64_t gpu_addr;
 	int r;

 	r = amdgpu_bo_reserve(adev->gart.robj, false);
 	if (unlikely(r != 0))
 		return r;
 	r = amdgpu_bo_pin(adev->gart.robj,
 				AMDGPU_GEM_DOMAIN_VRAM, &gpu_addr);
 	if (r) {
 		amdgpu_bo_unreserve(adev->gart.robj);
 		return r;
 	}
 	r = amdgpu_bo_kmap(adev->gart.robj, &adev->gart.ptr);
 	if (r)
 		amdgpu_bo_unpin(adev->gart.robj);
 	amdgpu_bo_unreserve(adev->gart.robj);
 	adev->gart.table_addr = gpu_addr;
 	return r;
 }

 /**
  * amdgpu_gart_table_vram_unpin - unpin gart page table in vram
  *
  * @adev: amdgpu_device pointer
  *
  * Unpin the GART page table in vram (pcie r4xx, r5xx+).
  * These asics require the gart table to be in video memory.
  */
 void amdgpu_gart_table_vram_unpin(struct amdgpu_device *adev)
 {
 	int r;

 	if (adev->gart.robj == NULL) {
 		return;
 	}
 	r = amdgpu_bo_reserve(adev->gart.robj, false);
 	if (likely(r == 0)) {
 		amdgpu_bo_kunmap(adev->gart.robj);
 		amdgpu_bo_unpin(adev->gart.robj);
 		amdgpu_bo_unreserve(adev->gart.robj);
 		adev->gart.ptr = NULL;
 	}
 }

 /**
  * amdgpu_gart_table_vram_free - free gart page table vram
  *
  * @adev: amdgpu_device pointer
  *
  * Free the video memory used for the GART page table
  * (pcie r4xx, r5xx+).  These asics require the gart table to
  * be in video memory.
  */
 void amdgpu_gart_table_vram_free(struct amdgpu_device *adev)
 {
 	if (adev->gart.robj == NULL) {
 		return;
 	}
 	amdgpu_bo_unref(&adev->gart.robj);
 }

 /*
  * Common gart functions.
  */
 /**
  * amdgpu_gart_unbind - unbind pages from the gart page table
  *
  * @adev: amdgpu_device pointer
  * @offset: offset into the GPU's gart aperture
  * @pages: number of pages to unbind
  *
  * Unbinds the requested pages from the gart page table and
  * replaces them with the dummy page (all asics).
  */
 void amdgpu_gart_unbind(struct amdgpu_device *adev, uint64_t offset,
 			int pages)
 {
 	unsigned t;
 	unsigned p;
 	int i, j;
 	u64 page_base;
 	uint32_t flags = AMDGPU_PTE_SYSTEM;

 	if (!adev->gart.ready) {
 		WARN(1, "trying to unbind memory from uninitialized GART !\n");
 		return;
 	}

 	t = offset / AMDGPU_GPU_PAGE_SIZE;
 	p = t / (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE);
 	for (i = 0; i < pages; i++, p++) {
 		if (adev->gart.pages[p]) {
 			adev->gart.pages[p] = NULL;
 			adev->gart.pages_addr[p] = adev->dummy_page.addr;
 			page_base = adev->gart.pages_addr[p];
 			if (!adev->gart.ptr)
 				continue;

 			for (j = 0; j < (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE); j++, t++) {
 				amdgpu_gart_set_pte_pde(adev, adev->gart.ptr,
 							t, page_base, flags);
 				page_base += AMDGPU_GPU_PAGE_SIZE;
 			}
 		}
 	}
 	mb();
 	amdgpu_gart_flush_gpu_tlb(adev, 0);
 }

 /**
  * amdgpu_gart_bind - bind pages into the gart page table
  *
  * @adev: amdgpu_device pointer
  * @offset: offset into the GPU's gart aperture
  * @pages: number of pages to bind
  * @pagelist: pages to bind
  * @dma_addr: DMA addresses of pages
  *
  * Binds the requested pages to the gart page table
  * (all asics).
  * Returns 0 for success, -EINVAL for failure.
  */
 int amdgpu_gart_bind(struct amdgpu_device *adev, uint64_t offset,
 		     int pages, struct page **pagelist, dma_addr_t *dma_addr,
 		     uint32_t flags)
 {
 	unsigned t;
 	unsigned p;
 	uint64_t page_base;
 	int i, j;

 	if (!adev->gart.ready) {
 		WARN(1, "trying to bind memory to uninitialized GART !\n");
 		return -EINVAL;
 	}

 	t = offset / AMDGPU_GPU_PAGE_SIZE;
 	p = t / (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE);

 	for (i = 0; i < pages; i++, p++) {
 		adev->gart.pages_addr[p] = dma_addr[i];
 		adev->gart.pages[p] = pagelist[i];
 		if (adev->gart.ptr) {
 			page_base = adev->gart.pages_addr[p];
 			for (j = 0; j < (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE); j++, t++) {
 				amdgpu_gart_set_pte_pde(adev, adev->gart.ptr, t, page_base, flags);
 				page_base += AMDGPU_GPU_PAGE_SIZE;
 			}
 		}
 	}
 	mb();
 	amdgpu_gart_flush_gpu_tlb(adev, 0);
 	return 0;
 }

 /**
  * amdgpu_gart_init - init the driver info for managing the gart
  *
  * @adev: amdgpu_device pointer
  *
  * Allocate the dummy page and init the gart driver info (all asics).
  * Returns 0 for success, error for failure.
  */
 int amdgpu_gart_init(struct amdgpu_device *adev)
 {
 	int r, i;

 	if (adev->gart.pages) {
 		return 0;
 	}
 	/* We need PAGE_SIZE >= AMDGPU_GPU_PAGE_SIZE */
 	if (PAGE_SIZE < AMDGPU_GPU_PAGE_SIZE) {
 		DRM_ERROR("Page size is smaller than GPU page size!\n");
 		return -EINVAL;
 	}
 	r = amdgpu_dummy_page_init(adev);
 	if (r)
 		return r;
 	/* Compute table size */
 	adev->gart.num_cpu_pages = adev->mc.gtt_size / PAGE_SIZE;
 	adev->gart.num_gpu_pages = adev->mc.gtt_size / AMDGPU_GPU_PAGE_SIZE;
 	DRM_INFO("GART: num cpu pages %u, num gpu pages %u\n",
 		 adev->gart.num_cpu_pages, adev->gart.num_gpu_pages);
 	/* Allocate pages table */
 	adev->gart.pages = vzalloc(sizeof(void *) * adev->gart.num_cpu_pages);
 	if (adev->gart.pages == NULL) {
 		amdgpu_gart_fini(adev);
 		return -ENOMEM;
 	}
 	adev->gart.pages_addr = vzalloc(sizeof(dma_addr_t) *
 					adev->gart.num_cpu_pages);
 	if (adev->gart.pages_addr == NULL) {
 		amdgpu_gart_fini(adev);
 		return -ENOMEM;
 	}
 	/* set GART entry to point to the dummy page by default */
 	for (i = 0; i < adev->gart.num_cpu_pages; i++) {
 		adev->gart.pages_addr[i] = adev->dummy_page.addr;
 	}
 	return 0;
 }

 /**
  * amdgpu_gart_fini - tear down the driver info for managing the gart
  *
  * @adev: amdgpu_device pointer
  *
  * Tear down the gart driver info and free the dummy page (all asics).
  */
 void amdgpu_gart_fini(struct amdgpu_device *adev)
 {
 	if (adev->gart.pages && adev->gart.pages_addr && adev->gart.ready) {
 		/* unbind pages */
 		amdgpu_gart_unbind(adev, 0, adev->gart.num_cpu_pages);
 	}
 	adev->gart.ready = false;
 	vfree(adev->gart.pages);
 	vfree(adev->gart.pages_addr);
 	adev->gart.pages = NULL;
 	adev->gart.pages_addr = NULL;

 	amdgpu_dummy_page_fini(adev);
 }
	/*
	* Copyright 2008 Advanced Micro Devices, Inc.
	* Copyright 2008 Red Hat Inc.
	* Copyright 2009 Jerome Glisse.
	*
	* 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 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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: Dave Airlie
	* Alex Deucher
	* Jerome Glisse
	*/
	#include <drm/drmP.h>
	#include <drm/amdgpu_drm.h>
	#include "amdgpu.h"

	/*
	* GART
	* The GART (Graphics Aperture Remapping Table) is an aperture
	* in the GPU's address space. System pages can be mapped into
	* the aperture and look like contiguous pages from the GPU's
	* perspective. A page table maps the pages in the aperture
	* to the actual backing pages in system memory.
	*
	* Radeon GPUs support both an internal GART, as described above,
	* and AGP. AGP works similarly, but the GART table is configured
	* and maintained by the northbridge rather than the driver.
	* Radeon hw has a separate AGP aperture that is programmed to
	* point to the AGP aperture provided by the northbridge and the
	* requests are passed through to the northbridge aperture.
	* Both AGP and internal GART can be used at the same time, however
	* that is not currently supported by the driver.
	*
	* This file handles the common internal GART management.
	*/

	/*
	* Common GART table functions.
	*/
	/**
	* amdgpu_gart_table_ram_alloc - allocate system ram for gart page table
	*
	* @adev: amdgpu_device pointer
	*
	* Allocate system memory for GART page table
	* (r1xx-r3xx, non-pcie r4xx, rs400). These asics require the
	* gart table to be in system memory.
	* Returns 0 for success, -ENOMEM for failure.
	*/
	int amdgpu_gart_table_ram_alloc(struct amdgpu_device *adev)
	{
	void *ptr;

	ptr = pci_alloc_consistent(adev->pdev, adev->gart.table_size,
	&adev->gart.table_addr);
	if (ptr == NULL) {
	return -ENOMEM;
	}
	#ifdef CONFIG_X86
	if (0) {
	set_memory_uc((unsigned long)ptr,
	adev->gart.table_size >> PAGE_SHIFT);
	}
	#endif
	adev->gart.ptr = ptr;
	memset((void *)adev->gart.ptr, 0, adev->gart.table_size);
	return 0;
	}

	/**
	* amdgpu_gart_table_ram_free - free system ram for gart page table
	*
	* @adev: amdgpu_device pointer
	*
	* Free system memory for GART page table
	* (r1xx-r3xx, non-pcie r4xx, rs400). These asics require the
	* gart table to be in system memory.
	*/
	void amdgpu_gart_table_ram_free(struct amdgpu_device *adev)
	{
	if (adev->gart.ptr == NULL) {
	return;
	}
	#ifdef CONFIG_X86
	if (0) {
	set_memory_wb((unsigned long)adev->gart.ptr,
	adev->gart.table_size >> PAGE_SHIFT);
	}
	#endif
	pci_free_consistent(adev->pdev, adev->gart.table_size,
	(void *)adev->gart.ptr,
	adev->gart.table_addr);
	adev->gart.ptr = NULL;
	adev->gart.table_addr = 0;
	}

	/**
	* amdgpu_gart_table_vram_alloc - allocate vram for gart page table
	*
	* @adev: amdgpu_device pointer
	*
	* Allocate video memory for GART page table
	* (pcie r4xx, r5xx+). These asics require the
	* gart table to be in video memory.
	* Returns 0 for success, error for failure.
	*/
	int amdgpu_gart_table_vram_alloc(struct amdgpu_device *adev)
	{
	int r;

	if (adev->gart.robj == NULL) {
	r = amdgpu_bo_create(adev, adev->gart.table_size,
	PAGE_SIZE, true, AMDGPU_GEM_DOMAIN_VRAM,
	AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED,
	NULL, NULL, &adev->gart.robj);
	if (r) {
	return r;
	}
	}
	return 0;
	}

	/**
	* amdgpu_gart_table_vram_pin - pin gart page table in vram
	*
	* @adev: amdgpu_device pointer
	*
	* Pin the GART page table in vram so it will not be moved
	* by the memory manager (pcie r4xx, r5xx+). These asics require the
	* gart table to be in video memory.
	* Returns 0 for success, error for failure.
	*/
	int amdgpu_gart_table_vram_pin(struct amdgpu_device *adev)
	{
	uint64_t gpu_addr;
	int r;

	r = amdgpu_bo_reserve(adev->gart.robj, false);
	if (unlikely(r != 0))
	return r;
	r = amdgpu_bo_pin(adev->gart.robj,
	AMDGPU_GEM_DOMAIN_VRAM, &gpu_addr);
	if (r) {
	amdgpu_bo_unreserve(adev->gart.robj);
	return r;
	}
	r = amdgpu_bo_kmap(adev->gart.robj, &adev->gart.ptr);
	if (r)
	amdgpu_bo_unpin(adev->gart.robj);
	amdgpu_bo_unreserve(adev->gart.robj);
	adev->gart.table_addr = gpu_addr;
	return r;
	}

	/**
	* amdgpu_gart_table_vram_unpin - unpin gart page table in vram
	*
	* @adev: amdgpu_device pointer
	*
	* Unpin the GART page table in vram (pcie r4xx, r5xx+).
	* These asics require the gart table to be in video memory.
	*/
	void amdgpu_gart_table_vram_unpin(struct amdgpu_device *adev)
	{
	int r;

	if (adev->gart.robj == NULL) {
	return;
	}
	r = amdgpu_bo_reserve(adev->gart.robj, false);
	if (likely(r == 0)) {
	amdgpu_bo_kunmap(adev->gart.robj);
	amdgpu_bo_unpin(adev->gart.robj);
	amdgpu_bo_unreserve(adev->gart.robj);
	adev->gart.ptr = NULL;
	}
	}

	/**
	* amdgpu_gart_table_vram_free - free gart page table vram
	*
	* @adev: amdgpu_device pointer
	*
	* Free the video memory used for the GART page table
	* (pcie r4xx, r5xx+). These asics require the gart table to
	* be in video memory.
	*/
	void amdgpu_gart_table_vram_free(struct amdgpu_device *adev)
	{
	if (adev->gart.robj == NULL) {
	return;
	}
	amdgpu_bo_unref(&adev->gart.robj);
	}

	/*
	* Common gart functions.
	*/
	/**
	* amdgpu_gart_unbind - unbind pages from the gart page table
	*
	* @adev: amdgpu_device pointer
	* @offset: offset into the GPU's gart aperture
	* @pages: number of pages to unbind
	*
	* Unbinds the requested pages from the gart page table and
	* replaces them with the dummy page (all asics).
	*/
	void amdgpu_gart_unbind(struct amdgpu_device *adev, uint64_t offset,
	int pages)
	{
	unsigned t;
	unsigned p;
	int i, j;
	u64 page_base;
	uint32_t flags = AMDGPU_PTE_SYSTEM;

	if (!adev->gart.ready) {
	WARN(1, "trying to unbind memory from uninitialized GART !\n");
	return;
	}

	t = offset / AMDGPU_GPU_PAGE_SIZE;
	p = t / (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE);
	for (i = 0; i < pages; i++, p++) {
	if (adev->gart.pages[p]) {
	adev->gart.pages[p] = NULL;
	adev->gart.pages_addr[p] = adev->dummy_page.addr;
	page_base = adev->gart.pages_addr[p];
	if (!adev->gart.ptr)
	continue;

	for (j = 0; j < (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE); j++, t++) {
	amdgpu_gart_set_pte_pde(adev, adev->gart.ptr,
	t, page_base, flags);
	page_base += AMDGPU_GPU_PAGE_SIZE;
	}
	}
	}
	mb();
	amdgpu_gart_flush_gpu_tlb(adev, 0);
	}

	/**
	* amdgpu_gart_bind - bind pages into the gart page table
	*
	* @adev: amdgpu_device pointer
	* @offset: offset into the GPU's gart aperture
	* @pages: number of pages to bind
	* @pagelist: pages to bind
	* @dma_addr: DMA addresses of pages
	*
	* Binds the requested pages to the gart page table
	* (all asics).
	* Returns 0 for success, -EINVAL for failure.
	*/
	int amdgpu_gart_bind(struct amdgpu_device *adev, uint64_t offset,
	int pages, struct page *pagelist, dma_addr_t dma_addr,
	uint32_t flags)
	{
	unsigned t;
	unsigned p;
	uint64_t page_base;
	int i, j;

	if (!adev->gart.ready) {
	WARN(1, "trying to bind memory to uninitialized GART !\n");
	return -EINVAL;
	}

	t = offset / AMDGPU_GPU_PAGE_SIZE;
	p = t / (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE);

	for (i = 0; i < pages; i++, p++) {
	adev->gart.pages_addr[p] = dma_addr[i];
	adev->gart.pages[p] = pagelist[i];
	if (adev->gart.ptr) {
	page_base = adev->gart.pages_addr[p];
	for (j = 0; j < (PAGE_SIZE / AMDGPU_GPU_PAGE_SIZE); j++, t++) {
	amdgpu_gart_set_pte_pde(adev, adev->gart.ptr, t, page_base, flags);
	page_base += AMDGPU_GPU_PAGE_SIZE;
	}
	}
	}
	mb();
	amdgpu_gart_flush_gpu_tlb(adev, 0);
	return 0;
	}

	/**
	* amdgpu_gart_init - init the driver info for managing the gart
	*
	* @adev: amdgpu_device pointer
	*
	* Allocate the dummy page and init the gart driver info (all asics).
	* Returns 0 for success, error for failure.
	*/
	int amdgpu_gart_init(struct amdgpu_device *adev)
	{
	int r, i;

	if (adev->gart.pages) {
	return 0;
	}
	/* We need PAGE_SIZE >= AMDGPU_GPU_PAGE_SIZE */
	if (PAGE_SIZE < AMDGPU_GPU_PAGE_SIZE) {
	DRM_ERROR("Page size is smaller than GPU page size!\n");
	return -EINVAL;
	}
	r = amdgpu_dummy_page_init(adev);
	if (r)
	return r;
	/* Compute table size */
	adev->gart.num_cpu_pages = adev->mc.gtt_size / PAGE_SIZE;
	adev->gart.num_gpu_pages = adev->mc.gtt_size / AMDGPU_GPU_PAGE_SIZE;
	DRM_INFO("GART: num cpu pages %u, num gpu pages %u\n",
	adev->gart.num_cpu_pages, adev->gart.num_gpu_pages);
	/* Allocate pages table */
	adev->gart.pages = vzalloc(sizeof(void ) adev->gart.num_cpu_pages);
	if (adev->gart.pages == NULL) {
	amdgpu_gart_fini(adev);
	return -ENOMEM;
	}
	adev->gart.pages_addr = vzalloc(sizeof(dma_addr_t) *
	adev->gart.num_cpu_pages);
	if (adev->gart.pages_addr == NULL) {
	amdgpu_gart_fini(adev);
	return -ENOMEM;
	}
	/* set GART entry to point to the dummy page by default */
	for (i = 0; i < adev->gart.num_cpu_pages; i++) {
	adev->gart.pages_addr[i] = adev->dummy_page.addr;
	}
	return 0;
	}

	/**
	* amdgpu_gart_fini - tear down the driver info for managing the gart
	*
	* @adev: amdgpu_device pointer
	*
	* Tear down the gart driver info and free the dummy page (all asics).
	*/
	void amdgpu_gart_fini(struct amdgpu_device *adev)
	{
	if (adev->gart.pages && adev->gart.pages_addr && adev->gart.ready) {
	/* unbind pages */
	amdgpu_gart_unbind(adev, 0, adev->gart.num_cpu_pages);
	}
	adev->gart.ready = false;
	vfree(adev->gart.pages);
	vfree(adev->gart.pages_addr);
	adev->gart.pages = NULL;
	adev->gart.pages_addr = NULL;

	amdgpu_dummy_page_fini(adev);
	}