arch/arm64/mm/dma-mapping.c - kernel/msm-5.4 - Gitiles

 /*
  * SWIOTLB-based DMA API implementation
  *
  * Copyright (C) 2012 ARM Ltd.
  * Author: Catalin Marinas <catalin.marinas@arm.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/gfp.h>
 #include <linux/acpi.h>
 #include <linux/memblock.h>
 #include <linux/cache.h>
 #include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/genalloc.h>
 #include <linux/dma-direct.h>
 #include <linux/dma-noncoherent.h>
 #include <linux/dma-contiguous.h>
 #include <linux/vmalloc.h>
 #include <linux/swiotlb.h>
 #include <linux/pci.h>

 #include <asm/cacheflush.h>

 pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
 		unsigned long attrs)
 {
 	if (!dev_is_dma_coherent(dev) || (attrs & DMA_ATTR_WRITE_COMBINE))
 		return pgprot_writecombine(prot);
 	return prot;
 }

 void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
 		size_t size, enum dma_data_direction dir)
 {
 	__dma_map_area(phys_to_virt(paddr), size, dir);
 }

 void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
 		size_t size, enum dma_data_direction dir)
 {
 	__dma_unmap_area(phys_to_virt(paddr), size, dir);
 }

 void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	__dma_flush_area(page_address(page), size);
 }

 #ifdef CONFIG_IOMMU_DMA
 static int __swiotlb_get_sgtable_page(struct sg_table *sgt,
 				      struct page *page, size_t size)
 {
 	int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

 	if (!ret)
 		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);

 	return ret;
 }

 static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
 			      unsigned long pfn, size_t size)
 {
 	int ret = -ENXIO;
 	unsigned long nr_vma_pages = vma_pages(vma);
 	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long off = vma->vm_pgoff;

 	if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
 		ret = remap_pfn_range(vma, vma->vm_start,
 				      pfn + off,
 				      vma->vm_end - vma->vm_start,
 				      vma->vm_page_prot);
 	}

 	return ret;
 }
 #endif /* CONFIG_IOMMU_DMA */

 static int __init arm64_dma_init(void)
 {
 	WARN_TAINT(ARCH_DMA_MINALIGN < cache_line_size(),
 		   TAINT_CPU_OUT_OF_SPEC,
 		   "ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)",
 		   ARCH_DMA_MINALIGN, cache_line_size());
 	return dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC));
 }
 arch_initcall(arm64_dma_init);

 #ifdef CONFIG_IOMMU_DMA
 #include <linux/dma-iommu.h>
 #include <linux/platform_device.h>
 #include <linux/amba/bus.h>

 /* Thankfully, all cache ops are by VA so we can ignore phys here */
 static void flush_page(struct device *dev, const void *virt, phys_addr_t phys)
 {
 	__dma_flush_area(virt, PAGE_SIZE);
 }

 static void *__iommu_alloc_attrs(struct device *dev, size_t size,
 				 dma_addr_t *handle, gfp_t gfp,
 				 unsigned long attrs)
 {
 	bool coherent = dev_is_dma_coherent(dev);
 	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
 	size_t iosize = size;
 	void *addr;

 	if (WARN(!dev, "cannot create IOMMU mapping for unknown device\n"))
 		return NULL;

 	size = PAGE_ALIGN(size);

 	/*
 	 * Some drivers rely on this, and we probably don't want the
 	 * possibility of stale kernel data being read by devices anyway.
 	 */
 	gfp |= __GFP_ZERO;

 	if (!gfpflags_allow_blocking(gfp)) {
 		struct page *page;
 		/*
 		 * In atomic context we can't remap anything, so we'll only
 		 * get the virtually contiguous buffer we need by way of a
 		 * physically contiguous allocation.
 		 */
 		if (coherent) {
 			page = alloc_pages(gfp, get_order(size));
 			addr = page ? page_address(page) : NULL;
 		} else {
 			addr = dma_alloc_from_pool(size, &page, gfp);
 		}
 		if (!addr)
 			return NULL;

 		*handle = iommu_dma_map_page(dev, page, 0, iosize, ioprot);
 		if (*handle == DMA_MAPPING_ERROR) {
 			if (coherent)
 				__free_pages(page, get_order(size));
 			else
 				dma_free_from_pool(addr, size);
 			addr = NULL;
 		}
 	} else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
 		pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
 		struct page *page;

 		page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
 					get_order(size), gfp & __GFP_NOWARN);
 		if (!page)
 			return NULL;

 		*handle = iommu_dma_map_page(dev, page, 0, iosize, ioprot);
 		if (*handle == DMA_MAPPING_ERROR) {
 			dma_release_from_contiguous(dev, page,
 						    size >> PAGE_SHIFT);
 			return NULL;
 		}
 		addr = dma_common_contiguous_remap(page, size, VM_USERMAP,
 						   prot,
 						   __builtin_return_address(0));
 		if (addr) {
 			if (!coherent)
 				__dma_flush_area(page_to_virt(page), iosize);
 			memset(addr, 0, size);
 		} else {
 			iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs);
 			dma_release_from_contiguous(dev, page,
 						    size >> PAGE_SHIFT);
 		}
 	} else {
 		pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
 		struct page **pages;

 		pages = iommu_dma_alloc(dev, iosize, gfp, attrs, ioprot,
 					handle, flush_page);
 		if (!pages)
 			return NULL;

 		addr = dma_common_pages_remap(pages, size, VM_USERMAP, prot,
 					      __builtin_return_address(0));
 		if (!addr)
 			iommu_dma_free(dev, pages, iosize, handle);
 	}
 	return addr;
 }

 static void __iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 			       dma_addr_t handle, unsigned long attrs)
 {
 	size_t iosize = size;

 	size = PAGE_ALIGN(size);
 	/*
 	 * @cpu_addr will be one of 4 things depending on how it was allocated:
 	 * - A remapped array of pages for contiguous allocations.
 	 * - A remapped array of pages from iommu_dma_alloc(), for all
 	 *   non-atomic allocations.
 	 * - A non-cacheable alias from the atomic pool, for atomic
 	 *   allocations by non-coherent devices.
 	 * - A normal lowmem address, for atomic allocations by
 	 *   coherent devices.
 	 * Hence how dodgy the below logic looks...
 	 */
 	if (dma_in_atomic_pool(cpu_addr, size)) {
 		iommu_dma_unmap_page(dev, handle, iosize, 0, 0);
 		dma_free_from_pool(cpu_addr, size);
 	} else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
 		struct page *page = vmalloc_to_page(cpu_addr);

 		iommu_dma_unmap_page(dev, handle, iosize, 0, attrs);
 		dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
 		dma_common_free_remap(cpu_addr, size, VM_USERMAP);
 	} else if (is_vmalloc_addr(cpu_addr)){
 		struct vm_struct *area = find_vm_area(cpu_addr);

 		if (WARN_ON(!area || !area->pages))
 			return;
 		iommu_dma_free(dev, area->pages, iosize, &handle);
 		dma_common_free_remap(cpu_addr, size, VM_USERMAP);
 	} else {
 		iommu_dma_unmap_page(dev, handle, iosize, 0, 0);
 		__free_pages(virt_to_page(cpu_addr), get_order(size));
 	}
 }

 static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
 			      void *cpu_addr, dma_addr_t dma_addr, size_t size,
 			      unsigned long attrs)
 {
 	struct vm_struct *area;
 	int ret;

 	vma->vm_page_prot = arch_dma_mmap_pgprot(dev, vma->vm_page_prot, attrs);

 	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
 		return ret;

 	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
 		/*
 		 * DMA_ATTR_FORCE_CONTIGUOUS allocations are always remapped,
 		 * hence in the vmalloc space.
 		 */
 		unsigned long pfn = vmalloc_to_pfn(cpu_addr);
 		return __swiotlb_mmap_pfn(vma, pfn, size);
 	}

 	area = find_vm_area(cpu_addr);
 	if (WARN_ON(!area || !area->pages))
 		return -ENXIO;

 	return iommu_dma_mmap(area->pages, size, vma);
 }

 static int __iommu_get_sgtable(struct device *dev, struct sg_table *sgt,
 			       void *cpu_addr, dma_addr_t dma_addr,
 			       size_t size, unsigned long attrs)
 {
 	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	struct vm_struct *area = find_vm_area(cpu_addr);

 	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
 		/*
 		 * DMA_ATTR_FORCE_CONTIGUOUS allocations are always remapped,
 		 * hence in the vmalloc space.
 		 */
 		struct page *page = vmalloc_to_page(cpu_addr);
 		return __swiotlb_get_sgtable_page(sgt, page, size);
 	}

 	if (WARN_ON(!area || !area->pages))
 		return -ENXIO;

 	return sg_alloc_table_from_pages(sgt, area->pages, count, 0, size,
 					 GFP_KERNEL);
 }

 static void __iommu_sync_single_for_cpu(struct device *dev,
 					dma_addr_t dev_addr, size_t size,
 					enum dma_data_direction dir)
 {
 	phys_addr_t phys;

 	if (dev_is_dma_coherent(dev))
 		return;

 	phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dev_addr);
 	arch_sync_dma_for_cpu(dev, phys, size, dir);
 }

 static void __iommu_sync_single_for_device(struct device *dev,
 					   dma_addr_t dev_addr, size_t size,
 					   enum dma_data_direction dir)
 {
 	phys_addr_t phys;

 	if (dev_is_dma_coherent(dev))
 		return;

 	phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dev_addr);
 	arch_sync_dma_for_device(dev, phys, size, dir);
 }

 static dma_addr_t __iommu_map_page(struct device *dev, struct page *page,
 				   unsigned long offset, size_t size,
 				   enum dma_data_direction dir,
 				   unsigned long attrs)
 {
 	bool coherent = dev_is_dma_coherent(dev);
 	int prot = dma_info_to_prot(dir, coherent, attrs);
 	dma_addr_t dev_addr = iommu_dma_map_page(dev, page, offset, size, prot);

 	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
 	    dev_addr != DMA_MAPPING_ERROR)
 		__dma_map_area(page_address(page) + offset, size, dir);

 	return dev_addr;
 }

 static void __iommu_unmap_page(struct device *dev, dma_addr_t dev_addr,
 			       size_t size, enum dma_data_direction dir,
 			       unsigned long attrs)
 {
 	if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
 		__iommu_sync_single_for_cpu(dev, dev_addr, size, dir);

 	iommu_dma_unmap_page(dev, dev_addr, size, dir, attrs);
 }

 static void __iommu_sync_sg_for_cpu(struct device *dev,
 				    struct scatterlist *sgl, int nelems,
 				    enum dma_data_direction dir)
 {
 	struct scatterlist *sg;
 	int i;

 	if (dev_is_dma_coherent(dev))
 		return;

 	for_each_sg(sgl, sg, nelems, i)
 		arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir);
 }

 static void __iommu_sync_sg_for_device(struct device *dev,
 				       struct scatterlist *sgl, int nelems,
 				       enum dma_data_direction dir)
 {
 	struct scatterlist *sg;
 	int i;

 	if (dev_is_dma_coherent(dev))
 		return;

 	for_each_sg(sgl, sg, nelems, i)
 		arch_sync_dma_for_device(dev, sg_phys(sg), sg->length, dir);
 }

 static int __iommu_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
 				int nelems, enum dma_data_direction dir,
 				unsigned long attrs)
 {
 	bool coherent = dev_is_dma_coherent(dev);

 	if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
 		__iommu_sync_sg_for_device(dev, sgl, nelems, dir);

 	return iommu_dma_map_sg(dev, sgl, nelems,
 				dma_info_to_prot(dir, coherent, attrs));
 }

 static void __iommu_unmap_sg_attrs(struct device *dev,
 				   struct scatterlist *sgl, int nelems,
 				   enum dma_data_direction dir,
 				   unsigned long attrs)
 {
 	if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
 		__iommu_sync_sg_for_cpu(dev, sgl, nelems, dir);

 	iommu_dma_unmap_sg(dev, sgl, nelems, dir, attrs);
 }

 static const struct dma_map_ops iommu_dma_ops = {
 	.alloc = __iommu_alloc_attrs,
 	.free = __iommu_free_attrs,
 	.mmap = __iommu_mmap_attrs,
 	.get_sgtable = __iommu_get_sgtable,
 	.map_page = __iommu_map_page,
 	.unmap_page = __iommu_unmap_page,
 	.map_sg = __iommu_map_sg_attrs,
 	.unmap_sg = __iommu_unmap_sg_attrs,
 	.sync_single_for_cpu = __iommu_sync_single_for_cpu,
 	.sync_single_for_device = __iommu_sync_single_for_device,
 	.sync_sg_for_cpu = __iommu_sync_sg_for_cpu,
 	.sync_sg_for_device = __iommu_sync_sg_for_device,
 	.map_resource = iommu_dma_map_resource,
 	.unmap_resource = iommu_dma_unmap_resource,
 };

 static int __init __iommu_dma_init(void)
 {
 	return iommu_dma_init();
 }
 arch_initcall(__iommu_dma_init);

 static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 				  const struct iommu_ops *ops)
 {
 	struct iommu_domain *domain;

 	if (!ops)
 		return;

 	/*
 	 * The IOMMU core code allocates the default DMA domain, which the
 	 * underlying IOMMU driver needs to support via the dma-iommu layer.
 	 */
 	domain = iommu_get_domain_for_dev(dev);

 	if (!domain)
 		goto out_err;

 	if (domain->type == IOMMU_DOMAIN_DMA) {
 		if (iommu_dma_init_domain(domain, dma_base, size, dev))
 			goto out_err;

 		dev->dma_ops = &iommu_dma_ops;
 	}

 	return;

 out_err:
 	 pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
 		 dev_name(dev));
 }

 void arch_teardown_dma_ops(struct device *dev)
 {
 	dev->dma_ops = NULL;
 }

 #else

 static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 				  const struct iommu_ops *iommu)
 { }

 #endif  /* CONFIG_IOMMU_DMA */

 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 			const struct iommu_ops *iommu, bool coherent)
 {
 	dev->dma_coherent = coherent;
 	__iommu_setup_dma_ops(dev, dma_base, size, iommu);

 #ifdef CONFIG_XEN
 	if (xen_initial_domain()) {
 		dev->archdata.dev_dma_ops = dev->dma_ops;
 		dev->dma_ops = xen_dma_ops;
 	}
 #endif
 }
	/*
	* SWIOTLB-based DMA API implementation
	*
	* Copyright (C) 2012 ARM Ltd.
	* Author: Catalin Marinas <catalin.marinas@arm.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/gfp.h>
	#include <linux/acpi.h>
	#include <linux/memblock.h>
	#include <linux/cache.h>
	#include <linux/export.h>
	#include <linux/slab.h>
	#include <linux/genalloc.h>
	#include <linux/dma-direct.h>
	#include <linux/dma-noncoherent.h>
	#include <linux/dma-contiguous.h>
	#include <linux/vmalloc.h>
	#include <linux/swiotlb.h>
	#include <linux/pci.h>

	#include <asm/cacheflush.h>

	pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
	unsigned long attrs)
	{
	if (!dev_is_dma_coherent(dev) \|\| (attrs & DMA_ATTR_WRITE_COMBINE))
	return pgprot_writecombine(prot);
	return prot;
	}

	void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
	size_t size, enum dma_data_direction dir)
	{
	__dma_map_area(phys_to_virt(paddr), size, dir);
	}

	void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
	size_t size, enum dma_data_direction dir)
	{
	__dma_unmap_area(phys_to_virt(paddr), size, dir);
	}

	void arch_dma_prep_coherent(struct page *page, size_t size)
	{
	__dma_flush_area(page_address(page), size);
	}

	#ifdef CONFIG_IOMMU_DMA
	static int __swiotlb_get_sgtable_page(struct sg_table *sgt,
	struct page *page, size_t size)
	{
	int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

	if (!ret)
	sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);

	return ret;
	}

	static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
	unsigned long pfn, size_t size)
	{
	int ret = -ENXIO;
	unsigned long nr_vma_pages = vma_pages(vma);
	unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
	unsigned long off = vma->vm_pgoff;

	if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
	ret = remap_pfn_range(vma, vma->vm_start,
	pfn + off,
	vma->vm_end - vma->vm_start,
	vma->vm_page_prot);
	}

	return ret;
	}
	#endif /* CONFIG_IOMMU_DMA */

	static int __init arm64_dma_init(void)
	{
	WARN_TAINT(ARCH_DMA_MINALIGN < cache_line_size(),
	TAINT_CPU_OUT_OF_SPEC,
	"ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (%d < %d)",
	ARCH_DMA_MINALIGN, cache_line_size());
	return dma_atomic_pool_init(GFP_DMA32, __pgprot(PROT_NORMAL_NC));
	}
	arch_initcall(arm64_dma_init);

	#ifdef CONFIG_IOMMU_DMA
	#include <linux/dma-iommu.h>
	#include <linux/platform_device.h>
	#include <linux/amba/bus.h>

	/* Thankfully, all cache ops are by VA so we can ignore phys here */
	static void flush_page(struct device dev, const void virt, phys_addr_t phys)
	{
	__dma_flush_area(virt, PAGE_SIZE);
	}

	static void __iommu_alloc_attrs(struct device dev, size_t size,
	dma_addr_t *handle, gfp_t gfp,
	unsigned long attrs)
	{
	bool coherent = dev_is_dma_coherent(dev);
	int ioprot = dma_info_to_prot(DMA_BIDIRECTIONAL, coherent, attrs);
	size_t iosize = size;
	void *addr;

	if (WARN(!dev, "cannot create IOMMU mapping for unknown device\n"))
	return NULL;

	size = PAGE_ALIGN(size);

	/*
	* Some drivers rely on this, and we probably don't want the
	* possibility of stale kernel data being read by devices anyway.
	*/
	gfp \|= __GFP_ZERO;

	if (!gfpflags_allow_blocking(gfp)) {
	struct page *page;
	/*
	* In atomic context we can't remap anything, so we'll only
	* get the virtually contiguous buffer we need by way of a
	* physically contiguous allocation.
	*/
	if (coherent) {
	page = alloc_pages(gfp, get_order(size));
	addr = page ? page_address(page) : NULL;
	} else {
	addr = dma_alloc_from_pool(size, &page, gfp);
	}
	if (!addr)
	return NULL;

	*handle = iommu_dma_map_page(dev, page, 0, iosize, ioprot);
	if (*handle == DMA_MAPPING_ERROR) {
	if (coherent)
	__free_pages(page, get_order(size));
	else
	dma_free_from_pool(addr, size);
	addr = NULL;
	}
	} else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
	pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
	struct page *page;

	page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
	get_order(size), gfp & __GFP_NOWARN);
	if (!page)
	return NULL;

	*handle = iommu_dma_map_page(dev, page, 0, iosize, ioprot);
	if (*handle == DMA_MAPPING_ERROR) {
	dma_release_from_contiguous(dev, page,
	size >> PAGE_SHIFT);
	return NULL;
	}
	addr = dma_common_contiguous_remap(page, size, VM_USERMAP,
	prot,
	__builtin_return_address(0));
	if (addr) {
	if (!coherent)
	__dma_flush_area(page_to_virt(page), iosize);
	memset(addr, 0, size);
	} else {
	iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs);
	dma_release_from_contiguous(dev, page,
	size >> PAGE_SHIFT);
	}
	} else {
	pgprot_t prot = arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs);
	struct page **pages;

	pages = iommu_dma_alloc(dev, iosize, gfp, attrs, ioprot,
	handle, flush_page);
	if (!pages)
	return NULL;

	addr = dma_common_pages_remap(pages, size, VM_USERMAP, prot,
	__builtin_return_address(0));
	if (!addr)
	iommu_dma_free(dev, pages, iosize, handle);
	}
	return addr;
	}

	static void __iommu_free_attrs(struct device dev, size_t size, void cpu_addr,
	dma_addr_t handle, unsigned long attrs)
	{
	size_t iosize = size;

	size = PAGE_ALIGN(size);
	/*
	* @cpu_addr will be one of 4 things depending on how it was allocated:
	* - A remapped array of pages for contiguous allocations.
	* - A remapped array of pages from iommu_dma_alloc(), for all
	* non-atomic allocations.
	* - A non-cacheable alias from the atomic pool, for atomic
	* allocations by non-coherent devices.
	* - A normal lowmem address, for atomic allocations by
	* coherent devices.
	* Hence how dodgy the below logic looks...
	*/
	if (dma_in_atomic_pool(cpu_addr, size)) {
	iommu_dma_unmap_page(dev, handle, iosize, 0, 0);
	dma_free_from_pool(cpu_addr, size);
	} else if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
	struct page *page = vmalloc_to_page(cpu_addr);

	iommu_dma_unmap_page(dev, handle, iosize, 0, attrs);
	dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
	dma_common_free_remap(cpu_addr, size, VM_USERMAP);
	} else if (is_vmalloc_addr(cpu_addr)){
	struct vm_struct *area = find_vm_area(cpu_addr);

	if (WARN_ON(!area \|\| !area->pages))
	return;
	iommu_dma_free(dev, area->pages, iosize, &handle);
	dma_common_free_remap(cpu_addr, size, VM_USERMAP);
	} else {
	iommu_dma_unmap_page(dev, handle, iosize, 0, 0);
	__free_pages(virt_to_page(cpu_addr), get_order(size));
	}
	}

	static int __iommu_mmap_attrs(struct device dev, struct vm_area_struct vma,
	void *cpu_addr, dma_addr_t dma_addr, size_t size,
	unsigned long attrs)
	{
	struct vm_struct *area;
	int ret;

	vma->vm_page_prot = arch_dma_mmap_pgprot(dev, vma->vm_page_prot, attrs);

	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
	return ret;

	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
	/*
	* DMA_ATTR_FORCE_CONTIGUOUS allocations are always remapped,
	* hence in the vmalloc space.
	*/
	unsigned long pfn = vmalloc_to_pfn(cpu_addr);
	return __swiotlb_mmap_pfn(vma, pfn, size);
	}

	area = find_vm_area(cpu_addr);
	if (WARN_ON(!area \|\| !area->pages))
	return -ENXIO;

	return iommu_dma_mmap(area->pages, size, vma);
	}

	static int __iommu_get_sgtable(struct device dev, struct sg_table sgt,
	void *cpu_addr, dma_addr_t dma_addr,
	size_t size, unsigned long attrs)
	{
	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
	struct vm_struct *area = find_vm_area(cpu_addr);

	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
	/*
	* DMA_ATTR_FORCE_CONTIGUOUS allocations are always remapped,
	* hence in the vmalloc space.
	*/
	struct page *page = vmalloc_to_page(cpu_addr);
	return __swiotlb_get_sgtable_page(sgt, page, size);
	}

	if (WARN_ON(!area \|\| !area->pages))
	return -ENXIO;

	return sg_alloc_table_from_pages(sgt, area->pages, count, 0, size,
	GFP_KERNEL);
	}

	static void __iommu_sync_single_for_cpu(struct device *dev,
	dma_addr_t dev_addr, size_t size,
	enum dma_data_direction dir)
	{
	phys_addr_t phys;

	if (dev_is_dma_coherent(dev))
	return;

	phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dev_addr);
	arch_sync_dma_for_cpu(dev, phys, size, dir);
	}

	static void __iommu_sync_single_for_device(struct device *dev,
	dma_addr_t dev_addr, size_t size,
	enum dma_data_direction dir)
	{
	phys_addr_t phys;

	if (dev_is_dma_coherent(dev))
	return;

	phys = iommu_iova_to_phys(iommu_get_dma_domain(dev), dev_addr);
	arch_sync_dma_for_device(dev, phys, size, dir);
	}

	static dma_addr_t __iommu_map_page(struct device dev, struct page page,
	unsigned long offset, size_t size,
	enum dma_data_direction dir,
	unsigned long attrs)
	{
	bool coherent = dev_is_dma_coherent(dev);
	int prot = dma_info_to_prot(dir, coherent, attrs);
	dma_addr_t dev_addr = iommu_dma_map_page(dev, page, offset, size, prot);

	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
	dev_addr != DMA_MAPPING_ERROR)
	__dma_map_area(page_address(page) + offset, size, dir);

	return dev_addr;
	}

	static void __iommu_unmap_page(struct device *dev, dma_addr_t dev_addr,
	size_t size, enum dma_data_direction dir,
	unsigned long attrs)
	{
	if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
	__iommu_sync_single_for_cpu(dev, dev_addr, size, dir);

	iommu_dma_unmap_page(dev, dev_addr, size, dir, attrs);
	}

	static void __iommu_sync_sg_for_cpu(struct device *dev,
	struct scatterlist *sgl, int nelems,
	enum dma_data_direction dir)
	{
	struct scatterlist *sg;
	int i;

	if (dev_is_dma_coherent(dev))
	return;

	for_each_sg(sgl, sg, nelems, i)
	arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir);
	}

	static void __iommu_sync_sg_for_device(struct device *dev,
	struct scatterlist *sgl, int nelems,
	enum dma_data_direction dir)
	{
	struct scatterlist *sg;
	int i;

	if (dev_is_dma_coherent(dev))
	return;

	for_each_sg(sgl, sg, nelems, i)
	arch_sync_dma_for_device(dev, sg_phys(sg), sg->length, dir);
	}

	static int __iommu_map_sg_attrs(struct device dev, struct scatterlist sgl,
	int nelems, enum dma_data_direction dir,
	unsigned long attrs)
	{
	bool coherent = dev_is_dma_coherent(dev);

	if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
	__iommu_sync_sg_for_device(dev, sgl, nelems, dir);

	return iommu_dma_map_sg(dev, sgl, nelems,
	dma_info_to_prot(dir, coherent, attrs));
	}

	static void __iommu_unmap_sg_attrs(struct device *dev,
	struct scatterlist *sgl, int nelems,
	enum dma_data_direction dir,
	unsigned long attrs)
	{
	if ((attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
	__iommu_sync_sg_for_cpu(dev, sgl, nelems, dir);

	iommu_dma_unmap_sg(dev, sgl, nelems, dir, attrs);
	}

	static const struct dma_map_ops iommu_dma_ops = {
	.alloc = __iommu_alloc_attrs,
	.free = __iommu_free_attrs,
	.mmap = __iommu_mmap_attrs,
	.get_sgtable = __iommu_get_sgtable,
	.map_page = __iommu_map_page,
	.unmap_page = __iommu_unmap_page,
	.map_sg = __iommu_map_sg_attrs,
	.unmap_sg = __iommu_unmap_sg_attrs,
	.sync_single_for_cpu = __iommu_sync_single_for_cpu,
	.sync_single_for_device = __iommu_sync_single_for_device,
	.sync_sg_for_cpu = __iommu_sync_sg_for_cpu,
	.sync_sg_for_device = __iommu_sync_sg_for_device,
	.map_resource = iommu_dma_map_resource,
	.unmap_resource = iommu_dma_unmap_resource,
	};

	static int __init __iommu_dma_init(void)
	{
	return iommu_dma_init();
	}
	arch_initcall(__iommu_dma_init);

	static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
	const struct iommu_ops *ops)
	{
	struct iommu_domain *domain;

	if (!ops)
	return;

	/*
	* The IOMMU core code allocates the default DMA domain, which the
	* underlying IOMMU driver needs to support via the dma-iommu layer.
	*/
	domain = iommu_get_domain_for_dev(dev);

	if (!domain)
	goto out_err;

	if (domain->type == IOMMU_DOMAIN_DMA) {
	if (iommu_dma_init_domain(domain, dma_base, size, dev))
	goto out_err;

	dev->dma_ops = &iommu_dma_ops;
	}

	return;

	out_err:
	pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
	dev_name(dev));
	}

	void arch_teardown_dma_ops(struct device *dev)
	{
	dev->dma_ops = NULL;
	}

	#else

	static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
	const struct iommu_ops *iommu)
	{ }

	#endif /* CONFIG_IOMMU_DMA */

	void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
	const struct iommu_ops *iommu, bool coherent)
	{
	dev->dma_coherent = coherent;
	__iommu_setup_dma_ops(dev, dma_base, size, iommu);

	#ifdef CONFIG_XEN
	if (xen_initial_domain()) {
	dev->archdata.dev_dma_ops = dev->dma_ops;
	dev->dma_ops = xen_dma_ops;
	}
	#endif
	}