[RFC PATCH v2 2/3] arm64: add IOMMU dma_ops

Robin Murphy robin.murphy at arm.com
Fri Feb 6 06:55:14 PST 2015


Taking some inspiration from the arch/arm code, implement the
arch-specific side of the DMA mapping ops using the new IOMMU-DMA layer.

Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
 arch/arm64/include/asm/device.h      |   3 +
 arch/arm64/include/asm/dma-mapping.h |  17 ++
 arch/arm64/mm/dma-mapping.c          | 320 +++++++++++++++++++++++++++++++++++
 3 files changed, 340 insertions(+)

diff --git a/arch/arm64/include/asm/device.h b/arch/arm64/include/asm/device.h
index 243ef25..510cee1 100644
--- a/arch/arm64/include/asm/device.h
+++ b/arch/arm64/include/asm/device.h
@@ -20,6 +20,9 @@ struct dev_archdata {
 	struct dma_map_ops *dma_ops;
 #ifdef CONFIG_IOMMU_API
 	void *iommu;			/* private IOMMU data */
+#ifdef CONFIG_IOMMU_DMA
+	struct iommu_dma_domain *dma_domain;
+#endif
 #endif
 	bool dma_coherent;
 };
diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
index 6932bb5..c1b271f 100644
--- a/arch/arm64/include/asm/dma-mapping.h
+++ b/arch/arm64/include/asm/dma-mapping.h
@@ -62,13 +62,30 @@ static inline bool is_device_dma_coherent(struct device *dev)
 
 #include <asm-generic/dma-mapping-common.h>
 
+#ifdef CONFIG_IOMMU_DMA
+static inline struct iommu_dma_domain *get_dma_domain(struct device *dev)
+{
+	return dev->archdata.dma_domain;
+}
+
+static inline void set_dma_domain(struct device *dev,
+				  struct iommu_dma_domain *dma_domain)
+{
+	dev->archdata.dma_domain = dma_domain;
+}
+#endif
+
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
+	if (WARN_ON(dev && get_dma_domain(dev)))
+		return DMA_ERROR_CODE;
 	return (dma_addr_t)paddr;
 }
 
 static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t dev_addr)
 {
+	if (WARN_ON(dev && get_dma_domain(dev)))
+		return 0;
 	return (phys_addr_t)dev_addr;
 }
 
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 0a24b9b..28e771c 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -23,6 +23,7 @@
 #include <linux/genalloc.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
+#include <linux/dma-iommu.h>
 #include <linux/vmalloc.h>
 #include <linux/swiotlb.h>
 
@@ -426,6 +427,7 @@ static int __init arm64_dma_init(void)
 
 	ret |= swiotlb_late_init();
 	ret |= atomic_pool_init();
+	ret |= iommu_dma_init();
 
 	return ret;
 }
@@ -439,3 +441,321 @@ static int __init dma_debug_do_init(void)
 	return 0;
 }
 fs_initcall(dma_debug_do_init);
+
+
+#ifdef CONFIG_IOMMU_DMA
+
+static struct page **__atomic_get_pages(void *addr)
+{
+	struct page *page;
+	phys_addr_t phys;
+
+	phys = gen_pool_virt_to_phys(atomic_pool, (unsigned long)addr);
+	page = phys_to_page(phys);
+
+	return (struct page **)page;
+}
+
+static struct page **__iommu_get_pages(void *cpu_addr, struct dma_attrs *attrs)
+{
+	struct vm_struct *area;
+
+	if (__in_atomic_pool(cpu_addr, PAGE_SIZE))
+		return __atomic_get_pages(cpu_addr);
+
+	area = find_vm_area(cpu_addr);
+	if (!area)
+		return NULL;
+
+	return area->pages;
+}
+
+static void *__iommu_alloc_atomic(struct device *dev, size_t size,
+				  dma_addr_t *handle, bool coherent)
+{
+	struct page *page;
+	void *addr;
+
+	addr = __alloc_from_pool(size, &page);
+	if (!addr)
+		return NULL;
+
+	*handle = iommu_dma_create_iova_mapping(dev, &page, size, coherent);
+	if (*handle == DMA_ERROR_CODE) {
+		__free_from_pool(addr, size);
+		return NULL;
+	}
+	return addr;
+}
+
+static void __iommu_free_atomic(struct device *dev, void *cpu_addr,
+				dma_addr_t handle, size_t size)
+{
+	iommu_dma_release_iova_mapping(dev, handle, size);
+	__free_from_pool(cpu_addr, size);
+}
+
+static void __dma_clear_buffer(struct page *page, size_t size)
+{
+	void *ptr = page_address(page);
+
+	memset(ptr, 0, size);
+	__dma_flush_range(ptr, ptr + size);
+}
+
+static void *__iommu_alloc_attrs(struct device *dev, size_t size,
+				 dma_addr_t *handle, gfp_t gfp,
+				 struct dma_attrs *attrs)
+{
+	bool coherent = is_device_dma_coherent(dev);
+	pgprot_t prot = coherent ? __pgprot(PROT_NORMAL) :
+				   __pgprot(PROT_NORMAL_NC);
+	struct page **pages;
+	void *addr = NULL;
+
+	*handle = DMA_ERROR_CODE;
+	size = PAGE_ALIGN(size);
+
+	if (!(gfp & __GFP_WAIT))
+		return __iommu_alloc_atomic(dev, size, handle, coherent);
+	/*
+	 * FIXME: This isn't even true any more!
+	 *
+	 * Following is a work-around (a.k.a. hack) to prevent pages
+	 * with __GFP_COMP being passed to split_page() which cannot
+	 * handle them.  The real problem is that this flag probably
+	 * should be 0 on ARM as it is not supported on this
+	 * platform; see CONFIG_HUGETLBFS.
+	 */
+	gfp &= ~(__GFP_COMP);
+
+	pages = iommu_dma_alloc_buffer(dev, size, gfp, attrs,
+			__dma_clear_buffer);
+	if (!pages)
+		return NULL;
+
+	*handle = iommu_dma_create_iova_mapping(dev, pages, size, coherent);
+	if (*handle == DMA_ERROR_CODE)
+		goto err_mapping;
+
+	addr = dma_common_pages_remap(pages, size, VM_USERMAP,
+				      __get_dma_pgprot(attrs, prot, coherent),
+				      __builtin_return_address(0));
+	if (addr)
+		return addr;
+
+	iommu_dma_release_iova_mapping(dev, *handle, size);
+err_mapping:
+	iommu_dma_free_buffer(dev, pages, size, attrs);
+	return NULL;
+}
+
+static void __iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
+			       dma_addr_t handle, struct dma_attrs *attrs)
+{
+	struct page **pages;
+
+	size = PAGE_ALIGN(size);
+	if (__in_atomic_pool(cpu_addr, size)) {
+		__iommu_free_atomic(dev, cpu_addr, handle, size);
+		return;
+	}
+
+	pages = __iommu_get_pages(cpu_addr, attrs);
+	if (!pages) {
+		WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
+		return;
+	}
+
+	dma_common_free_remap(cpu_addr, size, VM_USERMAP);
+
+	iommu_dma_release_iova_mapping(dev, handle, size);
+	iommu_dma_free_buffer(dev, pages, size, attrs);
+}
+
+static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
+			      void *cpu_addr, dma_addr_t dma_addr, size_t size,
+			      struct dma_attrs *attrs)
+{
+	unsigned long uaddr = vma->vm_start;
+	unsigned long usize = vma->vm_end - vma->vm_start;
+	struct page **pages = __iommu_get_pages(cpu_addr, attrs);
+	int ret;
+
+	if (!pages)
+		return -ENXIO;
+
+	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot,
+					     is_device_dma_coherent(dev));
+
+	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
+		return ret;
+
+	do {
+		ret = vm_insert_page(vma, uaddr, *pages++);
+		if (ret) {
+			pr_err("Remapping memory failed: %d\n", ret);
+			return ret;
+		}
+		uaddr += PAGE_SIZE;
+		usize -= PAGE_SIZE;
+	} while (usize > 0);
+
+	return 0;
+}
+
+static void __iommu_sync_single_for_cpu(struct device *dev,
+					dma_addr_t dev_addr, size_t size,
+					enum dma_data_direction dir)
+{
+	if (!is_device_dma_coherent(dev) && (dev_addr != DMA_ERROR_CODE)) {
+		struct iommu_dma_domain *dma_domain = get_dma_domain(dev);
+		struct iommu_domain *domain = iommu_dma_raw_domain(dma_domain);
+		phys_addr_t phys = iommu_iova_to_phys(domain, dev_addr);
+
+		__dma_unmap_area(phys_to_virt(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)
+{
+	if (!is_device_dma_coherent(dev) && (dev_addr != DMA_ERROR_CODE)) {
+		struct iommu_dma_domain *dma_domain = get_dma_domain(dev);
+		struct iommu_domain *domain = iommu_dma_raw_domain(dma_domain);
+		phys_addr_t phys = iommu_iova_to_phys(domain, dev_addr);
+
+		__dma_map_area(phys_to_virt(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,
+				   struct dma_attrs *attrs)
+{
+	dma_addr_t dev_addr;
+
+	if (is_device_dma_coherent(dev))
+		return iommu_dma_coherent_map_page(dev, page, offset, size,
+				dir, attrs);
+
+	dev_addr = iommu_dma_map_page(dev, page, offset, size, dir, attrs);
+
+	if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+		__iommu_sync_single_for_device(dev, dev_addr, 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,
+			       struct dma_attrs *attrs)
+{
+	if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+		__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 (is_device_dma_coherent(dev))
+		return;
+
+	for_each_sg(sgl, sg, nelems, i)
+		__dma_unmap_area(sg_virt(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 (is_device_dma_coherent(dev))
+		return;
+
+	for_each_sg(sgl, sg, nelems, i)
+		__dma_map_area(sg_virt(sg), sg->length, dir);
+}
+
+static int __iommu_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
+				int nelems, enum dma_data_direction dir,
+				struct dma_attrs *attrs)
+{
+	if (is_device_dma_coherent(dev))
+		return iommu_dma_coherent_map_sg(dev, sgl, nelems, dir, attrs);
+
+	if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+		__iommu_sync_sg_for_device(dev, sgl, nelems, dir);
+
+	return iommu_dma_map_sg(dev, sgl, nelems, dir, attrs);
+}
+
+static void __iommu_unmap_sg_attrs(struct device *dev,
+				   struct scatterlist *sgl, int nelems,
+				   enum dma_data_direction dir,
+				   struct dma_attrs *attrs)
+{
+	if (!dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
+		__iommu_sync_sg_for_cpu(dev, sgl, nelems, dir);
+
+	iommu_dma_unmap_sg(dev, sgl, nelems, dir, attrs);
+}
+
+static struct dma_map_ops iommu_dma_ops = {
+	.alloc = __iommu_alloc_attrs,
+	.free = __iommu_free_attrs,
+	.mmap = __iommu_mmap_attrs,
+	.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,
+	.dma_supported = iommu_dma_supported,
+	.mapping_error = iommu_dma_mapping_error,
+};
+
+static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+				  const struct iommu_ops *ops)
+{
+	struct iommu_dma_domain *dma_domain;
+
+	if (!ops)
+		return;
+
+	dma_domain = iommu_dma_create_domain(ops, dma_base, size);
+	if (!dma_domain) {
+		pr_warn("Failed to create %llu-byte IOMMU mapping for device %s\n",
+				size, dev_name(dev));
+		return;
+	}
+
+	if (iommu_dma_attach_device(dev, dma_domain))
+		pr_warn("Failed to attach device %s to IOMMU mapping\n",
+				dev_name(dev));
+	else
+		dev->archdata.dma_ops = &iommu_dma_ops;
+
+	/* drop the initial mapping refcount */
+	iommu_dma_release_domain(dma_domain);
+}
+
+#else
+
+static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+				  struct iommu_ops *iommu)
+{ }
+
+#endif  /* CONFIG_IOMMU_DMA */
-- 
1.9.1





More information about the linux-arm-kernel mailing list