[PATCH v2 2/4] iommu: Implement common IOMMU ops for DMA mapping
Robin Murphy
robin.murphy at arm.com
Thu Jun 11 08:54:22 PDT 2015
Taking inspiration from the existing arch/arm code, break out some
generic functions to interface the DMA-API to the IOMMU-API. This will
do the bulk of the heavy lifting for IOMMU-backed dma-mapping.
Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
drivers/iommu/Kconfig | 7 +
drivers/iommu/Makefile | 1 +
drivers/iommu/dma-iommu.c | 560 ++++++++++++++++++++++++++++++++++++++++++++++
include/linux/dma-iommu.h | 94 ++++++++
4 files changed, 662 insertions(+)
create mode 100644 drivers/iommu/dma-iommu.c
create mode 100644 include/linux/dma-iommu.h
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 1ae4e54..9107b6e 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -48,6 +48,13 @@ config OF_IOMMU
def_bool y
depends on OF && IOMMU_API
+# IOMMU-agnostic DMA-mapping layer
+config IOMMU_DMA
+ bool
+ depends on NEED_SG_DMA_LENGTH
+ select IOMMU_API
+ select IOMMU_IOVA
+
config FSL_PAMU
bool "Freescale IOMMU support"
depends on PPC32
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 080ffab..574b241 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -1,6 +1,7 @@
obj-$(CONFIG_IOMMU_API) += iommu.o
obj-$(CONFIG_IOMMU_API) += iommu-traces.o
obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
+obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
obj-$(CONFIG_IOMMU_IOVA) += iova.o
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
new file mode 100644
index 0000000..ae65c76
--- /dev/null
+++ b/drivers/iommu/dma-iommu.c
@@ -0,0 +1,560 @@
+/*
+ * A fairly generic DMA-API to IOMMU-API glue layer.
+ *
+ * Copyright (C) 2014-2015 ARM Ltd.
+ *
+ * based in part on arch/arm/mm/dma-mapping.c:
+ * Copyright (C) 2000-2004 Russell King
+ *
+ * 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/>.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/device.h>
+#include <linux/dma-iommu.h>
+#include <linux/huge_mm.h>
+#include <linux/iommu.h>
+#include <linux/iova.h>
+#include <linux/mm.h>
+
+int iommu_dma_init(void)
+{
+ return iommu_iova_cache_init();
+}
+
+struct iommu_dma_domain {
+ struct iommu_domain *domain;
+ struct iova_domain *iovad;
+ struct kref kref;
+};
+
+/**
+ * iommu_dma_create_domain - Create a DMA mapping domain
+ * @ops: iommu_ops representing the IOMMU backing this domain. It is down to
+ * the IOMMU driver whether a domain may span multiple IOMMU instances
+ * @base: IOVA at which the mappable address space starts
+ * @size: Size of IOVA space
+ *
+ * @base and @size should be exact multiples of IOMMU page granularity to
+ * avoid rounding surprises. If necessary, we reserve the page at address 0
+ * to ensure it is an invalid IOVA.
+ *
+ * Return: Pointer to a domain initialised with the given IOVA range,
+ * or NULL on failure. If successful, the caller holds an initial
+ * reference, which may be released with iommu_dma_release_domain()
+ * once a device is attached.
+ */
+struct iommu_dma_domain *iommu_dma_create_domain(const struct iommu_ops *ops,
+ dma_addr_t base, u64 size)
+{
+ struct iommu_dma_domain *dom;
+ struct iommu_domain *domain;
+ struct iova_domain *iovad;
+ unsigned long order, base_pfn, end_pfn;
+
+ dom = kzalloc(sizeof(*dom), GFP_KERNEL);
+ if (!dom)
+ return NULL;
+ /*
+ * HACK(sort of): These domains currently belong to this layer and are
+ * opaque from outside it, so they are "unmanaged" by the IOMMU API
+ * itself. Once we have default domain support worked out, then we can
+ * turn things inside out and put these inside managed IOMMU domains...
+ */
+ domain = ops->domain_alloc(IOMMU_DOMAIN_UNMANAGED);
+ if (!domain)
+ goto out_free_dma_domain;
+
+ domain->ops = ops;
+ domain->type = IOMMU_DOMAIN_UNMANAGED;
+
+ /* Use the smallest supported page size for IOVA granularity */
+ order = __ffs(ops->pgsize_bitmap);
+ base_pfn = max_t(unsigned long, 1, base >> order);
+ end_pfn = (base + size - 1) >> order;
+
+ /* Check the domain allows at least some access to the device... */
+ if (domain->geometry.force_aperture) {
+ if (base > domain->geometry.aperture_end ||
+ base + size <= domain->geometry.aperture_start) {
+ pr_warn("specified DMA range outside IOMMU capability\n");
+ goto out_free_iommu_domain;
+ }
+ /* ...then finally give it a kicking to make sure it fits */
+ base_pfn = max_t(unsigned long, base_pfn,
+ domain->geometry.aperture_start >> order);
+ end_pfn = min_t(unsigned long, end_pfn,
+ domain->geometry.aperture_end >> order);
+ }
+ /*
+ * Note that this almost certainly breaks the case where multiple
+ * devices with different DMA capabilities need to share a domain,
+ * but we don't have the necessary information to handle that here
+ * anyway - "proper" group and domain allocation needs to involve
+ * the IOMMU driver and a complete view of the bus.
+ */
+
+ iovad = kzalloc(sizeof(*iovad), GFP_KERNEL);
+ if (!iovad)
+ goto out_free_iommu_domain;
+
+ init_iova_domain(iovad, 1UL << order, base_pfn, end_pfn);
+
+ dom->domain = domain;
+ dom->iovad = iovad;
+ kref_init(&dom->kref);
+ return dom;
+
+out_free_iommu_domain:
+ ops->domain_free(domain);
+out_free_dma_domain:
+ kfree(dom);
+ return NULL;
+}
+
+static void __iommu_dma_free_domain(struct kref *kref)
+{
+ struct iommu_dma_domain *dom;
+
+ dom = container_of(kref, struct iommu_dma_domain, kref);
+ put_iova_domain(dom->iovad);
+ iommu_domain_free(dom->domain);
+ kfree(dom);
+}
+
+void iommu_dma_release_domain(struct iommu_dma_domain *dom)
+{
+ kref_put(&dom->kref, __iommu_dma_free_domain);
+}
+
+struct iommu_domain *iommu_dma_raw_domain(struct iommu_dma_domain *dom)
+{
+ return dom->domain;
+}
+
+int iommu_dma_attach_device(struct device *dev, struct iommu_dma_domain *dom)
+{
+ int ret;
+
+ kref_get(&dom->kref);
+ ret = iommu_attach_device(dom->domain, dev);
+ if (!ret)
+ arch_set_dma_domain(dev, dom);
+ return ret;
+}
+
+void iommu_dma_detach_device(struct device *dev)
+{
+ struct iommu_dma_domain *dom = arch_get_dma_domain(dev);
+
+ arch_set_dma_domain(dev, NULL);
+ iommu_detach_device(dom->domain, dev);
+ iommu_dma_release_domain(dom);
+}
+
+/*
+ * IOVAs are IOMMU _input_ addresses, so there still exists the possibility
+ * for static bus translation between device output and IOMMU input (yuck).
+ */
+static inline dma_addr_t dev_dma_addr(struct device *dev, dma_addr_t addr)
+{
+ dma_addr_t offset = (dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT;
+
+ BUG_ON(addr < offset);
+ return addr - offset;
+}
+
+/**
+ * dma_direction_to_prot - Translate DMA API directions to IOMMU API page flags
+ * @dir: Direction of DMA transfer
+ * @coherent: Is the DMA master cache-coherent?
+ *
+ * Return: corresponding IOMMU API page protection flags
+ */
+int dma_direction_to_prot(enum dma_data_direction dir, bool coherent)
+{
+ int prot = coherent ? IOMMU_CACHE : 0;
+
+ switch (dir) {
+ case DMA_BIDIRECTIONAL:
+ return prot | IOMMU_READ | IOMMU_WRITE;
+ case DMA_TO_DEVICE:
+ return prot | IOMMU_READ;
+ case DMA_FROM_DEVICE:
+ return prot | IOMMU_WRITE;
+ default:
+ return 0;
+ }
+}
+
+static struct iova *__alloc_iova(struct device *dev, size_t size, bool coherent)
+{
+ struct iommu_dma_domain *dom = arch_get_dma_domain(dev);
+ struct iova_domain *iovad = dom->iovad;
+ unsigned long shift = iova_shift(iovad);
+ unsigned long length = iova_align(iovad, size) >> shift;
+ u64 dma_limit = coherent ? dev->coherent_dma_mask : dma_get_mask(dev);
+
+ /*
+ * Enforce size-alignment to be safe - there should probably be
+ * an attribute to control this per-device, or at least per-domain...
+ */
+ return alloc_iova(iovad, length, dma_limit >> shift, true);
+}
+
+/* The IOVA allocator knows what we mapped, so just unmap whatever that was */
+static void __iommu_dma_unmap(struct iommu_dma_domain *dom, dma_addr_t dma_addr)
+{
+ struct iova_domain *iovad = dom->iovad;
+ unsigned long shift = iova_shift(iovad);
+ unsigned long pfn = dma_addr >> shift;
+ struct iova *iova = find_iova(iovad, pfn);
+ size_t size = iova_size(iova) << shift;
+
+ /* ...and if we can't, then something is horribly, horribly wrong */
+ BUG_ON(iommu_unmap(dom->domain, pfn << shift, size) < size);
+ __free_iova(iovad, iova);
+}
+
+static void __iommu_dma_free_pages(struct page **pages, int count)
+{
+ while (count--)
+ __free_page(pages[count]);
+ kvfree(pages);
+}
+
+static struct page **__iommu_dma_alloc_pages(unsigned int count, gfp_t gfp)
+{
+ struct page **pages;
+ unsigned int i = 0, array_size = count * sizeof(*pages);
+
+ if (array_size <= PAGE_SIZE)
+ pages = kzalloc(array_size, GFP_KERNEL);
+ else
+ pages = vzalloc(array_size);
+ if (!pages)
+ return NULL;
+
+ while (count) {
+ struct page *page = NULL;
+ int j, order = __fls(count);
+
+ /*
+ * Higher-order allocations are a convenience rather
+ * than a necessity, hence using __GFP_NORETRY until
+ * falling back to single-page allocations.
+ */
+ for (order = min(order, MAX_ORDER); order > 0; order--) {
+ page = alloc_pages(gfp | __GFP_NORETRY, order);
+ if (!page)
+ continue;
+ if (PageCompound(page)) {
+ if (!split_huge_page(page))
+ break;
+ __free_pages(page, order);
+ } else {
+ split_page(page, order);
+ break;
+ }
+ }
+ if (!page)
+ page = alloc_page(gfp);
+ if (!page) {
+ __iommu_dma_free_pages(pages, i);
+ return NULL;
+ }
+ j = 1 << order;
+ count -= j;
+ while (j--)
+ pages[i++] = page++;
+ }
+ return pages;
+}
+
+/**
+ * iommu_dma_free - Free a buffer allocated by iommu_dma_alloc()
+ * @dev: Device which owns this buffer
+ * @pages: Array of buffer pages as returned by iommu_dma_alloc()
+ * @size: Size of buffer in bytes
+ * @handle: DMA address of buffer
+ *
+ * Frees both the pages associated with the buffer, and the array
+ * describing them
+ */
+void iommu_dma_free(struct device *dev, struct page **pages, size_t size,
+ dma_addr_t *handle)
+{
+ __iommu_dma_unmap(arch_get_dma_domain(dev), *handle);
+ __iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
+ *handle = DMA_ERROR_CODE;
+}
+
+/**
+ * iommu_dma_alloc - Allocate and map a buffer contiguous in IOVA space
+ * @dev: Device to allocate memory for. Must be a real device
+ * attached to an iommu_dma_domain
+ * @size: Size of buffer in bytes
+ * @gfp: Allocation flags
+ * @prot: IOMMU mapping flags
+ * @coherent: Which dma_mask to base IOVA allocation on
+ * @handle: Out argument for allocated DMA handle
+ * @flush_page: Arch callback to flush a single page from caches as
+ * necessary. May be NULL for coherent allocations
+ *
+ * If @size is less than PAGE_SIZE, then a full CPU page will be allocated,
+ * but an IOMMU which supports smaller pages might not map the whole thing.
+ * For now, the buffer is unconditionally zeroed for compatibility
+ *
+ * Return: Array of struct page pointers describing the buffer,
+ * or NULL on failure.
+ */
+struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
+ int prot, bool coherent, dma_addr_t *handle,
+ void (*flush_page)(const void *, phys_addr_t))
+{
+ struct iommu_dma_domain *dom = arch_get_dma_domain(dev);
+ struct iova_domain *iovad = dom->iovad;
+ struct iova *iova;
+ struct page **pages;
+ struct sg_table sgt;
+ struct sg_mapping_iter miter;
+ dma_addr_t dma_addr;
+ unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+ *handle = DMA_ERROR_CODE;
+
+ /* IOMMU can map any pages, so himem can also be used here */
+ gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
+ pages = __iommu_dma_alloc_pages(count, gfp);
+ if (!pages)
+ return NULL;
+
+ iova = __alloc_iova(dev, size, coherent);
+ if (!iova)
+ goto out_free_pages;
+
+ if (sg_alloc_table_from_pages(&sgt, pages, count, 0, size, GFP_KERNEL))
+ goto out_free_iova;
+
+ dma_addr = iova_dma_addr(iovad, iova);
+ if (iommu_map_sg(dom->domain, dma_addr, sgt.sgl, sgt.orig_nents, prot)
+ < size)
+ goto out_free_sg;
+
+ /* Using the non-flushing flag since we're doing our own */
+ sg_miter_start(&miter, sgt.sgl, sgt.orig_nents, SG_MITER_FROM_SG);
+ while (sg_miter_next(&miter)) {
+ memset(miter.addr, 0, PAGE_SIZE);
+ if (flush_page)
+ flush_page(miter.addr, page_to_phys(miter.page));
+ }
+ sg_miter_stop(&miter);
+ sg_free_table(&sgt);
+
+ *handle = dma_addr;
+ return pages;
+
+out_free_sg:
+ sg_free_table(&sgt);
+out_free_iova:
+ __free_iova(iovad, iova);
+out_free_pages:
+ __iommu_dma_free_pages(pages, count);
+ return NULL;
+}
+
+/**
+ * iommu_dma_mmap - Map a buffer into provided user VMA
+ * @pages: Array representing buffer from iommu_dma_alloc()
+ * @size: Size of buffer in bytes
+ * @vma: VMA describing requested userspace mapping
+ *
+ * Maps the pages of the buffer in @pages into @vma. The caller is responsible
+ * for verifying the correct size and protection of @vma beforehand.
+ */
+
+int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma)
+{
+ unsigned long uaddr = vma->vm_start;
+ unsigned int i, count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ int ret = -ENXIO;
+
+ for (i = vma->vm_pgoff; i < count && uaddr < vma->vm_end; i++) {
+ ret = vm_insert_page(vma, uaddr, pages[i]);
+ if (ret)
+ break;
+ uaddr += PAGE_SIZE;
+ }
+ return ret;
+}
+
+dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size, int prot, bool coherent)
+{
+ dma_addr_t dma_addr;
+ struct iommu_dma_domain *dom = arch_get_dma_domain(dev);
+ struct iova_domain *iovad = dom->iovad;
+ phys_addr_t phys = page_to_phys(page) + offset;
+ size_t iova_off = iova_offset(iovad, phys);
+ size_t len = iova_align(iovad, size + iova_off);
+ struct iova *iova = __alloc_iova(dev, len, coherent);
+
+ if (!iova)
+ return DMA_ERROR_CODE;
+
+ dma_addr = iova_dma_addr(iovad, iova);
+ if (!iommu_map(dom->domain, dma_addr, phys - iova_off, len, prot))
+ return dev_dma_addr(dev, dma_addr + iova_off);
+
+ __free_iova(iovad, iova);
+ return DMA_ERROR_CODE;
+}
+
+void iommu_dma_unmap_page(struct device *dev, dma_addr_t handle, size_t size,
+ enum dma_data_direction dir, struct dma_attrs *attrs)
+{
+ __iommu_dma_unmap(arch_get_dma_domain(dev), handle);
+}
+
+static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
+ dma_addr_t dma_addr)
+{
+ struct scatterlist *s, *seg = sg;
+ unsigned long seg_mask = dma_get_seg_boundary(dev);
+ unsigned int max_len = dma_get_max_seg_size(dev);
+ unsigned int seg_len = 0, seg_dma = 0;
+ int i, count = 1;
+
+ for_each_sg(sg, s, nents, i) {
+ /* Un-swizzling the fields here, hence the naming mismatch */
+ unsigned int s_offset = sg_dma_address(s);
+ unsigned int s_length = sg_dma_len(s);
+ unsigned int s_dma_len = s->length;
+
+ s->offset = s_offset;
+ s->length = s_length;
+ sg_dma_address(s) = DMA_ERROR_CODE;
+ sg_dma_len(s) = 0;
+
+ if (seg_len && (seg_dma + seg_len == dma_addr + s_offset) &&
+ (seg_len + s_dma_len <= max_len) &&
+ ((seg_dma & seg_mask) <= seg_mask - (seg_len + s_length))
+ ) {
+ sg_dma_len(seg) += s_dma_len;
+ } else {
+ if (seg_len) {
+ seg = sg_next(seg);
+ count++;
+ }
+ sg_dma_len(seg) = s_dma_len - s_offset;
+ sg_dma_address(seg) = dma_addr + s_offset;
+
+ seg_len = s_offset;
+ seg_dma = dma_addr + s_offset;
+ }
+ seg_len += s_length;
+ dma_addr += s_dma_len;
+ }
+ return count;
+}
+
+static void __invalidate_sg(struct scatterlist *sg, int nents)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i) {
+ if (sg_dma_address(s) != DMA_ERROR_CODE)
+ s->offset = sg_dma_address(s);
+ if (sg_dma_len(s))
+ s->length = sg_dma_len(s);
+ sg_dma_address(s) = DMA_ERROR_CODE;
+ sg_dma_len(s) = 0;
+ }
+}
+
+int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
+ int nents, int prot, bool coherent)
+{
+ struct iommu_dma_domain *dom = arch_get_dma_domain(dev);
+ struct iova_domain *iovad = dom->iovad;
+ struct iova *iova;
+ struct scatterlist *s;
+ dma_addr_t dma_addr;
+ size_t iova_len = 0;
+ int i;
+
+ /*
+ * Work out how much IOVA space we need, and align the segments to
+ * IOVA granules for the IOMMU driver to handle. With some clever
+ * trickery we can modify the list in a reversible manner.
+ */
+ for_each_sg(sg, s, nents, i) {
+ size_t s_offset = iova_offset(iovad, s->offset);
+ size_t s_length = s->length;
+
+ sg_dma_address(s) = s->offset;
+ sg_dma_len(s) = s_length;
+ s->offset -= s_offset;
+ s_length = iova_align(iovad, s_length + s_offset);
+ s->length = s_length;
+
+ iova_len += s_length;
+ }
+
+ iova = __alloc_iova(dev, iova_len, coherent);
+ if (!iova)
+ goto out_restore_sg;
+
+ /*
+ * We'll leave any physical concatenation to the IOMMU driver's
+ * implementation - it knows better than we do.
+ */
+ dma_addr = iova_dma_addr(iovad, iova);
+ if (iommu_map_sg(dom->domain, dma_addr, sg, nents, prot) < iova_len)
+ goto out_free_iova;
+
+ return __finalise_sg(dev, sg, nents, dev_dma_addr(dev, dma_addr));
+
+out_free_iova:
+ __free_iova(iovad, iova);
+out_restore_sg:
+ __invalidate_sg(sg, nents);
+ return 0;
+}
+
+void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+ enum dma_data_direction dir, struct dma_attrs *attrs)
+{
+ /*
+ * The scatterlist segments are mapped contiguously
+ * in IOVA space, so this is incredibly easy.
+ */
+ __iommu_dma_unmap(arch_get_dma_domain(dev), sg_dma_address(sg));
+}
+
+int iommu_dma_supported(struct device *dev, u64 mask)
+{
+ /*
+ * 'Special' IOMMUs which don't have the same addressing capability
+ * as the CPU will have to wait until we have some way to query that
+ * before they'll be able to use this framework.
+ */
+ return 1;
+}
+
+int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+ return dma_addr == DMA_ERROR_CODE;
+}
diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
new file mode 100644
index 0000000..6708a8a
--- /dev/null
+++ b/include/linux/dma-iommu.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2014-2015 ARM Ltd.
+ *
+ * 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/>.
+ */
+#ifndef __DMA_IOMMU_H
+#define __DMA_IOMMU_H
+
+#ifdef __KERNEL__
+
+#include <linux/dma-mapping.h>
+
+#ifdef CONFIG_IOMMU_DMA
+
+int iommu_dma_init(void);
+
+/* Fundamental domain management */
+struct iommu_dma_domain *iommu_dma_create_domain(const struct iommu_ops *ops,
+ dma_addr_t base, u64 size);
+void iommu_dma_release_domain(struct iommu_dma_domain *dma_domain);
+
+int iommu_dma_attach_device(struct device *dev, struct iommu_dma_domain *domain);
+void iommu_dma_detach_device(struct device *dev);
+
+/* Helpers for DMA-API <-> IOMMU-API interaction */
+struct iommu_domain *iommu_dma_raw_domain(struct iommu_dma_domain *dma_domain);
+int dma_direction_to_prot(enum dma_data_direction dir, bool coherent);
+
+/*
+ * Arch code must provide implementations of these - it can associate domains
+ * with devices however it likes, provided the lookup is efficient
+ */
+static inline struct iommu_dma_domain *arch_get_dma_domain(struct device *dev);
+static inline void arch_set_dma_domain(struct device *dev,
+ struct iommu_dma_domain *dma_domain);
+
+/*
+ * These implement the bulk of the relevant DMA mapping callbacks, but require
+ * the arch code to handle attributes and provide IOMMU-specific parameters
+ */
+struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
+ int prot, bool coherent, dma_addr_t *handle,
+ void (*flush_page)(const void *, phys_addr_t));
+void iommu_dma_free(struct device *dev, struct page **pages, size_t size,
+ dma_addr_t *handle);
+
+int iommu_dma_mmap(struct page **pages, size_t size, struct vm_area_struct *vma);
+
+dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size, int prot, bool coherent);
+int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg,
+ int nents, int prot, bool coherent);
+
+/*
+ * Arch code with no special attribute handling may use these
+ * directly as DMA mapping callbacks for simplicity
+ */
+void iommu_dma_unmap_page(struct device *dev, dma_addr_t handle, size_t size,
+ enum dma_data_direction dir, struct dma_attrs *attrs);
+void iommu_dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
+ enum dma_data_direction dir, struct dma_attrs *attrs);
+int iommu_dma_supported(struct device *dev, u64 mask);
+int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
+#else
+
+static inline int iommu_dma_init(void)
+{
+ return 0;
+}
+
+#endif /* CONFIG_IOMMU_DMA */
+
+static inline struct iommu_dma_domain *arch_get_dma_domain(struct device *dev)
+{
+ return NULL;
+}
+
+static inline void arch_set_dma_domain(struct device *dev,
+ struct iommu_dma_domain *dma_domain)
+{ }
+
+#endif /* __KERNEL__ */
+#endif /* __DMA_IOMMU_H */
--
1.9.1
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