Add a new API that returns a potentiall virtually non-contigous sg_table
and a DMA address. This API is only properly implemented for dma-iommu
and will simply return a contigious chunk as a fallback.
The intent is that media drivers can use this API if either:
- no kernel mapping or only temporary kernel mappings are required.
That is as a better replacement for DMA_ATTR_NO_KERNEL_MAPPING
- a kernel mapping is required for cached and DMA mapped pages, but
the driver also needs the pages to e.g. map them to userspace.
In that sense it is a replacement for some aspects of the recently
removed and never fully implemented DMA_ATTR_NON_CONSISTENT
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
Documentation/core-api/dma-api.rst | 74 +++++++++++++++++++++
include/linux/dma-map-ops.h | 18 +++++
include/linux/dma-mapping.h | 31 +++++++++
kernel/dma/mapping.c | 103 +++++++++++++++++++++++++++++
4 files changed, 226 insertions(+)
diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
index 157a474ae54416..e24b2447f4bfe6 100644
--- a/Documentation/core-api/dma-api.rst
+++ b/Documentation/core-api/dma-api.rst
@@ -594,6 +594,80 @@ dev, size, dma_handle and dir must all be the same as those passed into
dma_alloc_noncoherent(). cpu_addr must be the virtual address returned by
dma_alloc_noncoherent().
+::
+
+ struct sg_table *
+ dma_alloc_noncontiguous(struct device *dev, size_t size,
+ enum dma_data_direction dir, gfp_t gfp)
+
+This routine allocates <size> bytes of non-coherent and possibly non-contiguous
+memory. It returns a pointer to struct sg_table that describes the allocated
+and DMA mapped memory, or NULL if the allocation failed. The resulting memory
+can be used for struct page mapped into a scatterlist are suitable for.
+
+The return sg_table is guaranteed to have 1 single DMA mapped segment as
+indicated by sgt->nents, but it might have multiple CPU side segments as
+indicated by sgt->orig_nents.
+
+The dir parameter specified if data is read and/or written by the device,
+see dma_map_single() for details.
+
+The gfp parameter allows the caller to specify the ``GFP_`` flags (see
+kmalloc()) for the allocation, but rejects flags used to specify a memory
+zone such as GFP_DMA or GFP_HIGHMEM.
+
+Before giving the memory to the device, dma_sync_sgtable_for_device() needs
+to be called, and before reading memory written by the device,
+dma_sync_sgtable_for_cpu(), just like for streaming DMA mappings that are
+reused.
+
+::
+
+ void
+ dma_free_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt,
+ enum dma_data_direction dir)
+
+Free memory previously allocated using dma_alloc_noncontiguous(). dev, size,
+and dir must all be the same as those passed into dma_alloc_noncontiguous().
+sgt must be the pointer returned by dma_alloc_noncontiguous().
+
+::
+
+ void *
+ dma_vmap_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt)
+
+Return a contiguous kernel mapping for an allocation returned from
+dma_alloc_noncontiguous(). dev and size must be the same as those passed into
+dma_alloc_noncontiguous(). sgt must be the pointer returned by
+dma_alloc_noncontiguous().
+
+Once a non-contiguous allocation is mapped using this function, the
+flush_kernel_vmap_range() and invalidate_kernel_vmap_range() APIs must be used
+to manage the coherency of the kernel mapping.
+
+::
+
+ void
+ dma_vunmap_noncontiguous(struct device *dev, void *vaddr)
+
+Unmap a kernel mapping returned by dma_vmap_noncontiguous(). dev must be the
+same the one passed into dma_alloc_noncontiguous(). vaddr must be the pointer
+returned by dma_vmap_noncontiguous().
+
+
+::
+
+ int
+ dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
+ size_t size, struct sg_table *sgt)
+
+Map an allocation returned from dma_alloc_noncontiguous() into a user address
+space. dev and size must be the same as those passed into
+dma_alloc_noncontiguous(). sgt must be the pointer returned by
+dma_alloc_noncontiguous().
+
::
int
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 11e02537b9e01b..fe46a41130e662 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -22,6 +22,10 @@ struct dma_map_ops {
gfp_t gfp);
void (*free_pages)(struct device *dev, size_t size, struct page *vaddr,
dma_addr_t dma_handle, enum dma_data_direction dir);
+ struct sg_table *(*alloc_noncontiguous)(struct device *dev, size_t size,
+ enum dma_data_direction dir, gfp_t gfp);
+ void (*free_noncontiguous)(struct device *dev, size_t size,
+ struct sg_table *sgt, enum dma_data_direction dir);
int (*mmap)(struct device *, struct vm_area_struct *,
void *, dma_addr_t, size_t, unsigned long attrs);
@@ -198,6 +202,20 @@ static inline int dma_mmap_from_global_coherent(struct vm_area_struct *vma,
}
#endif /* CONFIG_DMA_DECLARE_COHERENT */
+/*
+ * This is the actual return value from the ->alloc_noncontiguous method.
+ * The users of the DMA API should only care about the sg_table, but to make
+ * the DMA-API internal vmaping and freeing easier we stash away the page
+ * array as well (except for the fallback case). This can go away any time,
+ * e.g. when a vmap-variant that takes a scatterlist comes along.
+ */
+struct dma_sgt_handle {
+ struct sg_table sgt;
+ struct page **pages;
+};
+#define sgt_handle(sgt) \
+ container_of((sgt), struct dma_sgt_handle, sgt)
+
int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4977a748cb9483..6f4d34739f5cc6 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -144,6 +144,15 @@ u64 dma_get_required_mask(struct device *dev);
size_t dma_max_mapping_size(struct device *dev);
bool dma_need_sync(struct device *dev, dma_addr_t dma_addr);
unsigned long dma_get_merge_boundary(struct device *dev);
+struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
+ enum dma_data_direction dir, gfp_t gfp);
+void dma_free_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt, enum dma_data_direction dir);
+void *dma_vmap_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt);
+void dma_vunmap_noncontiguous(struct device *dev, void *vaddr);
+int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
+ size_t size, struct sg_table *sgt);
#else /* CONFIG_HAS_DMA */
static inline dma_addr_t dma_map_page_attrs(struct device *dev,
struct page *page, size_t offset, size_t size,
@@ -257,6 +266,28 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
{
return 0;
}
+static inline struct sg_table *dma_alloc_noncontiguous(struct device *dev,
+ size_t size, enum dma_data_direction dir, gfp_t gfp)
+{
+ return NULL;
+}
+static inline void dma_free_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt, enum dma_data_direction dir)
+{
+}
+static inline void *dma_vmap_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt)
+{
+ return NULL;
+}
+static inline void dma_vunmap_noncontiguous(struct device *dev, void *vaddr)
+{
+}
+static inline int dma_mmap_noncontiguous(struct device *dev,
+ struct vm_area_struct *vma, size_t size, struct sg_table *sgt)
+{
+ return -EINVAL;
+}
#endif /* CONFIG_HAS_DMA */
struct page *dma_alloc_pages(struct device *dev, size_t size,
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 5e87dac6cc6d9a..5a62439ed483af 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -537,6 +537,109 @@ int dma_mmap_pages(struct device *dev, struct vm_area_struct *vma,
}
EXPORT_SYMBOL_GPL(dma_mmap_pages);
+static struct sg_table *alloc_single_sgt(struct device *dev, size_t size,
+ enum dma_data_direction dir, gfp_t gfp)
+{
+ struct sg_table *sgt;
+ struct page *page;
+
+ sgt = kmalloc(sizeof(*sgt), gfp);
+ if (!sgt)
+ return NULL;
+ if (sg_alloc_table(sgt, 1, gfp))
+ goto out_free_sgt;
+ page = __dma_alloc_pages(dev, size, &sgt->sgl->dma_address, dir, gfp);
+ if (!page)
+ goto out_free_table;
+ sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
+ sg_dma_len(sgt->sgl) = sgt->sgl->length;
+ return sgt;
+out_free_table:
+ sg_free_table(sgt);
+out_free_sgt:
+ kfree(sgt);
+ return NULL;
+}
+
+struct sg_table *dma_alloc_noncontiguous(struct device *dev, size_t size,
+ enum dma_data_direction dir, gfp_t gfp)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+ struct sg_table *sgt;
+
+ if (ops && ops->alloc_noncontiguous)
+ sgt = ops->alloc_noncontiguous(dev, size, dir, gfp);
+ else
+ sgt = alloc_single_sgt(dev, size, dir, gfp);
+
+ if (sgt) {
+ sgt->nents = 1;
+ debug_dma_map_sg(dev, sgt->sgl, sgt->orig_nents, 1, dir);
+ }
+ return sgt;
+}
+EXPORT_SYMBOL_GPL(dma_alloc_noncontiguous);
+
+static void free_single_sgt(struct device *dev, size_t size,
+ struct sg_table *sgt, enum dma_data_direction dir)
+{
+ __dma_free_pages(dev, size, sg_page(sgt->sgl), sgt->sgl->dma_address,
+ dir);
+ sg_free_table(sgt);
+ kfree(sgt);
+}
+
+void dma_free_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt, enum dma_data_direction dir)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ debug_dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
+ if (ops && ops->free_noncontiguous)
+ ops->free_noncontiguous(dev, size, sgt, dir);
+ else
+ free_single_sgt(dev, size, sgt, dir);
+}
+EXPORT_SYMBOL_GPL(dma_free_noncontiguous);
+
+void *dma_vmap_noncontiguous(struct device *dev, size_t size,
+ struct sg_table *sgt)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+ unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+ if (ops && ops->alloc_noncontiguous)
+ return vmap(sgt_handle(sgt)->pages, count, VM_MAP, PAGE_KERNEL);
+ return page_address(sg_page(sgt->sgl));
+}
+EXPORT_SYMBOL_GPL(dma_vmap_noncontiguous);
+
+void dma_vunmap_noncontiguous(struct device *dev, void *vaddr)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ if (ops && ops->alloc_noncontiguous)
+ vunmap(vaddr);
+}
+EXPORT_SYMBOL_GPL(dma_vunmap_noncontiguous);
+
+int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
+ size_t size, struct sg_table *sgt)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ if (ops && ops->alloc_noncontiguous) {
+ unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+ if (vma->vm_pgoff >= count ||
+ vma_pages(vma) > count - vma->vm_pgoff)
+ return -ENXIO;
+ return vm_map_pages(vma, sgt_handle(sgt)->pages, count);
+ }
+ return dma_mmap_pages(dev, vma, size, sg_page(sgt->sgl));
+}
+EXPORT_SYMBOL_GPL(dma_mmap_noncontiguous);
+
int dma_supported(struct device *dev, u64 mask)
{
const struct dma_map_ops *ops = get_dma_ops(dev);
--
2.29.2
