diff options
author | Christoph Hellwig <hch@lst.de> | 2021-01-28 16:54:18 +0300 |
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committer | Christoph Hellwig <hch@lst.de> | 2021-03-15 12:02:31 +0300 |
commit | 7d5b5738d1514e9dd8ed452660e2a4d25beb9483 (patch) | |
tree | 9171f83e841b5029329a8bd9664205494e6b0fa3 /kernel/dma | |
parent | 198c50e2ccff5c78ddbe0cb01593ac32458deb69 (diff) | |
download | linux-7d5b5738d1514e9dd8ed452660e2a4d25beb9483.tar.xz |
dma-mapping: add a dma_alloc_noncontiguous API
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 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@lst.de>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Ricardo Ribalda <ribalda@chromium.org>
Diffstat (limited to 'kernel/dma')
-rw-r--r-- | kernel/dma/mapping.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 07f964ebcda1..2b06a809d0b9 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -539,6 +539,112 @@ 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, unsigned long attrs) +{ + const struct dma_map_ops *ops = get_dma_ops(dev); + struct sg_table *sgt; + + if (WARN_ON_ONCE(attrs & ~DMA_ATTR_ALLOC_SINGLE_PAGES)) + return NULL; + + if (ops && ops->alloc_noncontiguous) + sgt = ops->alloc_noncontiguous(dev, size, dir, gfp, attrs); + 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); |