[PATCH 07/22] swiotlb: add common swiotlb_map_ops

Christoph Hellwig
2018-01-10T08:10:06Z

Currently all architectures that want to use swiotlb have to implement
their own dma_map_ops instances. Provide a generic one based on the
x86 implementation which first calls into dma_direct to try a full blown
direct mapping implementation (including e.g. CMA) before falling back
allocating from the swiotlb buffer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/swiotlb.h | 8 ++++++++
lib/swiotlb.c | 43 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 606375e35d87..5b1f2a00491c 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -66,6 +66,12 @@ extern void swiotlb_tbl_sync_single(struct device *hwdev,
enum dma_sync_target target);

/* Accessory functions. */
+
+void *swiotlb_alloc(struct device *hwdev, size_t size, dma_addr_t *dma_handle,
+ gfp_t flags, unsigned long attrs);
+void swiotlb_free(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_addr, unsigned long attrs);
+
extern void
*swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, gfp_t flags);
@@ -126,4 +132,6 @@ extern void swiotlb_print_info(void);
extern int is_swiotlb_buffer(phys_addr_t paddr);
extern void swiotlb_set_max_segment(unsigned int);

+extern const struct dma_map_ops swiotlb_dma_ops;
+
#endif /* __LINUX_SWIOTLB_H */
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index cf5311908fa9..0fae2f45c3c0 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -1087,3 +1087,46 @@ swiotlb_dma_supported(struct device *hwdev, u64 mask)
return swiotlb_phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
}
EXPORT_SYMBOL(swiotlb_dma_supported);
+
+#ifdef CONFIG_DMA_DIRECT_OPS
+void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+ gfp_t gfp, unsigned long attrs)
+{
+ void *vaddr;
+
+ /*
+ * Don't print a warning when the first allocation attempt fails.
+ * swiotlb_alloc_coherent() will print a warning when the DMA memory
+ * allocation ultimately failed.
+ */
+ gfp |= __GFP_NOWARN;
+
+ vaddr = dma_direct_alloc(dev, size, dma_handle, gfp, attrs);
+ if (!vaddr)
+ vaddr = swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
+ return vaddr;
+}
+
+void swiotlb_free(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_addr, unsigned long attrs)
+{
+ if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
+ swiotlb_free_coherent(dev, size, vaddr, dma_addr);
+ else
+ dma_direct_free(dev, size, vaddr, dma_addr, attrs);
+}
+
+const struct dma_map_ops swiotlb_dma_ops = {
+ .mapping_error = swiotlb_dma_mapping_error,
+ .alloc = swiotlb_alloc,
+ .free = swiotlb_free,
+ .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
+ .sync_single_for_device = swiotlb_sync_single_for_device,
+ .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
+ .sync_sg_for_device = swiotlb_sync_sg_for_device,
+ .map_sg = swiotlb_map_sg_attrs,
+ .unmap_sg = swiotlb_unmap_sg_attrs,
+ .map_page = swiotlb_map_page,
+ .unmap_page = swiotlb_unmap_page,
+};
+#endif /* CONFIG_DMA_DIRECT_OPS */
--
2.14.2