xen: swiotlb: Wire up map_resource callback

When running Xen on iMX8QXP, an Arm SoC without IOMMU, DMA performed via
its eDMA v3 DMA engine fail with a mapping error.

The eDMA performs DMA between RAM and MMIO space, and it's the MMIO side
that cannot be mapped.

MMIO->RAM DMA access cannot be bounce buffered if it would straddle a page
boundary and on Xen the MMIO space is 1:1 mapped for Arm, and x86 PV Dom0.
Cases where MMIO space is not 1:1 mapped, such as x86 PVH Dom0, requires an
IOMMU present to deal with the mapping.

Considering the above the map_resource callback can just be wired to the
existing dma_direct_map_resource() function.

There is nothing to do for unmap so the unmap callback is not needed.

Signed-off-by: John Ernberg <john.ernberg@actia.se>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Message-ID: <20250512071440.3726697-1-john.ernberg@actia.se>
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index ef56a2500ed69a70d8628cc3f83f8b969014aeb7..da1a7d3d377cf1792da7a33612bc9724e7ed9171 100644 (file)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -426,4 +426,5 @@ const struct dma_map_ops xen_swiotlb_dma_ops = {
        .alloc_pages_op = dma_common_alloc_pages,
        .free_pages = dma_common_free_pages,
        .max_mapping_size = swiotlb_max_mapping_size,
+       .map_resource = dma_direct_map_resource,
 };