iommu/io-pgtable-arm: Allow appropriate DMA API use
Currently, users of the LPAE page table code are (ab)using dma_map_page()
as a means to flush page table updates for non-coherent IOMMUs. Since
from the CPU's point of view, creating IOMMU page tables *is* passing
DMA buffers to a device (the IOMMU's page table walker), there's little
reason not to use the DMA API correctly.
Allow IOMMU drivers to opt into DMA API operations for page table
allocation and updates by providing their appropriate device pointer.
The expectation is that an LPAE IOMMU should have a full view of system
memory, so use streaming mappings to avoid unnecessary pressure on
ZONE_DMA, and treat any DMA translation as a warning sign.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/drivers/iommu/io-pgtable.h b/drivers/iommu/io-pgtable.h
index 10e32f6..c69529c 100644
--- a/drivers/iommu/io-pgtable.h
+++ b/drivers/iommu/io-pgtable.h
@@ -41,6 +41,8 @@
* @ias: Input address (iova) size, in bits.
* @oas: Output address (paddr) size, in bits.
* @tlb: TLB management callbacks for this set of tables.
+ * @iommu_dev: The device representing the DMA configuration for the
+ * page table walker.
*/
struct io_pgtable_cfg {
#define IO_PGTABLE_QUIRK_ARM_NS (1 << 0) /* Set NS bit in PTEs */
@@ -49,6 +51,7 @@
unsigned int ias;
unsigned int oas;
const struct iommu_gather_ops *tlb;
+ struct device *iommu_dev;
/* Low-level data specific to the table format */
union {