[PATCH v2 09/16] dma-mapping: handle MMIO flow in dma_map|unmap_page

[Leon Romanovsky]

From: Leon Romanovsky <leonro at nvidia.com>

Extend base DMA page API to handle MMIO flow and follow
existing dma_map_resource() implementation to rely on dma_map_direct()
only to take DMA direct path.

Signed-off-by: Leon Romanovsky <leonro at nvidia.com>
---
 kernel/dma/mapping.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 709405d46b2b..8725508a6c57 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -158,6 +158,7 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page,
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 	phys_addr_t phys = page_to_phys(page) + offset;
+	bool is_mmio = attrs & DMA_ATTR_MMIO;
 	dma_addr_t addr;
 
 	BUG_ON(!valid_dma_direction(dir));
@@ -166,12 +167,23 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page,
 		return DMA_MAPPING_ERROR;
 
 	if (dma_map_direct(dev, ops) ||
-	    arch_dma_map_phys_direct(dev, phys + size))
+	    (!is_mmio && arch_dma_map_phys_direct(dev, phys + size)))
 		addr = dma_direct_map_phys(dev, phys, size, dir, attrs);
 	else if (use_dma_iommu(dev))
 		addr = iommu_dma_map_phys(dev, phys, size, dir, attrs);
-	else
+	else if (is_mmio) {
+		if (!ops->map_resource)
+			return DMA_MAPPING_ERROR;
+
+		addr = ops->map_resource(dev, phys, size, dir, attrs);
+	} else {
+		/*
+		 * The dma_ops API contract for ops->map_page() requires
+		 * kmappable memory, while ops->map_resource() does not.
+		 */
 		addr = ops->map_page(dev, page, offset, size, dir, attrs);
+	}
+
 	kmsan_handle_dma(phys, size, dir);
 	trace_dma_map_phys(dev, phys, addr, size, dir, attrs);
 	debug_dma_map_phys(dev, phys, size, dir, addr, attrs);
@@ -184,14 +196,18 @@ void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size,
 		enum dma_data_direction dir, unsigned long attrs)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
+	bool is_mmio = attrs & DMA_ATTR_MMIO;
 
 	BUG_ON(!valid_dma_direction(dir));
 	if (dma_map_direct(dev, ops) ||
-	    arch_dma_unmap_phys_direct(dev, addr + size))
+	    (!is_mmio && arch_dma_unmap_phys_direct(dev, addr + size)))
 		dma_direct_unmap_phys(dev, addr, size, dir, attrs);
 	else if (use_dma_iommu(dev))
 		iommu_dma_unmap_phys(dev, addr, size, dir, attrs);
-	else
+	else if (is_mmio) {
+		if (ops->unmap_resource)
+			ops->unmap_resource(dev, addr, size, dir, attrs);
+	} else
 		ops->unmap_page(dev, addr, size, dir, attrs);
 	trace_dma_unmap_phys(dev, addr, size, dir, attrs);
 	debug_dma_unmap_phys(dev, addr, size, dir);
-- 
2.50.1