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

[Leon Romanovsky]

From: Leon Romanovsky <leo...@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 <leo...@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