From: Leon Romanovsky <leonro@nvidia.com>

Convert the DMA direct mapping functions to accept physical addresses
directly instead of page+offset parameters. The functions were already
operating on physical addresses internally, so this change eliminates
the redundant page-to-physical conversion at the API boundary.

The functions dma_direct_map_page() and dma_direct_unmap_page() are
renamed to dma_direct_map_phys() and dma_direct_unmap_phys() respectively,
with their calling convention changed from (struct page *page,
unsigned long offset) to (phys_addr_t phys).

Architecture-specific functions arch_dma_map_page_direct() and
arch_dma_unmap_page_direct() are similarly renamed to
arch_dma_map_phys_direct() and arch_dma_unmap_phys_direct().

The is_pci_p2pdma_page() checks are replaced with DMA_ATTR_MMIO checks
to allow integration with dma_direct_map_resource and dma_direct_map_phys()
is extended to support MMIO path either.

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
  arch/powerpc/kernel/dma-iommu.c |  4 +--
  include/linux/dma-map-ops.h     |  8 ++---
  kernel/dma/direct.c             |  6 ++--
  kernel/dma/direct.h             | 57 +++++++++++++++++++++------------
  kernel/dma/mapping.c            |  8 ++---
  5 files changed, 49 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index 4d64a5db50f3..0359ab72cd3b 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c

@@ -14,7 +14,7 @@
  #define can_map_direct(dev, addr) \
  	((dev)->bus_dma_limit >= phys_to_dma((dev), (addr)))
  
-bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr)
+bool arch_dma_map_phys_direct(struct device *dev, phys_addr_t addr)
  {
  	if (likely(!dev->bus_dma_limit))
  		return false;

@@ -24,7 +24,7 @@ bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr)
  
  #define is_direct_handle(dev, h) ((h) >= (dev)->archdata.dma_offset)
  
-bool arch_dma_unmap_page_direct(struct device *dev, dma_addr_t dma_handle)
+bool arch_dma_unmap_phys_direct(struct device *dev, dma_addr_t dma_handle)
  {
  	if (likely(!dev->bus_dma_limit))
  		return false;

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index f48e5fb88bd5..71f5b3025415 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h

@@ -392,15 +392,15 @@ void *arch_dma_set_uncached(void *addr, size_t size);
  void arch_dma_clear_uncached(void *addr, size_t size);
  
  #ifdef CONFIG_ARCH_HAS_DMA_MAP_DIRECT
-bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr);
-bool arch_dma_unmap_page_direct(struct device *dev, dma_addr_t dma_handle);
+bool arch_dma_map_phys_direct(struct device *dev, phys_addr_t addr);
+bool arch_dma_unmap_phys_direct(struct device *dev, dma_addr_t dma_handle);
  bool arch_dma_map_sg_direct(struct device *dev, struct scatterlist *sg,
  		int nents);
  bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg,
  		int nents);
  #else
-#define arch_dma_map_page_direct(d, a)		(false)
-#define arch_dma_unmap_page_direct(d, a)	(false)
+#define arch_dma_map_phys_direct(d, a)		(false)
+#define arch_dma_unmap_phys_direct(d, a)	(false)
  #define arch_dma_map_sg_direct(d, s, n)		(false)
  #define arch_dma_unmap_sg_direct(d, s, n)	(false)
  #endif

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 24c359d9c879..fa75e3070073 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c

@@ -453,7 +453,7 @@ void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
  		if (sg_dma_is_bus_address(sg))
  			sg_dma_unmark_bus_address(sg);
  		else
-			dma_direct_unmap_page(dev, sg->dma_address,
+			dma_direct_unmap_phys(dev, sg->dma_address,
  					      sg_dma_len(sg), dir, attrs);
  	}
  }

@@ -476,8 +476,8 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
  			 */
  			break;
  		case PCI_P2PDMA_MAP_NONE:
-			sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
-					sg->offset, sg->length, dir, attrs);
+			sg->dma_address = dma_direct_map_phys(dev, sg_phys(sg),
+					sg->length, dir, attrs);
  			if (sg->dma_address == DMA_MAPPING_ERROR) {
  				ret = -EIO;
  				goto out_unmap;

diff --git a/kernel/dma/direct.h b/kernel/dma/direct.h
index d2c0b7e632fc..3f4792910604 100644
--- a/kernel/dma/direct.h
+++ b/kernel/dma/direct.h

@@ -80,42 +80,57 @@ static inline void dma_direct_sync_single_for_cpu(struct device *dev,
  		arch_dma_mark_clean(paddr, size);
  }
  
-static inline dma_addr_t dma_direct_map_page(struct device *dev,
-		struct page *page, unsigned long offset, size_t size,
-		enum dma_data_direction dir, unsigned long attrs)
+static inline dma_addr_t dma_direct_map_phys(struct device *dev,
+		phys_addr_t phys, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
  {
-	phys_addr_t phys = page_to_phys(page) + offset;
-	dma_addr_t dma_addr = phys_to_dma(dev, phys);
+	dma_addr_t dma_addr;
  
  	if (is_swiotlb_force_bounce(dev)) {
-		if (is_pci_p2pdma_page(page))
-			return DMA_MAPPING_ERROR;
+		if (attrs & DMA_ATTR_MMIO)
+			goto err_overflow;
+
  		return swiotlb_map(dev, phys, size, dir, attrs);
  	}
  
-	if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
-	    dma_kmalloc_needs_bounce(dev, size, dir)) {
-		if (is_pci_p2pdma_page(page))
-			return DMA_MAPPING_ERROR;
-		if (is_swiotlb_active(dev))
-			return swiotlb_map(dev, phys, size, dir, attrs);
-
-		dev_WARN_ONCE(dev, 1,
-			     "DMA addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
-			     &dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
-		return DMA_MAPPING_ERROR;
+	if (attrs & DMA_ATTR_MMIO) {
+		dma_addr = phys;
+		if (unlikely(dma_capable(dev, dma_addr, size, false)))

+			goto err_overflow;
+	} else {
+		dma_addr = phys_to_dma(dev, phys);
+		if (unlikely(!dma_capable(dev, dma_addr, size, true)) ||
+		    dma_kmalloc_needs_bounce(dev, size, dir)) {
+			if (is_swiotlb_active(dev))
+				return swiotlb_map(dev, phys, size, dir, attrs);
+
+			goto err_overflow;
+		}
  	}
  
-	if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+	if (!dev_is_dma_coherent(dev) &&
+	    !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO)))
  		arch_sync_dma_for_device(phys, size, dir);
  	return dma_addr;
+
+err_overflow:
+	dev_WARN_ONCE(
+		dev, 1,
+		"DMA addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
+		&dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
+	return DMA_MAPPING_ERROR;
  }
  
-static inline void dma_direct_unmap_page(struct device *dev, dma_addr_t addr,
+static inline void dma_direct_unmap_phys(struct device *dev, dma_addr_t addr,
  		size_t size, enum dma_data_direction dir, unsigned long attrs)
  {
-	phys_addr_t phys = dma_to_phys(dev, addr);
+	phys_addr_t phys;
+
+	if (attrs & DMA_ATTR_MMIO)
+		/* nothing to do: uncached and no swiotlb */
+		return;
  
+	phys = dma_to_phys(dev, addr);
  	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  		dma_direct_sync_single_for_cpu(dev, addr, size, dir);
  

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 58482536db9b..80481a873340 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c

@@ -166,8 +166,8 @@ 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_page_direct(dev, phys + size))
-		addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
+	    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

@@ -187,8 +187,8 @@ void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size,
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (dma_map_direct(dev, ops) ||
-	    arch_dma_unmap_page_direct(dev, addr + size))
-		dma_direct_unmap_page(dev, addr, size, dir, attrs);
+	    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