[RFC PATCH 1/3] dma-mapping: introduce a new dma api dma_addr_to_phys_addr()

[Laurentiu Tudor]

From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>

Introduce a new dma map op called dma_addr_to_phys_addr() that converts
a dma address to the physical address backing it up and add wrapper for
it.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
---
 include/linux/dma-mapping.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4a1c4fca475a..5965d159c9a9 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -132,6 +132,8 @@ struct dma_map_ops {
 	u64 (*get_required_mask)(struct device *dev);
 	size_t (*max_mapping_size)(struct device *dev);
 	unsigned long (*get_merge_boundary)(struct device *dev);
+	phys_addr_t (*dma_addr_to_phys_addr)(struct device *dev,
+					     dma_addr_t dma_handle);
 };
 
 #define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
@@ -442,6 +444,19 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 	return 0;
 }
 
+static inline phys_addr_t dma_addr_to_phys_addr(struct device *dev,
+						dma_addr_t dma_handle)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	if (dma_is_direct(ops))
+		return (phys_addr_t)dma_handle;
+	else if (ops->dma_addr_to_phys_addr)
+		return ops->dma_addr_to_phys_addr(dev, dma_handle);
+
+	return 0;
+}
+
 void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
 		gfp_t flag, unsigned long attrs);
 void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
@@ -578,6 +593,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
 {
 	return 0;
 }
+
+static inline phys_addr_t dma_addr_to_phys_addr(struct device *dev,
+						dma_addr_t dma_handle)
+{
+	return 0;
+}
 #endif /* CONFIG_HAS_DMA */
 
 static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
-- 
2.17.1