[PATCH 1/5] driver: Adopt DMA mask concept from Linux

[Andrey Smirnov <andrew.smirnov@gmail.com>]

In order to be able to detect cases where DMA isn't capable of
reaching every memory address, port the concept of DMA mask,
dma_set_mask() function and add appropriate check to
dma_mapping_error().

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 include/dma.h    | 12 +++++++++++-
 include/driver.h |  2 ++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/dma.h b/include/dma.h
index 5fdcb1733..7f9578263 100644
--- a/include/dma.h
+++ b/include/dma.h
@@ -35,11 +35,21 @@ dma_addr_t dma_map_single(struct device_d *dev, void *ptr, size_t size,
 void dma_unmap_single(struct device_d *dev, dma_addr_t addr, size_t size,
 		      enum dma_data_direction dir);
 
+#define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
+
+#define DMA_MASK_NONE	0x0ULL
+
+static inline void dma_set_mask(struct device_d *dev, u64 dma_mask)
+{
+	dev->dma_mask = dma_mask;
+}
+
 #define DMA_ERROR_CODE  (~(dma_addr_t)0)
 
 static inline int dma_mapping_error(struct device_d *dev, dma_addr_t dma_addr)
 {
-	return dma_addr == DMA_ERROR_CODE;
+	return dma_addr == DMA_ERROR_CODE ||
+		(dev->dma_mask && dma_addr > dev->dma_mask);
 }
 
 /* streaming DMA - implement the below calls to support HAS_DMA */
diff --git a/include/driver.h b/include/driver.h
index 91653b794..1b61f2066 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -82,6 +82,8 @@ struct device_d {
 
 	const struct of_device_id *of_id_entry;
 
+	u64 dma_mask;
+
 	void    (*info) (struct device_d *);
 	/*
 	 * For devices which take longer to probe this is called
-- 
2.17.1


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