[PATCH] dma-buf: Add support for mapping buffers with DMA attributes

[<guangming.cao@xxxxxxxxxxxx>]

From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>

When mapping the memory represented by a dma-buf into a device's
address space, it might be desireable to map the memory with
certain DMA attributes. Thus, introduce the dma_mapping_attrs
field in the dma_buf_attachment structure so that when
the memory is mapped with dma_buf_map_attachment, it is mapped
with the desired DMA attributes.

Signed-off-by: Isaac J. Manjarres <isaacm@xxxxxxxxxxxxxx>
Signed-off-by: Sandeep Patil <sspatil@xxxxxxxxxx>
Signed-off-by: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
---
 drivers/dma-buf/heaps/cma_heap.c    | 6 ++++--
 drivers/dma-buf/heaps/system_heap.c | 6 ++++--
 include/linux/dma-buf.h             | 3 +++
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 0c05b79870f9..2c9feb3bfc3e 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -99,9 +99,10 @@ static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachme
 {
 	struct dma_heap_attachment *a = attachment->priv;
 	struct sg_table *table = &a->table;
+	int attrs = attachment->dma_map_attrs;
 	int ret;
 
-	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
+	ret = dma_map_sgtable(attachment->dev, table, direction, attrs);
 	if (ret)
 		return ERR_PTR(-ENOMEM);
 	a->mapped = true;
@@ -113,9 +114,10 @@ static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
 				   enum dma_data_direction direction)
 {
 	struct dma_heap_attachment *a = attachment->priv;
+	int attrs = attachment->dma_map_attrs;
 
 	a->mapped = false;
-	dma_unmap_sgtable(attachment->dev, table, direction, 0);
+	dma_unmap_sgtable(attachment->dev, table, direction, attrs);
 }
 
 static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 23a7e74ef966..fc7b1e02988e 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -130,9 +130,10 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac
 {
 	struct dma_heap_attachment *a = attachment->priv;
 	struct sg_table *table = a->table;
+	int attrs = attachment->dma_map_attrs;
 	int ret;
 
-	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
+	ret = dma_map_sgtable(attachment->dev, table, direction, attrs);
 	if (ret)
 		return ERR_PTR(ret);
 
@@ -145,9 +146,10 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
 				      enum dma_data_direction direction)
 {
 	struct dma_heap_attachment *a = attachment->priv;
+	int attrs = attachment->dma_map_attrs;
 
 	a->mapped = false;
-	dma_unmap_sgtable(attachment->dev, table, direction, 0);
+	dma_unmap_sgtable(attachment->dev, table, direction, attrs);
 }
 
 static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index efdc56b9d95f..4d650731766e 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -379,6 +379,8 @@ struct dma_buf_attach_ops {
  * @importer_ops: importer operations for this attachment, if provided
  * dma_buf_map/unmap_attachment() must be called with the dma_resv lock held.
  * @importer_priv: importer specific attachment data.
+ * @dma_map_attrs: DMA attributes to be used when the exporter maps the buffer
+ * through dma_buf_map_attachment.
  *
  * This structure holds the attachment information between the dma_buf buffer
  * and its user device(s). The list contains one attachment struct per device
@@ -399,6 +401,7 @@ struct dma_buf_attachment {
 	const struct dma_buf_attach_ops *importer_ops;
 	void *importer_priv;
 	void *priv;
+	unsigned long dma_map_attrs;
 };
 
 /**
-- 
2.17.1