[PATCH v2] staging: ion: Add a default struct device for cma heap

[Feng Tang <feng.tang@intel.com>]

When trying to use several cma heaps on our platforms,
we met a memory issue due to that the several cma_heaps
are sharing the same "struct device *".

As in current code base, the normal cma heap creating
process is, one platform device is created during boot,
and it will sequentially create cma heaps (usually passing
its own struct device * as a parameter)

For the multiple cma heaps case, there will be one "struct
cma" created for each cma heap, and this "struct cma *" is
saved in dev->cma_area. So the single platform device can't
meet the requirement here.

This patch adds one default device for each cma heap to avoid
sharing the same "struct device", thus fix the issue. And it
doesn't break existing code by only using that default device
when no "struct device *" is passed in.

Also, since the cma framework has been cleaned up recently,
this patch also adds a platform data member to pass the
"struct cma*" to ion_cma_heap_create().

Signed-off-by: Feng Tang <feng.tang@intel.com>
[From CMA’s point of view: ]
Acked-by: Michal Nazarewicz <mina86@mina86.com>
---
 drivers/staging/android/ion/ion.h          |    4 ++++
 drivers/staging/android/ion/ion_cma_heap.c |   20 +++++++++++++++++---
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index 443db84..11336df 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -44,6 +44,9 @@ struct ion_buffer;
  * @base:	base address of heap in physical memory if applicable
  * @size:	size of the heap in bytes if applicable
  * @align:	required alignment in physical memory if applicable
+ * @cma:	when creating CMA heap, platform device should better also
+ *		pass the "struct cma *" info, so that the cma buffer request
+ *		know where to go for the buffer
  * @priv:	private info passed from the board file
  *
  * Provided by the board file.
@@ -55,6 +58,7 @@ struct ion_platform_heap {
 	ion_phys_addr_t base;
 	size_t size;
 	ion_phys_addr_t align;
+	struct cma *cma;
 	void *priv;
 };
 
diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
index f4211f1..27f218a 100644
--- a/drivers/staging/android/ion/ion_cma_heap.c
+++ b/drivers/staging/android/ion/ion_cma_heap.c
@@ -29,6 +29,7 @@
 struct ion_cma_heap {
 	struct ion_heap heap;
 	struct device *dev;
+	struct device default_dma_dev;
 };
 
 #define to_cma_heap(x) container_of(x, struct ion_cma_heap, heap)
@@ -180,9 +181,22 @@ struct ion_heap *ion_cma_heap_create(struct ion_platform_heap *data)
 		return ERR_PTR(-ENOMEM);
 
 	cma_heap->heap.ops = &ion_cma_ops;
-	/* get device from private heaps data, later it will be
-	 * used to make the link with reserved CMA memory */
-	cma_heap->dev = data->priv;
+
+	/*
+	 * data->priv for cma heap is currently supposed to point
+	 * to a "struct device *"
+	 */
+	if (data->priv) {
+		cma_heap->dev = data->priv;
+	} else {
+		cma_heap->dev = &cma_heap->default_dma_dev;
+		cma_heap->dev->coherent_dma_mask = DMA_BIT_MASK(32);
+		cma_heap->dev->dma_mask = &cma_heap->dev->coherent_dma_mask;
+	}
+
+	if (data->cma)
+		dev_set_cma_area(cma_heap->dev, data->cma);
+
 	cma_heap->heap.type = ION_HEAP_TYPE_DMA;
 	return &cma_heap->heap;
 }
-- 
1.7.9.5