FROMLIST: dma-buf: dma-heap: Keep track of the heap device struct

Keep track of the heap device struct.

This will be useful for special DMA allocations
and actions.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/lkml/20201110034934.70898-7-john.stultz@linaro.org/
Bug: 170887642
Change-Id: I55b8df5fd9fd46795a8f0171318895297d2dd379

include/linux/dma-heap.h

@@ -50,6 +50,15 @@ struct dma_heap_export_info {
  */
 void *dma_heap_get_drvdata(struct dma_heap *heap);
 
+/**
+ * dma_heap_get_dev() - get device struct for the heap
+ * @heap: DMA-Heap to retrieve device struct from
+ *
+ * Returns:
+ * The device struct for the heap.
+ */
+struct device *dma_heap_get_dev(struct dma_heap *heap);
+
 /**
  * dma_heap_add - adds a heap to dmabuf heaps
  * @exp_info:		information needed to register this heap