dma-debug: add a check dma memory leaks

Impact: allow architectures to monitor busses for dma mem leakage

This patch adds checking code to detect if a device has pending DMA
operations when it is about to be unbound from its device driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index 46a11c1..e851d23 100644
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -24,9 +24,12 @@
 
 struct device;
 struct scatterlist;
+struct bus_type;
 
 #ifdef CONFIG_DMA_API_DEBUG
 
+extern void dma_debug_add_bus(struct bus_type *bus);
+
 extern void dma_debug_init(u32 num_entries);
 
 extern void debug_dma_map_page(struct device *dev, struct page *page,
@@ -80,6 +83,10 @@
 
 #else /* CONFIG_DMA_API_DEBUG */
 
+void dma_debug_add_bus(struct bus_type *bus)
+{
+}
+
 static inline void dma_debug_init(u32 num_entries)
 {
 }