[PATCH 2/5] swiotlb: Add is_swiotlb_active() function

[Joerg Roedel <joro@8bytes.org>]

From: Joerg Roedel <jroedel@suse.de>

This function will be used from dma_direct code to determine
the maximum segment size of a dma mapping.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 include/linux/swiotlb.h | 6 ++++++
 kernel/dma/swiotlb.c    | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index ceb623321f38..5c087d330b4b 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -63,6 +63,7 @@ extern void swiotlb_tbl_sync_single(struct device *hwdev,
 extern int
 swiotlb_dma_supported(struct device *hwdev, u64 mask);
 extern size_t swiotlb_max_mapping_size(struct device *dev);
+bool is_swiotlb_active(void);
 
 #ifdef CONFIG_SWIOTLB
 extern enum swiotlb_force swiotlb_force;
@@ -100,6 +101,11 @@ static inline size_t swiotlb_max_mapping_size(struct device *dev)
 {
 	return SIZE_MAX;
 }
+
+static inline bool is_swiotlb_active(void)
+{
+	return false;
+}
 #endif /* CONFIG_SWIOTLB */
 
 extern void swiotlb_print_info(void);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 9cb21259cb0b..9fbd075081d9 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -667,3 +667,8 @@ size_t swiotlb_max_mapping_size(struct device *dev)
 {
 	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
 }
+
+bool is_swiotlb_active(void)
+{
+	return !no_iotlb_memory;
+}
-- 
2.17.1