[PATCH RFC v1 5/7] swiotlb: add interface to set dev->dma_io_tlb_mem

[Dongli Zhang <dongli.zhang@oracle.com>]

The interface re-configures dev->dma_io_tlb_mem conditionally, if the
'io_tlb_high_mem' is active.

Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
---
 include/linux/swiotlb.h |  6 ++++++
 kernel/dma/swiotlb.c    | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 8196bf961aab..78217d8bbee2 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -131,6 +131,7 @@ unsigned int swiotlb_max_segment(void);
 size_t swiotlb_max_mapping_size(struct device *dev);
 bool is_swiotlb_active(struct device *dev);
 void __init swiotlb_adjust_size(unsigned long size);
+bool swiotlb_use_high(struct device *dev);
 #else
 static inline void swiotlb_init(bool addressing_limited, unsigned int flags)
 {
@@ -163,6 +164,11 @@ static inline bool is_swiotlb_active(struct device *dev)
 static inline void swiotlb_adjust_size(unsigned long size)
 {
 }
+
+static bool swiotlb_use_high(struct device *dev);
+{
+	return false;
+}
 #endif /* CONFIG_SWIOTLB */
 
 extern bool swiotlb_high_active(void);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index ff82b281ce01..0dcdd25ea95d 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -121,6 +121,16 @@ bool swiotlb_high_active(void)
 	return high_nslabs && io_tlb_high_mem.nslabs;
 }
 
+bool swiotlb_use_high(struct device *dev)
+{
+	if (!swiotlb_high_active())
+		return false;
+
+	dev->dma_io_tlb_mem = &io_tlb_high_mem;
+	return true;
+}
+EXPORT_SYMBOL_GPL(swiotlb_use_high);
+
 unsigned int swiotlb_max_segment(void)
 {
 	if (!io_tlb_default_mem.nslabs)
-- 
2.17.1