[PATCH 5.0 125/238] swiotlb: Introduce swiotlb_max_mapping_size()

[Greg Kroah-Hartman]

5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joerg Roedel <jroedel@xxxxxxx>

commit abe420bfae528c92bd8cc5ecb62dc95672b1fd6f upstream.

The function returns the maximum size that can be remapped
by the SWIOTLB implementation. This function will be later
exposed to users through the DMA-API.

Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 include/linux/swiotlb.h |    5 +++++
 kernel/dma/swiotlb.c    |    5 +++++
 2 files changed, 10 insertions(+)

--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -76,6 +76,7 @@ bool swiotlb_map(struct device *dev, phy
 		size_t size, enum dma_data_direction dir, unsigned long attrs);
 void __init swiotlb_exit(void);
 unsigned int swiotlb_max_segment(void);
+size_t swiotlb_max_mapping_size(struct device *dev);
 #else
 #define swiotlb_force SWIOTLB_NO_FORCE
 static inline bool is_swiotlb_buffer(phys_addr_t paddr)
@@ -95,6 +96,10 @@ static inline unsigned int swiotlb_max_s
 {
 	return 0;
 }
+static inline size_t swiotlb_max_mapping_size(struct device *dev)
+{
+	return SIZE_MAX;
+}
 #endif /* CONFIG_SWIOTLB */
 
 extern void swiotlb_print_info(void);
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -662,3 +662,8 @@ swiotlb_dma_supported(struct device *hwd
 {
 	return __phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
 }
+
+size_t swiotlb_max_mapping_size(struct device *dev)
+{
+	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
+}