From: Joerg Roedel <jroedel@suse.de>
Date: Thu, 7 Feb 2019 12:59:13 +0100
Subject: swiotlb: Introduce swiotlb_max_mapping_size()
Git-commit: abe420bfae528c92bd8cc5ecb62dc95672b1fd6f
Patch-mainline: v5.1-rc1
References: bsc#1120008

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.

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 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
@@ -116,9 +116,14 @@ swiotlb_dma_supported(struct device *hwd
 #ifdef CONFIG_SWIOTLB
 extern void __init swiotlb_free(void);
 unsigned int swiotlb_max_segment(void);
+size_t swiotlb_max_mapping_size(struct device *dev);
 #else
 static inline void swiotlb_free(void) { }
 static inline unsigned int swiotlb_max_segment(void) { return 0; }
+static inline size_t swiotlb_max_mapping_size(struct device *dev)
+{
+	return SIZE_MAX;
+}
 #endif
 
 extern void swiotlb_print_info(void);
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -1087,3 +1087,9 @@ swiotlb_dma_supported(struct device *hwd
 	return swiotlb_phys_to_dma(hwdev, io_tlb_end - 1) <= mask;
 }
 EXPORT_SYMBOL(swiotlb_dma_supported);
+
+size_t swiotlb_max_mapping_size(struct device *dev)
+{
+	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
+}
+EXPORT_SYMBOL(swiotlb_max_mapping_size);