From 492366f7b4237257ef50ca9c431a6a0d50225aca Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Thu, 7 Feb 2019 12:59:14 +0100 Subject: swiotlb: Add is_swiotlb_active() function This function will be used from dma_direct code to determine the maximum segment size of a dma mapping. Cc: stable@vger.kernel.org Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Christoph Hellwig Signed-off-by: Joerg Roedel Signed-off-by: Michael S. Tsirkin --- kernel/dma/swiotlb.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/dma') diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 9cb21259cb0b..c873f9cc2146 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -667,3 +667,12 @@ size_t swiotlb_max_mapping_size(struct device *dev) { return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE; } + +bool is_swiotlb_active(void) +{ + /* + * When SWIOTLB is initialized, even if io_tlb_start points to physical + * address zero, io_tlb_end surely doesn't. + */ + return io_tlb_end != 0; +} -- cgit v1.2.3