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swiotlb: Add is_swiotlb_active() function

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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 <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>
This commit is contained in:
Joerg Roedel 2019-02-07 12:59:14 +01:00 committed by Michael S. Tsirkin
parent abe420bfae
commit 492366f7b4
2 changed files with 15 additions and 0 deletions
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6
include/linux/swiotlb.h
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@ -77,6 +77,7 @@ bool swiotlb_map(struct device *dev, phys_addr_t *phys, dma_addr_t *dma_addr,
void __init swiotlb_exit(void);
unsigned int swiotlb_max_segment(void);
size_t swiotlb_max_mapping_size(struct device *dev);
bool is_swiotlb_active(void);
#else
#define swiotlb_force SWIOTLB_NO_FORCE
static inline bool is_swiotlb_buffer(phys_addr_t paddr)
@ -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);

9
kernel/dma/swiotlb.c
View File

@ -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;
}