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iommu: add iommu_num_pages helper function

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Calculating the number of pages from given address and length numbers is a task
required in multiple IOMMU implementations. So implement this as a generic
function into the IOMMU helper code.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: robert.richter@amd.com
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Joerg Roedel 2008-07-25 14:57:58 +02:00 committed by Ingo Molnar
parent 024e8ac044
commit 3bc9f79ee1
2 changed files with 9 additions and 0 deletions
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1
include/linux/iommu-helper.h
View file

@ -8,3 +8,4 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
unsigned long align_mask);
extern void iommu_area_free(unsigned long *map, unsigned long start,
unsigned int nr);
extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len);

8
lib/iommu-helper.c
View file

@ -80,3 +80,11 @@ void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
}
}
EXPORT_SYMBOL(iommu_area_free);
unsigned long iommu_num_pages(unsigned long addr, unsigned long len)
{
unsigned long size = roundup((addr & ~PAGE_MASK) + len, PAGE_SIZE);
return size >> PAGE_SHIFT;
}
EXPORT_SYMBOL(iommu_num_pages);