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author | 2011-03-24 20:50:06 +0000 | |
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committer | 2011-03-30 10:44:00 +1100 | |
commit | 6090912c4abcfc6c81b156cf2bb4cda23ae6e847 (patch) | |
tree | 9bddd5b697883f706a53ef0413181845bb735250 /arch/powerpc/mm | |
parent | powerpc/nvram: Don't overwrite oops/panic report on normal shutdown (diff) | |
download | linux-6090912c4abcfc6c81b156cf2bb4cda23ae6e847.tar.gz linux-6090912c4abcfc6c81b156cf2bb4cda23ae6e847.tar.bz2 linux-6090912c4abcfc6c81b156cf2bb4cda23ae6e847.zip |
powerpc: Implement dma_mmap_coherent()
This is used by Alsa to mmap buffers allocated with dma_alloc_coherent()
into userspace. We need a special variant to handle machines with
non-coherent DMAs as those buffers have "special" virt addresses and
require non-cachable mappings
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/mm')
-rw-r--r-- | arch/powerpc/mm/dma-noncoherent.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/powerpc/mm/dma-noncoherent.c b/arch/powerpc/mm/dma-noncoherent.c index 757c0bed9a91..b42f76c4948d 100644 --- a/arch/powerpc/mm/dma-noncoherent.c +++ b/arch/powerpc/mm/dma-noncoherent.c @@ -399,3 +399,23 @@ void __dma_sync_page(struct page *page, unsigned long offset, #endif } EXPORT_SYMBOL(__dma_sync_page); + +/* + * Return the PFN for a given cpu virtual address returned by + * __dma_alloc_coherent. This is used by dma_mmap_coherent() + */ +unsigned long __dma_get_coherent_pfn(unsigned long cpu_addr) +{ + /* This should always be populated, so we don't test every + * level. If that fails, we'll have a nice crash which + * will be as good as a BUG_ON() + */ + pgd_t *pgd = pgd_offset_k(cpu_addr); + pud_t *pud = pud_offset(pgd, cpu_addr); + pmd_t *pmd = pmd_offset(pud, cpu_addr); + pte_t *ptep = pte_offset_kernel(pmd, cpu_addr); + + if (pte_none(*ptep) || !pte_present(*ptep)) + return 0; + return pte_pfn(*ptep); +} |