aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc/mm
diff options
context:
space:
mode:
authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-03-24 20:50:06 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-03-30 10:44:00 +1100
commit6090912c4abcfc6c81b156cf2bb4cda23ae6e847 (patch)
tree9bddd5b697883f706a53ef0413181845bb735250 /arch/powerpc/mm
parent15d260b36facc1aa769fb39b0efc41f4c8c44729 (diff)
downloadlinaro-lsk-6090912c4abcfc6c81b156cf2bb4cda23ae6e847.tar.gz
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.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/powerpc/mm/dma-noncoherent.c b/arch/powerpc/mm/dma-noncoherent.c
index 757c0bed9a9..b42f76c4948 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);
+}