microblaze: Fix mmap for cache coherent memory

When running in non-cache coherent configuration the memory that was
allocated with dma_alloc_coherent() has a custom mapping and so there is no
1-to-1 relationship between the kernel virtual address and the PFN. This
means that virt_to_pfn() will not work correctly for those addresses and the
default mmap implementation in the form of dma_common_mmap() will map some
random, but not the requested, memory area.

Fix this by providing a custom mmap implementation that looks up the PFN
from the page table rather than using virt_to_pfn.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

1 files changed, 20 insertions, 5 deletions

diff --git a/arch/microblaze/mm/consistent.c b/arch/microblaze/mm/consistent.c
index e10ad930895e..b06c3a7faf20 100644
--- a/arch/microblaze/mm/consistent.c
+++ b/arch/microblaze/mm/consistent.c
@@ -156,6 +156,25 @@ void *consistent_alloc(gfp_t gfp, size_t size, dma_addr_t *dma_handle)
 }
 EXPORT_SYMBOL(consistent_alloc);
 
+#ifdef CONFIG_MMU
+static pte_t *consistent_virt_to_pte(void *vaddr)
+{
+	unsigned long addr = (unsigned long)vaddr;
+
+	return pte_offset_kernel(pmd_offset(pgd_offset_k(addr), addr), addr);
+}
+
+unsigned long consistent_virt_to_pfn(void *vaddr)
+{
+	pte_t *ptep = consistent_virt_to_pte(vaddr);
+
+	if (pte_none(*ptep) || !pte_present(*ptep))
+		return 0;
+
+	return pte_pfn(*ptep);
+}
+#endif
+
 /*
  * free page(s) as defined by the above mapping.
  */
@@ -181,13 +200,9 @@ void consistent_free(size_t size, void *vaddr)
 	} while (size -= PAGE_SIZE);
 #else
 	do {
-		pte_t *ptep;
+		pte_t *ptep = consistent_virt_to_pte(vaddr);
 		unsigned long pfn;
 
-		ptep = pte_offset_kernel(pmd_offset(pgd_offset_k(
-						(unsigned int)vaddr),
-					(unsigned int)vaddr),
-				(unsigned int)vaddr);
 		if (!pte_none(*ptep) && pte_present(*ptep)) {
 			pfn = pte_pfn(*ptep);
 			pte_clear(&init_mm, (unsigned int)vaddr, ptep);