[PATCH v1 12/16] powerpc/powernv: Return non-zero TCE from pnv_tce_build

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This returns old TCE values to the caller if requested.
The caller is expectded to call put_page() for them.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/platforms/powernv/pci.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index e002c66..a9165a5 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -575,6 +575,7 @@ static int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
 	u64 proto_tce;
 	__be64 *tcep, *tces;
 	u64 rpn;
+	long i;
 
 	proto_tce = TCE_PCI_READ; // Read allowed
 
@@ -584,9 +585,13 @@ static int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
 	tces = tcep = ((__be64 *)tbl->it_base) + index - tbl->it_offset;
 	rpn = __pa(uaddr) >> tbl->it_page_shift;
 
-	while (npages--)
-		*(tcep++) = cpu_to_be64(proto_tce |
-				(rpn++ << tbl->it_page_shift));
+	for (i = 0; i < npages; i++) {
+		unsigned long oldtce = xchg(tcep, cpu_to_be64(proto_tce |
+				(rpn++ << tbl->it_page_shift)));
+		if (old_tces)
+			old_tces[i] = (unsigned long) __va(oldtce);
+		tcep++;
+	}
 
 	pnv_tce_invalidate(tbl, tces, tcep - 1, rm);
 
-- 
2.0.0