[POWERPC] Don't enable cell IOMMU fixed mapping if there are no dma-ranges

In order for the cell IOMMU fixed mapping to work we need "dma-ranges"
properties in the device tree. If there are none then there's no point
enabling the fixed mapping support.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index a276064471b3..1f7b25474086 100644
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -917,6 +917,18 @@ static int __init cell_iommu_fixed_mapping_init(void)
                 return -1;
         }
 
+        /* We must have dma-ranges properties for fixed mapping to work */
+        for (np = NULL; (np = of_find_all_nodes(np));) {
+                if (of_find_property(np, "dma-ranges", NULL))
+                        break;
+        }
+        of_node_put(np);
+
+        if (!np) {
+                pr_debug("iommu: no dma-ranges found, no fixed mapping\n");
+                return -1;
+        }
+
         /* The default setup is to have the fixed mapping sit after the
          * dynamic region, so find the top of the largest IOMMU window
          * on any axon, then add the size of RAM and that's our max value.