powerpc/scom: Add support for "reg" property

When devices are direct children of a scom controller node, they
should be able to use the normal "reg" property instead of "scom-reg".

In that case, they also use #address-cells rather than #scom-cells
to indicate the size of an entry.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 17 insertions, 5 deletions

diff --git a/arch/powerpc/sysdev/scom.c b/arch/powerpc/sysdev/scom.c
index 10f1d9e56612..413622d54395 100644
--- a/arch/powerpc/sysdev/scom.c
+++ b/arch/powerpc/sysdev/scom.c
@@ -53,7 +53,7 @@ scom_map_t scom_map_device(struct device_node *dev, int index)
 {
         struct device_node *parent;
         unsigned int cells, size;
-        const u32 *prop;
+        const __be32 *prop, *sprop;
         u64 reg, cnt;
         scom_map_t ret;
 
@@ -62,12 +62,24 @@ scom_map_t scom_map_device(struct device_node *dev, int index)
         if (parent == NULL)
                 return 0;
 
-        prop = of_get_property(parent, "#scom-cells", NULL);
-        cells = prop ? *prop : 1;
-
+        /*
+         * We support "scom-reg" properties for adding scom registers
+         * to a random device-tree node with an explicit scom-parent
+         *
+         * We also support the simple "reg" property if the device is
+         * a direct child of a scom controller.
+         *
+         * In case both exist, "scom-reg" takes precedence.
+         */
         prop = of_get_property(dev, "scom-reg", &size);
+        sprop = of_get_property(parent, "#scom-cells", NULL);
+        if (!prop && parent == dev->parent) {
+                prop = of_get_property(dev, "reg", &size);
+                sprop = of_get_property(parent, "#address-cells", NULL);
+        }
         if (!prop)
-                return 0;
+                return NULL;
+        cells = sprop ? be32_to_cpup(sprop) : 1;
         size >>= 2;
 
         if (index >= (size / (2*cells)))