regmap: fix NULL pointer dereference in regmap_get_val_endian

Recents commits for getting reg endianness causing NULL pointer
dereference if dev is passed NULL in regmap_init_mmio. This patch
fixes this issue, and allows to parse reg endianness only if dev
and dev->of_node exist.

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 14 insertions, 9 deletions

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 01ae4b829360..fd7ae9a10c4d 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -477,7 +477,7 @@ static enum regmap_endian regmap_get_val_endian(struct device *dev,
                                         const struct regmap_bus *bus,
                                         const struct regmap_config *config)
 {
-        struct device_node *np = dev->of_node;
+        struct device_node *np;
         enum regmap_endian endian;
 
         /* Retrieve the endianness specification from the regmap config */
@@ -487,15 +487,20 @@ static enum regmap_endian regmap_get_val_endian(struct device *dev,
         if (endian != REGMAP_ENDIAN_DEFAULT)
                 return endian;
 
-        /* Parse the device's DT node for an endianness specification */
-        if (of_property_read_bool(np, "big-endian"))
-                endian = REGMAP_ENDIAN_BIG;
-        else if (of_property_read_bool(np, "little-endian"))
-                endian = REGMAP_ENDIAN_LITTLE;
+        /* If the dev and dev->of_node exist try to get endianness from DT */
+        if (dev && dev->of_node) {
+                np = dev->of_node;
 
-        /* If the endianness was specified in DT, use that */
-        if (endian != REGMAP_ENDIAN_DEFAULT)
-                return endian;
+                /* Parse the device's DT node for an endianness specification */
+                if (of_property_read_bool(np, "big-endian"))
+                        endian = REGMAP_ENDIAN_BIG;
+                else if (of_property_read_bool(np, "little-endian"))
+                        endian = REGMAP_ENDIAN_LITTLE;
+
+                /* If the endianness was specified in DT, use that */
+                if (endian != REGMAP_ENDIAN_DEFAULT)
+                        return endian;
+        }
 
         /* Retrieve the endianness specification from the bus config */
         if (bus && bus->val_format_endian_default)