refactor(fdt): introduce common fdt_node_is_enabled()

There are several users in the tree which want to check whether a given
FDT node is enabled or not: the "status" property holds that
information. So far all those users provide private implementations,
some of them having issues.

Export a generic implementation of that function in fdt_wrappers.h, as
a "static inline" function to not increase code size.
Also replace the existing implementation in Arm's fconf code, which had
a tiny bug in needlessly using the property length:
"status = [6f 6b 61 79 20];" would pass the check, where it should not.
The proper solution is also simpler: status must be a string, and
strings must be NUL-terminated in a DT. strcmp() would terminate on the
first NUL in *either* of the two strings it compares, so it would never
walk beyond the property boundary in the DTB.

Change-Id: I9d89093432f127c09add6cf5c93a725bc534e5de
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

diff --git a/include/common/fdt_wrappers.h b/include/common/fdt_wrappers.h
index 2929fc23d5bbffe38004eadef477382cc39d8a59..b16510f3d971b3b1d332d6b97ff3ff33aefda0e9 100644 (file)
--- a/include/common/fdt_wrappers.h
+++ b/include/common/fdt_wrappers.h
@@ -10,6 +10,7 @@
 #define FDT_WRAPPERS_H
 
 #include <libfdt_env.h>
+#include <libfdt.h>
 
 /* Number of cells, given total length in bytes. Each cell is 4 bytes long */
 #define NCELLS(len) ((len) / 4U)
@@ -53,6 +54,15 @@ static inline uint32_t fdt_blob_size(const void *dtb)
        return fdt32_to_cpu(dtb_header[1]);
 }
 
+static inline bool fdt_node_is_enabled(const void *fdt, int node)
+{
+       int len;
+       const void *prop = fdt_getprop(fdt, node, "status", &len);
+
+       /* A non-existing status property means the device is enabled. */
+       return (prop == NULL) || (len == 5 && strcmp(prop, "okay") == 0);
+}
+
 #define fdt_for_each_compatible_node(dtb, node, compatible_str)       \
 for (node = fdt_node_offset_by_compatible(dtb, -1, compatible_str);   \
      node >= 0;                                                       \

diff --git a/plat/arm/common/fconf/fconf_ethosn_getter.c b/plat/arm/common/fconf/fconf_ethosn_getter.c
index 0b48a9816338541e621920f268838e8942e1809b..251471e63b6ae313b4260c6258a44d4baecb4e54 100644 (file)
--- a/plat/arm/common/fconf/fconf_ethosn_getter.c
+++ b/plat/arm/common/fconf/fconf_ethosn_getter.c
@@ -20,21 +20,6 @@ struct ethosn_sub_allocator_t {
        uint32_t stream_id;
 };
 
-static bool fdt_node_is_enabled(const void *fdt, int node)
-{
-       int len;
-       const char *node_status;
-
-       node_status = fdt_getprop(fdt, node, "status", &len);
-       if (node_status == NULL ||
-           (len == 5 && /* Includes null character */
-            strncmp(node_status, "okay", 4U) == 0)) {
-               return true;
-       }
-
-       return false;
-}
-
 static bool fdt_node_has_reserved_memory(const void *fdt, int dev_node)
 {
        return fdt_get_property(fdt, dev_node, "memory-region", NULL) != NULL;