fdt: call fdt_parent_offset fewer times while translating addresses

fdt_parent_offset() is an expensive operation, so we'd like to reduce
unnecessary calls to it.

Further, the practice of iterating up to the root if address/size cells
aren't found was apparently done for Linux for compatibility with certain
buggy Open Firmware implementations, and U-Boot inherited the code.  The
compliant behavior is to treat a missing #address-cells as 2, and a missing
#size-cells as 1 -- never looking anywhere but the immediate parent of the
node of interest.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

diff --git a/common/fdt_support.c b/common/fdt_support.c
index 33336be062ed6e4a3c0530b413988a081385ff39..aef4fe23e058c0294a714bc1313725d7c1ddeea3 100644 (file)
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -874,35 +874,6 @@ static inline u64 of_read_number(const __be32 *cell, int size)
        return r;
 }
 
-static int of_n_cells(const void *blob, int nodeoffset, const char *name)
-{
-       int np;
-       const int *ip;
-
-       do {
-               np = fdt_parent_offset(blob, nodeoffset);
-
-               if (np >= 0)
-                       nodeoffset = np;
-               ip = (int *)fdt_getprop(blob, nodeoffset, name, NULL);
-               if (ip)
-                       return be32_to_cpup(ip);
-       } while (np >= 0);
-
-       /* No #<NAME>-cells property for the root node */
-       return 1;
-}
-
-int of_n_addr_cells(const void *blob, int nodeoffset)
-{
-       return of_n_cells(blob, nodeoffset, "#address-cells");
-}
-
-int of_n_size_cells(const void *blob, int nodeoffset)
-{
-       return of_n_cells(blob, nodeoffset, "#size-cells");
-}
-
 #define PRu64  "%llx"
 
 /* Max address size we deal with */
@@ -928,7 +899,7 @@ static void of_dump_addr(const char *s, const u32 *addr, int na) { }
 struct of_bus {
        const char      *name;
        const char      *addresses;
-       void            (*count_cells)(void *blob, int offset,
+       void            (*count_cells)(void *blob, int parentoffset,
                                int *addrc, int *sizec);
        u64             (*map)(u32 *addr, const u32 *range,
                                int na, int ns, int pna);
@@ -936,13 +907,26 @@ struct of_bus {
 };
 
 /* Default translator (generic bus) */
-static void of_bus_default_count_cells(void *blob, int offset,
+static void of_bus_default_count_cells(void *blob, int parentoffset,
                                        int *addrc, int *sizec)
 {
-       if (addrc)
-               *addrc = of_n_addr_cells(blob, offset);
-       if (sizec)
-               *sizec = of_n_size_cells(blob, offset);
+       const u32 *prop;
+
+       if (addrc) {
+               prop = fdt_getprop(blob, parentoffset, "#address-cells", NULL);
+               if (prop)
+                       *addrc = be32_to_cpup(prop);
+               else
+                       *addrc = 2;
+       }
+
+       if (sizec) {
+               prop = fdt_getprop(blob, parentoffset, "#size-cells", NULL);
+               if (prop)
+                       *sizec = be32_to_cpup(prop);
+               else
+                       *sizec = 1;
+       }
 }
 
 static u64 of_bus_default_map(u32 *addr, const u32 *range,
@@ -1068,7 +1052,7 @@ u64 __of_translate_address(void *blob, int node_offset, const u32 *in_addr,
        bus = &of_busses[0];
 
        /* Cound address cells & copy address locally */
-       bus->count_cells(blob, node_offset, &na, &ns);
+       bus->count_cells(blob, parent, &na, &ns);
        if (!OF_CHECK_COUNTS(na, ns)) {
                printf("%s: Bad cell count for %s\n", __FUNCTION__,
                       fdt_get_name(blob, node_offset, NULL));
@@ -1095,7 +1079,7 @@ u64 __of_translate_address(void *blob, int node_offset, const u32 *in_addr,
 
                /* Get new parent bus and counts */
                pbus = &of_busses[0];
-               pbus->count_cells(blob, node_offset, &pna, &pns);
+               pbus->count_cells(blob, parent, &pna, &pns);
                if (!OF_CHECK_COUNTS(pna, pns)) {
                        printf("%s: Bad cell count for %s\n", __FUNCTION__,
                                fdt_get_name(blob, node_offset, NULL));