1 files changed, 64 insertions, 0 deletions

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 9faa9a5cbdf0..dd9057cb7aa7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -19,3 +19,67 @@ char *find_flat_dt_string(u32 offset)
         return ((char *)initial_boot_params) +
                 initial_boot_params->off_dt_strings + offset;
 }
+
+/**
+ * of_scan_flat_dt - scan flattened tree blob and call callback on each.
+ * @it: callback function
+ * @data: context data pointer
+ *
+ * This function is used to scan the flattened device-tree, it is
+ * used to extract the memory information at boot before we can
+ * unflatten the tree
+ */
+int __init of_scan_flat_dt(int (*it)(unsigned long node,
+                                     const char *uname, int depth,
+                                     void *data),
+                           void *data)
+{
+        unsigned long p = ((unsigned long)initial_boot_params) +
+                initial_boot_params->off_dt_struct;
+        int rc = 0;
+        int depth = -1;
+
+        do {
+                u32 tag = *((u32 *)p);
+                char *pathp;
+
+                p += 4;
+                if (tag == OF_DT_END_NODE) {
+                        depth--;
+                        continue;
+                }
+                if (tag == OF_DT_NOP)
+                        continue;
+                if (tag == OF_DT_END)
+                        break;
+                if (tag == OF_DT_PROP) {
+                        u32 sz = *((u32 *)p);
+                        p += 8;
+                        if (initial_boot_params->version < 0x10)
+                                p = _ALIGN(p, sz >= 8 ? 8 : 4);
+                        p += sz;
+                        p = _ALIGN(p, 4);
+                        continue;
+                }
+                if (tag != OF_DT_BEGIN_NODE) {
+                        pr_err("Invalid tag %x in flat device tree!\n", tag);
+                        return -EINVAL;
+                }
+                depth++;
+                pathp = (char *)p;
+                p = _ALIGN(p + strlen(pathp) + 1, 4);
+                if ((*pathp) == '/') {
+                        char *lp, *np;
+                        for (lp = NULL, np = pathp; *np; np++)
+                                if ((*np) == '/')
+                                        lp = np+1;
+                        if (lp != NULL)
+                                pathp = lp;
+                }
+                rc = it(p, pathp, depth, data);
+                if (rc != 0)
+                        break;
+        } while (1);
+
+        return rc;
+}