of: Introduce common early_init_dt_scan

Most architectures scan the all the same items early in the FDT and none
are really architecture specific. Create a common early_init_dt_scan to
unify the early scan of root, memory, and chosen nodes in the flattened
DT.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@linaro.org>

drivers/of/fdt.c

@@ -785,6 +785,32 @@ void * __init __weak early_init_dt_alloc_memory_arch(u64 size, u64 align)
 }
 #endif
 
+bool __init early_init_dt_scan(void *params)
+{
+	if (!params)
+		return false;
+
+	/* Setup flat device-tree pointer */
+	initial_boot_params = params;
+
+	/* check device tree validity */
+	if (be32_to_cpu(initial_boot_params->magic) != OF_DT_HEADER) {
+		initial_boot_params = NULL;
+		return false;
+	}
+
+	/* Retrieve various information from the /chosen node */
+	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+
+	/* Initialize {size,address}-cells info */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+
+	/* Setup memory, calling early_init_dt_add_memory_arch */
+	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+
+	return true;
+}
+
 /**
  * unflatten_device_tree - create tree of device_nodes from flat blob
  *

include/linux/of_fdt.h

@@ -116,6 +116,8 @@ extern void early_init_dt_setup_initrd_arch(u64 start, u64 end);
 extern int early_init_dt_scan_root(unsigned long node, const char *uname,
 				   int depth, void *data);
 
+extern bool early_init_dt_scan(void *params);
+
 /* Other Prototypes */
 extern void unflatten_device_tree(void);
 extern void unflatten_and_copy_device_tree(void);