powerpc: use libfdt accessors for header data

With libfdt support, we can take advantage of helper accessors in libfdt
for accessing the FDT header data. This makes the code more readable and
makes the FDT blob structure more opaque to the kernel. This also
prepares for removing struct boot_param_header completely.
Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Tested-by: Grant Likely <grant.likely@linaro.org>
Tested-by: Stephen Chivers <schivers@csc.com>

arch/powerpc/kernel/Makefile

@@ -2,6 +2,7 @@
 # Makefile for the linux kernel.
 #
 
+CFLAGS_prom.o		= -I$(src)/../../../scripts/dtc/libfdt
 CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
 
 subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror

arch/powerpc/kernel/prom.c

@@ -33,6 +33,7 @@
 #include <linux/memblock.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
+#include <linux/libfdt.h>
 
 #include <asm/prom.h>
 #include <asm/rtas.h>
@@ -117,14 +118,14 @@ static void __init move_device_tree(void)
 	DBG("-> move_device_tree\n");
 
 	start = __pa(initial_boot_params);
-	size = be32_to_cpu(initial_boot_params->totalsize);
+	size = fdt_totalsize(initial_boot_params);
 
 	if ((memory_limit && (start + size) > PHYSICAL_START + memory_limit) ||
 			overlaps_crashkernel(start, size) ||
 			overlaps_initrd(start, size)) {
 		p = __va(memblock_alloc(size, PAGE_SIZE));
 		memcpy(p, initial_boot_params, size);
-		initial_boot_params = (struct boot_param_header *)p;
+		initial_boot_params = p;
 		DBG("Moved device tree to 0x%p\n", p);
 	}
 
@@ -324,9 +325,9 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
 		 * version 2 of the kexec param format adds the phys cpuid of
 		 * booted proc.
 		 */
-		if (be32_to_cpu(initial_boot_params->version) >= 2) {
+		if (fdt_version(initial_boot_params) >= 2) {
 			if (be32_to_cpu(intserv[i]) ==
-			    be32_to_cpu(initial_boot_params->boot_cpuid_phys)) {
+			    fdt_boot_cpuid_phys(initial_boot_params)) {
 				found = boot_cpu_count;
 				found_thread = i;
 			}
@@ -599,7 +600,7 @@ static void __init early_reserve_mem(void)
 	__be64 *reserve_map;
 
 	reserve_map = (__be64 *)(((unsigned long)initial_boot_params) +
-			be32_to_cpu(initial_boot_params->off_mem_rsvmap));
+			fdt_off_mem_rsvmap(initial_boot_params));
 
 	/* Look for the new "reserved-regions" property in the DT */
 	early_reserve_mem_dt();