rpi4/fdt: Move dtb_size() function to fdt_wrappers.h

Getting the actual size of a DTB blob is useful beyond the Raspberry Pi
port, so let's move this helper to a common header.

Change-Id: Ia5be46e9353ca859a1e5ad9e3c057a322dfe22e2
Signed-off-by: Andre Przywara <andre.przywara@arm.com>

include/common/fdt_wrappers.h

@@ -9,6 +9,8 @@
 #ifndef FDT_WRAPPERS_H
 #define FDT_WRAPPERS_H
 
+#include <libfdt_env.h>
+
 /* Number of cells, given total length in bytes. Each cell is 4 bytes long */
 #define NCELLS(len) ((len) / 4U)
 
@@ -37,4 +39,11 @@ int fdt_get_stdout_node_offset(const void *dtb);
 uint64_t fdtw_translate_address(const void *dtb, int bus_node,
 				uint64_t base_address);
 
+static inline uint32_t fdt_blob_size(const void *dtb)
+{
+	const uint32_t *dtb_header = dtb;
+
+	return fdt32_to_cpu(dtb_header[1]);
+}
+
 #endif /* FDT_WRAPPERS_H */

plat/rpi/rpi4/rpi4_bl31_setup.c

@@ -17,6 +17,7 @@
 #include <lib/xlat_tables/xlat_tables_v2.h>
 #include <plat/common/platform.h>
 #include <common/fdt_fixup.h>
+#include <common/fdt_wrappers.h>
 #include <libfdt.h>
 
 #include <drivers/arm/gicv2.h>
@@ -200,13 +201,6 @@ void bl31_plat_arch_setup(void)
 	enable_mmu_el3(0);
 }
 
-static uint32_t dtb_size(const void *dtb)
-{
-	const uint32_t *dtb_header = dtb;
-
-	return fdt32_to_cpu(dtb_header[1]);
-}
-
 static void rpi4_prepare_dtb(void)
 {
 	void *dtb = (void *)rpi4_get_dtb_address();
@@ -250,7 +244,7 @@ static void rpi4_prepare_dtb(void)
 	if (ret < 0)
 		ERROR("Failed to pack Device Tree at %p: error %d\n", dtb, ret);
 
-	clean_dcache_range((uintptr_t)dtb, dtb_size(dtb));
+	clean_dcache_range((uintptr_t)dtb, fdt_blob_size(dtb));
 	INFO("Changed device tree to advertise PSCI.\n");
 }