Makefile: Change CONFIG_SPL_PAD_TO to image offset

Change CONFIG_SPL_PAD_TO from a link address to an image offset since this is
more handy and closer to the purpose of this config.

Automatically define CONFIG_SPL_PAD_TO to CONFIG_SPL_MAX_SIZE (or 0 without
CONFIG_SPL_MAX_SIZE).

Test that CONFIG_SPL_PAD_TO >= CONFIG_SPL_MAX_SIZE if CONFIG_SPL_PAD_TO is
non-zero.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>

Makefile

@@ -486,9 +486,8 @@ $(obj)u-boot.dis:	$(obj)u-boot
 
 
 $(obj)u-boot-with-spl.bin: $(obj)spl/u-boot-spl.bin $(obj)u-boot.bin
-		$(OBJCOPY) ${OBJCFLAGS} --pad-to=$(or $(CONFIG_SPL_PAD_TO),0) \
-			-O binary $(obj)spl/u-boot-spl \
-			$(obj)spl/u-boot-spl-pad.bin
+		$(OBJCOPY) ${OBJCFLAGS} --pad-to=$(CONFIG_SPL_PAD_TO) \
+			-I binary -O binary $< $(obj)spl/u-boot-spl-pad.bin
 		cat $(obj)spl/u-boot-spl-pad.bin $(obj)u-boot.bin > $@
 		rm $(obj)spl/u-boot-spl-pad.bin
 

README

@@ -2908,8 +2908,11 @@ FIT uImage format:
 		Support for lib/libgeneric.o in SPL binary
 
 		CONFIG_SPL_PAD_TO
-		Linker address to which the SPL should be padded before
-		appending the SPL payload.
+		Image offset to which the SPL should be padded before appending
+		the SPL payload. By default, this is defined as
+		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
+		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
+		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
 
 		CONFIG_SPL_TARGET
 		Final target image containing SPL and payload.  Some SPLs

include/config_fallbacks.h

@@ -9,6 +9,22 @@
 #ifndef __CONFIG_FALLBACKS_H
 #define __CONFIG_FALLBACKS_H
 
+#ifdef CONFIG_SPL
+#ifdef CONFIG_SPL_PAD_TO
+#ifdef CONFIG_SPL_MAX_SIZE
+#if CONFIG_SPL_PAD_TO && CONFIG_SPL_PAD_TO < CONFIG_SPL_MAX_SIZE
+#error CONFIG_SPL_PAD_TO < CONFIG_SPL_MAX_SIZE
+#endif
+#endif
+#else
+#ifdef CONFIG_SPL_MAX_SIZE
+#define CONFIG_SPL_PAD_TO	CONFIG_SPL_MAX_SIZE
+#else
+#define CONFIG_SPL_PAD_TO	0
+#endif
+#endif
+#endif
+
 #ifndef CONFIG_SYS_BAUDRATE_TABLE
 #define CONFIG_SYS_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200 }
 #endif

include/configs/MPC8313ERDB.h

@@ -52,7 +52,7 @@
 #define CONFIG_SYS_TEXT_BASE	0x00100000 /* CONFIG_SYS_NAND_U_BOOT_DST */
 #define CONFIG_SYS_TEXT_BASE_SPL 0xfff00000
 #define CONFIG_SPL_MAX_SIZE	(4 * 1024)
-#define CONFIG_SPL_PAD_TO	0xfff04000
+#define CONFIG_SPL_PAD_TO	0x4000
 
 #define CONFIG_SYS_NAND_U_BOOT_SIZE  (512 << 10)
 #define CONFIG_SYS_NAND_U_BOOT_DST   0x00100000

include/configs/p1_p2_rdb_pc.h

@@ -164,7 +164,7 @@
 #define CONFIG_SPL_TARGET		"u-boot-with-spl.bin"
 
 #define CONFIG_SPL_TEXT_BASE		0xfffff000
-#define CONFIG_SPL_MAX_SIZE		(4 * 1024)
+#define CONFIG_SPL_MAX_SIZE		4096
 
 #ifdef CONFIG_SYS_INIT_L2_ADDR
 /* We multiply CONFIG_SPL_MAX_SIZE by two to leave some room for BSS. */