sunxi: retrieve FEL-provided values to environment variables

This patch extends the misc_init_r() function on sunxi boards
to test for the presence of a suitable "sunxi" SPL header. If
found, and the loader ("fel" utility) provided a non-zero value
for the boot.scr address, then the corresponding environment
variable fel_scriptaddr gets set.

misc_init_r() also sets (or clears) the "fel_booted" variable depending
on the active boot device, using the same logic as spl_boot_device().

The goal is to provide sufficient information (within the U-Boot
environment) to make intelligent decisions on how to continue the boot
process, allowing specific customizations for the "FEL boot" case.

Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/arch/arm/include/asm/arch-sunxi/spl.h b/arch/arm/include/asm/arch-sunxi/spl.h
index d2ce848..a129dd4 100644
--- a/arch/arm/include/asm/arch-sunxi/spl.h
+++ b/arch/arm/include/asm/arch-sunxi/spl.h
@@ -12,6 +12,9 @@
 #define SPL_SIGNATURE		"SPL" /* marks "sunxi" SPL header */
 #define SPL_HEADER_VERSION	1
 
+/* Note: A80 will require special handling here: SPL_ADDR 0x10000 */
+#define SPL_ADDR		0x0
+
 /* boot head definition from sun4i boot code */
 struct boot_file_head {
 	uint32_t b_instruction;	/* one intruction jumping to real code */
@@ -42,4 +45,6 @@
 	uint32_t reserved;		/* padding, align to 32 bytes */
 };
 
+#define is_boot0_magic(addr)	(memcmp((void *)addr, BOOT0_MAGIC, 8) == 0)
+
 #endif