sunxi: Factor out eGON BROM header description

To be able to easily share the Allwinner eGON BROM header structure
between the tools and the SPL code, move the struct definition into a
separate header file.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Samuel Holland <samuel@sholland.org>
diff --git a/include/sunxi_image.h b/include/sunxi_image.h
new file mode 100644
index 0000000..d0d1290e
--- /dev/null
+++ b/include/sunxi_image.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2007-2011
+ * Allwinner Technology Co., Ltd. <www.allwinnertech.com>
+ * Tom Cubie <tangliang@allwinnertech.com>
+ *
+ * Constants and data structures used in Allwinner "eGON" images, as
+ * parsed by the Boot-ROM.
+ *
+ * Shared between mkimage and the SPL.
+ */
+#ifndef	SUNXI_IMAGE_H
+#define	SUNXI_IMAGE_H
+
+#define BOOT0_MAGIC		"eGON.BT0"
+#define SPL_SIGNATURE		"SPL" /* marks "sunxi" SPL header */
+#define SPL_MAJOR_BITS		3
+#define SPL_MINOR_BITS		5
+#define SPL_VERSION(maj, min)						\
+	((((maj) & ((1U << SPL_MAJOR_BITS) - 1)) << SPL_MINOR_BITS) | \
+	((min) & ((1U << SPL_MINOR_BITS) - 1)))
+
+#define SPL_HEADER_VERSION	SPL_VERSION(0, 2)
+
+#define SPL_ENV_HEADER_VERSION	SPL_VERSION(0, 1)
+#define SPL_DT_HEADER_VERSION	SPL_VERSION(0, 2)
+#define SPL_DRAM_HEADER_VERSION	SPL_VERSION(0, 3)
+
+/* boot head definition from sun4i boot code */
+struct boot_file_head {
+	uint32_t b_instruction;	/* one intruction jumping to real code */
+	uint8_t magic[8];	/* ="eGON.BT0" or "eGON.BT1", not C-style str */
+	uint32_t check_sum;	/* generated by PC */
+	uint32_t length;	/* generated by PC */
+	/*
+	 * We use a simplified header, only filling in what is needed
+	 * by the boot ROM. To be compatible with Allwinner tools we
+	 * would need to implement the proper fields here instead of
+	 * padding.
+	 *
+	 * Actually we want the ability to recognize our "sunxi" variant
+	 * of the SPL. To do so, let's place a special signature into the
+	 * "pub_head_size" field. We can reasonably expect Allwinner's
+	 * boot0 to always have the upper 16 bits of this set to 0 (after
+	 * all the value shouldn't be larger than the limit imposed by
+	 * SRAM size).
+	 * If the signature is present (at 0x14), then we know it's safe
+	 * to use the remaining 8 bytes (at 0x18) for our own purposes.
+	 * (E.g. sunxi-tools "fel" utility can pass information there.)
+	 */
+	union {
+		uint32_t pub_head_size;
+		uint8_t spl_signature[4];
+	};
+	uint32_t fel_script_address;	/* since v0.1, set by sunxi-fel */
+	/*
+	 * If the fel_uEnv_length member below is set to a non-zero value,
+	 * it specifies the size (byte count) of data at fel_script_address.
+	 * At the same time this indicates that the data is in uEnv.txt
+	 * compatible format, ready to be imported via "env import -t".
+	 */
+	uint32_t fel_uEnv_length;	/* since v0.1, set by sunxi-fel */
+	/*
+	 * Offset of an ASCIIZ string (relative to the SPL header), which
+	 * contains the default device tree name (CONFIG_DEFAULT_DEVICE_TREE).
+	 * This is optional and may be set to NULL. Is intended to be used
+	 * by flash programming tools for providing nice informative messages
+	 * to the users.
+	 */
+	uint32_t dt_name_offset;	/* since v0.2, set by mksunxiboot */
+	uint32_t dram_size;		/* in MiB, since v0.3, set by SPL */
+	uint32_t boot_media;		/* written here by the boot ROM */
+	/* A padding area (may be used for storing text strings) */
+	uint32_t string_pool[13];	/* since v0.2, filled by mksunxiboot */
+	/* The header must be a multiple of 32 bytes (for VBAR alignment) */
+};
+
+/* Compile time check to assure proper alignment of structure */
+typedef char boot_file_head_not_multiple_of_32[1 - 2*(sizeof(struct boot_file_head) % 32)];
+
+#endif