rockchip: Add the rkimage format to mkimage

Rockchip SoCs require certain formats for code that they execute, The
simplest format is a 4-byte header at the start of a binary file. Add
support for this so that we can create images that the boot ROM understands.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/rkcommon.c b/tools/rkcommon.c
new file mode 100644
index 0000000..4389622
--- /dev/null
+++ b/tools/rkcommon.c
@@ -0,0 +1,72 @@
+/*
+ * (C) Copyright 2015 Google,  Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ *
+ * Helper functions for Rockchip images
+ */
+
+#include "imagetool.h"
+#include <image.h>
+#include <rc4.h>
+#include "mkimage.h"
+#include "rkcommon.h"
+
+enum {
+	RK_SIGNATURE		= 0x0ff0aa55,
+};
+
+/**
+ * struct header0_info - header block for boot ROM
+ *
+ * This is stored at SD card block 64 (where each block is 512 bytes, or at
+ * the start of SPI flash. It is encoded with RC4.
+ *
+ * @signature:		Signature (must be RKSD_SIGNATURE)
+ * @disable_rc4:	0 to use rc4 for boot image,  1 to use plain binary
+ * @code1_offset:	Offset in blocks of the SPL code from this header
+ *			block. E.g. 4 means 2KB after the start of this header.
+ * Other fields are not used by U-Boot
+ */
+struct header0_info {
+	uint32_t signature;
+	uint8_t reserved[4];
+	uint32_t disable_rc4;
+	uint16_t code1_offset;
+	uint16_t code2_offset;
+	uint8_t reserved1[490];
+	uint16_t usflashdatasize;
+	uint16_t ucflashbootsize;
+	uint8_t reserved2[2];
+};
+
+static unsigned char rc4_key[16] = {
+	124, 78, 3, 4, 85, 5, 9, 7,
+	45, 44, 123, 56, 23, 13, 23, 17
+};
+
+int rkcommon_set_header(void *buf, uint file_size)
+{
+	struct header0_info *hdr;
+
+	if (file_size > RK_MAX_CODE1_SIZE)
+		return -ENOSPC;
+
+	memset(buf,  '\0', RK_CODE1_OFFSET * RK_BLK_SIZE);
+	hdr = (struct header0_info *)buf;
+	hdr->signature = RK_SIGNATURE;
+	hdr->disable_rc4 = 1;
+	hdr->code1_offset = RK_CODE1_OFFSET;
+	hdr->code2_offset = 8;
+
+	hdr->usflashdatasize = (file_size + RK_BLK_SIZE - 1) / RK_BLK_SIZE;
+	hdr->usflashdatasize = (hdr->usflashdatasize + 3) & ~3;
+	hdr->ucflashbootsize = hdr->usflashdatasize;
+
+	debug("size=%x, %x\n", params->file_size, hdr->usflashdatasize);
+
+	rc4_encode(buf, RK_BLK_SIZE, rc4_key);
+
+	return 0;
+}