rockchip: mkimage: Allow encoding of loader code in spl images

Rockchip SoCs allow the spl code to be rc4-encoded, not only the
image header, but only newer SoCs allow this encoding to be disabled.

The rk3188 is not part of those and requires its boot code to be
rc4-encoded with the regular key. So add the ability to do this
encoding via a setting on a per-soc basis when building spl images.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>

tools/rkcommon.h

@@ -55,4 +55,26 @@ int rkcommon_get_spl_size(struct image_tool_params *params);
 int rkcommon_set_header(void *buf, uint file_size,
 			struct image_tool_params *params);
 
+/**
+ * rkcommon_need_rc4_spl() - check if rc4 encoded spl is required
+ *
+ * Some socs cannot disable the rc4-encryption of the spl binary.
+ * rc4 encryption is disabled normally except on socs that cannot
+ * handle unencrypted binaries.
+ * @return true or false depending on rc4 being required.
+ */
+bool rkcommon_need_rc4_spl(struct image_tool_params *params);
+
+/**
+ * rkcommon_rc4_encode_spl() - encode the spl binary
+ *
+ * Encrypts the SPL binary using the generic rc4 key as required
+ * by some socs.
+ *
+ * @buf:	Pointer to the SPL data (header and SPL binary)
+ * @offset:	offset inside buf to start at
+ * @size:	number of bytes to encode
+ */
+void rkcommon_rc4_encode_spl(void *buf, unsigned int offset, unsigned int size);
+
 #endif