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.c

@@ -46,17 +46,19 @@ struct header0_info {
  * @imagename:		Image name(passed by "mkimage -n")
  * @spl_hdr:		Boot ROM requires a 4-bytes spl header
  * @spl_size:		Spl size(include extra 4-bytes spl header)
+ * @spl_rc4:		RC4 encode the SPL binary (same key as header)
  */
 struct spl_info {
 	const char *imagename;
 	const char *spl_hdr;
 	const uint32_t spl_size;
+	const bool spl_rc4;
 };
 
 static struct spl_info spl_infos[] = {
-	{ "rk3036", "RK30", 0x1000 },
-	{ "rk3288", "RK32", 0x8000 },
-	{ "rk3399", "RK33", 0x20000 },
+	{ "rk3036", "RK30", 0x1000, false },
+	{ "rk3288", "RK32", 0x8000, false },
+	{ "rk3399", "RK33", 0x20000, false },
 };
 
 static unsigned char rc4_key[16] = {
@@ -113,6 +115,16 @@ int rkcommon_get_spl_size(struct image_tool_params *params)
 	return info->spl_size;
 }
 
+bool rkcommon_need_rc4_spl(struct image_tool_params *params)
+{
+	struct spl_info *info = rkcommon_get_spl_info(params->imagename);
+
+	/*
+	 * info would not be NULL, because of we checked params before.
+	 */
+	return info->spl_rc4;
+}
+
 int rkcommon_set_header(void *buf, uint file_size,
 			struct image_tool_params *params)
 {
@@ -124,7 +136,7 @@ int rkcommon_set_header(void *buf, uint file_size,
 	memset(buf,  '\0', RK_INIT_OFFSET * RK_BLK_SIZE);
 	hdr = (struct header0_info *)buf;
 	hdr->signature = RK_SIGNATURE;
-	hdr->disable_rc4 = 1;
+	hdr->disable_rc4 = !rkcommon_need_rc4_spl(params);
 	hdr->init_offset = RK_INIT_OFFSET;
 
 	hdr->init_size = (file_size + RK_BLK_SIZE - 1) / RK_BLK_SIZE;
@@ -135,3 +147,16 @@ int rkcommon_set_header(void *buf, uint file_size,
 
 	return 0;
 }
+
+void rkcommon_rc4_encode_spl(void *buf, unsigned int offset, unsigned int size)
+{
+	unsigned int remaining = size;
+
+	while (remaining > 0) {
+		int step = (remaining > RK_BLK_SIZE) ? RK_BLK_SIZE : remaining;
+
+		rc4_encode(buf + offset, step, rc4_key);
+		offset += RK_BLK_SIZE;
+		remaining -= step;
+	}
+}

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

tools/rkimage.c

@@ -28,6 +28,9 @@ static void rkimage_set_header(void *buf, struct stat *sbuf, int ifd,
 {
 	memcpy(buf + RK_SPL_HDR_START, rkcommon_get_spl_hdr(params),
 	       RK_SPL_HDR_SIZE);
+
+	if (rkcommon_need_rc4_spl(params))
+		rkcommon_rc4_encode_spl(buf, 4, params->file_size);
 }
 
 static int rkimage_extract_subimage(void *buf, struct image_tool_params *params)

tools/rksd.c

@@ -41,6 +41,10 @@ static void rksd_set_header(void *buf,  struct stat *sbuf,  int ifd,
 
 	memcpy(buf + RK_SPL_HDR_START, rkcommon_get_spl_hdr(params),
 	       RK_SPL_HDR_SIZE);
+
+	if (rkcommon_need_rc4_spl(params))
+		rkcommon_rc4_encode_spl(buf, RK_SPL_START - 4,
+					params->file_size - RK_SPL_START + 4);
 }
 
 static int rksd_extract_subimage(void *buf,  struct image_tool_params *params)

tools/rkspi.c

@@ -48,6 +48,10 @@ static void rkspi_set_header(void *buf, struct stat *sbuf, int ifd,
 	memcpy(buf + RK_SPL_HDR_START, rkcommon_get_spl_hdr(params),
 	       RK_SPL_HDR_SIZE);
 
+	if (rkcommon_need_rc4_spl(params))
+		rkcommon_rc4_encode_spl(buf, RK_SPL_START - 4,
+					params->file_size - RK_SPL_START + 4);
+
 	/*
 	 * Spread the image out so we only use the first 2KB of each 4KB
 	 * region. This is a feature of the SPI format required by the Rockchip