imx: caam: new u-boot command to set PRIBLOB bitfield from CAAM SCFGR register to 0x3

It is highly recommended to set the PRIBLOB bitfield to 0x3 once your
encrypted boot image has booted up, this prevents the generation of new
blobs that can be used to decrypt an encrypted boot image. The PRIBLOB is
a sticky type bit and cannot be changed until the next power on reset.

Add the set_priblob_bitfield U-Boot command to prevent the generation of
new blobs.

Signed-off-by: Clement Le Marquis <clement.lemarquis@nxp.com>
Acked-by: Ye Li <Ye.Li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/priblob.c b/arch/arm/mach-imx/priblob.c
new file mode 100644
index 00000000000..e253eddfdc1
--- /dev/null
+++ b/arch/arm/mach-imx/priblob.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 NXP
+ */
+
+/*
+ * Boot command to get and set the PRIBLOB bitfield form the SCFGR register
+ * of the CAAM IP. It is recommended to set this bitfield to 3 once your
+ * encrypted boot image is ready, to prevent the generation of blobs usable
+ * to decrypt an encrypted boot image.
+ */
+
+#include <asm/io.h>
+#include <common.h>
+#include <command.h>
+#include "../drivers/crypto/fsl_caam_internal.h"
+
+int do_priblob_write(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	writel((readl(CAAM_SCFGR) & 0xFFFFFFFC) | 3, CAAM_SCFGR);
+	printf("New priblob setting = 0x%x\n", readl(CAAM_SCFGR) & 0x3);
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	set_priblob_bitfield, 1, 0, do_priblob_write,
+	"Set the PRIBLOB bitfield to 3",
+	"<value>\n"
+	"    - Write 3 in PRIBLOB bitfield of SCFGR regiter of CAAM IP.\n"
+	"    Prevent the generation of blobs usable to decrypt an\n"
+	"    encrypted boot image."
+);