[PATCH v3 4/5] commands: hab: extend by field_return fuse burn

[Fabian Pflug <f.pflug@pengutronix.de>]

Extend hab command with an additional parameter to burn the field return
fuse.
Since there is now a convenient way to burn the field return fuse, give
a hint at the Kconfig option about this, as it already describes what to
do in order to burn the fuse to make it complete.

Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Fabian Pflug <f.pflug@pengutronix.de>
---
 arch/arm/mach-imx/Kconfig |  6 +++++-
 commands/hab.c            | 24 ++++++++++++++++++++----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index 5f50d1a823..5fea0bbbca 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -926,13 +926,17 @@ config HABV4_CSF_UNLOCK_UID
           feature. This value must match the per device UNIQUE_ID fuses.
 
 	  The below example shows the expected format. The UNIQUE_ID is
-	  queried by Linux via:
+	  printed during boot by barebox:
+	    i.MX___ unique ID: 7766554433221100
+	  or it can be queried by Linux via:
             - cat /sys/devices/soc0/serial_number
 	      7766554433221100
 
 	  So this value have to be set:
 	    - 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77
 
+	  Afterwards, the `hab -p -r` command can be used to burn the fuse.
+
 config HABV4_IMG_CRT_PEM
 	string "Path to IMG certificate"
 	default "../crts/IMG1_1_sha256_4096_65537_v3_usr_crt.pem"
diff --git a/commands/hab.c b/commands/hab.c
index 8ae943a4c8..df045df470 100644
--- a/commands/hab.c
+++ b/commands/hab.c
@@ -16,9 +16,9 @@ static int do_hab(int argc, char *argv[])
 	char *srkhashfile = NULL, *srkhash = NULL;
 	unsigned flags = 0;
 	u8 srk[SRK_HASH_SIZE];
-	int lockdown = 0, info = 0;
+	int lockdown = 0, info = 0, field_return = 0;
 
-	while ((opt = getopt(argc, argv, "s:fpx:li")) > 0) {
+	while ((opt = getopt(argc, argv, "s:fpx:lir")) > 0) {
 		switch (opt) {
 		case 's':
 			srkhashfile = optarg;
@@ -38,12 +38,15 @@ static int do_hab(int argc, char *argv[])
 		case 'i':
 			info = 1;
 			break;
+		case 'r':
+			field_return = 1;
+			break;
 		default:
 			return COMMAND_ERROR_USAGE;
 		}
 	}
 
-	if (!info && !lockdown && !srkhashfile && !srkhash) {
+	if (!info && !lockdown && !srkhashfile && !srkhash && !field_return) {
 		printf("Nothing to do\n");
 		return COMMAND_ERROR_USAGE;
 	}
@@ -94,7 +97,19 @@ static int do_hab(int argc, char *argv[])
 		printf("Device successfully locked down\n");
 	}
 
-	return 0;
+	if (field_return) {
+		ret = imx_hab_field_return(flags & IMX_SRK_HASH_WRITE_PERMANENT);
+		if (ret == -EINVAL && IS_ENABLED(CONFIG_HABV4_CSF_UNLOCK_FIELD_RETURN))
+			printf("Field-return burn failed, check HABV4_CSF_UNLOCK_UID!\n");
+		else if (ret == -EINVAL && !IS_ENABLED(CONFIG_HABV4_CSF_UNLOCK_FIELD_RETURN))
+			printf("Field-return burn failed because CONFIG_HABV4_CSF_UNLOCK_FIELD_RETURN=n\n");
+		else if (ret)
+			printf("Field-return burn failed\n");
+		else
+			printf("Field return fuse successfully burnt\n");
+	}
+
+	return ret;
 }
 
 BAREBOX_CMD_HELP_START(hab)
@@ -105,6 +120,7 @@ BAREBOX_CMD_HELP_OPT ("-x <sha256>",  "Burn Super Root Key hash from hex string"
 BAREBOX_CMD_HELP_OPT ("-i",  "Print HAB info")
 BAREBOX_CMD_HELP_OPT ("-f",  "Force. Write even when a key is already written")
 BAREBOX_CMD_HELP_OPT ("-l",  "Lockdown device. Dangerous! After executing only signed images can be booted")
+BAREBOX_CMD_HELP_OPT ("-r",  "Field Return. Dangerous! Access to device keys will be disabled forever")
 BAREBOX_CMD_HELP_OPT ("-p",  "Permanent. Really burn fuses. Be careful!")
 BAREBOX_CMD_HELP_END
 

-- 
2.47.3