[PATCH v2 9/9] i.MX: HAB: add imx_hab_field_return support

[Marco Felsch <m.felsch@xxxxxxxxxxxxxx>]

Add a convenient helper to burn the field-return fuse which wraps the
platform specific hook. At the moment only i.MX8M devices are supported.
Adding support for other platforms can be done by providing the platform
specific hook.

Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
---
 drivers/hab/hab.c                | 41 ++++++++++++++++++++++++++++++++++++++++
 include/hab.h                    |  1 +
 include/mach/imx/ocotp-fusemap.h |  1 +
 3 files changed, 43 insertions(+)

diff --git a/drivers/hab/hab.c b/drivers/hab/hab.c
index 7c840303d395..73d470be131e 100644
--- a/drivers/hab/hab.c
+++ b/drivers/hab/hab.c
@@ -252,6 +252,23 @@ static int imx8m_hab_revoke_key_ocotp(unsigned key_idx)
 	return ret;
 }
 
+static int imx8m_hab_field_return_ocotp(void)
+{
+	int ret;
+
+	ret = imx_ocotp_field_return_locked();
+	if (ret < 0)
+		return ret;
+
+	/* Return -EINVAL in case the FIELD_RETURN write is locked */
+	if (ret == 1)
+		return -EINVAL;
+
+	ret = imx_ocotp_write_field(MX8M_OCOTP_FIELD_RETURN, 1);
+
+	return ret;
+}
+
 struct imx_hab_ops {
 	int (*write_srk_hash)(const u8 *srk, unsigned flags);
 	int (*read_srk_hash)(u8 *srk);
@@ -260,6 +277,7 @@ struct imx_hab_ops {
 	int (*device_locked_down)(void);
 	int (*print_status)(void);
 	int (*revoke_key)(unsigned key_idx);
+	int (*field_return)(void);
 };
 
 static struct imx_hab_ops imx_hab_ops_iim = {
@@ -288,6 +306,7 @@ static struct imx_hab_ops imx8m_hab_ops_ocotp = {
 	.permanent_write_enable = imx_hab_permanent_write_enable_ocotp,
 	.print_status = imx8m_hab_print_status,
 	.revoke_key = imx8m_hab_revoke_key_ocotp,
+	.field_return = imx8m_hab_field_return_ocotp,
 };
 
 static int imx_ahab_write_srk_hash(const u8 *__newsrk, unsigned flags)
@@ -581,3 +600,25 @@ int imx_hab_revoke_key(unsigned key_idx, bool permanent)
 
 	return ret;
 }
+
+int imx_hab_field_return(bool permanent)
+{
+	struct imx_hab_ops *ops = imx_get_hab_ops();
+	int ret;
+
+	if (!ops || !ops->field_return)
+		return -ENOSYS;
+
+	if (permanent) {
+		ret = ops->permanent_write_enable(1);
+		if (ret)
+			return ret;
+	}
+
+	ret = ops->field_return();
+
+	if (permanent)
+		ops->permanent_write_enable(0);
+
+	return ret;
+}
diff --git a/include/hab.h b/include/hab.h
index 7a70c67f0488..393cf0513e0c 100644
--- a/include/hab.h
+++ b/include/hab.h
@@ -52,5 +52,6 @@ int imx_hab_lockdown_device(unsigned flags);
 int imx_hab_device_locked_down(void);
 int imx_hab_print_status(void);
 int imx_hab_revoke_key(unsigned key_idx, bool permanent);
+int imx_hab_field_return(bool permanent);
 
 #endif /* __HABV4_H */
diff --git a/include/mach/imx/ocotp-fusemap.h b/include/mach/imx/ocotp-fusemap.h
index 1aece9195ff9..37f1ee8298c2 100644
--- a/include/mach/imx/ocotp-fusemap.h
+++ b/include/mach/imx/ocotp-fusemap.h
@@ -67,6 +67,7 @@
 #define MX8M_OCOTP_TZASC_EN		(OCOTP_WORD(0x480) | OCOTP_BIT(11) | OCOTP_WIDTH(1))
 #define MX8MP_OCOTP_ROM_NO_LOG		(OCOTP_WORD(0x480) | OCOTP_BIT(22) | OCOTP_WIDTH(1))
 #define MX8M_OCOTP_RECOVERY_SDMMC_BOOT_DIS	(OCOTP_WORD(0x490) | OCOTP_BIT(23) | OCOTP_WIDTH(1))
+#define MX8M_OCOTP_FIELD_RETURN		(OCOTP_WORD(0x630) | OCOTP_BIT(0) | OCOTP_WIDTH(1))
 #define MX8M_OCOTP_SRK_REVOKE		(OCOTP_WORD(0x670) | OCOTP_BIT(0) | OCOTP_WIDTH(4))
 
 #endif /* __MACH_IMX_OCOTP_FUSEMAP_H */

-- 
2.39.2