[PATCH master] i.MX: HAB: fix i.MX8MP field-return fuse

[Marco Felsch <m.felsch@pengutronix.de>]

Current tests showed that fusing just the single field-return bit(0) on
i.MX8MP SoCs brick the device.

All i.MX8M SoCs have a single field-return bit except for the i.MX8MP
which requires a pattern. The pattern is not documented but was
discussed here [1] and the final u-boot commit [2] added the support
accordingly.

This commit is based on the outcome of [1, 2].

[1] https://lore.kernel.org/all/20240621130626.729666-1-paul.geurts@prodrive-technologies.com/
[2] https://github.com/u-boot/u-boot/blob/v2025.01/arch/arm/mach-imx/hab.c#L35

Tested-by: Johannes Schneider <johannes.schneider@leica-geosystems.com>
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
 drivers/hab/hab.c                | 12 +++++++++++-
 include/mach/imx/ocotp-fusemap.h |  1 +
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/hab/hab.c b/drivers/hab/hab.c
index 73d470be131e..74ba4a48557c 100644
--- a/drivers/hab/hab.c
+++ b/drivers/hab/hab.c
@@ -252,6 +252,12 @@ static int imx8m_hab_revoke_key_ocotp(unsigned key_idx)
 	return ret;
 }
 
+/*
+ * The fuse pattern for i.MX8M Plus is 0x28001401, but bit 2 is already set from factory.
+ * This means when field return is set, the fuse word value reads 0x28001405
+ */
+#define MX8MP_FIELD_RETURN_PATTERN	0x28001401
+
 static int imx8m_hab_field_return_ocotp(void)
 {
 	int ret;
@@ -264,7 +270,11 @@ static int imx8m_hab_field_return_ocotp(void)
 	if (ret == 1)
 		return -EINVAL;
 
-	ret = imx_ocotp_write_field(MX8M_OCOTP_FIELD_RETURN, 1);
+	if (cpu_is_mx8mp())
+		ret = imx_ocotp_write_field(MX8MP_OCOTP_FIELD_RETURN,
+					    MX8MP_FIELD_RETURN_PATTERN);
+	else
+		ret = imx_ocotp_write_field(MX8M_OCOTP_FIELD_RETURN, 1);
 
 	return ret;
 }
diff --git a/include/mach/imx/ocotp-fusemap.h b/include/mach/imx/ocotp-fusemap.h
index 37f1ee8298c2..587fe8b15eab 100644
--- a/include/mach/imx/ocotp-fusemap.h
+++ b/include/mach/imx/ocotp-fusemap.h
@@ -68,6 +68,7 @@
 #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 MX8MP_OCOTP_FIELD_RETURN	(OCOTP_WORD(0x630) | OCOTP_BIT(0) | OCOTP_WIDTH(32))
 #define MX8M_OCOTP_SRK_REVOKE		(OCOTP_WORD(0x670) | OCOTP_BIT(0) | OCOTP_WIDTH(4))
 
 #endif /* __MACH_IMX_OCOTP_FUSEMAP_H */
-- 
2.39.5