ARM: imx: Fix boot crash if ocotp is not found

The imx_soc_device_init functions tries to fetch the ocotp regmap in
order to soc serial number. If regmap fetch fails then a message is
printed but regmap_read is called anyway and the system crashes.

Failing to lookup ocotp regmap shouldn't be a fatal boot error so check
that the pointer is valid.

Only side-effect of ocotp lookup failure now is that serial number will
be reported as all-zeros which is acceptable.

Cc: stable@vger.kernel.org
Fixes: 8267ff89b713 ("ARM: imx: Add serial number support for i.MX6/7 SoCs")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Tested-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c
index 0fb0c4a264c318dbf14fdcb74949c2da0f0ac36a..871f98342d50e67e9962ae863436bf839c8cb4e7 100644 (file)
--- a/arch/arm/mach-imx/cpu.c
+++ b/arch/arm/mach-imx/cpu.c
@@ -84,7 +84,7 @@ struct device * __init imx_soc_device_init(void)
        const char *ocotp_compat = NULL;
        struct soc_device *soc_dev;
        struct device_node *root;
-       struct regmap *ocotp;
+       struct regmap *ocotp = NULL;
        const char *soc_id;
        u64 soc_uid = 0;
        u32 val;
@@ -175,7 +175,9 @@ struct device * __init imx_soc_device_init(void)
                ocotp = syscon_regmap_lookup_by_compatible(ocotp_compat);
                if (IS_ERR(ocotp))
                        pr_err("%s: failed to find %s regmap!\n", __func__, ocotp_compat);
+       }
 
+       if (!IS_ERR_OR_NULL(ocotp)) {
                regmap_read(ocotp, OCOTP_UID_H, &val);
                soc_uid = val;
                regmap_read(ocotp, OCOTP_UID_L, &val);