button: qcom-pmic: fix some error checking

The pmic_reg_read() function can return errors.  Add a check for that.

Fixes: 4e8aa0065d4b ("button: qcom-pmic: introduce Qualcomm PMIC button driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>

diff --git a/drivers/button/button-qcom-pmic.c b/drivers/button/button-qcom-pmic.c
index 34a976d1e6c6a9db951305f02edc0f7fb29272d7..e778e51a4f36c270961f38815dfd4e7cc76286b9 100644 (file)
--- a/drivers/button/button-qcom-pmic.c
+++ b/drivers/button/button-qcom-pmic.c
@@ -86,7 +86,7 @@ static int qcom_pwrkey_probe(struct udevice *dev)
        }
 
        ret = pmic_reg_read(priv->pmic, priv->base + REG_SUBTYPE);
-       if ((ret & 0x7) == 0) {
+       if (ret < 0 || (ret & 0x7) == 0) {
                printf("%s: unexpected PMCI function subtype %d\n", dev->name, ret);
                return -ENXIO;
        }