pinctrl: fsl: imx: Check for 0 config register

0 is used in all pinfunction definitions when a config register is not
available, for example imx25-pinfunc.h. If a configuration value is used
for such a pinfunction the driver will always write it to the
configuration register if it is not -1. For a 0 configuration register
the configuration value is written to offset 0x0. This can lead to a
crashing/hanging system without any warning message.

This patch checks for 0 config register and sets the internal value to
-1. If the configuration value is not NO_PADCTL this leads to an error
message that applying the configuration failed.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Stefan Agner <stefan@agner.ch>
Acked-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/pinctrl/freescale/pinctrl-imx.c b/drivers/pinctrl/freescale/pinctrl-imx.c
index 2ee0d9228e63..e261f1cf85c6 100644
--- a/drivers/pinctrl/freescale/pinctrl-imx.c
+++ b/drivers/pinctrl/freescale/pinctrl-imx.c
@@ -542,10 +542,13 @@ static int imx_pinctrl_parse_groups(struct device_node *np,
                 struct imx_pin_reg *pin_reg;
                 struct imx_pin *pin = &grp->pins[i];
 
-                if (info->flags & SHARE_MUX_CONF_REG)
+                if (info->flags & SHARE_MUX_CONF_REG) {
                         conf_reg = mux_reg;
-                else
+                } else {
                         conf_reg = be32_to_cpu(*list++);
+                        if (!conf_reg)
+                                conf_reg = -1;
+                }
 
                 pin_id = mux_reg ? mux_reg / 4 : conf_reg / 4;
                 pin_reg = &info->pin_regs[pin_id];