pinctrl: add some error checking for user interfaces

This patch can avoid kernel oops in case the mux or config
function is not supported by driver.

Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/pinctrl/pinconf.c b/drivers/pinctrl/pinconf.c
index eb3a14f4b866..384dcc166e44 100644
--- a/drivers/pinctrl/pinconf.c
+++ b/drivers/pinctrl/pinconf.c
@@ -448,8 +448,12 @@ static void pinconf_dump_pin(struct pinctrl_dev *pctldev,
 static int pinconf_pins_show(struct seq_file *s, void *what)
 {
         struct pinctrl_dev *pctldev = s->private;
+        const struct pinconf_ops *ops = pctldev->desc->confops;
         unsigned i, pin;
 
+        if (!ops || !ops->pin_config_get)
+                return 0;
+
         seq_puts(s, "Pin config settings per pin\n");
         seq_puts(s, "Format: pin (name): pinmux setting array\n");