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, 13 insertions, 2 deletions

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 8849830e5190..c494c37bf167 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -323,6 +323,11 @@ int pinmux_map_to_setting(struct pinctrl_map const *map,
         const unsigned *pins;
         unsigned num_pins;
 
+        if (!pmxops) {
+                dev_err(pctldev->dev, "does not support mux function\n");
+                return -EINVAL;
+        }
+
         setting->data.mux.func =
                 pinmux_func_name_to_selector(pctldev, map->data.mux.function);
         if (setting->data.mux.func < 0)
@@ -481,11 +486,14 @@ static int pinmux_functions_show(struct seq_file *s, void *what)
 {
         struct pinctrl_dev *pctldev = s->private;
         const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
-        unsigned nfuncs = pmxops->get_functions_count(pctldev);
+        unsigned nfuncs;
         unsigned func_selector = 0;
 
-        mutex_lock(&pinctrl_mutex);
+        if (!pmxops)
+                return 0;
 
+        mutex_lock(&pinctrl_mutex);
+        nfuncs = pmxops->get_functions_count(pctldev);
         while (func_selector < nfuncs) {
                 const char *func = pmxops->get_function_name(pctldev,
                                                           func_selector);
@@ -520,6 +528,9 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
         const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
         unsigned i, pin;
 
+        if (!pmxops)
+                return 0;
+
         seq_puts(s, "Pinmux settings per pin\n");
         seq_puts(s, "Format: pin (name): mux_owner gpio_owner hog?\n");