pinctrl: allows not to define the get_group_pins operation

When using a group only pinctrl driver, which does not have any
information on the pins it is useless to define a get_group_pins
always returning an empty list of pins.

When not using get_group_pin[1], a driver must implement it so
pins = NULL and num_pins = 0. This patch makes it the default
behaviour if not defined in the pinctrl driver when used in
pinmux enable and disable funtions and in pinctrl_groups_show.

It also adds a check in pinctrl_get_group_pins and return -EINVAL if
not defined. This function is called in the gpiolib when adding when
pingroup range. It cannot be used if no group is defined, so this seams
reasonable.

[1] get_group_pin(struct pinctrl_dev *pctldev,
		  unsigned selector,
		  const unsigned **pins,
		  unsigned *num_pins);

Signed-off-by: Antoine Ténart <antoine.tenart@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 9248ce4efed4..051e8592990e 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -391,14 +391,16 @@ int pinmux_enable_setting(struct pinctrl_setting const *setting)
         struct pinctrl_dev *pctldev = setting->pctldev;
         const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
         const struct pinmux_ops *ops = pctldev->desc->pmxops;
-        int ret;
-        const unsigned *pins;
-        unsigned num_pins;
+        int ret = 0;
+        const unsigned *pins = NULL;
+        unsigned num_pins = 0;
         int i;
         struct pin_desc *desc;
 
-        ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
-                                      &pins, &num_pins);
+        if (pctlops->get_group_pins)
+                ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
+                                              &pins, &num_pins);
+
         if (ret) {
                 const char *gname;
 
@@ -470,14 +472,15 @@ void pinmux_disable_setting(struct pinctrl_setting const *setting)
         struct pinctrl_dev *pctldev = setting->pctldev;
         const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
         const struct pinmux_ops *ops = pctldev->desc->pmxops;
-        int ret;
-        const unsigned *pins;
-        unsigned num_pins;
+        int ret = 0;
+        const unsigned *pins = NULL;
+        unsigned num_pins = 0;
         int i;
         struct pin_desc *desc;
 
-        ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
-                                      &pins, &num_pins);
+        if (pctlops->get_group_pins)
+                ret = pctlops->get_group_pins(pctldev, setting->data.mux.group,
+                                              &pins, &num_pins);
         if (ret) {
                 const char *gname;