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, 10 insertions, 7 deletions

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index c0fe6091566a..e09474ecde23 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -468,6 +468,9 @@ int pinctrl_get_group_pins(struct pinctrl_dev *pctldev, const char *pin_group,
         const struct pinctrl_ops *pctlops = pctldev->desc->pctlops;
         int gs;
 
+        if (!pctlops->get_group_pins)
+                return -EINVAL;
+
         gs = pinctrl_get_group_selector(pctldev, pin_group);
         if (gs < 0)
                 return gs;
@@ -1362,15 +1365,16 @@ static int pinctrl_groups_show(struct seq_file *s, void *what)
 
         seq_puts(s, "registered pin groups:\n");
         while (selector < ngroups) {
-                const unsigned *pins;
-                unsigned num_pins;
+                const unsigned *pins = NULL;
+                unsigned num_pins = 0;
                 const char *gname = ops->get_group_name(pctldev, selector);
                 const char *pname;
-                int ret;
+                int ret = 0;
                 int i;
 
-                ret = ops->get_group_pins(pctldev, selector,
-                                          &pins, &num_pins);
+                if (ops->get_group_pins)
+                        ret = ops->get_group_pins(pctldev, selector,
+                                                  &pins, &num_pins);
                 if (ret)
                         seq_printf(s, "%s [ERROR GETTING PINS]\n",
                                    gname);
@@ -1694,8 +1698,7 @@ static int pinctrl_check_ops(struct pinctrl_dev *pctldev)
 
         if (!ops ||
             !ops->get_groups_count ||
-            !ops->get_group_name ||
-            !ops->get_group_pins)
+            !ops->get_group_name)
                 return -EINVAL;
 
         if (ops->dt_node_to_map && !ops->dt_free_map)