pinctrl: Enable device link creation for pin control

A pin controller may want to create a link between itself
and its clients to be sure of suspend/resume call ordering.

Introduce link_consumers field in pinctrl_desc structure to let
pinctrl core knows that controller expect to create a link.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
[Renamed create_link to link_consumers]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/core.c

@@ -1216,6 +1216,15 @@ struct pinctrl_state *pinctrl_lookup_state(struct pinctrl *p,
 }
 EXPORT_SYMBOL_GPL(pinctrl_lookup_state);
 
+static void pinctrl_link_add(struct pinctrl_dev *pctldev,
+			     struct device *consumer)
+{
+	if (pctldev->desc->link_consumers)
+		device_link_add(consumer, pctldev->dev,
+				DL_FLAG_PM_RUNTIME |
+				DL_FLAG_AUTOREMOVE_CONSUMER);
+}
+
 /**
  * pinctrl_commit_state() - select/activate/program a pinctrl state to HW
  * @p: the pinctrl handle for the device that requests configuration
@@ -1261,6 +1270,8 @@ static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
 		if (ret < 0) {
 			goto unapply_new_state;
 		}
+
+		pinctrl_link_add(setting->pctldev, p->dev);
 	}
 
 	p->state = state;

include/linux/pinctrl/pinctrl.h

@@ -125,6 +125,10 @@ struct pinctrl_ops {
  *	the hardware description
  * @custom_conf_items: Information how to print @params in debugfs, must be
  *	the same size as the @custom_params, i.e. @num_custom_params
+ * @link_consumers: If true create a device link between pinctrl and its
+ *	consumers (i.e. the devices requesting pin control states). This is
+ *	sometimes necessary to ascertain the right suspend/resume order for
+ *	example.
  */
 struct pinctrl_desc {
 	const char *name;
@@ -139,6 +143,7 @@ struct pinctrl_desc {
 	const struct pinconf_generic_params *custom_params;
 	const struct pin_config_item *custom_conf_items;
 #endif
+	bool link_consumers;
 };
 
 /* External interface to pin controller */