pinctrl: starfive: Serialize adding groups and functions

The pinctrl dt_node_to_map method may be called in parallel which leads
us to call pinconf_generic_add_group and pinconf_generic_add_function
in parallel. This is not supported though and leads to errors, so add a
mutex to serialize these calls.

Signed-off-by: Jianlong Huang <jianlong.huang@starfivetech.com>
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Link: https://lore.kernel.org/r/20220627085333.1774396-1-emil.renner.berthing@canonical.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-starfive.c

@@ -207,6 +207,7 @@ struct starfive_pinctrl {
 	void __iomem *base;
 	void __iomem *padctl;
 	struct pinctrl_dev *pctl;
+	struct mutex mutex; /* serialize adding groups and functions */
 };
 
 static inline unsigned int starfive_pin_to_gpio(const struct starfive_pinctrl *sfp,
@@ -522,6 +523,7 @@ static int starfive_dt_node_to_map(struct pinctrl_dev *pctldev,
 
 	nmaps = 0;
 	ngroups = 0;
+	mutex_lock(&sfp->mutex);
 	for_each_child_of_node(np, child) {
 		int npins;
 		int i;
@@ -615,12 +617,14 @@ static int starfive_dt_node_to_map(struct pinctrl_dev *pctldev,
 
 	*maps = map;
 	*num_maps = nmaps;
+	mutex_unlock(&sfp->mutex);
 	return 0;
 
 put_child:
 	of_node_put(child);
 free_map:
 	pinctrl_utils_free_map(pctldev, map, nmaps);
+	mutex_unlock(&sfp->mutex);
 	return ret;
 }
 
@@ -1267,6 +1271,7 @@ static int starfive_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, sfp);
 	sfp->gc.parent = dev;
 	raw_spin_lock_init(&sfp->lock);
+	mutex_init(&sfp->mutex);
 
 	ret = devm_pinctrl_register_and_init(dev, &starfive_desc, sfp, &sfp->pctl);
 	if (ret)