pinctrl: stm32: fix optional IRQ support to gpios

To act as an interrupt controller, a gpio bank relies on the
"interrupt-parent" of the pin controller.
When this optional "interrupt-parent" misses, do not create any IRQ domain.

This fixes a "NULL pointer in stm32_gpio_domain_alloc()" kernel crash when
the interrupt-parent = <exti> property is not declared in the Device Tree.

Fixes: 0eb9f683 ("pinctrl: Add IRQ support to STM32 gpios")
Signed-off-by: Fabien Dessenne <fabien.dessenne@foss.st.com>
Link: https://lore.kernel.org/r/20220627142350.742973-1-fabien.dessenne@foss.st.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/stm32/pinctrl-stm32.c

@@ -1338,17 +1338,19 @@ static int stm32_gpiolib_register_bank(struct stm32_pinctrl *pctl, struct fwnode
 	bank->secure_control = pctl->match_data->secure_control;
 	spin_lock_init(&bank->lock);
 
+	if (pctl->domain) {
 		/* create irq hierarchical domain */
 		bank->fwnode = fwnode;
 
-	bank->domain = irq_domain_create_hierarchy(pctl->domain, 0,
-					STM32_GPIO_IRQ_LINE, bank->fwnode,
-					&stm32_gpio_domain_ops, bank);
+		bank->domain = irq_domain_create_hierarchy(pctl->domain, 0, STM32_GPIO_IRQ_LINE,
+							   bank->fwnode, &stm32_gpio_domain_ops,
+							   bank);
 
 		if (!bank->domain) {
 			err = -ENODEV;
 			goto err_clk;
 		}
+	}
 
 	err = gpiochip_add_data(&bank->gpio_chip, bank);
 	if (err) {
@@ -1510,6 +1512,8 @@ int stm32_pctl_probe(struct platform_device *pdev)
 	pctl->domain = stm32_pctrl_get_irq_domain(pdev);
 	if (IS_ERR(pctl->domain))
 		return PTR_ERR(pctl->domain);
+	if (!pctl->domain)
+		dev_warn(dev, "pinctrl without interrupt support\n");
 
 	/* hwspinlock is optional */
 	hwlock_id = of_hwspin_lock_get_id(pdev->dev.of_node, 0);