gpio: stmpe: Allow to compile as a module

Add the necessary boilerplate to also make this driver modular.
Keep the subsys_initcall to not change registration order for built-in.
Also add OF match table for module autoloading.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://lore.kernel.org/r/20250728060544.18169-1-alexander.stein@ew.tq-group.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: tq-steina

drivers/gpio/Kconfig

@@ -1559,7 +1559,7 @@ config GPIO_SL28CPLD
 	  called gpio-sl28cpld.
 
 config GPIO_STMPE
-	bool "STMPE GPIOs"
+	tristate "STMPE GPIOs"
 	depends on MFD_STMPE
 	depends on OF_GPIO
 	select GPIOLIB_IRQCHIP

drivers/gpio/gpio-stmpe.c

@@ -534,10 +534,16 @@ static int stmpe_gpio_probe(struct platform_device *pdev)
 	return devm_gpiochip_add_data(dev, &stmpe_gpio->chip, stmpe_gpio);
 }
 
+static const struct of_device_id stmpe_gpio_of_matches[] = {
+	{ .compatible = "st,stmpe-gpio", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, stmpe_gpio_of_matches);
+
 static struct platform_driver stmpe_gpio_driver = {
 	.driver = {
-		.suppress_bind_attrs	= true,
-		.name			= "stmpe-gpio",
+		.name = "stmpe-gpio",
+		.of_match_table = stmpe_gpio_of_matches,
 	},
 	.probe		= stmpe_gpio_probe,
 };
@@ -547,3 +553,13 @@ static int __init stmpe_gpio_init(void)
 	return platform_driver_register(&stmpe_gpio_driver);
 }
 subsys_initcall(stmpe_gpio_init);
+
+static void __exit stmpe_gpio_exit(void)
+{
+	platform_driver_unregister(&stmpe_gpio_driver);
+}
+module_exit(stmpe_gpio_exit);
+
+MODULE_DESCRIPTION("STMPE expander GPIO");
+MODULE_AUTHOR("Rabin Vincent <rabin.vincent@stericsson.com>");
+MODULE_LICENSE("GPL");