irqchip/meson-gpio: Make it possible to build as a module

In order to reduce the kernel Image size on multi-platform distributions,
make it possible to build the Amlogic GPIO IRQ controller as a module
by switching it to a platform driver.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Saravana Kannan <saravanak@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210902134914.176986-2-narmstrong@baylibre.com

drivers/irqchip/Kconfig

@@ -400,8 +400,9 @@ config IRQ_UNIPHIER_AIDET
 	  Support for the UniPhier AIDET (ARM Interrupt Detector).
 
 config MESON_IRQ_GPIO
-       bool "Meson GPIO Interrupt Multiplexer"
-       depends on ARCH_MESON
+       tristate "Meson GPIO Interrupt Multiplexer"
+       depends on ARCH_MESON || COMPILE_TEST
+       default ARCH_MESON
        select IRQ_DOMAIN_HIERARCHY
        help
          Support Meson SoC Family GPIO Interrupt Multiplexer

drivers/irqchip/irq-meson-gpio.c

@@ -436,8 +436,7 @@ static const struct irq_domain_ops meson_gpio_irq_domain_ops = {
 	.translate	= meson_gpio_irq_domain_translate,
 };
 
-static int __init meson_gpio_irq_parse_dt(struct device_node *node,
-					  struct meson_gpio_irq_controller *ctl)
+static int meson_gpio_irq_parse_dt(struct device_node *node, struct meson_gpio_irq_controller *ctl)
 {
 	const struct of_device_id *match;
 	int ret;
@@ -463,8 +462,7 @@ static int __init meson_gpio_irq_parse_dt(struct device_node *node,
 	return 0;
 }
 
-static int __init meson_gpio_irq_of_init(struct device_node *node,
-					 struct device_node *parent)
+static int meson_gpio_irq_of_init(struct device_node *node, struct device_node *parent)
 {
 	struct irq_domain *domain, *parent_domain;
 	struct meson_gpio_irq_controller *ctl;
@@ -521,5 +519,10 @@ static int __init meson_gpio_irq_of_init(struct device_node *node,
 	return ret;
 }
 
-IRQCHIP_DECLARE(meson_gpio_intc, "amlogic,meson-gpio-intc",
-		meson_gpio_irq_of_init);
+IRQCHIP_PLATFORM_DRIVER_BEGIN(meson_gpio_intc)
+IRQCHIP_MATCH("amlogic,meson-gpio-intc", meson_gpio_irq_of_init)
+IRQCHIP_PLATFORM_DRIVER_END(meson_gpio_intc)
+
+MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:meson-gpio-intc");