pinctrl: microchip-sgpio: allow sgpio driver to be used as a module

As the commit message suggests, this simply adds the ability to select
SGPIO pinctrl as a module. This becomes more practical when the SGPIO
hardware exists on an external chip, controlled indirectly by I2C or SPI.
This commit enables that level of control.

Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220905162132.2943088-5-colin.foster@in-advantage.com

drivers/pinctrl/Kconfig

@@ -292,7 +292,7 @@ config PINCTRL_MCP23S08
 	  corresponding interrupt-controller.
 
 config PINCTRL_MICROCHIP_SGPIO
-	bool "Pinctrl driver for Microsemi/Microchip Serial GPIO"
+	tristate "Pinctrl driver for Microsemi/Microchip Serial GPIO"
 	depends on OF
 	depends on HAS_IOMEM
 	select GPIOLIB
@@ -310,6 +310,9 @@ config PINCTRL_MICROCHIP_SGPIO
 	  connect control signals from SFP modules and to act as an
 	  LED controller.
 
+	  If compiled as a module, the module name will be
+	  pinctrl-microchip-sgpio.
+
 config PINCTRL_OCELOT
 	tristate "Pinctrl driver for the Microsemi Ocelot and Jaguar2 SoCs"
 	depends on OF

drivers/pinctrl/pinctrl-microchip-sgpio.c

@@ -999,6 +999,7 @@ static const struct of_device_id microchip_sgpio_gpio_of_match[] = {
 		/* sentinel */
 	}
 };
+MODULE_DEVICE_TABLE(of, microchip_sgpio_gpio_of_match);
 
 static struct platform_driver microchip_sgpio_pinctrl_driver = {
 	.driver = {
@@ -1008,4 +1009,7 @@ static struct platform_driver microchip_sgpio_pinctrl_driver = {
 	},
 	.probe = microchip_sgpio_probe,
 };
-builtin_platform_driver(microchip_sgpio_pinctrl_driver);
+module_platform_driver(microchip_sgpio_pinctrl_driver);
+
+MODULE_DESCRIPTION("Microchip SGPIO Pinctrl Driver");
+MODULE_LICENSE("GPL");