lib: utils/gpio: Use kconfig for enabling/disabling drivers

We update gpio drivers makefile to use kconfig for enabling/disabling
drivers. To avoid compile errors, we also enable appropriate gpio
drivers for each platform.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Tested-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Atish Patra <atishp@rivosinc.com>
Tested-by: Atish Patra <atishp@rivosinc.com>

lib/utils/gpio/Kconfig

@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: BSD-2-Clause
+
+menu "GPIO Support"
+
+config FDT_GPIO
+	bool "FDT based GPIO drivers"
+	select GPIO
+	default n
+
+if FDT_GPIO
+
+config FDT_GPIO_SIFIVE
+	bool "SiFive GPIO FDT driver"
+	default n
+
+endif
+
+config GPIO
+	bool "GPIO support"
+	default n
+
+endmenu

lib/utils/gpio/objects.mk

@@ -7,10 +7,10 @@
 #   Anup Patel <anup.patel@wdc.com>
 #
 
-libsbiutils-objs-y += gpio/fdt_gpio.o
-libsbiutils-objs-y += gpio/fdt_gpio_drivers.o
+libsbiutils-objs-$(CONFIG_FDT_GPIO) += gpio/fdt_gpio.o
+libsbiutils-objs-$(CONFIG_FDT_GPIO) += gpio/fdt_gpio_drivers.o
 
-carray-fdt_gpio_drivers-y += fdt_gpio_sifive
-libsbiutils-objs-y += gpio/fdt_gpio_sifive.o
+carray-fdt_gpio_drivers-$(CONFIG_FDT_GPIO_SIFIVE) += fdt_gpio_sifive
+libsbiutils-objs-$(CONFIG_FDT_GPIO_SIFIVE) += gpio/fdt_gpio_sifive.o
 
-libsbiutils-objs-y += gpio/gpio.o
+libsbiutils-objs-$(CONFIG_GPIO) += gpio/gpio.o