gpio: move ppc4xx gpio driver from arch/powerpc to drivers/gpio

Move the ppc4xx gpio driver out of arch/powerpc/platforms/44x/ into
drivers/gpio/gpio-ppc44x.c. The driver has no architecture-specific
dependencies and follows the same pattern as other PowerPC GPIO
drivers already in drivers/gpio/ (e.g. gpio-mpc8xxx, gpio-mpc5200).

- Renamed Kconfig symbol from PPC4xx_GPIO to GPIO_PPC44X
- Updated ppc44x_defconfig and warp_defconfig to use the new symbol
- Marked the new option as tristate (was bool) since the driver
  supports module build via module_platform_driver()

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260803223539.86303-2-rosenp@gmail.com

arch/powerpc/configs/44x/warp_defconfig

@@ -12,7 +12,7 @@ CONFIG_MODULE_UNLOAD=y
 # CONFIG_BLK_DEV_BSG is not set
 # CONFIG_EBONY is not set
 CONFIG_WARP=y
-CONFIG_PPC4xx_GPIO=y
+CONFIG_GPIO_PPC44X=y
 CONFIG_HZ_1000=y
 CONFIG_CMDLINE="ip=on"
 # CONFIG_PCI is not set

arch/powerpc/configs/ppc44x_defconfig

@@ -22,7 +22,7 @@ CONFIG_GLACIER=y
 CONFIG_REDWOOD=y
 CONFIG_EIGER=y
 CONFIG_YOSEMITE=y
-CONFIG_PPC4xx_GPIO=y
+CONFIG_GPIO_PPC44X=y
 CONFIG_MATH_EMULATION=y
 CONFIG_NET=y
 CONFIG_PACKET=y

arch/powerpc/platforms/44x/Kconfig

@@ -227,13 +227,6 @@ config PPC44x_SIMPLE
 	help
 	  This option enables the simple PowerPC 44x platform support.
 
-config PPC4xx_GPIO
-	bool "PPC4xx GPIO support"
-	depends on 44x
-	select GPIOLIB
-	help
-	  Enable gpiolib support for ppc440 based boards
-
 # 44x specific CPU modules, selected based on the board above.
 config 440EP
 	bool

arch/powerpc/platforms/44x/Makefile

@@ -15,4 +15,4 @@ obj-$(CONFIG_FSP2)	+= fsp2.o
 obj-$(CONFIG_PCI)		+= pci.o
 obj-$(CONFIG_PPC4xx_HSTA_MSI)	+= hsta_msi.o
 obj-$(CONFIG_PPC4xx_CPM)	+= cpm.o
-obj-$(CONFIG_PPC4xx_GPIO)	+= gpio.o
+

drivers/gpio/Kconfig

@@ -593,6 +593,13 @@ config GPIO_POLARFIRE_SOC
 	help
 	  Say yes here to support the GPIO controllers on Microchip FPGAs.
 
+config GPIO_PPC44X
+	tristate "PPC44x GPIO support"
+	depends on 44x
+	select GPIO_GENERIC
+	help
+	  Enable gpiolib support for ppc440 based boards.
+
 config GPIO_PXA
 	bool "PXA GPIO support"
 	depends on ARCH_PXA || ARCH_MMP || COMPILE_TEST

drivers/gpio/Makefile

@@ -147,6 +147,7 @@ obj-$(CONFIG_GPIO_PCIE_IDIO_24)		+= gpio-pcie-idio-24.o
 obj-$(CONFIG_GPIO_PCI_IDIO_16)		+= gpio-pci-idio-16.o
 obj-$(CONFIG_GPIO_PISOSR)		+= gpio-pisosr.o
 obj-$(CONFIG_GPIO_PL061)		+= gpio-pl061.o
+obj-$(CONFIG_GPIO_PPC44X)		+= gpio-ppc44x.o
 obj-$(CONFIG_GPIO_PMIC_EIC_SPRD)	+= gpio-pmic-eic-sprd.o
 obj-$(CONFIG_GPIO_POLARFIRE_SOC)	+= gpio-mpfs.o
 obj-$(CONFIG_GPIO_PXA)			+= gpio-pxa.o