build: Allow boards to disable digital input/output support

Allow the micro-controller code to be built without support for
regular gpio pins.  In this case, the code for endstops, steppers, and
gpiocmds will be disabled.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/Kconfig

@@ -21,6 +21,9 @@ source "src/simulator/Kconfig"
 
 # The HAVE_GPIO_x options allow boards to disable support for some
 # commands if the hardware does not support the feature.
+config HAVE_GPIO
+    bool
+    default n
 config HAVE_GPIO_ADC
     bool
     default n
@@ -41,4 +44,5 @@ config NO_UNSTEP_DELAY
 config INLINE_STEPPER_HACK
     # Enables gcc to inline stepper_event() into the main timer irq handler
     bool
+    depends on HAVE_GPIO
     default y

src/Makefile

@@ -1,6 +1,7 @@
 # Main code build rules
 
-src-y += sched.c command.c stepper.c basecmd.c debugcmds.c gpiocmds.c endstop.c
+src-y += sched.c command.c basecmd.c debugcmds.c
+src-$(CONFIG_HAVE_GPIO) += gpiocmds.c stepper.c endstop.c
 src-$(CONFIG_HAVE_GPIO_ADC) += adccmds.c
 src-$(CONFIG_HAVE_GPIO_SPI) += spicmds.c
 src-$(CONFIG_HAVE_GPIO_HARD_PWM) += pwmcmds.c

src/avr/Kconfig

@@ -5,6 +5,7 @@ if MACH_AVR
 config AVR_SELECT
     bool
     default y
+    select HAVE_GPIO
     select HAVE_GPIO_ADC
     select HAVE_GPIO_SPI
     select HAVE_GPIO_HARD_PWM

src/pru/Kconfig

@@ -5,6 +5,7 @@ if MACH_PRU
 config PRU_SELECT
     bool
     default y
+    select HAVE_GPIO
     select HAVE_GPIO_ADC
 
 config BOARD_DIRECTORY

src/sam3x8e/Kconfig

@@ -5,6 +5,7 @@ if MACH_SAM3X8E
 config SAM_SELECT
     bool
     default y
+    select HAVE_GPIO
     select HAVE_GPIO_ADC
 
 config BOARD_DIRECTORY

src/simulator/Kconfig

@@ -7,4 +7,12 @@ config BOARD_DIRECTORY
     string
     default "simulator"
 
+config SIMULATOR_SELECT
+    bool
+    default y
+    select HAVE_GPIO
+    select HAVE_GPIO_ADC
+    select HAVE_GPIO_SPI
+    select HAVE_GPIO_HARD_PWM
+
 endif