platform: cznic: turris-omnia-mcu: Make watchdog code optional

Make the watchdog part of the driver optional, under a boolean config
option. Move the dependency to WATCHDOG to this new option, and change
the WATCHDOG_CORE dependency to selection, as is done in most watchdog
drivers.

This makes the turris-omnia-mcu driver available for compilation even if
WATCHDOG is disabled.

Fixes: ed46f1f7 ("platform: cznic: turris-omnia-mcu: fix Kconfig dependencies")
Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20240719085756.30598-2-kabel@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/platform/cznic/Kconfig

@@ -17,11 +17,9 @@ config TURRIS_OMNIA_MCU
 	depends on MACH_ARMADA_38X || COMPILE_TEST
 	depends on I2C
 	depends on OF
-	depends on WATCHDOG
 	depends on GPIOLIB
 	depends on HW_RANDOM
 	depends on RTC_CLASS
-	depends on WATCHDOG_CORE
 	select GPIOLIB_IRQCHIP
 	help
 	  Say Y here to add support for the features implemented by the
@@ -31,7 +29,6 @@ config TURRIS_OMNIA_MCU
 	    disabled) and the ability to configure wake up from this mode (via
 	    rtcwake)
 	  - true random number generator (if available on the MCU)
-	  - MCU watchdog
 	  - GPIO pins
 	    - to get front button press events (the front button can be
 	      configured either to generate press events to the CPU or to change
@@ -44,7 +41,21 @@ config TURRIS_OMNIA_MCU
 	      to be able to program SOC's OTP on board revisions 32+
 	    - to get input from the LED output pins of the WAN ethernet PHY, LAN
 	      switch and MiniPCIe ports
+	  Other features can be enabled by subsequent config options.
 	  To compile this driver as a module, choose M here; the module will be
 	  called turris-omnia-mcu.
 
+if TURRIS_OMNIA_MCU
+
+config TURRIS_OMNIA_MCU_WATCHDOG
+	bool "Turris Omnia MCU watchdog"
+	default y
+	depends on WATCHDOG
+	select WATCHDOG_CORE
+	help
+	  Say Y here to add support for watchdog provided by CZ.NIC's Turris
+	  Omnia MCU.
+
+endif # TURRIS_OMNIA_MCU
+
 endif # CZNIC_PLATFORMS

drivers/platform/cznic/Makefile

@@ -5,4 +5,4 @@ turris-omnia-mcu-y		:= turris-omnia-mcu-base.o
 turris-omnia-mcu-y		+= turris-omnia-mcu-gpio.o
 turris-omnia-mcu-y		+= turris-omnia-mcu-sys-off-wakeup.o
 turris-omnia-mcu-y		+= turris-omnia-mcu-trng.o
-turris-omnia-mcu-y		+= turris-omnia-mcu-watchdog.o
+turris-omnia-mcu-$(CONFIG_TURRIS_OMNIA_MCU_WATCHDOG)		+= turris-omnia-mcu-watchdog.o

drivers/platform/cznic/turris-omnia-mcu.h

@@ -47,8 +47,10 @@ struct omnia_mcu {
 	u32 rtc_alarm;
 	bool front_button_poweron;
 
+#ifdef CONFIG_TURRIS_OMNIA_MCU_WATCHDOG
 	/* MCU watchdog */
 	struct watchdog_device wdt;
+#endif
 
 	/* true random number generator */
 	struct hwrng trng;
@@ -189,6 +191,14 @@ extern const struct attribute_group omnia_mcu_poweroff_group;
 int omnia_mcu_register_gpiochip(struct omnia_mcu *mcu);
 int omnia_mcu_register_sys_off_and_wakeup(struct omnia_mcu *mcu);
 int omnia_mcu_register_trng(struct omnia_mcu *mcu);
+
+#ifdef CONFIG_TURRIS_OMNIA_MCU_WATCHDOG
 int omnia_mcu_register_watchdog(struct omnia_mcu *mcu);
+#else
+static inline int omnia_mcu_register_watchdog(struct omnia_mcu *mcu)
+{
+	return 0;
+}
+#endif
 
 #endif /* __TURRIS_OMNIA_MCU_H */