mfd: Add Renesas RZ/G2L MTU3a core driver

The RZ/G2L multi-function timer pulse unit 3 (MTU3a) is embedded in
the Renesas RZ/G2L family SoCs. It consists of eight 16-bit timer
channels and one 32-bit timer channel. It supports the following
functions
 - Counter
 - Timer
 - PWM

The 8/16/32 bit registers are mixed in each channel.

Add MTU3a core driver for RZ/G2L SoC. The core driver shares the
clk and channel register access for the other child devices like
Counter, PWM and Clock event.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230330111632.169434-3-biju.das.jz@bp.renesas.com

Author: bijudas

drivers/mfd/Kconfig

@@ -1315,6 +1315,16 @@ config MFD_SC27XX_PMIC
 	  This driver provides common support for accessing the SC27xx PMICs,
 	  and it also adds the irq_chip parts for handling the PMIC chip events.
 
+config RZ_MTU3
+	bool "Renesas RZ/G2L MTU3a core driver"
+	depends on (ARCH_RZG2L && OF) || COMPILE_TEST
+	help
+	  Select this option to enable Renesas RZ/G2L MTU3a core driver for
+	  the Multi-Function Timer Pulse Unit 3 (MTU3a) hardware available
+	  on SoCs from Renesas. The core driver shares the clk and channel
+	  register access for the other child devices like Counter, PWM,
+	  Clock Source, and Clock event.
+
 config ABX500_CORE
 	bool "ST-Ericsson ABX500 Mixed Signal Circuit register functions"
 	depends on ARCH_U8500 || COMPILE_TEST

drivers/mfd/Makefile

@@ -174,6 +174,7 @@ pcf50633-objs			:= pcf50633-core.o pcf50633-irq.o
 obj-$(CONFIG_MFD_PCF50633)	+= pcf50633.o
 obj-$(CONFIG_PCF50633_ADC)	+= pcf50633-adc.o
 obj-$(CONFIG_PCF50633_GPIO)	+= pcf50633-gpio.o
+obj-$(CONFIG_RZ_MTU3)		+= rz-mtu3.o
 obj-$(CONFIG_ABX500_CORE)	+= abx500-core.o
 obj-$(CONFIG_MFD_DB8500_PRCMU)	+= db8500-prcmu.o
 # ab8500-core need to come after db8500-prcmu (which provides the channel)