iio: adc: Add Renesas GyroADC driver

Add IIO driver for the Renesas RCar GyroADC block. This block is a
simple 4/8-channel ADC which samples 12/15/24 bits of data every
cycle from all channels.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: linux-renesas-soc@vger.kernel.org
Cc: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

MAINTAINERS

@@ -10439,6 +10439,12 @@ L:	linux-renesas-soc@vger.kernel.org
 F:	drivers/net/ethernet/renesas/
 F:	include/linux/sh_eth.h
 
+RENESAS R-CAR GYROADC DRIVER
+M:	Marek Vasut <marek.vasut@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+F:	drivers/iio/adc/rcar_gyro_adc.c
+
 RENESAS USB2 PHY DRIVER
 M:	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
 L:	linux-renesas-soc@vger.kernel.org

drivers/iio/adc/Kconfig

@@ -458,6 +458,19 @@ config QCOM_SPMI_VADC
 	  To compile this driver as a module, choose M here: the module will
 	  be called qcom-spmi-vadc.
 
+config RCAR_GYRO_ADC
+	tristate "Renesas R-Car GyroADC driver"
+	depends on ARCH_RCAR_GEN2 || (ARM && COMPILE_TEST)
+	help
+	  Say yes here to build support for the GyroADC found in Renesas
+	  R-Car Gen2 SoCs. This block is a simple SPI offload engine for
+	  reading data out of attached compatible ADCs in a round-robin
+	  fashion. Up to 4 or 8 ADC channels are supported by this block,
+	  depending on which ADCs are attached.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rcar-gyroadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)

drivers/iio/adc/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
+obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_STM32_ADC_CORE) += stm32-adc-core.o