thermal: rcar_gen3_thermal: Add R-Car Gen3 thermal driver

Add support for R-Car Gen3 thermal sensors. Polling only for now,
interrupts will be added incrementally. Same goes for reading fuses.
This is documented already, but no hardware available for now.

Signed-off-by: Hien Dang <hien.dang.eb@renesas.com>
Signed-off-by: Thao Nguyen <thao.nguyen.yb@rvc.renesas.com>
Signed-off-by: Khiem Nguyen <khiem.nguyen.xt@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[Niklas: document and rework temperature calculation]
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index c2c056c..3912d24 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -245,6 +245,15 @@
 	  Enable this to plug the R-Car thermal sensor driver into the Linux
 	  thermal framework.
 
+config RCAR_GEN3_THERMAL
+	tristate "Renesas R-Car Gen3 thermal driver"
+	depends on ARCH_RENESAS || COMPILE_TEST
+	depends on HAS_IOMEM
+	depends on OF
+	help
+	  Enable this to plug the R-Car Gen3 thermal sensor driver into the Linux
+	  thermal framework.
+
 config KIRKWOOD_THERMAL
 	tristate "Temperature sensor on Marvell Kirkwood SoCs"
 	depends on MACH_KIRKWOOD || COMPILE_TEST