soc: mediatek: SVS: introduce MTK SVS engine

The Smart Voltage Scaling(SVS) engine is a piece of hardware
which calculates suitable SVS bank voltages to OPP voltage table.
Then, DVFS driver could apply those SVS bank voltages to PMIC/Buck
when receiving OPP_EVENT_ADJUST_VOLTAGE.

Signed-off-by: Roger Lu <roger.lu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20220516004311.18358-4-roger.lu@mediatek.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/Kconfig

@@ -73,4 +73,14 @@ config MTK_MMSYS
 	  Say yes here to add support for the MediaTek Multimedia
 	  Subsystem (MMSYS).
 
+config MTK_SVS
+	tristate "MediaTek Smart Voltage Scaling(SVS)"
+	depends on MTK_EFUSE && NVMEM
+	help
+	  The Smart Voltage Scaling(SVS) engine is a piece of hardware
+	  which has several controllers(banks) for calculating suitable
+	  voltage to different power domains(CPU/GPU/CCI) according to
+	  chip process corner, temperatures and other factors. Then DVFS
+	  driver could apply SVS bank voltage to PMIC/Buck.
+
 endmenu

drivers/soc/mediatek/Makefile

@@ -7,3 +7,4 @@ obj-$(CONFIG_MTK_SCPSYS) += mtk-scpsys.o
 obj-$(CONFIG_MTK_SCPSYS_PM_DOMAINS) += mtk-pm-domains.o
 obj-$(CONFIG_MTK_MMSYS) += mtk-mmsys.o
 obj-$(CONFIG_MTK_MMSYS) += mtk-mutex.o
+obj-$(CONFIG_MTK_SVS) += mtk-svs.o