rtc: nvvrs: add NVIDIA VRS RTC device driver

Add support for NVIDIA VRS (Voltage Regulator Specification) RTC device
driver. NVIDIA VRS is a Power Management IC (PMIC) that implements a
power sequencing solution with I2C interface. The device includes RTC
which provides functionality to get/set system time, retain system
time across boot, wake system from suspend and shutdown state.

Supported platforms:
- NVIDIA Jetson AGX Orin Developer Kit
- NVIDIA IGX Orin Development Kit
- NVIDIA Jetson Orin NX Developer Kit
- NVIDIA Jetson Orin Nano Developer Kit

Signed-off-by: Shubhi Garg <shgarg@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://patch.msgid.link/20251007135738.487694-4-shgarg@nvidia.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

MAINTAINERS

@@ -18428,6 +18428,14 @@ S:	Maintained
 F:	drivers/video/fbdev/nvidia/
 F:	drivers/video/fbdev/riva/
 
+NVIDIA VRS RTC DRIVER
+M:	Shubhi Garg <shgarg@nvidia.com>
+L:	linux-tegra@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/rtc/nvidia,vrs-10.yaml
+F:	drivers/rtc/rtc-nvidia-vrs10.c
+F:	include/linux/rtc/rtc-nvidia-vrs10.h
+
 NVIDIA WMI EC BACKLIGHT DRIVER
 M:	Daniel Dadap <ddadap@nvidia.com>
 L:	platform-driver-x86@vger.kernel.org

drivers/rtc/Kconfig

@@ -416,6 +416,15 @@ config RTC_DRV_SPACEMIT_P1
 	  This driver can also be built as a module, which will be called
 	  "spacemit-p1-rtc".
 
+config RTC_DRV_NVIDIA_VRS10
+	tristate "NVIDIA VRS10 RTC device"
+	help
+	  If you say yes here you will get support for the battery backed RTC device
+	  of NVIDIA VRS (Voltage Regulator Specification). The RTC is connected via
+	  I2C interface and supports alarm functionality.
+	  This driver can also be built as a module. If so, the module will be called
+	  rtc-nvidia-vrs10.
+
 config RTC_DRV_NCT3018Y
 	tristate "Nuvoton NCT3018Y"
 	depends on OF

drivers/rtc/Makefile

@@ -122,6 +122,7 @@ obj-$(CONFIG_RTC_DRV_GAMECUBE)	+= rtc-gamecube.o
 obj-$(CONFIG_RTC_DRV_NCT3018Y)	+= rtc-nct3018y.o
 obj-$(CONFIG_RTC_DRV_NCT6694)	+= rtc-nct6694.o
 obj-$(CONFIG_RTC_DRV_NTXEC)	+= rtc-ntxec.o
+obj-$(CONFIG_RTC_DRV_NVIDIA_VRS10)+= rtc-nvidia-vrs10.o
 obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_OPAL)	+= rtc-opal.o
 obj-$(CONFIG_RTC_DRV_OPTEE)	+= rtc-optee.o