[PATCH v3 3/4] arm64: dts: ti: k3-am6xx-phycore-som: Add overlay to disable rtc

[Nathan Morrisson <nmorrisson@phytec.com>]

Add an overlay to disable the rtc for all am6xx-phycore-som boards.
The EEPROM on am6xx-phycore-soms contains information about the
configuration of the SOM. The standard configuration of the SOM
has an rtc, but if no rtc is populated, the EEPROM will indicate that
change and we can use this overlay to cleanly disable the rtc.

Signed-off-by: Nathan Morrisson <nmorrisson@phytec.com>
---
v3:
  - Explain why we are adding the overlay in the commit message

v2:
  - Add build time tests in makefile

 arch/arm64/boot/dts/ti/Makefile                   |  5 +++++
 .../boot/dts/ti/k3-am6xx-phycore-disable-rtc.dtso | 15 +++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-rtc.dtso

diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dts/ti/Makefile
index 320da5ea38e0..3d0e87a78e09 100644
--- a/arch/arm64/boot/dts/ti/Makefile
+++ b/arch/arm64/boot/dts/ti/Makefile
@@ -56,6 +56,7 @@ dtb-$(CONFIG_ARCH_K3) += k3-am64-tqma64xxl-mbax4xxl-wlan.dtbo
 
 # Common overlays for the phyCORE-AM6* family of boards
 dtb-$(CONFIG_ARCH_K3) += k3-am6xx-phycore-disable-eth-phy.dtbo
+dtb-$(CONFIG_ARCH_K3) += k3-am6xx-phycore-disable-rtc.dtbo
 
 # Boards with AM65x SoC
 k3-am654-gp-evm-dtbs := k3-am654-base-board.dtb \
@@ -112,6 +113,8 @@ k3-am625-beagleplay-csi2-tevi-ov5640-dtbs := k3-am625-beagleplay.dtb \
 	k3-am625-beagleplay-csi2-tevi-ov5640.dtbo
 k3-am625-phyboard-lyra-disable-eth-phy-dtbs := k3-am625-phyboard-lyra-rdk.dtb \
 	k3-am6xx-phycore-disable-eth-phy.dtbo
+k3-am625-phyboard-lyra-disable-rtc-dtbs := k3-am625-phyboard-lyra-rdk.dtb \
+	k3-am6xx-phycore-disable-rtc.dtbo
 k3-am625-phyboard-lyra-gpio-fan-dtbs := k3-am625-phyboard-lyra-rdk.dtb \
 	k3-am62x-phyboard-lyra-gpio-fan.dtbo
 k3-am625-sk-csi2-imx219-dtbs := k3-am625-sk.dtb \
@@ -139,6 +142,8 @@ k3-am642-evm-icssg1-dualemac-dtbs := \
 	k3-am642-evm.dtb k3-am642-evm-icssg1-dualemac.dtbo
 k3-am642-phyboard-electra-disable-eth-phy-dtbs := \
 	k3-am642-phyboard-electra-rdk.dtb k3-am6xx-phycore-disable-eth-phy.dtbo
+k3-am642-phyboard-electra-disable-rtc-dtbs := \
+	k3-am642-phyboard-electra-rdk.dtb k3-am6xx-phycore-disable-rtc.dtbo
 k3-am642-phyboard-electra-gpio-fan-dtbs := \
 	k3-am642-phyboard-electra-rdk.dtb k3-am642-phyboard-electra-gpio-fan.dtbo
 k3-am642-tqma64xxl-mbax4xxl-sdcard-dtbs := \
diff --git a/arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-rtc.dtso b/arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-rtc.dtso
new file mode 100644
index 000000000000..8b24191f5948
--- /dev/null
+++ b/arch/arm64/boot/dts/ti/k3-am6xx-phycore-disable-rtc.dtso
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Copyright (C) 2023 PHYTEC America, LLC
+ * Author: Garrett Giordano <ggiordano@phytec.com>
+ *
+ * Copyright (C) 2024 PHYTEC America, LLC
+ * Author: Nathan Morrisson <nmorrisson@phytec.com>
+ */
+
+/dts-v1/;
+/plugin/;
+
+&i2c_som_rtc {
+	status = "disabled";
+};
-- 
2.25.1