[PATCH] arm64: dts: qcom: sa8540p-ride: enable rtc

[Eric Chanudet <echanude@redhat.com>]

SA8540P-ride is one of the Qualcomm platforms that does not have access
to UEFI runtime services and on which the RTC registers are read-only,
as described in:
https://lore.kernel.org/all/20230202155448.6715-1-johan+linaro@kernel.org/

Reserve four bytes in one of the PMIC registers to hold the RTC offset
the same way as it was done for sc8280xp-crd which has similar
limitations:
    commit e67b45582c5e ("arm64: dts: qcom: sc8280xp-crd: enable rtc")

One small difference on SA8540P-ride, the PMIC register bank SDAM6 is
not writable, so use SDAM7 instead.

Signed-off-by: Eric Chanudet <echanude@redhat.com>
---
 arch/arm64/boot/dts/qcom/sa8540p-pmics.dtsi | 10 +++++++++-
 arch/arm64/boot/dts/qcom/sa8540p-ride.dts   | 15 +++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/sa8540p-pmics.dtsi b/arch/arm64/boot/dts/qcom/sa8540p-pmics.dtsi
index 1221be89b3de..9c5dcad35cce 100644
--- a/arch/arm64/boot/dts/qcom/sa8540p-pmics.dtsi
+++ b/arch/arm64/boot/dts/qcom/sa8540p-pmics.dtsi
@@ -14,7 +14,7 @@ pmm8540a: pmic@0 {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		rtc@6000 {
+		pmm8540a_rtc: rtc@6000 {
 			compatible = "qcom,pm8941-rtc";
 			reg = <0x6000>, <0x6100>;
 			reg-names = "rtc", "alarm";
@@ -22,6 +22,14 @@ rtc@6000 {
 			wakeup-source;
 		};
 
+		pmm8540a_sdam_7: nvram@b610 {
+			compatible = "qcom,spmi-sdam";
+			reg = <0xb610>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+			ranges = <0 0xb610 0xb0>;
+		};
+
 		pmm8540a_gpios: gpio@c000 {
 			compatible = "qcom,pm8150-gpio", "qcom,spmi-gpio";
 			reg = <0xc000>;
diff --git a/arch/arm64/boot/dts/qcom/sa8540p-ride.dts b/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
index 5a26974dcf8f..608dd71a3f1c 100644
--- a/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
+++ b/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
@@ -407,6 +407,21 @@ &pcie3a_phy {
 	status = "okay";
 };
 
+&pmm8540a_rtc {
+	nvmem-cells = <&rtc_offset>;
+	nvmem-cell-names = "offset";
+
+	status = "okay";
+};
+
+&pmm8540a_sdam_7 {
+	status = "okay";
+
+	rtc_offset: rtc-offset@ac {
+		reg = <0xac 0x4>;
+	};
+};
+
 &qup0 {
 	status = "okay";
 };
-- 
2.41.0