[PATCH 3/3] [RFC] ARM: dts: stm32: Add nvmem-syscon node to TAMP to expose boot count on DHSOM

[Marek Vasut <marex@denx.de>]

Add nvmem-syscon subnode to expose TAMP_BKPxR register 19 to user space.
This register contains U-Boot boot counter, by exposing it to user space
the user space can reset the boot counter.

Read access example:
"
$ hexdump -vC /sys/bus/nvmem/devices/5c00a000.tamp\:nvmem0/nvmem
00000000  0c 00 c4 b0
"

Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Rafał Miłecki <rafal@milecki.pl>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: devicetree@vger.kernel.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-arm-kernel@lists.infradead.org
---
 arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi | 11 +++++++++++
 arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi | 11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
index 155843e1402fb..8277837be8a51 100644
--- a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
+++ b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
@@ -533,6 +533,17 @@ &sdmmc3 {
 	status = "okay";
 };
 
+&tamp {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	/* Boot counter */
+	nvmem {
+		compatible = "nvmem-syscon";
+		reg = <0x14c 0x4>;
+	};
+};
+
 &uart4 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart4_pins_a>;
diff --git a/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi b/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
index 134a798ad3f23..42a8d5cdd7024 100644
--- a/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
+++ b/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
@@ -271,3 +271,14 @@ &rng1 {
 &rtc {
 	status = "okay";
 };
+
+&tamp {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	/* Boot counter */
+	nvmem {
+		compatible = "nvmem-syscon";
+		reg = <0x14c 0x4>;
+	};
+};
-- 
2.35.1