Re: [PATCH v2 3/3] ARM: dts: stm32: Add nvmem-syscon node to TAMP to expose boot count on DHSOM

[Alexandre TORGUE <alexandre.torgue@foss.st.com>]

On 5/17/23 17:25, Marek Vasut wrote:
> 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: Conor Dooley <conor+dt@kernel.org>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> Cc: Marek Vasut <marex@denx.de>
> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
> Cc: devicetree@vger.kernel.org
> Cc: kernel@dh-electronics.com
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-stm32@st-md-mailman.stormreply.com
> ---
> V2: No change
> ---
>   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 74735552f4803..b2557bb718f52 100644
> --- a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
> +++ b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
> @@ -537,6 +537,17 @@ &sdmmc3 {
>   	status = "okay";
>   };
>   
> +&tamp {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +
> +	/* Boot counter */
> +	nvmem {

nvmem@14c ?

> +		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 bba19f21e5277..864960387e634 100644
> --- a/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
> +++ b/arch/arm/boot/dts/stm32mp15xx-dhcor-som.dtsi
> @@ -269,3 +269,14 @@ &rng1 {
>   &rtc {
>   	status = "okay";
>   };
> +
> +&tamp {
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +
> +	/* Boot counter */
> +	nvmem {

nvmem@14c ?

> +		compatible = "nvmem-syscon";
> +		reg = <0x14c 0x4>;
> +	};
> +};