[PATCH] arm64: dts: renesas: r8a78000: Add PSCI node

[PATCH] arm64: dts: renesas: r8a78000: Add PSCI node

[Marek Vasut]

Describe SMC based PSCI access in SoC DT. The system can interact
with TFA BL31 PSCI provider running on the Cortex-A cores via SMC
calls.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
---
 arch/arm64/boot/dts/renesas/r8a78000.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/boot/dts/renesas/r8a78000.dtsi b/arch/arm64/boot/dts/renesas/r8a78000.dtsi
index 73be51787265c..d14f0cc0ad360 100644
--- a/arch/arm64/boot/dts/renesas/r8a78000.dtsi
+++ b/arch/arm64/boot/dts/renesas/r8a78000.dtsi
@@ -665,6 +665,11 @@ extalr_clk: extalr-clk {
 		/* clock-frequency must be set on board */
 	};
 
+	psci {
+		compatible = "arm,psci-1.0";
+		method = "smc";
+	};
+
 	/* External SCIF clock - to be overridden by boards that provide it */
 	scif_clk: scif-clk {
 		compatible = "fixed-clock";
-- 
2.53.0

Re: [PATCH] arm64: dts: renesas: r8a78000: Add PSCI node

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missing 'enable-method' in CPU nodes prevents SMP bring-up.
--

commit 0e20af8dd1fbf54360d3f87985cba2a59a5ee08f
Author: Marek Vasut <marek.vasut+renesas@mailbox.org>
arm64: dts: renesas: r8a78000: Add PSCI node

This commit adds the PSCI node to the r8a78000 device tree to describe SMC
based access. This enables interaction with the TFA BL31 PSCI provider for
tasks such as CPU power management.

> diff --git a/arch/arm64/boot/dts/renesas/r8a78000.dtsi b/arch/arm64/boot/dts/renesas/r8a78000.dtsi
> index 4c97298fa7634..9e759ea46ee20 100644
> --- a/arch/arm64/boot/dts/renesas/r8a78000.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r8a78000.dtsi

[ ... ]

> @@ -665,6 +665,11 @@ extalr_clk: extalr-clk {
>  		/* clock-frequency must be set on board */
>  	};
>  
> +	psci {
> +		compatible = "arm,psci-1.0";
> +		method = "smc";
> +	};
> +

Does this also require updating the CPU nodes to actually use PSCI?

Looking at the ARM64 SMP bring-up in arch/arm64/kernel/cpu_ops.c, the kernel
relies on cpu_read_enable_method() to determine how to wake up secondary
CPUs. It expects an enable-method property in the device tree for each CPU
node:

arch/arm64/kernel/cpu_ops.c:cpu_read_enable_method() {
        ...
        dn = of_get_cpu_node(cpu, NULL);
        ...
        enable_method = of_get_property(dn, "enable-method", NULL);
        if (!enable_method) {
                ...
        }
        ...
}

Without adding enable-method = "psci" to the cpu nodes in r8a78000.dtsi,
does this cause an SMP regression where the system fails to initialize
secondary cores and boots as a single-core system?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260513225037.49803-1-marek.vasut+renesas@mailbox.org?part=1

Re: [PATCH] arm64: dts: renesas: r8a78000: Add PSCI node

[Marek Vasut]

On 5/14/26 1:31 PM, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] Missing 'enable-method' in CPU nodes prevents SMP bring-up.
> --
> 
> commit 0e20af8dd1fbf54360d3f87985cba2a59a5ee08f
> Author: Marek Vasut <marek.vasut+renesas@mailbox.org>
> arm64: dts: renesas: r8a78000: Add PSCI node
> 
> This commit adds the PSCI node to the r8a78000 device tree to describe SMC
> based access. This enables interaction with the TFA BL31 PSCI provider for
> tasks such as CPU power management.
> 
>> diff --git a/arch/arm64/boot/dts/renesas/r8a78000.dtsi b/arch/arm64/boot/dts/renesas/r8a78000.dtsi
>> index 4c97298fa7634..9e759ea46ee20 100644
>> --- a/arch/arm64/boot/dts/renesas/r8a78000.dtsi
>> +++ b/arch/arm64/boot/dts/renesas/r8a78000.dtsi
> 
> [ ... ]
> 
>> @@ -665,6 +665,11 @@ extalr_clk: extalr-clk {
>>   		/* clock-frequency must be set on board */
>>   	};
>>   
>> +	psci {
>> +		compatible = "arm,psci-1.0";
>> +		method = "smc";
>> +	};
>> +
> 
> Does this also require updating the CPU nodes to actually use PSCI?
> 
> Looking at the ARM64 SMP bring-up in arch/arm64/kernel/cpu_ops.c, the kernel
> relies on cpu_read_enable_method() to determine how to wake up secondary
> CPUs. It expects an enable-method property in the device tree for each CPU
> node:
> 
> arch/arm64/kernel/cpu_ops.c:cpu_read_enable_method() {
>          ...
>          dn = of_get_cpu_node(cpu, NULL);
>          ...
>          enable_method = of_get_property(dn, "enable-method", NULL);
>          if (!enable_method) {
>                  ...
>          }
>          ...
> }
> 
> Without adding enable-method = "psci" to the cpu nodes in r8a78000.dtsi,
> does this cause an SMP regression where the system fails to initialize
> secondary cores and boots as a single-core system?
PSCI is used here to power off / reboot the system, SMP enablement is a 
separate topic and a separate patch.