2023-09-12 14:46:45

by Krzysztof Kozlowski

Subject: Re: [PATCH v2 10/10] ARM: dts: stm32: add RNG node for STM32MP13x platforms

On 11/09/2023 14:02, Gatien Chevallier wrote:
> The RNG on STM32MP13 offers upgrades like customization of its
> configuration and the conditional reset.
>
> The hardware RNG should be managed in the secure world for but it
> is supported on Linux. Therefore, is it not default enabled.
>
> Signed-off-by: Gatien Chevallier <[email protected]>
> ---
> arch/arm/boot/dts/st/stm32mp131.dtsi | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/arm/boot/dts/st/stm32mp131.dtsi b/arch/arm/boot/dts/st/stm32mp131.dtsi
> index ac90fcbf0c09..39db82b782eb 100644
> --- a/arch/arm/boot/dts/st/stm32mp131.dtsi
> +++ b/arch/arm/boot/dts/st/stm32mp131.dtsi
> @@ -1220,6 +1220,14 @@ mdma: dma-controller@58000000 {
> dma-requests = <48>;
> };
>
> + rng: rng@54004000 {
> + compatible = "st,stm32mp13-rng";
> + reg = <0x54004000 0x400>;
> + clocks = <&rcc RNG1_K>;
> + resets = <&rcc RNG1_R>;
> + status = "disabled";

Why? What other resources are missing?

Best regards,
Krzysztof

2023-09-13 07:53:52

by Gatien CHEVALLIER

Subject: Re: [PATCH v2 10/10] ARM: dts: stm32: add RNG node for STM32MP13x platforms

On 9/12/23 16:38, Krzysztof Kozlowski wrote:
> On 11/09/2023 14:02, Gatien Chevallier wrote:
>> The RNG on STM32MP13 offers upgrades like customization of its
>> configuration and the conditional reset.
>>
>> The hardware RNG should be managed in the secure world for but it
>> is supported on Linux. Therefore, is it not default enabled.
>>
>> Signed-off-by: Gatien Chevallier <[email protected]>
>> ---
>> arch/arm/boot/dts/st/stm32mp131.dtsi | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/st/stm32mp131.dtsi b/arch/arm/boot/dts/st/stm32mp131.dtsi
>> index ac90fcbf0c09..39db82b782eb 100644
>> --- a/arch/arm/boot/dts/st/stm32mp131.dtsi
>> +++ b/arch/arm/boot/dts/st/stm32mp131.dtsi
>> @@ -1220,6 +1220,14 @@ mdma: dma-controller@58000000 {
>> dma-requests = <48>;
>> };
>>
>> + rng: rng@54004000 {
>> + compatible = "st,stm32mp13-rng";
>> + reg = <0x54004000 0x400>;
>> + clocks = <&rcc RNG1_K>;
>> + resets = <&rcc RNG1_R>;
>> + status = "disabled";
>
> Why? What other resources are missing?
>
> Best regards,
> Krzysztof
>

Hello Krzysztof,

Our default implementation is to handle the RNG in OP-TEE for
these platforms. Therefore, it goes through optee-rng driver.
The RNG services are exposed by a PTA (Pseudo Trusted Application)
in OP-TEE. In this case, there's no need to enable the RNG node
in the Linux Kernel.

Best regards,
Gatien