[PATCH] arm64: dts: exynos850: Add SRAM node

[PATCH] arm64: dts: exynos850: Add SRAM node

[Alexey Klimov]

SRAM is used by the ACPM protocol to retrieve the ACPM channels
information and configuration data. Add the SRAM node.

Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
---
 arch/arm64/boot/dts/exynos/exynos850.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
index cb55015c8dce..cf4a6168846c 100644
--- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
+++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
@@ -910,6 +910,14 @@ spi_2: spi@11d20000 {
 			};
 		};
 	};
+
+	apm_sram: sram@2039000 {
+		compatible = "mmio-sram";
+		reg = <0x0 0x2039000 0x40000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0x0 0x0 0x2039000 0x40000>;
+	};
 };
 
 #include "exynos850-pinctrl.dtsi"

---
base-commit: 66672af7a095d89f082c5327f3b15bc2f93d558e
change-id: 20260413-exynos850_sram-ca1200b99e82

Best regards,
-- 
Alexey Klimov <alexey.klimov@linaro.org>

Re: [PATCH] arm64: dts: exynos850: Add SRAM node

[Krzysztof Kozlowski]

On 13/04/2026 16:52, Alexey Klimov wrote:
> SRAM is used by the ACPM protocol to retrieve the ACPM channels
> information and configuration data. Add the SRAM node.
> 
> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
> ---
>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
> index cb55015c8dce..cf4a6168846c 100644
> --- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
> +++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
> @@ -910,6 +910,14 @@ spi_2: spi@11d20000 {
>  			};
>  		};
>  	};
> +
> +	apm_sram: sram@2039000 {
> +		compatible = "mmio-sram";
> +		reg = <0x0 0x2039000 0x40000>;
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		ranges = <0x0 0x0 0x2039000 0x40000>;

You miss here children.

Also, 'ranges' should be after 'reg'.

Best regards,
Krzysztof

Re: [PATCH] arm64: dts: exynos850: Add SRAM node

[Alexey Klimov]

On Mon Apr 13, 2026 at 4:23 PM BST, Krzysztof Kozlowski wrote:
> On 13/04/2026 16:52, Alexey Klimov wrote:
>> SRAM is used by the ACPM protocol to retrieve the ACPM channels
>> information and configuration data. Add the SRAM node.
>> 
>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>> ---
>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>> 
>> diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>> index cb55015c8dce..cf4a6168846c 100644
>> --- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
>> +++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>> @@ -910,6 +910,14 @@ spi_2: spi@11d20000 {
>>  			};
>>  		};
>>  	};
>> +
>> +	apm_sram: sram@2039000 {
>> +		compatible = "mmio-sram";
>> +		reg = <0x0 0x2039000 0x40000>;
>> +		#address-cells = <1>;
>> +		#size-cells = <1>;
>> +		ranges = <0x0 0x0 0x2039000 0x40000>;
>
> You miss here children.

Thank you! I guess I should convert it to smth like this:

apm_sram: sram@2039000 {
		compatible = "mmio-sram";
		reg = <0x0 0x2039000 0x40000>;
		ranges = <0x0 0x0 0x2039000 0x40000>;
		#address-cells = <1>;
		#size-cells = <1>;

		acpm_sram_region: sram-section@0 {
			reg = <0x0 0x40000>;
		};
	};

And then later reference shmem = &acpm_sram_region from acpm node.

> Also, 'ranges' should be after 'reg'.

Thanks, will fix this.

FWIW this commit is a copy of commit 48e7821b26904
https://lore.kernel.org/r/20250207-gs101-acpm-dt-v4-1-230ba8663a2d@linaro.org

Best regards,
Alexey

Re: [PATCH] arm64: dts: exynos850: Add SRAM node

[Krzysztof Kozlowski]

On 14/04/2026 11:00, Alexey Klimov wrote:
> On Mon Apr 13, 2026 at 4:23 PM BST, Krzysztof Kozlowski wrote:
>> On 13/04/2026 16:52, Alexey Klimov wrote:
>>> SRAM is used by the ACPM protocol to retrieve the ACPM channels
>>> information and configuration data. Add the SRAM node.
>>>
>>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>>> ---
>>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>> index cb55015c8dce..cf4a6168846c 100644
>>> --- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>> +++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>> @@ -910,6 +910,14 @@ spi_2: spi@11d20000 {
>>>  			};
>>>  		};
>>>  	};
>>> +
>>> +	apm_sram: sram@2039000 {
>>> +		compatible = "mmio-sram";
>>> +		reg = <0x0 0x2039000 0x40000>;
>>> +		#address-cells = <1>;
>>> +		#size-cells = <1>;
>>> +		ranges = <0x0 0x0 0x2039000 0x40000>;
>>
>> You miss here children.
> 
> Thank you! I guess I should convert it to smth like this:
> 
> apm_sram: sram@2039000 {
> 		compatible = "mmio-sram";
> 		reg = <0x0 0x2039000 0x40000>;
> 		ranges = <0x0 0x0 0x2039000 0x40000>;
> 		#address-cells = <1>;
> 		#size-cells = <1>;
> 
> 		acpm_sram_region: sram-section@0 {
> 			reg = <0x0 0x40000>;

This covers entire block, so feels pointless. Maybe requirement of
children should be dropped. What's the point of having children? Why
does the driver need them?

> 		};
> 	};
> 
> And then later reference shmem = &acpm_sram_region from acpm node.
> 
>> Also, 'ranges' should be after 'reg'.
> 
> Thanks, will fix this.
> 
> FWIW this commit is a copy of commit 48e7821b26904
> https://lore.kernel.org/r/20250207-gs101-acpm-dt-v4-1-230ba8663a2d@linaro.org


Huh, we should fix that one as well.


Best regards,
Krzysztof

Re: [PATCH] arm64: dts: exynos850: Add SRAM node

[Tudor Ambarus]

Hi!

On 4/14/26 12:08 PM, Krzysztof Kozlowski wrote:
> On 14/04/2026 11:00, Alexey Klimov wrote:
>> On Mon Apr 13, 2026 at 4:23 PM BST, Krzysztof Kozlowski wrote:
>>> On 13/04/2026 16:52, Alexey Klimov wrote:
>>>> SRAM is used by the ACPM protocol to retrieve the ACPM channels
>>>> information and configuration data. Add the SRAM node.
>>>>
>>>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>>>> ---
>>>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 8 ++++++++
>>>>  1 file changed, 8 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>>> index cb55015c8dce..cf4a6168846c 100644
>>>> --- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>>> +++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>>> @@ -910,6 +910,14 @@ spi_2: spi@11d20000 {
>>>>  			};
>>>>  		};
>>>>  	};
>>>> +
>>>> +	apm_sram: sram@2039000 {
>>>> +		compatible = "mmio-sram";
>>>> +		reg = <0x0 0x2039000 0x40000>;
>>>> +		#address-cells = <1>;
>>>> +		#size-cells = <1>;
>>>> +		ranges = <0x0 0x0 0x2039000 0x40000>;
>>>
>>> You miss here children.
>>
>> Thank you! I guess I should convert it to smth like this:
>>
>> apm_sram: sram@2039000 {
>> 		compatible = "mmio-sram";
>> 		reg = <0x0 0x2039000 0x40000>;
>> 		ranges = <0x0 0x0 0x2039000 0x40000>;
>> 		#address-cells = <1>;
>> 		#size-cells = <1>;
>>
>> 		acpm_sram_region: sram-section@0 {
>> 			reg = <0x0 0x40000>;
> 
> This covers entire block, so feels pointless. Maybe requirement of
> children should be dropped. What's the point of having children? Why
> does the driver need them?
> 
>> 		};
>> 	};
>>
>> And then later reference shmem = &acpm_sram_region from acpm node.
>>
>>> Also, 'ranges' should be after 'reg'.
>>
>> Thanks, will fix this.
>>
>> FWIW this commit is a copy of commit 48e7821b26904
>> https://lore.kernel.org/r/20250207-gs101-acpm-dt-v4-1-230ba8663a2d@linaro.org
> 
> 
> Huh, we should fix that one as well.
> 

On gs101, likely on e850 too, ACPM parses the SRAM and discovers at runtime where
the TX/RX queue offsets are in SRAM. So we can't define static partitions in DT.
I remember that I thought about extending the SRAM driver to add dynamic
partitions (clients to request the mmio-sram driver to create partitions at
runtime), but it was just ACPM that's using SRAM, so I didn't need it.

Cheers,
ta

Re: [PATCH] arm64: dts: exynos850: Add SRAM node

[Alexey Klimov]

On Tue Apr 14, 2026 at 10:08 AM BST, Krzysztof Kozlowski wrote:
> On 14/04/2026 11:00, Alexey Klimov wrote:
>> On Mon Apr 13, 2026 at 4:23 PM BST, Krzysztof Kozlowski wrote:
>>> On 13/04/2026 16:52, Alexey Klimov wrote:
>>>> SRAM is used by the ACPM protocol to retrieve the ACPM channels
>>>> information and configuration data. Add the SRAM node.
>>>>
>>>> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
>>>> ---
>>>>  arch/arm64/boot/dts/exynos/exynos850.dtsi | 8 ++++++++
>>>>  1 file changed, 8 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/exynos/exynos850.dtsi b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>>> index cb55015c8dce..cf4a6168846c 100644
>>>> --- a/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>>> +++ b/arch/arm64/boot/dts/exynos/exynos850.dtsi
>>>> @@ -910,6 +910,14 @@ spi_2: spi@11d20000 {
>>>>  			};
>>>>  		};
>>>>  	};
>>>> +
>>>> +	apm_sram: sram@2039000 {
>>>> +		compatible = "mmio-sram";
>>>> +		reg = <0x0 0x2039000 0x40000>;
>>>> +		#address-cells = <1>;
>>>> +		#size-cells = <1>;
>>>> +		ranges = <0x0 0x0 0x2039000 0x40000>;
>>>
>>> You miss here children.
>> 
>> Thank you! I guess I should convert it to smth like this:
>> 
>> apm_sram: sram@2039000 {
>> 		compatible = "mmio-sram";
>> 		reg = <0x0 0x2039000 0x40000>;
>> 		ranges = <0x0 0x0 0x2039000 0x40000>;
>> 		#address-cells = <1>;
>> 		#size-cells = <1>;
>> 
>> 		acpm_sram_region: sram-section@0 {
>> 			reg = <0x0 0x40000>;
>
> This covers entire block, so feels pointless. Maybe requirement of
> children should be dropped. What's the point of having children? Why
> does the driver need them?

Thinking further about this. I was looking at the schema file and
different commits and it the right approach could be:

- add separate compatible for mmio-sram region for this case. Similar
to scmi and scpi, i'd say it should be "exynos,acpm-sram" or
"samsung,acpm-sram";

- update schema sram.yaml to exclude requirement for having child nodes
and properties like ranges, address and size cells
Similar like in commit, for instance, git show d0fe6491ddd22
(or git show 2d4a22e79a5fd).

- then this addition becomes:

	apm_sram: sram@2039000 {
		compatible = "exynos,acpm-sram";
		reg = <0x0 0x2039000 0x40000>;
	};

and will be consumed as a whole region (also as Tudor mentioned in the
other email).
And then we should update gs101 dts as well. Thoughts?

I honestly don't know why be default schema requires child nodes unless
it is specifically excluded. Could be a good question to Rob?
Or maybe we should really drop a requirement for having children from
schema.


>> And then later reference shmem = &acpm_sram_region from acpm node.
>> 
>>> Also, 'ranges' should be after 'reg'.
>> 
>> Thanks, will fix this.
>> 
>> FWIW this commit is a copy of commit 48e7821b26904
>> https://lore.kernel.org/r/20250207-gs101-acpm-dt-v4-1-230ba8663a2d@linaro.org
>
>
> Huh, we should fix that one as well.

Best regardss,
Alexey