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[PATCH 3/7] arm64: dts: qcom: ipq6018: Add the IMEM node

Kathiravan Thirumoorthy posted 7 patches 3 months, 1 week ago
There is a newer version of this series
[PATCH 3/7] arm64: dts: qcom: ipq6018: Add the IMEM node
Posted by Kathiravan Thirumoorthy 3 months, 1 week ago 
Add the IMEM node to the device tree to extract debugging information
like system restart reason, which is populated via IMEM. Define the
IMEM region to enable this functionality.

As described, overall IMEM region is approximately 32KB but only initial
4KB is accessible by all masters in the SoC.

Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/ipq6018.dtsi | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
index bfe59b0208415902c69fd0c0c7565d97997d4207..7eca5ba416c2ef5ef1c4e0eb4f58f1ca94fc92f0 100644
--- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
@@ -659,6 +659,15 @@ qpic_nand: nand-controller@79b0000 {
 			status = "disabled";
 		};
 
+		sram@8600000 {
+			compatible = "qcom,ipq6018-imem", "syscon", "simple-mfd";
+			reg = <0 0x08600000 0 0x7fff>;
+			ranges = <0 0 0x08600000 0x7fff>;
+
+			#address-cells = <1>;
+			#size-cells = <1>;
+		};
+
 		usb3: usb@8af8800 {
 			compatible = "qcom,ipq6018-dwc3", "qcom,dwc3";
 			reg = <0x0 0x08af8800 0x0 0x400>;

-- 
2.34.1
Re: [PATCH 3/7] arm64: dts: qcom: ipq6018: Add the IMEM node
Posted by Konrad Dybcio 3 months, 1 week ago 
On 7/2/25 12:17 PM, Kathiravan Thirumoorthy wrote:
> Add the IMEM node to the device tree to extract debugging information
> like system restart reason, which is populated via IMEM. Define the
> IMEM region to enable this functionality.
> 
> As described, overall IMEM region is approximately 32KB but only initial
> 4KB is accessible by all masters in the SoC.
> 
> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/ipq6018.dtsi | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
> index bfe59b0208415902c69fd0c0c7565d97997d4207..7eca5ba416c2ef5ef1c4e0eb4f58f1ca94fc92f0 100644
> --- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
> +++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
> @@ -659,6 +659,15 @@ qpic_nand: nand-controller@79b0000 {
>  			status = "disabled";
>  		};
>  
> +		sram@8600000 {
> +			compatible = "qcom,ipq6018-imem", "syscon", "simple-mfd";
> +			reg = <0 0x08600000 0 0x7fff>;
> +			ranges = <0 0 0x08600000 0x7fff>;

I firmly believe there's an off-by-one in the docs and there
isn't an odd number of bytes reserved in the hw

Konrad
Re: [PATCH 3/7] arm64: dts: qcom: ipq6018: Add the IMEM node
Posted by Kathiravan Thirumoorthy 3 months ago 
On 7/2/2025 6:29 PM, Konrad Dybcio wrote:
> On 7/2/25 12:17 PM, Kathiravan Thirumoorthy wrote:
>> Add the IMEM node to the device tree to extract debugging information
>> like system restart reason, which is populated via IMEM. Define the
>> IMEM region to enable this functionality.
>>
>> As described, overall IMEM region is approximately 32KB but only initial
>> 4KB is accessible by all masters in the SoC.
>>
>> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
>> ---
>>   arch/arm64/boot/dts/qcom/ipq6018.dtsi | 9 +++++++++
>>   1 file changed, 9 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
>> index bfe59b0208415902c69fd0c0c7565d97997d4207..7eca5ba416c2ef5ef1c4e0eb4f58f1ca94fc92f0 100644
>> --- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
>> @@ -659,6 +659,15 @@ qpic_nand: nand-controller@79b0000 {
>>   			status = "disabled";
>>   		};
>>   
>> +		sram@8600000 {
>> +			compatible = "qcom,ipq6018-imem", "syscon", "simple-mfd";
>> +			reg = <0 0x08600000 0 0x7fff>;
>> +			ranges = <0 0 0x08600000 0x7fff>;
> I firmly believe there's an off-by-one in the docs and there
> isn't an odd number of bytes reserved in the hw
Thanks, I cross checked this in the SoC and I'm able to access the full 
4 byte at the end. Let me fix this up in the V2.
>
> Konrad
Re: [PATCH 3/7] arm64: dts: qcom: ipq6018: Add the IMEM node
Posted by Krzysztof Kozlowski 3 months, 1 week ago 
On 02/07/2025 12:17, Kathiravan Thirumoorthy wrote:
> Add the IMEM node to the device tree to extract debugging information
> like system restart reason, which is populated via IMEM. Define the
> IMEM region to enable this functionality.
> 
> As described, overall IMEM region is approximately 32KB but only initial
> 4KB is accessible by all masters in the SoC.
> 
> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/ipq6018.dtsi | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
> index bfe59b0208415902c69fd0c0c7565d97997d4207..7eca5ba416c2ef5ef1c4e0eb4f58f1ca94fc92f0 100644
> --- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
> +++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
> @@ -659,6 +659,15 @@ qpic_nand: nand-controller@79b0000 {
>  			status = "disabled";
>  		};
>  
> +		sram@8600000 {
> +			compatible = "qcom,ipq6018-imem", "syscon", "simple-mfd";

No, this is not a simple MFD. Where are any children if this is a MFD?

> +			reg = <0 0x08600000 0 0x7fff>;
> +			ranges = <0 0 0x08600000 0x7fff>;

Why different style?

> +
> +			#address-cells = <1>;
> +			#size-cells = <1>;
> +		};
> +
>  		usb3: usb@8af8800 {
>  			compatible = "qcom,ipq6018-dwc3", "qcom,dwc3";
>  			reg = <0x0 0x08af8800 0x0 0x400>;

Look here.

> 


Best regards,
Krzysztof
Re: [PATCH 3/7] arm64: dts: qcom: ipq6018: Add the IMEM node
Posted by Konrad Dybcio 3 months, 1 week ago 
On 7/2/25 12:50 PM, Krzysztof Kozlowski wrote:
> On 02/07/2025 12:17, Kathiravan Thirumoorthy wrote:
>> Add the IMEM node to the device tree to extract debugging information
>> like system restart reason, which is populated via IMEM. Define the
>> IMEM region to enable this functionality.
>>
>> As described, overall IMEM region is approximately 32KB but only initial
>> 4KB is accessible by all masters in the SoC.
>>
>> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
>> ---
>>  arch/arm64/boot/dts/qcom/ipq6018.dtsi | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/ipq6018.dtsi b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
>> index bfe59b0208415902c69fd0c0c7565d97997d4207..7eca5ba416c2ef5ef1c4e0eb4f58f1ca94fc92f0 100644
>> --- a/arch/arm64/boot/dts/qcom/ipq6018.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/ipq6018.dtsi
>> @@ -659,6 +659,15 @@ qpic_nand: nand-controller@79b0000 {
>>  			status = "disabled";
>>  		};
>>  
>> +		sram@8600000 {
>> +			compatible = "qcom,ipq6018-imem", "syscon", "simple-mfd";
> 
> No, this is not a simple MFD. Where are any children if this is a MFD?

IMEM is just a block of SRAM shared across cores on the platform.
It's present on all Qualcomm platforms and usually stores cookies
such as reboot reason.

A user would be welcome, but I'm not opposed to a lone description
either, at it still shrinks the undescribed-reg-space-hole

Konrad

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