[PATCH v2 2/2] dt-bindings: introduce Command DB for QCOM SoCs

[PATCH v2 2/2] dt-bindings: introduce Command DB for QCOM SoCs

[Lina Iyer]

From: Mahesh Sivasubramanian <msivasub@codeaurora.org>

Command DB provides information on shared resources like clocks,
regulators etc., probed at boot by the remote subsytem and made
available in shared memory.

Cc: devicetree@vger.kernel.org
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>
---
 .../devicetree/bindings/arm/msm/cmd-db.txt         | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/msm/cmd-db.txt

diff --git a/Documentation/devicetree/bindings/arm/msm/cmd-db.txt b/Documentation/devicetree/bindings/arm/msm/cmd-db.txt
new file mode 100644
index 000000000000..e21666e40ebf
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/msm/cmd-db.txt
@@ -0,0 +1,38 @@
+Command DB
+---------
+
+Command DB is a database that provides a mapping between resource key and the
+resource address for a system resource managed by a remote processor. The data
+is stored in a shared memory region and is loaded by the remote processor.
+
+Some of the Qualcomm Technologies Inc SoC's have hardware accelerators for
+controlling shared resources. Depending on the board configuration the shared
+resource properties may change. These properties are dynamically probed by the
+remote processor and made available in the shared memory.
+
+The devicetree representation of the command DB driver should be:
+
+PROPERTIES:
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: Should be "qcom,cmd-db"
+
+- memory-region:
+	Usage: required
+	Value type: <phandle>
+	Definition: The phandle to the reserved memory region.
+
+Example:
+
+	reserved-memory {
+		[...]
+		cmd_db_mem: qcom,cmd-db@c3f000c {
+			reg = <0x0 0xc3f000c 0x0 0x8>;
+		};
+	};
+
+	qcom,cmd-db@c3f000c {
+		compatible = "qcom,cmd-db";
+		memory-region = <&cmd_db_mem>;
+	};
-- 
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a Linux Foundation Collaborative Project

Re: [PATCH v2 2/2] dt-bindings: introduce Command DB for QCOM SoCs

[Bjorn Andersson]

On Thu 08 Feb 11:51 PST 2018, Lina Iyer wrote:

> From: Mahesh Sivasubramanian <msivasub-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> 
> Command DB provides information on shared resources like clocks,
> regulators etc., probed at boot by the remote subsytem and made
> available in shared memory.
> 
> Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Signed-off-by: Mahesh Sivasubramanian <msivasub-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Signed-off-by: Lina Iyer <ilina-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> ---
>  .../devicetree/bindings/arm/msm/cmd-db.txt         | 38 ++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/msm/cmd-db.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/msm/cmd-db.txt b/Documentation/devicetree/bindings/arm/msm/cmd-db.txt
> new file mode 100644
> index 000000000000..e21666e40ebf
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/msm/cmd-db.txt
> @@ -0,0 +1,38 @@
> +Command DB
> +---------
> +
> +Command DB is a database that provides a mapping between resource key and the
> +resource address for a system resource managed by a remote processor. The data
> +is stored in a shared memory region and is loaded by the remote processor.
> +
> +Some of the Qualcomm Technologies Inc SoC's have hardware accelerators for
> +controlling shared resources. Depending on the board configuration the shared
> +resource properties may change. These properties are dynamically probed by the
> +remote processor and made available in the shared memory.
> +
> +The devicetree representation of the command DB driver should be:
> +
> +PROPERTIES:
> +- compatible:
> +	Usage: required
> +	Value type: <string>
> +	Definition: Should be "qcom,cmd-db"
> +
> +- memory-region:
> +	Usage: required
> +	Value type: <phandle>
> +	Definition: The phandle to the reserved memory region.
> +
> +Example:
> +
> +	reserved-memory {
> +		[...]
> +		cmd_db_mem: qcom,cmd-db@c3f000c {
> +			reg = <0x0 0xc3f000c 0x0 0x8>;

I was hoping that we can describe the actual memory here, as I got the
impression that it will also be a chunk of memory carved out from System
RAM.

If not it would seem unlikely that there's a 8 byte carveout in the
middle of DDR, what else is here?

> +		};
> +	};
> +
> +	qcom,cmd-db@c3f000c {
> +		compatible = "qcom,cmd-db";

Add "qcom,cmd-db" to "reserved_mem_matches" in drivers/of/platform.c,
use of_reserved_mem_lookup(pdev->dev.of_node) to get the reserved_mem
and you can just put the compatible directly on the reserved-memory
node.

That way you don't need this separate node that doesn't really represent
anything.

> +		memory-region = <&cmd_db_mem>;
> +	};

Regards,
Bjorn
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Re: [PATCH v2 2/2] dt-bindings: introduce Command DB for QCOM SoCs

[Lina Iyer]

On Wed, Feb 14 2018 at 19:34 +0000, Bjorn Andersson wrote:
>On Thu 08 Feb 11:51 PST 2018, Lina Iyer wrote:
>
>> From: Mahesh Sivasubramanian <msivasub@codeaurora.org>
>>
>> Command DB provides information on shared resources like clocks,
>> regulators etc., probed at boot by the remote subsytem and made
>> available in shared memory.
>>
>> Cc: devicetree@vger.kernel.org
>> Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
>> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
>> ---
>>  .../devicetree/bindings/arm/msm/cmd-db.txt         | 38 ++++++++++++++++++++++
>>  1 file changed, 38 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/arm/msm/cmd-db.txt
>>
>> diff --git a/Documentation/devicetree/bindings/arm/msm/cmd-db.txt b/Documentation/devicetree/bindings/arm/msm/cmd-db.txt
>> new file mode 100644
>> index 000000000000..e21666e40ebf
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/msm/cmd-db.txt
>> @@ -0,0 +1,38 @@
>> +Command DB
>> +---------
>> +
>> +Command DB is a database that provides a mapping between resource key and the
>> +resource address for a system resource managed by a remote processor. The data
>> +is stored in a shared memory region and is loaded by the remote processor.
>> +
>> +Some of the Qualcomm Technologies Inc SoC's have hardware accelerators for
>> +controlling shared resources. Depending on the board configuration the shared
>> +resource properties may change. These properties are dynamically probed by the
>> +remote processor and made available in the shared memory.
>> +
>> +The devicetree representation of the command DB driver should be:
>> +
>> +PROPERTIES:
>> +- compatible:
>> +	Usage: required
>> +	Value type: <string>
>> +	Definition: Should be "qcom,cmd-db"
>> +
>> +- memory-region:
>> +	Usage: required
>> +	Value type: <phandle>
>> +	Definition: The phandle to the reserved memory region.
>> +
>> +Example:
>> +
>> +	reserved-memory {
>> +		[...]
>> +		cmd_db_mem: qcom,cmd-db@c3f000c {
>> +			reg = <0x0 0xc3f000c 0x0 0x8>;
>
>I was hoping that we can describe the actual memory here, as I got the
>impression that it will also be a chunk of memory carved out from System
>RAM.
>
Yes, it can be described. But, the location should always be read from
the address above. Generally, the CMD DB memory would not change, but it
is not always guaranteed.

>If not it would seem unlikely that there's a 8 byte carveout in the
>middle of DDR, what else is here?
>
>> +		};
>> +	};
>> +
>> +	qcom,cmd-db@c3f000c {
>> +		compatible = "qcom,cmd-db";
>
>Add "qcom,cmd-db" to "reserved_mem_matches" in drivers/of/platform.c,
>use of_reserved_mem_lookup(pdev->dev.of_node) to get the reserved_mem
>and you can just put the compatible directly on the reserved-memory
>node.
>
>That way you don't need this separate node that doesn't really represent
>anything.
>
Oh okay. I can take care of that.

Thanks,
Lina
>> +		memory-region = <&cmd_db_mem>;
>> +	};