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SubjectRe: [Patch v15 4/5] dt-bindings: arm-smmu: Add bindings for qcom,smmu-v2
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Hi Rob,


On 8/29/2018 2:04 AM, Rob Herring wrote:
> On Mon, Aug 27, 2018 at 04:25:50PM +0530, Vivek Gautam wrote:
>> Add bindings doc for Qcom's smmu-v2 implementation.
>>
>> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
>> Reviewed-by: Tomasz Figa <tfiga@chromium.org>
>> Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
>> ---
>>
>> Changes since v14:
>> - This is a new patch added in v15 after noticing the new
>> checkpatch warning for separate dt-bindings doc.
>> - This patch also addresses comments given by Rob and Robin to add
>> a list of valid values of '<soc>' in "qcom,<soc>-smmu-v2"
>> compatible string.
>>
>> .../devicetree/bindings/iommu/arm,smmu.txt | 47 ++++++++++++++++++++++
>> 1 file changed, 47 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> index 8a6ffce12af5..52198a539606 100644
>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> @@ -17,10 +17,24 @@ conditions.
>> "arm,mmu-401"
>> "arm,mmu-500"
>> "cavium,smmu-v2"
>> + "qcom,<soc>-smmu-v2", "qcom,smmu-v2"
> The v2 in the compatible string is kind of redundant unless the SoC has
> other SMMU types.

sdm845 has smmu-v2, and smmu-500 [1].

>>
>> depending on the particular implementation and/or the
>> version of the architecture implemented.
>>
>> + A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
>> + "qcom,<soc>-smmu-v2" represents a soc specific compatible
>> + string that should be present along with the "qcom,smmu-v2"
>> + to facilitate SoC specific clocks/power connections and to
>> + address specific bug fixes.
>> + '<soc>' string in "qcom,<soc>-smmu-v2" should be one of the
>> + following:
>> + msm8996 - for msm8996 Qcom SoC.
>> + sdm845 - for sdm845 Qcom Soc.
> Rather than all this prose, it would be simpler to just add 2 lines with
> the full compatibles rather than <soc>. The <soc> thing is not going to
> work when/if we move bindings to json-schema also.

then we keep adding
         "qcom,msm8996-smmu-v2", "qcom,smmu-v2"
         "qcom,msm8998-smmu-v2", "qcom,smmu-v2"
         "qcom,sdm845-smmu-v2", "qcom,smmu-v2",
and from [1]
         "qcom,sdm845-smmu-500", "arm,mmu-500", etc.
for each SoCs?

>
>> +
>> + An example string would be -
>> + "qcom,msm8996-smmu-v2", "qcom,smmu-v2".
>> +
>> - reg : Base address and size of the SMMU.
>>
>> - #global-interrupts : The number of global interrupts exposed by the
>> @@ -71,6 +85,22 @@ conditions.
>> or using stream matching with #iommu-cells = <2>, and
>> may be ignored if present in such cases.
>>
>> +- clock-names: List of the names of clocks input to the device. The
>> + required list depends on particular implementation and
>> + is as follows:
>> + - for "qcom,smmu-v2":
>> + - "bus": clock required for downstream bus access and
>> + for the smmu ptw,
>> + - "iface": clock required to access smmu's registers
>> + through the TCU's programming interface.
>> + - unspecified for other implementations.
>> +
>> +- clocks: Specifiers for all clocks listed in the clock-names property,
>> + as per generic clock bindings.
>> +
>> +- power-domains: Specifiers for power domains required to be powered on for
>> + the SMMU to operate, as per generic power domain bindings.
>> +
>> ** Deprecated properties:
>>
>> - mmu-masters (deprecated in favour of the generic "iommus" binding) :
>> @@ -137,3 +167,20 @@ conditions.
>> iommu-map = <0 &smmu3 0 0x400>;
>> ...
>> };
>> +
>> + /* Qcom's arm,smmu-v2 implementation */
>> + smmu4: iommu {
> Needs a unit-address.

I went in symmetry with another example in this file for 'smmu1'. I will
add the address here.
And if you would like, I can squash a change for 'smmu1' too in this
patch, although that will be trivial.

[1] https://patchwork.kernel.org/patch/10565291/

Best regards
Vivek

[snip]

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