[RFC 3/5] dt-bindings: arm-smmu: Add reserved-msi-region

[Jitendra Bhivare]

On Tue, Mar 6, 2018 at 5:17 PM, Robin Murphy <robin.murphy at arm.com> wrote:
> On 06/03/18 04:59, Jitendra Bhivare wrote:
>>
>> iPROC SoC has a special device window to treat GICv3 ITS MSI.
>
>
> Ugh, really? After preferably printing out 100 copies of the SBSA, binding
> them all together and dropping the lot onto the hardware designers from a
> great height, could you clarify what exactly the special behaviour is here?
>
> Robin.
>
The special device window needs to programmed so that writes to
specified address
region helps for specific ordering of traffic prior to it.
>
>> Current code maps MSI to IOVA space. Add SMMU node property to use
>> direct mappings for MSI region.
>>
>> This property is read and reserved when arm_smmu_get_resv_regions
>> gets called.
>>
>> Signed-off-by: Jitendra Bhivare <jitendra.bhivare at broadcom.com>
>> ---
>>   Documentation/devicetree/bindings/iommu/arm,smmu.txt | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> index 8a6ffce..13fa2b9 100644
>> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
>> @@ -71,6 +71,15 @@ conditions.
>>                     or using stream matching with #iommu-cells = <2>, and
>>                     may be ignored if present in such cases.
>>   +- reserved-msi-region: MSI region to be reserved with specific prot in
>> IOVA
>> +                 space for direct mapping. The region is specified in
>> tuple
>> +                 of (busno,prot,bus_addr,size).
>> +
>> +- #region-address-cells: specifies number of cells needed to encode
>> bus_addr
>> +
>> +- #region-size-cells: specifies number of cells needed to encode size
>> +
>> +
>>   ** Deprecated properties:
>>     - mmu-masters (deprecated in favour of the generic "iommus" binding) :
>> @@ -95,6 +104,9 @@ conditions.
>>                                <0 36 4>,
>>                                <0 37 4>;
>>                   #iommu-cells = <1>;
>> +               #region-address-cells = <1>;
>> +               #region-size-cells = <1>;
>> +               reserved-msi-region = <0x0 0x1a 0x63c3000 0x8000>;
>>           };
>>             /* device with two stream IDs, 0 and 7 */
>>
>