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    SubjectRe: [PATCH v4 03/10] of/irq: document properties for wakeup interrupt parent
    On Mon, Apr 15 2019 at 06:42 -0600, Marc Zyngier wrote:
    >On 04/04/2019 16:58, Lina Iyer wrote:
    >> On Mon, Mar 18 2019 at 11:54 -0600, Marc Zyngier wrote:
    >>> On Wed, 13 Mar 2019 15:18:37 -0600
    >>> Lina Iyer <ilina@codeaurora.org> wrote:
    >>>
    >>> Please do Cc Rob when posting DT related patches.
    >>>
    >>>> Some interrupt controllers in a SoC, are always powered on and have a
    >>>> select interrupts routed to them, so that they can wakeup the SoC from
    >>>> suspend. Add wakeup-parent DT property to refer to these interrupt
    >>>> controllers.
    >>>>
    >>>> If the interrupts routed to the wakeup parent are not sequential, than a
    >>>> map needs to exist to associate the same interrupt line on multiple
    >>>> interrupt controllers. Providing this map in every driver is cumbersome.
    >>>> Let's add this in the device tree and document the properties to map the
    >>>> interrupt specifiers
    >>>>
    >>>> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
    >>>> ---
    >>>> Changes in v4:
    >>>> - Added this documentation
    >>>> ---
    >>>> .../interrupt-controller/interrupts.txt | 39 +++++++++++++++++++
    >>>> 1 file changed, 39 insertions(+)
    >>>>
    >>>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt b/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
    >>>> index 8a3c40829899..917b598317f5 100644
    >>>> --- a/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
    >>>> +++ b/Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
    >>>> @@ -108,3 +108,42 @@ commonly used:
    >>>> sensitivity = <7>;
    >>>> };
    >>>> };
    >>>> +
    >>>> +3) Interrupt wakeup parent
    >>>> +--------------------------
    >>>> +
    >>>> +Some interrupt controllers in a SoC, are always powered on and have a select
    >>>> +interrupts routed to them, so that they can wakeup the SoC from suspend. These
    >>>> +interrupt controllers do not fall into the category of a parent interrupt
    >>>> +controller and can be specified by the "wakeup-parent" property and contain a
    >>>> +single phandle referring to the wakeup capable interrupt controller.
    >>>> +
    >>>> + Example:
    >>>> + wakeup-parent = <&pdc_intc>;
    >>>> +
    >>>> +
    >>>> +4) Interrupt mapping
    >>>> +--------------------
    >>>> +
    >>>> +Sometimes interrupts may be detected by more than one interrupt controller
    >>>> +(depending on which controller is active). The interrupt controllers may not
    >>>> +be in hierarchy and therefore the interrupt controller driver is required to
    >>>> +establish the relationship between the same interrupt at different interrupt
    >>>> +controllers. If these interrupts are not sequential then a map needs to be
    >>>> +specified to help identify these interrupts.
    >>>> +
    >>>> +Mapping the interrupt specifiers in the device tree can be done using the
    >>>> +"irqdomain-map" property. The property contains interrupt specifier at the
    >>>> +current interrupt controller followed by the interrupt specifier at the mapped
    >>>> +interrupt controller.
    >>>> +
    >>>> + irqdomain-map = <incoming-interrupt-specifier mapped-interrupt-specifier>
    >>>> +
    >>>> +The optional properties "irqdomain-map-mask" and "irqdomain-map-pass-thru" may
    >>>> +be provided to help interpret the valid bits of the incoming and mapped
    >>>> +interrupt specifiers respectively.
    >>>> +
    >>>> + Example:
    >>>> + irqdomain-map = <22 0 &intc 36 0>, <24 0 &intc 37 0>;
    >>>> + irqdomain-map-mask = <0xff 0>;
    >>>> + irqdomain-map-pass-thru = <0 0xff>;
    >>>
    >>>
    >>> This doesn't quite explain how the mask and pass-thru properties are
    >>> used. I guess that the mask is used to define the 'useful bits' on the
    >>> incoming side, but pass-thru puzzles me. In your example, does it mean
    >>> that incoming lines map to outgoing interrupt <0 0>?
    >>>
    >> Sorry about the late reply.
    >>
    >> How about this to go with the rest of the documentation -
    >>
    >> In the above example, the input interrupt specifier map-mask <0xff 0> applied
    >> on the incoming interrupt specifier of the map <22 0>, <24 0>, returns the
    >> input interrupt 22, 24 etc. The second argument being irq type is immaterial
    >> from the map and is used from the incoming request instead. The pass-thru
    >> specifier parses the output interrupt specifier from the rest of the unparsed
    >> argments from the map <&intc 36 0>, <&intc 37 0> etc to return the output
    >> interrupt 36, 37 etc.
    >
    >I think you need to add #interrupt-cells in your example, which is
    >otherwise hard to interpret.
    >
    Ok. Thanks, will add.

    --Lina

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