Messages in this thread | | | Date | Tue, 16 Apr 2019 11:42:35 -0600 | From | Lina Iyer <> | Subject | Re: [PATCH v4 03/10] of/irq: document properties for wakeup interrupt parent |
| |
On Tue, Apr 16 2019 at 10:54 -0600, Stephen Boyd wrote: >Quoting Lina Iyer (2019-04-04 08:58:38) >> 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 see two things going on here. Do both need to happen? > > #1: Specifying wakeup parent phandle > #2: Mapping GPIO interrupts to a parent irqdomain > >Do we need the method of specifying the wakeup parent if with a dt >property if we have a way to map irqdomains from one to another? I think >I may have already said on the list that we must have #1 but now I'm not >so sure. It looks like we could get away with just looking into the >irqdomain-map and then pick out the wakeup parent that way. > I thought about it. But the wakeup-parent seems to be needed outside the irqdomain-map to setup the gpiochip's hierarchy. This could be done by reading the map, but I am not sure if that approach is clean enough.
>The way the bindings are written shows one way to map interrupts between >domains but I don't know if it lets us differentiate which irqs go from >which domain to what other domain. It seems that we assume we're looking >at only the GPIO to wakeup parent irqdomain mapping from the >irqdomain-map property in this series. If we had a way to do this with >the irqdomain map then we could avoid needing a special 'wakeup-parent' >property. >
| |