On 04/09/13 02:08, Mark Rutland wrote: > On Tue, Apr 09, 2013 at 03:30:20AM +0100, Stephen Boyd wrote: >> >> -** Timer node properties: >> +** CP15 Timer node properties: >> >> - compatible : Should at least contain one of >> "arm,armv7-timer" >> @@ -26,3 +30,55 @@ Example: >> <1 10 0xf08>; >> clock-frequency = <100000000>; >> }; >> + >> +** Memory mapped timer node properties >> + >> +- compatible : Should at least contain "arm,armv7-timer-mem". >> + >> +- #address-cells : Must be 1. > What about LPAE systems? > > How about something like the following: > > #address-cells : If the ranges property is empty, the same value as the > parent node's #address-cells property. Otherwise, a > value such that the ranges property specifies a > mapping to the parent node's address space.
Yes that is much better. I wasn't trying to preclude LPAE or 64 bit systems. >> + >> +- #size-cells : Must be 1. >> + >> +- ranges : Indicates parent and child bus address space are the same. >> + > Similarly, what if someone wants to write a more complex mapping for some > reason? > > We should be able to handle it if we use the standard accessors. Maybe I should just leave this part out? They are standard DT properties so I could assume DT writers know what to do. >> +- clock-frequency : The frequency of the main counter, in Hz. Optional. >> + >> +- reg : The control frame base address. >> + >> +Frame: >> + >> +- frame-id: Encoded as follows: >> + bits[3:0] frame number: 0 to 7. >> + bits[10:8] frame usage: >> + 0 - user/kernel >> + 1 - hyp >> + 2 - secure >> + > Could we not just have a disabled status property for those frames claimed by > a > higher level (either secure firmware or hypervisor)? Or have I missed > something > here? Using disabled status would work. I was also thinking maybe we should use a compatible string in each frame's node. Then we could match against compatible children like "frame-user", "frame-kernel", "frame-hyp", "frame-secure", "frame-user-kernel", etc. It allows us flexibility if we should need to add something else in the future. Also to get the frame number, I was thinking maybe we should expand the reg property to have two address cells. Then we could have reg = <0 0xf0001000 0x1000>. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss
