[PATCH v2 1/2] powerpc/mpic: Add Open-PIC global timer document

[Wang Dongsheng-B40534]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Wednesday, August 15, 2012 5:19 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; benh at kernel.crashing.org; paulus at samba.org;
> linuxppc-dev at lists.ozlabs.org; devicetree-discuss at lists.ozlabs.org; Gala
> Kumar-B11780; Li Yang-R58472
> Subject: Re: [PATCH v2 1/2] powerpc/mpic: Add Open-PIC global timer
> document
> 
> On 08/13/2012 09:40 PM, Wang Dongsheng-B40534 wrote:
> >>>> +Example 2:
> >>>>> +
> >>>>> +	timer: timer at 010f0 {
> >>>>> +		compatible = "open-pic,global-timer";
> >>>>> +		device_type = "open-pic";
> >>>>> +		reg = <0x010f0 4 0x01100 0x100>;
> >>>>> +		interrupts = <0 0 3 0
> >>>>> +			      1 0 3 0
> >>>>> +			      2 0 3 0
> >>>>> +		              3 0 3 0>;
> >>>>> +	};
> >>>>
> >>>> 4-cell interrupt specifiers are specific to Freescale MPICs.  This
> >>>> means there's no way to describe the timer interrupt on a non-
> >> Freescale openpic.
> >>>> Again, I suggest we not bother with this in the absence of an actual
> >>>> need to support the timer on non-Freescale openpic in partitioned
> >> scenarios.
> >>>> The existing openpic node is sufficient to describe the
> >>>> hardware in the absence of partitioning.   We could have an
> >>>> "openpic-no-timer" property to indicate that we're describing it
> >>>> separately, so that the absence of a timer node isn't ambiguous as
> to
> >>>> whether it's an old tree or a partitioned scenario.  An fsl,mpic
> >>>> compatible would imply openpic-no-timer.
> >>>>
> >>>> Note that I believe many of the non-Freescale openpic nodes are
> going
> >>>> to be found on systems with real Open Firmware, so we can't go
> >>>> changing the device tree for them.
> >>> [Wang Dongsheng] In the Open-PIC specification, there are four timer.
> >>> 		interrupts = <0 0 3 0
> >>> 			      1 0 3 0
> >>> 			      2 0 3 0
> >>> 		              3 0 3 0>;
> >>>
> >>> The "interrupts" just let user know there are four timers. Usage
> based
> >> "interrupts"
> >>> binding to change dts.
> >>
> >> I can't understand the above or how it's a response to what I wrote.
> >>
> > [Wang Dongsheng] I mean this just to tell how many timers to support in
> Open-PIC
> > specification. If someone needs to write "interrupts" into dts, this
> must comply
> > with the specification of the interrupt to write. this is based on the
> pic driver
> > should be changed in different platforms.
> 
> My point (beyond that examples provided should be valid for *some*
> system) is there is no valid thing to put in the interrupts property
> here when the interrupt controller is not "fsl,mpic", so this doesn't
> work.
> 
[Wang Dongsheng] Fine, I will remove this document of Open-PIC global timer.
We only support mpic timer. Driver will be compatible with OPEN-PIC
specification. Let someone who cares about ordinary OpenPIC drivers add
support?

> -Scott