> -----Original Message----- > From: Meador Inge [mailto:meador_i...@mentor.com] > Sent: Wednesday, January 19, 2011 2:25 PM > To: Yoder Stuart-B08248 > Cc: linuxppc-dev@lists.ozlabs.org; devicetree-disc...@lists.ozlabs.org; > Blanchard, Hollis > Subject: Re: [PATCH 1/2] powerpc: document the MPIC device tree binding > > On 01/18/2011 02:21 PM, Yoder Stuart-B08248 wrote: > >> Documentation/powerpc/dts-bindings/mpic.txt | 78 > > > > This is really the binding for an open-pic interrupt controller and I > > think the name should reflect that-- open-pic.txt. > > Yup, agreed. > > >> +This binding specifies what properties and child nodes must be > >> +available on the device tree representation of the "MPIC" interrupt > >> +controller. This binding is based on the binding defined for Open > >> +PIC in [1] and is a superset of that binding. > > > > I think it would be better to base this on the ePAPR binding which was > > based on the original chrp binding. Properties like "name" > > and "device_type" are deprecated not being used in flat device trees. > > > > <http://www.power.org/resources/downloads/Power_ePAPR_APPROVED_v1.0.pd > > f> > > > > The proposed new properties really should go back into the ePAPR. > > I read portions of ePAPR while writing this binding and considered that. > My only worry was that ePAPR is focused on embedded systems and this > binding will have to cover non-embedded systems that exist in the kernel. > However, perhaps that is not a legitimate concern?
The ePAPR tried to codify what was previously implemented in Linux, so I don't think lack of things like "name" and "device_type" in the binding are an issue. > >> + > >> +** Required properties: > >> + > >> + NOTE: Many of these descriptions were paraphrased from [1] to aid > >> + readability. > >> + > >> + - name : Specifies the name of the MPIC. > > > > Drop this. No DTS files use it. > > Done. > > >> + - device_type : Specifies the device type of this MPIC. The > >> + value of this > >> + property shall be "open-pic". > > > > device_type is deprecated, since this is not real open-firmware. In > > practice the kernel is matching on device_type, but we want to move > > away from that to match on "compatible", just hasn't been implemented > > yet. > > I will drop this property with the expectation that the kernel will be > fixed. From a quick grep of '.../arch/powerpc' it looks like most uses are > of the form: > > np = of_find_node_by_type(NULL, "open-pic"); > if (np == NULL) > return; > > In most of these cases I suppose the 'of_find_node_by_type' calls could > just be replaced with calls to 'of_find_compatible_node(NULL, "open-pic")'. For backwards compatibility, we should continue to accept the old/deprecated device_type="open-pic", but in addition we should accept the compatible="open-pic". > >> + - reg : Specifies the base physical address(s) and size(s) of this > >> + MPIC's > >> + addressable register space. > >> + - compatible : Specifies the compatibility list for the MPIC. The > >> + property > >> + value shall include "chrp,open-pic". > > > > In the ePAPR we modified this to just "open-pic", because this has > > nothing to do with chrp anymore. I think just "open-pic" is > > what we want. > > OK, but as a migration path we should allow the kernel to accept both > (Scott mentioned this in another reply), but "open-pic" is the > documented correct way. Right. > >> + - interrupt-controller : The presence of this property identifies > >> + the node > >> + as a MPIC. No property value should be > >> defined. > >> + - #address-cells : Specifies the number of cells needed to encode an > >> + address. The value of this property shall always > >> + be 0 > >> + so that 'interrupt-map' nodes do not have to > >> + specify a > >> + parent unit address. > >> + - #interrupt-cells : Specifies the number of cells needed to encode > >> + an > >> + interrupt source. > > > > Should be 2, correct? > > Yup. > > >> +** Optional properties: > >> + > >> + - no-reset : The presence of this property indicates that the MPIC > >> + should not be reset during runtime initialization. > >> + - protected-sources : Specifies a list of interrupt sources that are > >> + not > >> + available for use and whose corresponding > >> + vectors > >> + should not be initialized. A typical use case > >> + for > >> + this property is in AMP systems where multiple > >> + independent operating systems need to share > >> + the MPIC > >> + without clobbering each other. > > > > I do think you need to include the definition of interrupt > > specifiers here. Feel free to cut/paste text from my > > Freescale mpic binding. > > OK, I will look into that. Thanks. I have a version 2 I hope to send out later today. Stuart _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
