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From:   Biwen Li <biwen.li@nxp.com>
To:     Leo Li <leoyang.li@nxp.com>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        Ran Wang <ran.wang_1@nxp.com>
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        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: RE: [v3,3/3] Documentation: dt: binding: fsl: Add
 'fsl,ippdexpcr-alt-addr' property
Thread-Topic: [v3,3/3] Documentation: dt: binding: fsl: Add
 'fsl,ippdexpcr-alt-addr' property
Thread-Index: AQHVcoOnab7d5ysBNkWsXmY0PrfSuKc6/L+AgAC3JZCAAAkFAIAAANMggAABmICAAAIKMIAAAb8AgAACHkA=
Date:   Wed, 25 Sep 2019 04:06:25 +0000
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> >
> > > > > > > >
> > > > > > > > The 'fsl,ippdexpcr-alt-addr' property is used to handle an
> > > > > > > > errata
> > > > > > > > A-008646 on LS1021A
> > > > > > > >
> > > > > > > > Signed-off-by: Biwen Li <biwen.li@nxp.com>
> > > > > > > > ---
> > > > > > > > Change in v3:
> > > > > > > > 	- rename property name
> > > > > > > > 	  fsl,rcpm-scfg -> fsl,ippdexpcr-alt-addr
> > > > > > > >
> > > > > > > > Change in v2:
> > > > > > > > 	- update desc of the property 'fsl,rcpm-scfg'
> > > > > > > >
> > > > > > > >  Documentation/devicetree/bindings/soc/fsl/rcpm.txt | 14
> > > > > > > > ++++++++++++++
> > > > > > > >  1 file changed, 14 insertions(+)
> > > > > > > >
> > > > > > > > diff --git
> > > > > > > > a/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > > > > > b/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > > > > > index 5a33619d881d..157dcf6da17c 100644
> > > > > > > > --- a/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > > > > > +++ b/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > > > > > @@ -34,6 +34,11 @@ Chassis Version		Example
> > Chips
> > > > > > > >  Optional properties:
> > > > > > > >   - little-endian : RCPM register block is Little Endian.
> > > > > > > > Without it
> > > RCPM
> > > > > > > >     will be Big Endian (default case).
> > > > > > > > + - fsl,ippdexpcr-alt-addr : Must add the property for SoC
> > > > > > > > + LS1021A,
> > > > > > >
> > > > > > > You probably should mention this is related to a hardware
> > > > > > > issue on LS1021a and only needed on LS1021a.
> > > > > > Okay, got it, thanks, I will add this in v4.
> > > > > > >
> > > > > > > > +   Must include n + 1 entries (n =3D #fsl,rcpm-wakeup-cell=
s, such
> as:
> > > > > > > > +   #fsl,rcpm-wakeup-cells equal to 2, then must include 2
> > > > > > > > + +
> > > > > > > > + 1
> > > entries).
> > > > > > >
> > > > > > > #fsl,rcpm-wakeup-cells is the number of IPPDEXPCR registers
> > > > > > > on an
> > > SoC.
> > > > > > > However you are defining an offset to scfg registers here.
> > > > > > > Why these two are related?  The length here should actually
> > > > > > > be related to the #address-cells of the soc/.  But since
> > > > > > > this is only needed for LS1021, you can
> > > > > > just make it 3.
> > > > > > I need set the value of IPPDEXPCR resgiters from ftm_alarm0
> > > > > > device node(fsl,rcpm-wakeup =3D <&rcpm 0x0 0x20000000>;
> > > > > > 0x0 is a value for IPPDEXPCR0, 0x20000000 is a value for
> > > IPPDEXPCR1).
> > > > > > But because of the hardware issue on LS1021A, I need store the
> > > > > > value of IPPDEXPCR registers to an alt address. So I defining
> > > > > > an offset to scfg registers, then RCPM driver get an abosolute
> > > > > > address from offset, RCPM driver write the value of IPPDEXPCR
> > > > > > registers to these abosolute addresses(backup the value of
> > > > > > IPPDEXPCR
> > > registers).
> > > > >
> > > > > I understand what you are trying to do.  The problem is that the
> > > > > new fsl,ippdexpcr-alt-addr property contains a phandle and an off=
set.
> > > > > The size of it shouldn't be related to #fsl,rcpm-wakeup-cells.
> > > > You maybe like this: fsl,ippdexpcr-alt-addr =3D <&scfg 0x51c>;/*
> > > > SCFG_SPARECR8 */
> > >
> > > No.  The #address-cell for the soc/ is 2, so the offset to scfg
> > > should be 0x0 0x51c.  The total size should be 3, but it shouldn't
> > > be coming from #fsl,rcpm-wakeup-cells like you mentioned in the bindi=
ng.
> > Oh, I got it. You want that fsl,ippdexpcr-alt-add is relative with
> > #address-cells instead of #fsl,rcpm-wakeup-cells.
>=20
> Yes.
I got an example from drivers/pci/controller/dwc/pci-layerscape.c
and arch/arm/boot/dts/ls1021a.dtsi as follows:
fsl,pcie-scfg =3D <&scfg 0>, 0 is an index

In my fsl,ippdexpcr-alt-addr =3D <&scfg 0x0 0x51c>,
It means that 0x0 is an alt offset address for IPPDEXPCR0, 0x51c is an alt =
offset address
For IPPDEXPCR1 instead of 0x0 and 0x51c compose to an alt address of SCFG_S=
PARECR8.
>=20
> Regards,
> Leo
> > >
> > > > >
> > > > > > >
> > > > > > > > +   The first entry must be a link to the SCFG device node.
> > > > > > > > +   The non-first entry must be offset of registers of SCFG=
.
> > > > > > > >
> > > > > > > >  Example:
> > > > > > > >  The RCPM node for T4240:
> > > > > > > > @@ -43,6 +48,15 @@ The RCPM node for T4240:
> > > > > > > >  		#fsl,rcpm-wakeup-cells =3D <2>;
> > > > > > > >  	};
> > > > > > > >
> > > > > > > > +The RCPM node for LS1021A:
> > > > > > > > +	rcpm: rcpm@1ee2140 {
> > > > > > > > +		compatible =3D "fsl,ls1021a-rcpm", "fsl,qoriq-rcpm-
> > > > 2.1+";
> > > > > > > > +		reg =3D <0x0 0x1ee2140 0x0 0x8>;
> > > > > > > > +		#fsl,rcpm-wakeup-cells =3D <2>;
> > > > > > > > +		fsl,ippdexpcr-alt-addr =3D <&scfg 0x0 0x51c>; /*
> > > > > > > > SCFG_SPARECR8 */
> > > > > > > > +	};
> > > > > > > > +
> > > > > > > > +
> > > > > > > >  * Freescale RCPM Wakeup Source Device Tree Bindings
> > > > > > > >  -------------------------------------------
> > > > > > > >  Required fsl,rcpm-wakeup property should be added to a
> > > > > > > > device node if the device
> > > > > > > > --
> > > > > > > > 2.17.1