linux-kernel - Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

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Date:	Thu, 31 Dec 2015 15:40:49 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Rongrong Zou <zourongrong@...wei.com>
Cc:	Rongrong Zou <zourongrong@...il.com>, minyard@....org,
	gregkh@...uxfoundation.org, catalin.marinas@....com,
	will.deacon@....com, linuxarm@...wei.com,
	linux-kernel@...r.kernel.org, benh@...nel.crashing.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

On Thursday 31 December 2015 22:12:19 Rongrong Zou wrote:
> 在 2015/12/30 17:06, Arnd Bergmann 写道:
> > On Tuesday 29 December 2015 21:33:52 Rongrong Zou wrote:
> >> +Example:
> >> +
> >> +        lpc_0: lpc@...b0000 {
> >> +		#address-cells = <1>;
> >> +		#size-cells = <1>;
> >> +                compatible = "low-pin-count";
> >> +                reg = <0x0 0xa01b0000 0x0 0x10000>;
> >> +        };
> >
> > One more thought: please try to stick as closely as possible to the existing
> > ISA binding that is documented at
> >
> > http://www.firmware.org/1275/bindings/isa/isa0_4d.ps
>  From the specification, I think I should use 2 32bit integer to describe the isa addr in dts.
> >
> > In particular, this should cover the possibility of describing both memory
> > and I/O spaces in child devices.
> >
> 
> I found below config in powerpc dts "arch/powerpc/boot/dts/mpc8544ds.dts"
> 
> isa@1e {
>                                  device_type = "isa";
>                                  #interrupt-cells = <2>;
>                                  #size-cells = <1>;
>                                  #address-cells = <2>;
>                                  reg = <0xf000 0x0 0x0 0x0 0x0>;
>                                  ranges = <0x1 0x0 0x1000000 0x0 0x0
>                                            0x1000>;
>                                  interrupt-parent = <&i8259>;
> 
> 
> 
>                                  rtc@70 {
>                                          compatible = "pnpPNP,b00";
>                                          reg = <0x1 0x70 0x2>;
>                                  };
>   the isa space in child-node: reg = <0x1 0x70 0x2>;
>   0x1 means IO space, 70 means addr, 0x2 is size.
>   but when i config the following in dts, the ipmi_0 node can't be probed,
>   I think there may be some problems.
> 
> lpc_0: lpc@...b0000 {
> 	compatible = "low-pin-count";
> 	device_type = "isa";
> 	#address-cells = <2>;
> 	#size-cells = <1>;
> 	reg = <0x0 0xa01b0000 0x0 0x10000>;
> 
> 	ipmi_0:ipmi@...000e4{
> 		device_type = "ipmi";
> 		compatible = "ipmi-bt";
> 		reg = <0x1 0x000000e4 0x4>;
> };

The DT sample above looks good in principle. I believe what you are missing
here is code in your driver to scan the child nodes to create the platform
devices. of_bus_isa_translate() should work with your definition here
and create the correct IORESOURCE_IO resources. You don't have any MMIO
resources, so the absence of a ranges property is ok. Maybe all you 
are missing is a call to of_platform_populate() or of_platform_bus_probe()?

	Arnd
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