linux-kernel - Re: [PATCH 06/17] pci: host: pcie-designware: Use *base-mask* for configuring the iATU

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Date:	Mon, 19 May 2014 14:45:47 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	Jingoo Han <jg1.han@...sung.com>,
	'Santosh Shilimkar' <santosh.shilimkar@...com>,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-omap@...r.kernel.org, linux-pci@...r.kernel.org,
	rogerq@...com, balajitk@...com,
	'Bjorn Helgaas' <bhelgaas@...gle.com>,
	'Marek Vasut' <marex@...x.de>
Subject: Re: [PATCH 06/17] pci: host: pcie-designware: Use *base-mask* for configuring the iATU

On Friday 16 May 2014 14:30:56 Kishon Vijay Abraham I wrote:
> On Wednesday 14 May 2014 06:15 PM, Arnd Bergmann wrote:
> > On Wednesday 14 May 2014 11:14:45 Kishon Vijay Abraham I wrote:
> > / {
> >       #address-cells = <1>; // or <2> if you support > 4GB address space
> >       #size-cells = <1>;
> > 
> >       soc {
> >               #address-cells <1>;
> >               #size-cells = <1>;
> >               ranges;
> >               dma-ranges;
> > 
> >               ... // all normal devices
> > 
> >               axi@...00000 {
> >                       #size-cells = <1>;
> >                       #address-cells = <1>;
> >                       dma-ranges; // can access all 4GB outbound
> >                       ranges = <0 0x20000000 0x10000000>; // 28-bit bus
> > 
> >                       pci@0 {
> >                               reg = <0x0    0x1000>, // internal regs
> >                                     <0x1000 0x2000>; // config space
> 
> The internal reg address space starts at 0x51000000. By Using this <0
> 0x20000000 0x10000000>; as ranges, we are not able to get the memory resource
> properly. Can we use multiple ranges? how do we specify which ranges the *reg*
> property to use?

Yes, multiple ranges will work fine. You can make up a representation
yourself if you don't know what the hardware really does.

Two possible ways of doing this would be

a)

	/* two separate physical connections represented as one logical bus */
	axi@...00000 {
		#address-cells = <2>;
		#size-cells = <1>;
		ranges = <0 0 0x20000000 0x10000000>, /* configurable registers */
			 <1 0 0x51000000 0x01000000>; /* PCI host registers */

		pci@1.0 {
			reg = <1 0 0x01000000>, /* host registers */
				<0 0x1000 0x2000>; /* config space */
		}

	};

b) 

	/* one physical bus, with some address munging */
	axi@...00000 {
		#address-cells = <1>;
		#size-cells = <1>;
		ranges = <0 0x20000000 0x10000000>, /* configurable registers */
			 <0x51000000 0x51000000 0x01000000>; /* PCI host registers */

		pci@1.0 {
			reg = <0x51000000 0x01000000>, /* host registers */
				<0x1000 0x2000>; /* config space */
		}

	};


> Btw I was using *simple-bus* as compatible to *axi*. Or should I create a new
> *axi* driver to create the pcie memory resources myself?

simple-bus is best here, since you don't have a complex bus that needs to
be set up using register accesses or that generates interrupts.

	Arnd
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