On Fri, 17 Apr 2015 01:38:16 -0700
Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx> wrote:
> On 17.04.2015 05:50, Jisheng Zhang wrote:
> > I got the solution, the ranges can define two or more ranges. What I need to do
> > is just add ranges for 0xe0000000 - 0xf0000000 as the following:
>
> Jisheng,
>
> the beauty of ranges property often reminds me of perl code: once you
> stop looking at it, you cannot recall how you did it nor how that
> has ever worked.
>
> What the ranges property does is to map an address range back to the
> address space of the parent node. In this case, the parent node of
> "soc" is the root node with "ranges;", i.e. 1:1 mapping.
>
> > soc {
> > ranges = <0 0xf7000000 0x1000000
>
> The line above maps 0x1000000 bytes starting at 0 back to 0xf7000000
> of the parent node's address space. This allows us to leave the 0xf7
> prefix for each of the internal bus nodes below.
>
> > 0xe0000000 0xe0000000 0x10000000>; //add this line
>
> You could have chosen any address as the first value that does not
> interfere with 0x0-0x1000000 of the first range, e.g.
>
> 0x20000000 0xe0000000 0x10000000
>
> would allow you to access the pcie memory space at 0x20000000 in nodes
> below that ranges property.
>
Thanks for this explanation which gives me good guide about the "ranges" usage.
>
> > pcie: pcie@e40000 {
> > ...
> > reg = <0xe40000 0x10000>, <0xe0000000 0x8000000>;
> > reg-names = "dbi", "pad", "config";
> > ...
> > };
> > }
> >
> > Now, we can get the config space correctly.
>
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