[U-Boot] MIPS UHI spec

[Daniel Schwierzeck]

2015-02-26 11:17 GMT+01:00 Paul Burton <paul.burton at imgtec.com>:
> On Thu, Feb 19, 2015 at 01:50:23PM +0000, Matthew Fortune wrote:
>> Hi Daniel,
>>
>> The spec for MIPS Unified Hosting Interface is available here:
>>
>> http://prplfoundation.org/wiki/MIPS_documentation
>>
>> As we have previously discussed, this is an ideal place to
>> define the handover of device tree data from bootloader to
>> kernel. Using a0 == -2 and defining which register(s) you
>> need for the actual data will fit nicely. I'll happily
>> include whatever is decided into the next version of the spec.

this originates from an off-list discussion some months ago started by
John Crispin.

(CC +John, Ralf, Jonas, linux-mips)

>
> (CC +Andrew, Ezequiel, James, James)
>
> On the talk of DT handover, this recent patchset adding support for a
> system doing so to Linux is relevant:
>
>     http://www.linux-mips.org/archives/linux-mips/2015-02/msg00312.html
>
> I'm also working on a system for which I'll need to implement DT
> handover very soon. It would be very nice if we could agree on some
> standard way of doing so (and eventually if the code on the Linux side
> can be generic enough to allow a multiplatform kernel).
>

to be conformant with UHI I propose $a0 == -2 and $a1 == address of DT
blob. It is a simple extension and should not interfere with the
various legacy boot interfaces.

U-Boot mainline code is almost ready for DT handover. I have prepared
a patch [1] which completes it by implementing my proposal.

[1] http://git.denx.de/?p=u-boot/u-boot-mips.git;a=commitdiff;h=3464e8de491c640d14d72853a741cc367ebabc79

-- 
- Daniel