[PATCH V4 2/2] riscv: board: Support OpenPiton SoC

[Sean Anderson <seanga2@gmail.com>]

On 5/7/21 9:11 AM, Bin Meng wrote:
> On Fri, May 7, 2021 at 9:03 PM Sean Anderson <seanga2@gmail.com> wrote:
>>
>> On 5/6/21 11:48 PM, Tianrui Wei wrote:
>>>
>>> On 5/7/2021 11:41 AM, Sean Anderson wrote:
>>>> On 5/6/21 11:28 PM, Tianrui Wei wrote:
>>>>>
>>>>> On 5/7/2021 11:15 AM, Sean Anderson wrote:
>>>>>> On 5/6/21 11:06 PM, Tianrui Wei wrote:
>>>>>>> Hi Sean,
>>>>>>>
>>>>>>>
>>>>>>> Many thanks again for reviewing our code! We really appreciate it. Will fix the things you're suggesting ;p Though I have a few questions in line in the comment. Also, checkpatch didn't catch any of the identation issues. I was wondering if there are some specific flags to enable some of the checks? I'm running ./utils/checkpatch.pl this.patch right now.
>>>>>>>
> 
> [snip]
> 
>>>>>>>
>>>>>>>
>>>>>>> No we don't support fit yet for some hardware reasons.
>>>>>>
>>>>>> Can you elaborate on that? I wasn't aware of any restrictions in this
>>>>>> area.
>>>>>
>>>>>
>>>>> So OpenPiton is actually some kind of SoC generator that generates
>>>>> different SoC on FPGA. The device tree was generated at bitstream
>>>>> creation time to facilitate different configurations, so each board
>>>>> can have different device trees. We're aware of any way to do this in
>>>>> FIT.
>>>>
>>>> Oh, so you're saying that the devicetree is placed at a specific address
>>>> in hardware? Does it need any fixups?
>>>
>>>
>>> No for now we just embed it in SPL, will be converted into the bootrom for the chip with a small ZSBL.
>>
>> Well, atm you are using the DTS embedded in U-Boot.
>>
>> I don't know what the correct way to do this is...
>>
>> +CC Bin, Heinrich: Do you have a comment on this?
> 
> I am not sure I followed this correctly. Ideally we should use OF_SEPARATE.

As I understand it, Tianrui would like to use the same FDT that U-Boot
uses for Linux as well. Is doing something like

>> +    "fdt addr ${fdtcontroladdr}; " \
>> +    "fdt move ${fdtcontroladdr} ${fdt_addr_r}; " \
>> +    "booti ${loadaddr} - ${fdt_addr_r}; " 

the right way to go about this? Can any other platforms be used as a
reference here (perhaps qemu)?

--Sean

> 
>>
>>>
>>> Also, now that you mention fixups u-boot spl doesn't work at high address like 0xffffff0000 for now. Is that the case?
>>
>> What happens why you try that?
>>
> 
> Regards,
> Bin
>