[U-Boot] [PATCH v2 00/11] SiFive FU540 Support

[Atish Patra]

On 1/20/19 12:34 PM, Auer, Lukas wrote:
> Hi Anup,
> 
> On Fri, 2019-01-18 at 11:18 +0000, Anup Patel wrote:
>> This patchset adds SiFive Freedom Unleashed (FU540) support
>> to RISC-V U-Boot.
>>
>> The patches are based upon latest RISC-V U-Boot tree
>> (git://git.denx.de/u-boot-riscv.git) at commit id
>> 91882c472d8c0aef4db699d3f2de55bf43d4ae4b
>>
>> All drivers namely: SiFive PRCI, SiFive Serial, and Cadance
>> MACB Ethernet work fine on actual SiFive Unleashed board and
>> QEMU sifive_u machine.
>>
> 
> Thanks for working on this! Are you also planning on adding the
> features of the FSBL to U-Boot to remove it from the boot flow?
> 

That would also mean that adding M-mode capability in U-boot. As of now 
the expected boot flow is

ZSBL->FSBL------->BBL/OpenSBI--------->U-boot------------->Linux
(M mode from ROM)  (M mode from DRAM)  (S Mode from DRAM)  (S Mode from 
DRAM)

This is not the mandated boot flow but running the last stage boot 
loader from S-mode gives flexibility in virtualization in future.

> I was able to run U-Boot and boot Linux successfully on a SiFive HiFive
> Unleashed board with this patch series. I had to make one more change,
> because U-Boot was not able to find a serial driver and paniced as a
> result.
> 
> I fixed this by making the serial driver available pre-relocation. For
> this, the soc compatible has to be added to cpu/generic/cpu.c and the
> serial driver must have the DM_FLAG_PRE_RELOC flag set.
> 
> Another way would be to add a "stdout-path" property to the chosen node
> of the device tree.
> 

Currently, we modified the DT to add stdout-path in prior stage boot loader.

Regards,
Atish
> Thanks,
> Lukas
>