Re: Question: SiFive U SPI and SD

[Alistair Francis]

On Mon, Feb 10, 2020 at 7:51 AM Bin Meng <address@hidden> wrote:
>
> Hi Nikita,
>
> On Sun, Feb 9, 2020 at 10:56 PM Nikita Ermakov <address@hidden> wrote:
> >
> > Hello!
> >
> > I am trying to make an SD card working on the sifive_u 
> > (hw/riscv/sifive_u.c) SoC machine.
> > As far as I understand there is no way to connect an SD card to the SoC 
> > with cmdline for now. So, I started to dig in to the QEMU internals and 
> > especially sifive_u SoC implementation to try to understand how I could 
> > connect SD card to this SoC.
> >
> > From what I understood I need to:
> > 1) Implement SiFive U SPI controller.
>
> This one is definitely needed.
>
> > 2) Implement spi-sd adapter in a way like the hw/sd/ssi-sd.c
>
> I believe we can just use hw/sd/ssi-sd.c.

I had a crack at this awhile ago and you can see the patches here (I
just rebased them):
https://github.com/alistair23/qemu/tree/mainline/alistair/sifive_spi.next

Debugging failures was really hard in Linux, but now that U-Boot and
Oreboot (https://github.com/oreboot/oreboot/pull/234) have SPI support
it is probably easier to debug.

If you wanted to help you could try to debug that branch and figure
out why it isn't working.

Alistair

>
> >
> > Probably I should merge 1) and 2) into one hw/riscv/sifive_u_spi.c source 
> > file.
> >
> > Could somebody correct me please if I am wrong at some point?
> > I am newbie in the QEMU internals :)
> >
> > The purpose is why I want to implement this is to boot up the Linux kernel 
> > on '-machine sifive_u' and load rootfs from SD.
>
> Regards,
> Bin
>