Question: SiFive U SPI and SD

Question: SiFive U SPI and SD

[Nikita Ermakov]

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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.
2) Implement spi-sd adapter in a way like the hw/sd/ssi-sd.c

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.

-- 
Thanks,
Nikita
B8 00 4C CD 21

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Re: Question: SiFive U SPI and SD

[Bin Meng]

Hi Nikita,

On Sun, Feb 9, 2020 at 10:56 PM Nikita Ermakov <arei@altlinux.org> 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.

>
> 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

Re: Question: SiFive U SPI and SD

[Alistair Francis]

On Mon, Feb 10, 2020 at 7:51 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> Hi Nikita,
>
> On Sun, Feb 9, 2020 at 10:56 PM Nikita Ermakov <arei@altlinux.org> 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
>

Re: Question: SiFive U SPI and SD

[Nikita Ermakov]

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Hello, Bin, Alistair,

Thank you for the answers!

On Thu, 13 Feb 2020 at 00:16, Alistair Francis <alistair23@gmail.com> wrote:

> 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.
>
Thanks! I will try that.

-- 
Thanks,
Nikita
B8 00 4C CD 21

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