kwboot: Marvell Dove UART booting

[Tony Dinh]

Hi Pali

On Sat, Jan 1, 2022 at 3:12 PM Pali Rohár <pali at kernel.org> wrote:
>
> On Saturday 01 January 2022 14:54:34 Tony Dinh wrote:
> > Hi Pali,
> >
> > On Sat, Jan 1, 2022 at 1:53 PM Pali Rohár <pali at kernel.org> wrote:
> > >
> > > On Sunday 26 December 2021 13:41:03 Tony Dinh wrote:
> > > > Follow up on the UART booting session before.
> > > >
> > > > Thanks for the advice about the Reset Strapping documentation. I've
> > > > extracted the attachment 88AP510_Reset_Strapping.xls from the HW Spec
> > > > for Dove at:
> > > > https://www.kernel.org/doc/html/latest/arm/marvell.html
> > > >
> > > > Listed below are the Boot Modes that are relevant to this subject
> > > > (there are other Boot Modes for SATA, NAND but we are not interested
> > > > in those):
> > > >
> > > > 0x00 Direct boot from SPI
> > > > 0x01 Boot from SPI with 3 address cycles
> > > > 0x02 Boot from SPI with 4 address cycles
> > > > 0x0E Boot from UART0 using Xmodem
> > > > 0x0F Boot from UART1 using Xmodem
> > > > 0x10 Open BootROM debug prompt on UART0
> > > > 0x11 Open BootROM debug prompt on UART1
> > > >
> > > > So it does look like the jumper on this HP T5335z is actually to put
> > > > the box into BootROM debug mode using 0x10. And from there, we can use
> > > > 0x0E to put the BootROM into UART0 booting mode.
> > > >
> > > > Oddly, I've also tried booting from SPI while at the BootROM debug
> > > > prompt, but have not been successful with either 0x00, 0x01, or 0x02.
> > > > I was hoping that it would make testing easier if I could run "Boot
> > > > from SPI" to boot into Linux without having to remove the jumper.
> > >
> > > And which hex mode is activated when jumper is not set to that Debug
> > > prompt UART mode? You should be able to check current mode by reading
> > > 0xD00D0214 address which should contain latched sample at reset value.
> > > E.g. in U-Boot by 'md 0xD00D0214 1' command.
> >
> > Without the jumper inserted, it was set to 0x00.
> >
> > HP>> md 0xD00D0214 1
> > d00d0214: 00000000    ....
>
> Sample at reset register should not be zero. So it is located at
> different address. You could try to look into the functional
> specification...

It must have been the liquor yesterday :) of course there are other
settings in this register... it cannot be zero.

>
> Maybe internal registers are at space 0xf1000000? Then register is 0xf10d0214

I think 0xf1000000 is more like it. I've double checked, the Kirkwood
SatR is 0xF1010030.

Functional Spec:
"The BootROM firmware is located on the device’s Read Only Memory
(ROM), and is executed according to the sample at reset configuration
bits[4:0] in the Sample at Reset 0 Register (Table 976 p. 959)"

HP>> md f10D0214 1
f10d0214: b40a24a1    .$..

So it looks like the boot mode is 00001?

Thanks,
Tony