barebox for a ti am335x based board

[Giorgio Dal Molin]

Hi,

thank you for the answer, meanwhile I also found the bootinfo
details in the ~5000 pages am335x datasheet.

Starting the second stage bootloader (barebox.bin file on the mmc)
from the MLO also works ('out of the box' actually).

giorgio

> On February 16, 2018 at 8:51 AM Sascha Hauer <s.hauer at pengutronix.de> wrote:
> 
> 
> Hi Giorgio,
> 
> On Tue, Feb 13, 2018 at 11:12:54PM +0100, Giorgio Dal Molin wrote:
> > Hi all,
> > 
> > I'm trying to add board code for an am335x based HW project.
> > I had a look at similar boards like 'boards/phytec-som-am335x'
> > or 'boards/beaglebone'.
> > I understand that I need two images: the (little) MLO and the
> > (bigger) barebox.
> > 
> > What it's not really clear is how the MLO loads and starts the
> > barebox.
> 
> See arch/arm/mach-omap/xload.c. It is compiled when no shell is enabled
> (I think at least for clarity there should be a separate Kconfig
> symbol). In this file omap_xload() detects where the SoC has booted from
> and loads the full barebox from the same source.
> 
> > 
> > Moreover I saw there's always a call to:
> > 
> >  am33xx_save_bootinfo((void *)bootinfo);
> > 
> > in the MLO lowlevel entry function; I suspect the argument
> > 'bootinfo' is the register r0 left by the function __barebox_arm_head()
> > but I cannot really understand the logic behind it.
> 
> When the am335x ROM passes control to the bootloader then it passes in
> R0 a pointer to the bootinfo. This is a three word structure which has
> informations where the SoC has booted from. In am33xx_save_bootinfo() we
> copy the information to a known place where we can pick it up later, see
> am33xx_bootsource().
> 
> Sascha
> 
> 
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