New dt-only arm/mach

New dt-only arm/mach

[Alexander Shiyan]

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 Hello All.

I want to add new arch into barebox. n the kernel this arch is dt-only.
I talking about mach-sunxi. So, how we should handle such platform
in the barebox? We need always provide dtb to the kernel, then where
it should be in barebox?
I think about dtb-file in /env, but not sure...
Thanks.

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Re: New dt-only arm/mach

[Sascha Hauer]

Hi Alexander,

On Sun, Mar 10, 2013 at 06:13:43PM +0400, Alexander Shiyan wrote:
>  Hello All.
> 
> I want to add new arch into barebox. n the kernel this arch is dt-only.
> I talking about mach-sunxi. So, how we should handle such platform
> in the barebox? We need always provide dtb to the kernel, then where
> it should be in barebox?

You asked me privatly whether we should put dtc and friends into
barebox, by that time I answered it needs some more time. Maybe this
time has come now. I currently have a branch in the making to add dtc
support and also integration into barebox.

With this we are able to compile a dts(p) and link the binary into
barebox, so...

> I think about dtb-file in /env, but not sure...

...you could provide a dtb in the binary *)

Furthermore you could probe barebox itself from the devicetree.

I'm still not sure whether we should add fullblown devicetrees into
barebox or stripped down versions with only the devices barebox needs.
I think time will tell.

Give me some hours time, I think then I can post a first version of the
patches.

Sascha


*) This of course shouldn't mean it can't be overwritten with another
dtb during runtime.

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
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Re[2]: New dt-only arm/mach

[Alexander Shiyan]

> Hi Alexander,
> 
> On Sun, Mar 10, 2013 at 06:13:43PM +0400, Alexander Shiyan wrote:
> >  Hello All.
> > 
> > I want to add new arch into barebox. n the kernel this arch is dt-only.
> > I talking about mach-sunxi. So, how we should handle such platform
> > in the barebox? We need always provide dtb to the kernel, then where
> > it should be in barebox?
> 
> You asked me privatly whether we should put dtc and friends into
The previous question was about the architecture that can be loaded
without dtb. Now a little another. :)

> barebox, by that time I answered it needs some more time. Maybe this
> time has come now. I currently have a branch in the making to add dtc
> support and also integration into barebox.
> 
> With this we are able to compile a dts(p) and link the binary into
> barebox, so...
> 
> > I think about dtb-file in /env, but not sure...
> 
> ...you could provide a dtb in the binary *)
> 
> Furthermore you could probe barebox itself from the devicetree.
> 
> I'm still not sure whether we should add fullblown devicetrees into
> barebox or stripped down versions with only the devices barebox needs.
> I think time will tell.
> 
> Give me some hours time, I think then I can post a first version of the
> patches.

OK. Np. I just want to tell that we already have dt-only archs.

> 
> *) This of course shouldn't mean it can't be overwritten with another
> dtb during runtime.

Or provide dts in /env and compile it in runtime.

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Re: New dt-only arm/mach

[Maxime Ripard]

Hi Alexander,

Le 10/03/2013 15:13, Alexander Shiyan a écrit :
> Hello All.
> 
> I want to add new arch into barebox. n the kernel this arch is
> dt-only. I talking about mach-sunxi.

Wow, that would be great :)

I've been thinking about doing this for quite some time now, but I don't
have so much time to do both the kernel and barebox ports, so it didn't
go further than "it would be cool".

> So, how we should handle such platform in the barebox? We need always
> provide dtb to the kernel, then where it should be in barebox?

There's no strong requirements here. It can be anywhere as long as
barebox knows how and where to find it, basically like the kernel image,
so it can be from a MMC, TFTP, etc.

But really, the fact that sunxi is only bootable through device tree
doesn't change a thing compared to other platforms with device tree
support: the bootloader has to load the kernel image, the dtb and that's it.

> I think about dtb-file in /env, but not sure... Thanks.

It can be done as well I guess, but that doesn't sound that familiar
from what I've seen in the other barebox boards.

Maxime

-- 
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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Re: New dt-only arm/mach

[Jean-Christophe PLAGNIOL-VILLARD]

On 18:13 Sun 10 Mar     , Alexander Shiyan wrote:
>    Hello All.
> 
>    I want to add new arch into barebox. n the kernel this arch is dt-only.
>    I talking about mach-sunxi. So, how we should handle such platform
>    in the barebox? We need always provide dtb to the kernel, then where
>    it should be in barebox?
>    I think about dtb-file in /env, but not sure...

sama5, sama9x5, sam9n12 are pure DTB kernel

Calxeda Highbank is pure DT with barebox dt probe

Best Regards,
J.
>    Thanks.
> 
>    ---

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Re[2]: New dt-only arm/mach

[Alexander Shiyan]

> Le 10/03/2013 15:13, Alexander Shiyan a écrit :
> > Hello All.
> > 
> > I want to add new arch into barebox. n the kernel this arch is
> > dt-only. I talking about mach-sunxi.
> 
> Wow, that would be great :)
> 
> I've been thinking about doing this for quite some time now, but I don't
> have so much time to do both the kernel and barebox ports, so it didn't
> go further than "it would be cool".
> 
> > So, how we should handle such platform in the barebox? We need always
> > provide dtb to the kernel, then where it should be in barebox?
> 
> There's no strong requirements here. It can be anywhere as long as
> barebox knows how and where to find it, basically like the kernel image,
> so it can be from a MMC, TFTP, etc.
> 
> But really, the fact that sunxi is only bootable through device tree
> doesn't change a thing compared to other platforms with device tree
> support: the bootloader has to load the kernel image, the dtb and that's it.
> 
> > I think about dtb-file in /env, but not sure... Thanks.
> 
> It can be done as well I guess, but that doesn't sound that familiar
> from what I've seen in the other barebox boards.

Kernel no contain any board for mach-sunxi.
This mean than all stuff is described via DT.
In the barebox we should have "mach" & "board", so I think we
should create empty (fake) board for architectures like this.
Any other opinions?

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Re: New dt-only arm/mach

[Maxime Ripard]

Hi,

Le 12/03/2013 18:50, Alexander Shiyan a écrit :
>> Le 10/03/2013 15:13, Alexander Shiyan a écrit :
>> It can be done as well I guess, but that doesn't sound that familiar
>> from what I've seen in the other barebox boards.
> 
> Kernel no contain any board for mach-sunxi.
> This mean than all stuff is described via DT.
> In the barebox we should have "mach" & "board", so I think we
> should create empty (fake) board for architectures like this.

Yes, thanks, I'm pretty familiar with the kernel code for mach-sunxi...

Barebox is not the kernel. And there's already a number of other
architectures that are supported in barebox that boot a kernel that
supports only the device tree, like Jean-Christophe said, such as imx,
mxs, highbank, at91, etc...

So, really, there's nothing fancy about supporting an architecture which
*kernel* requires device tree.

Maxime

-- 
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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Re: New dt-only arm/mach

[Sascha Hauer]

On Tue, Mar 12, 2013 at 09:50:26PM +0400, Alexander Shiyan wrote:
> > > I think about dtb-file in /env, but not sure... Thanks.
> > 
> > It can be done as well I guess, but that doesn't sound that familiar
> > from what I've seen in the other barebox boards.
> 
> Kernel no contain any board for mach-sunxi.
> This mean than all stuff is described via DT.
> In the barebox we should have "mach" & "board", so I think we
> should create empty (fake) board for architectures like this.
> Any other opinions?

Where would you put the SDRAM setup then?

I think it shouldn't be a problem to change barebox to compile
without a board directory if you really don't need one, but I assume
some board specific code will be left.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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Re[2]: New dt-only arm/mach

[Alexander Shiyan]

> On Tue, Mar 12, 2013 at 09:50:26PM +0400, Alexander Shiyan wrote:
> > > > I think about dtb-file in /env, but not sure... Thanks.
> > > 
> > > It can be done as well I guess, but that doesn't sound that familiar
> > > from what I've seen in the other barebox boards.
> > 
> > Kernel no contain any board for mach-sunxi.
> > This mean than all stuff is described via DT.
> > In the barebox we should have "mach" & "board", so I think we
> > should create empty (fake) board for architectures like this.
> > Any other opinions?
> 
> Where would you put the SDRAM setup then?

I do not know yet :) Development at planning stage. There are many
questions that I am trying to solve. It seems that in order to start, I make
a fixed load initially, and then I will try to use the options from DT.

> I think it shouldn't be a problem to change barebox to compile
> without a board directory if you really don't need one, but I assume
> some board specific code will be left.

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