[U-Boot] reinitialize peripherals

[U-Boot] reinitialize peripherals

[Fundu]

I have a PPC440GX based board.

Do I need to reinitialize Peripheral Bank Configuration Registers (EBC0_B0CR-EBC0_B7CR) from the kernel ?
I'm quite sure that we don't, but just want to make sure. Because the problem
that i'm seeing strongly suggest that something isn't initializing. 

Here's the problem i'm getting a kernel "kernel access of bad
 area" when i erase flash region, surprisingly i can easily erase it from u-boot. which makes me ask the earlier question.   

any insights welcome.

thanks ! 


      

[U-Boot] reinitialize peripherals

[vb]

On Tue, Aug 26, 2008 at 8:06 PM, Fundu <fundu_1999@yahoo.com> wrote:
> I have a PPC440GX based board.
>
> Do I need to reinitialize Peripheral Bank Configuration Registers (EBC0_B0CR-EBC0_B7CR) from the kernel ?
> I'm quite sure that we don't, but just want to make sure. Because the problem
> that i'm seeing strongly suggest that something isn't initializing.
>
> Here's the problem i'm getting a kernel "kernel access of bad
>  area" when i erase flash region, surprisingly i can easily erase it from u-boot. which makes me ask the earlier question.
>

The problem is that the kernel needs to ioremap the areas you are
trying to access (this includes flash, BTW). How it gets the
information about the address ranges is the tricky part: it comes from
the device tree, (unless you are building your kernel from arch/ppc).
There are a lot of examples in arch/powerpc/boot/dts.

Also, keep in mind that on ppc460  (I am not sure if 440gx is the
same, but it might be) the addresses of  the peripherals driven by CSs
have nonzero nibble in four MSBs of the 36 bit address, so phys_addr_t
is 64 bits in size.

good luck.
/vb



> any insights welcome.
>
> thanks !
>
>
>
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
>

[U-Boot] reinitialize peripherals

[Stefan Roese]

On Wednesday 27 August 2008, vb wrote:
> > Do I need to reinitialize Peripheral Bank Configuration Registers
> > (EBC0_B0CR-EBC0_B7CR) from the kernel ? I'm quite sure that we don't, but
> > just want to make sure. Because the problem that i'm seeing strongly
> > suggest that something isn't initializing.
> >
> > Here's the problem i'm getting a kernel "kernel access of bad
> >  area" when i erase flash region, surprisingly i can easily erase it from
> > u-boot. which makes me ask the earlier question.
>
> The problem is that the kernel needs to ioremap the areas you are
> trying to access (this includes flash, BTW). How it gets the
> information about the address ranges is the tricky part: it comes from
> the device tree, (unless you are building your kernel from arch/ppc).
> There are a lot of examples in arch/powerpc/boot/dts.
>
> Also, keep in mind that on ppc460  (I am not sure if 440gx is the
> same, but it might be) the addresses of  the peripherals driven by CSs
> have nonzero nibble in four MSBs of the 36 bit address, so phys_addr_t
> is 64 bits in size.

Yes. And the upper 4bits are usually non-zero for EBC space on 44x. The 
address used in U-Boot is a virtual 32bit address where the lower 32bits 
(when possible) match the lower 32bits of the 36bit physical address.

Best regards,
Stefan

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[U-Boot] reinitialize peripherals

[Fundu]

> The problem is that the kernel needs to ioremap the areas
> you are

i'm calling ioremap from linux/driver/mtd/maps/physmap.c and  int __init init_physmap(void) 

> the
> information about the address ranges is the tricky part: it
> comes from
> the device tree, (unless you are building your kernel from
> arch/ppc).
> There are a lot of examples in arch/powerpc/boot/dts.
> 

forgot to mention i'm using u-boot-1.2.0 and kernel 2.4.20, and i think it doesn't use the device trees.

what's interesting is I can erase any of the first 64mb, its only while operating on the other 64mb that i get the error. And as mentioned earlier from u-boot i can easily erase the whole flash.

> Also, keep in mind that on ppc460  (I am not sure if 440gx
> is the
> same, but it might be) the addresses of  the peripherals
> driven by CSs
> have nonzero nibble in four MSBs of the 36 bit address, so
> phys_addr_t
> is 64 bits in size.

yeah that right. 
how do i figure what the four MSBs of the 36 bit address should be ?
I know from u-boot i can use CFG_FLASH_BASE. 
what should it be from kernel ?

thanks vb your response was informative.
 



      

[U-Boot] reinitialize peripherals

[Fundu]

> i'm calling ioremap from
> linux/driver/mtd/maps/physmap.c and  int __init
> init_physmap(void) 
> 
i think i found what the problem is. stupid fault the size was incorrect in the map_info structure's .size set to 64mb instead of 128mb and that's why i couldn't work with the upper 64mb.

will try tomorrow. 

goodnight & thank you all.