[U-Boot] write to mcBsp address space

[U-Boot] write to mcBsp address space

[Ran Shalit]

Hello,

I'm working on OMAPL138 EVM board, with the U-BOOT.
I'm trying to access and write into the register (which have write bits),
but I always read 0 in all the map space of the mcBSP0 and mcBSP1.
(0x01d10000 - 0x1d10800, 0x01d11000 - 0x1d11800).
I wonder what I missed here. any ideas are welcomed.

Thank you very much,

Ran

[U-Boot] write to mcBsp address space

[Albert ARIBAUD]

Hi Ran,

Le 15/02/2011 07:35, Ran Shalit a ?crit :
> Hello,
>
> I'm working on OMAPL138 EVM board, with the U-BOOT.
> I'm trying to access and write into the register (which have write bits),
> but I always read 0 in all the map space of the mcBSP0 and mcBSP1.
> (0x01d10000 - 0x1d10800, 0x01d11000 - 0x1d11800).
> I wonder what I missed here. any ideas are welcomed.

Many SoCs have "base address registers" that allow remapping internal or 
peripheral registers anywhere in the address space, which means the 
actual address you're trying to get at might not be the right one. Did 
you check the BAR(s) and make sure the mcBsp address you're targetting 
is the right one for your board?

> Thank you very much,
>
> Ran

Amicalement,
-- 
Albert.

[U-Boot] write to mcBsp address space

[Ran]

Albert ARIBAUD <albert.aribaud <at> free.fr> writes:

> 
> Hi Ran,
> 
> Le 15/02/2011 07:35, Ran Shalit a ?crit :
> > Hello,
> >
> > I'm working on OMAPL138 EVM board, with the U-BOOT.
> > I'm trying to access and write into the register (which have write bits),
> > but I always read 0 in all the map space of the mcBSP0 and mcBSP1.
> > (0x01d10000 - 0x1d10800, 0x01d11000 - 0x1d11800).
> > I wonder what I missed here. any ideas are welcomed.
> 
> Many SoCs have "base address registers" that allow remapping internal or 
> peripheral registers anywhere in the address space, which means the 
> actual address you're trying to get at might not be the right one. Did 
> you check the BAR(s) and make sure the mcBsp address you're targetting 
> is the right one for your board?
> 
> > Thank you very much,
> >
> > Ran
> 
> Amicalement,

Hello Albert,

Thank you very much for your reply.
I've checked the datasheet but I see no reference to base address registers 
for the mcBSP.

mcBSP: http://www.ti.com/litv/pdf/sprugj6c
OMAPL138: http://www.ti.com/lit/gpn/omap-l138

thanks again,

Ran

[U-Boot] write to mcBsp address space

[Albert ARIBAUD]

Le 15/02/2011 09:21, Ran a ?crit :
> Albert ARIBAUD<albert.aribaud<at>  free.fr>  writes:
>
>>
>> Hi Ran,
>>
>> Le 15/02/2011 07:35, Ran Shalit a ?crit :
>>> Hello,
>>>
>>> I'm working on OMAPL138 EVM board, with the U-BOOT.
>>> I'm trying to access and write into the register (which have write bits),
>>> but I always read 0 in all the map space of the mcBSP0 and mcBSP1.
>>> (0x01d10000 - 0x1d10800, 0x01d11000 - 0x1d11800).
>>> I wonder what I missed here. any ideas are welcomed.
>>
>> Many SoCs have "base address registers" that allow remapping internal or
>> peripheral registers anywhere in the address space, which means the
>> actual address you're trying to get at might not be the right one. Did
>> you check the BAR(s) and make sure the mcBsp address you're targetting
>> is the right one for your board?
>>
>>> Thank you very much,
>>>
>>> Ran
>>
>> Amicalement,
>
> Hello Albert,
>
> Thank you very much for your reply.
> I've checked the datasheet but I see no reference to base address registers
> for the mcBSP.
>
> mcBSP: http://www.ti.com/litv/pdf/sprugj6c
> OMAPL138: http://www.ti.com/lit/gpn/omap-l138

Evidently the mcBsp specs won't tell you how the device is mapped within 
a given SoC. As for the OMAPL138 SoC, it looks more like an overview. 
You would need to refer to a detailed spec, one with register level 
description of the module.

> thanks again,
>
> Ran

Amicalement,
-- 
Albert.

[U-Boot] write to mcBsp address space

[Ran]

Albert ARIBAUD <albert.aribaud <at> free.fr> writes:


> 
> Evidently the mcBsp specs won't tell you how the device is mapped within 
> a given SoC. As for the OMAPL138 SoC, it looks more like an overview. 
> You would need to refer to a detailed spec, one with register level 
> description of the module.
> 

the mcBSP link above has a detailed description of the registers in the mcBSP 
module, but it does not refer to base address register. it is interesting to 
note that in the UART case I have no suce problem. The UART's and mcBSP are 
quite similiar. 

Regards,

Ran

[U-Boot] write to mcBsp address space

[Albert ARIBAUD]

Le 15/02/2011 12:50, Ran a ?crit :
> Albert ARIBAUD<albert.aribaud<at>  free.fr>  writes:
>
>
>>
>> Evidently the mcBsp specs won't tell you how the device is mapped within
>> a given SoC. As for the OMAPL138 SoC, it looks more like an overview.
>> You would need to refer to a detailed spec, one with register level
>> description of the module.
>
> the mcBSP link above has a detailed description of the registers in the mcBSP
> module, but it does not refer to base address register.

Yes, that's what I wrote above. The base address register mapping the 
mcBsp at a given address would be described in the detailed spec of the 
SoC, the one with all registers.

> it is interesting to
> note that in the UART case I have no suce problem. The UART's and mcBSP are
> quite similiar.

Indeed, but this does not mean they are mapped the same way. You can 
only tell by looking at the detailed register map of the SoC.

> Regards,
>
> Ran

Amicalement,
-- 
Albert.

[U-Boot] write to mcBsp address space

[Aneesh V]

Hello Ran,

On Tuesday 15 February 2011 04:05 PM, Albert ARIBAUD wrote:
> Le 15/02/2011 09:21, Ran a ?crit :
>> Albert ARIBAUD<albert.aribaud<at>   free.fr>   writes:
>>
>>>
>>> Hi Ran,
>>>
>>> Le 15/02/2011 07:35, Ran Shalit a ?crit :
>>>> Hello,
>>>>
>>>> I'm working on OMAPL138 EVM board, with the U-BOOT.
>>>> I'm trying to access and write into the register (which have write bits),
>>>> but I always read 0 in all the map space of the mcBSP0 and mcBSP1.
>>>> (0x01d10000 - 0x1d10800, 0x01d11000 - 0x1d11800).
>>>> I wonder what I missed here. any ideas are welcomed.
>>>
>>> Many SoCs have "base address registers" that allow remapping internal or
>>> peripheral registers anywhere in the address space, which means the
>>> actual address you're trying to get at might not be the right one. Did
>>> you check the BAR(s) and make sure the mcBsp address you're targetting
>>> is the right one for your board?
>>>
>>>> Thank you very much,
>>>>
>>>> Ran
>>>
>>> Amicalement,
>>
>> Hello Albert,
>>
>> Thank you very much for your reply.
>> I've checked the datasheet but I see no reference to base address registers
>> for the mcBSP.
>>
>> mcBSP: http://www.ti.com/litv/pdf/sprugj6c
>> OMAPL138: http://www.ti.com/lit/gpn/omap-l138
>
> Evidently the mcBsp specs won't tell you how the device is mapped within
> a given SoC. As for the OMAPL138 SoC, it looks more like an overview.
> You would need to refer to a detailed spec, one with register level
> description of the module.

I have no idea about this particular OMAP SoC. But OMAPs in general do
not have the concept of base address register.

One typical issue is that the module in question may not be clocked. So
reads or writes to memory mapped IO locations in the module will fail.
However, if this is the case it would typically generate a data abort.

How about viewing this memory using a JTAG debugger?

br,
Aneesh

[U-Boot] write to mcBsp address space

[Bedia, Vaibhav]

On Tuesday, February 15, 2011 12:05 PM, Ran Shalit wrote:
> Hello,
> 
> I'm working on OMAPL138 EVM board, with the U-BOOT.
> I'm trying to access and write into the register (which have
> write bits), but I always read 0 in all the map space of the
> mcBSP0 and mcBSP1. (0x01d10000 - 0x1d10800, 0x01d11000 -
> 0x1d11800).  
> I wonder what I missed here. any ideas are welcomed.
> 
> Thank you very much,
> 
> Ran

Only the modules which are necessary are enabled in U-Boot. Most likely McBSP is not one of those. 

You can check how other modules are enabled for da8xx and modify the code appropriately for experimentation.

If you have further queries on the McBSP in specific please post them on the TI E2E community http://e2e.ti.com in the appropriate forum.

Regards,
Vaibhav