[U-Boot] write to mcBsp address space

[Aneesh V <aneesh@ti.com>]

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