[U-Boot] [PATCH] ns16550: allow UART address to be set dynamically

[Stephen Warren]

On 12/13/2012 03:29 AM, Wolfgang Denk wrote:
> Dear Stephen Warren,
> 
> In message <50C918A5.6090207 at wwwdotorg.org> you wrote:
>>
>>> This seems reasonable in the interim while we are hard-coding things
>>> but needing more flexibility. How do you plan to configure the actual
>>> address - is it with the ODM data or FDT?
>>
>> I intend to use the ODMDATA. This already includes a field that
>> specifies which UART to use. I'm working on some patches (to
>> BCT-generation tools and U-Boot) that define an ODMDATA2 value, which
>> will indicate the complete pinmux configuration required for the UART,
>> so everything can be self-contained. I'm fairly close to publishing
>> these patches.
> 
> Arghh... Do we really, really have to invent yet another way to pass
> hardware configuration information?  Especially one totally
> incompatible to any other system?

This is a special case for the console UART. The idea is to get that up
and running well before device tree is parsed in any way. For example,
Tegra's SPL doesn't touch the device tree in any way (or even know one
exists) but does want to print (possibly error) messages in a generic
fashion. Similarly, many problems could occur before the device tree is
parsed (e.g. the user forgets to provide one...), and having
specifically the console UART set up before that allows those errors to
be reported, rather than requiring a JTAG or similar debugger.

My intent is that ODMDATA will definitely only be used for the console
UART, and will NOT be used for anything else like LCD, RTC, ... Those
other devices will certainly be configured via device tree.