[U-Boot] [PATCH 2/3] arm: mx6: tqma6: Update to optionally configure an alternative SPI setup

[Markus Niebel <list-09_u-boot@tqsc.de>]

Hello Stefan,
Am 12.03.2015 um 16:18 schrieb Stefan Roese:
> Hi Markus,
> 
> On 12.03.2015 15:25, Markus Niebel wrote:
>> Am 12.03.2015 um 13:34 schrieb Stefan Roese:
>>> By making the tqma6_iomuxc_spi() weak, this patch adds the possibility to
>>> add a different function for this SPI configuration. This can be used
>>> by other baseboards, that might have a different SPI setup.
>>>
>>> This patch will be used by the upcoming WRU-IV board support which also
>>> uses the TQMa6 SoM.
>>>
>>> Signed-off-by: Stefan Roese <sr@denx.de>
>>> ---
>>>   board/tqc/tqma6/tqma6.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/board/tqc/tqma6/tqma6.c b/board/tqc/tqma6/tqma6.c
>>> index c9e163e..29db838 100644
>>> --- a/board/tqc/tqma6/tqma6.c
>>> +++ b/board/tqc/tqma6/tqma6.c
>>> @@ -145,7 +145,7 @@ static unsigned const tqma6_ecspi1_cs[] = {
>>>       TQMA6_SF_CS_GPIO,
>>>   };
>>>
>>> -static void tqma6_iomuxc_spi(void)
>>> +__weak void tqma6_iomuxc_spi(void)
>>>   {
>>>       unsigned i;
>>>
>> When implementing an baseboard specific init handler, we will get
>> a warning about unused
>> tqma6_ecspi1_pads and tqma6_ecspi1_cs, or did I miss something?
> 
> I'm not getting one with the current (unfinished) WRU4 baseboard. Which has no SPI.
> 
Oops, not understand the weak mechanism completely - compiler sees usage of data
in weak function but linker selects function from baseboard - correct?
If this is the case, we have only the duplication of IOMUX and CS gpio.

>> Just as a thought (not ready): Could we supply CS initialisation
>> data via defines in the
>> baseboard config header and append it to the tables if needed?
> 
> Not sure if I understand this correctly. Could you give an example? Again, my current baseboard has no SPI at all.
> 

tqma6_iomux_spi is for the SPI controller the serial nor is connected,
so baseboard specific data are additional CS.

You could solve the data duplication using 

#define TQMA6_BB_ECSPI1_CS_GPIO	IMX_GPIO_NR(n, mm),
#define TQMA6_BB_CS_PAD_CTRL	NEW_PAD_CTRL(MX6_PAD_bla__GPIOn, IOmm, <PAD_CTRL)

and in the board file:

if !defined(TQMA6_BB_ECSPI1_CS_GPIO)
#define TQMA6_BB_ECSPI1_CS_GPIO
#endif

static unsigned const tqma6_ecspi1_cs[] = {
       TQMA6_SF_CS_GPIO,
       TQMA6_BB_ECSPI1_CS_GPIO	
};

But OK, this looks not very nice

As I said, not completely ready, but would prevent some code duplication.

> Thanks,
> Stefan
>