[PATCH 05/14] ARM: at91: add pinctrl support

[Jean-Christophe PLAGNIOL-VILLARD]

On 11:49 Thu 23 Aug     , Stephen Warren wrote:
> On 08/23/2012 01:06 AM, Richard Genoud wrote:
> > 2012/8/22 Stephen Warren <swarren at wwwdotorg.org>:
> >>>> +Required properties for iomux controller:
> >>>> +- compatible: "atmel,at91rm9200-pinctrl"
> >>>> +- atmel,mux-mask: array of mask (periph per bank) to describe if a pin can be
> >>>> +  configured in this periph mode. All the periph and bank need to be describe.
> >>>
> >>> Can you please be more elaborate on this mux-mask, like what each bit
> >>> means and why the bits are arranged like that and what it means on the
> >>> AT91 platform.... I was first reading the .dts and was like ?woot? so
> >>> I go to the bindings doc and I read this and I'm still like ?woot?..
> >>
> >> Yes, I'm a little confused what this is, and wouldn't have a clue how to
> >> fill it in.
> >
> > With a practical example it's easier to understand.
> > Take a SAM9X5 release manual (here is sam9g35):
> > http://www.atmel.com/Images/doc11053.pdf page 11 (§4.3 package pinout)
> > in the file arch/arm/boot/dts/at91sam9x5.dtsi you've got the the
> > atmel,mux-mask like that:
> >
> > /* periphA  periphB    periphC     */
> > 0xffffffff 0xffe0399f 0xc000001c  /* pioA */
> > 0x0007ffff 0x8000fe3f 0x00000000  /* pioB */
> > 0x80000000 0x07c0ffff 0xb83fffff  /* pioC */
> > 0x003fffff 0x003f8000 0x00000000  /* pioD */
> > 
> > Let's take the PioA - peripheral B: 0xffe0399f
> > From the documentation table 4-3, we can extract the column PIO
> > Periperal B for all signals PA0-PA31:
> ...
> > Each time it's possible to mux a pin to the peripheral B function (ie
> > when there's no "-----") the corresponding bit is set:
> ...
> > => this gives 0x399f
> 
> Ah OK. It would be a good idea to briefly describe this process in the
> binding document I think. I assume this property exists to avoid the
> kernel driver having to contain tables for each Atmel device; the driver
> is generic.
Yeap I did this exactly for this

I do not want to maintain such code for the whole bunch of at91
and this way I add other SoC with just via dtsi without touching c code

I think other driver should do so too

Best Regards,
J.