Re: [PATCH] pinctrl: single: support GPIO for bits pinctrl

[Tony Lindgren <tony@xxxxxxxxxxx>]

* Jun Nie <jun.nie@xxxxxxxxxx> [150706 01:43]:
> 2015-06-23 18:18 GMT+08:00 Jun Nie <jun.nie@xxxxxxxxxx>:
> > 2015-06-23 18:14 GMT+08:00 Tony Lindgren <tony@xxxxxxxxxxx>:
> >> * Jun Nie <jun.nie@xxxxxxxxxx> [150623 02:56]:
> >>> 2015-06-17 15:17 GMT+08:00 Tony Lindgren <tony@xxxxxxxxxxx>:
> >>> > * Jun Nie <jun.nie@xxxxxxxxxx> [150616 18:58]:
> >>> >> +             if (pcs->bits_per_mux) {
> >>> >> +                     int pin_pos, byte_num, num_pins_in_register;
> >>> >> +
> >>> >> +                     num_pins_in_register = pcs->width / pcs->bits_per_pin;
> >>> >> +                     byte_num = (pcs->bits_per_pin * pin) / BITS_PER_BYTE;
> >>> >> +                     offset = (byte_num / mux_bytes) * mux_bytes;
> >>> >> +                     pin_pos = pin % num_pins_in_register;
> >>> >> +                     pin_pos *= pcs->bits_per_pin;
> >>> >> +                     data = pcs->read(pcs->base + offset) &
> >>> >> +                             ~(pcs->fmask << pin_pos);
> >>> >
> >>> > Should you check the pcs->fmask here too in case some bits are reserved?
> >>> >
> >>> Did not catch your idea? Those bits set in fmask are dedicated for one
> >>> pin mux control and should be clear before set as desired value per my
> >>> understanding. Do you mean some bits may be reserved and not for any
> >>> function?
> >>
> >> Right, can you please check that we don't try to write to reserved
> >> bits in the hardawre if the mask is set?
>
> > Then I have question that how can I know what bits is for function
> > mask, what bits are for reserved? Do we have any other value to
> > indicate it? I did not find it in one register for one pin mux case.
> 
> Could you help elaborate this? Thanks!

We can only write to the bits specified in pinctrl-single,function-mask.

Regards,

Tony
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