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

[Jun Nie <jun.nie@xxxxxxxxxx>]

2015-07-06 17:03 GMT+08:00 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.
>
I see, you want below mask to make sure gpiofunc value does not exceed
expected bits though it should be safe if dts data is correct. Right?
+                       data = pcs->read(pcs->base + offset) &
+                               ~(pcs->fmask << pin_pos);
+                       data |= (pcs->fmask & frange->gpiofunc) << pin_pos;

> Regards,
>
> Tony
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