Re: [PATCH v2] pinctrl: single: support GPIO for bits pinctrl

[Jun Nie <jun.nie@xxxxxxxxxx>]

2015-07-06 23:42 GMT+08:00 Tony Lindgren <tony@xxxxxxxxxxx>:
> * Jun Nie <jun.nie@xxxxxxxxxx> [150706 06:59]:
>> Support GPIO for one register control multiple pins case
>> with calculating register offset first, then bit offset.
>>
>> Signed-off-by: Jun Nie <jun.nie@xxxxxxxxxx>
>> ---
>>  drivers/pinctrl/pinctrl-single.c | 22 ++++++++++++++++++----
>>  1 file changed, 18 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
>> index 13b45f2..4f23ef0 100644
>> --- a/drivers/pinctrl/pinctrl-single.c
>> +++ b/drivers/pinctrl/pinctrl-single.c
>> @@ -494,7 +494,7 @@ static int pcs_request_gpio(struct pinctrl_dev *pctldev,
>>       struct pcs_device *pcs = pinctrl_dev_get_drvdata(pctldev);
>>       struct pcs_gpiofunc_range *frange = NULL;
>>       struct list_head *pos, *tmp;
>> -     int mux_bytes = 0;
>> +     int offset, mux_bytes = 0;
>>       unsigned data;
>>
>>       /* If function mask is null, return directly. */
>> @@ -507,9 +507,23 @@ static int pcs_request_gpio(struct pinctrl_dev *pctldev,
>>                       || pin < frange->offset)
>>                       continue;
>>               mux_bytes = pcs->width / BITS_PER_BYTE;
>> -             data = pcs->read(pcs->base + pin * mux_bytes) & ~pcs->fmask;
>> -             data |= frange->gpiofunc;
>> -             pcs->write(data, pcs->base + pin * mux_bytes);
>> +             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);
>> +                     data |= (frange->gpiofunc & pcs->fmask) << pin_pos;
>
> I don't quite follow you here.. The pcs->fmask is for the whole register,
> so I think the fmask should be checked the same way in this case also:
>
>                         data = pcs->read(pcs->base + offset) & ~pcs->fmask;
>                         ...
>
> I don't think we can safely assume the fmask would behave differently
> in this case.

My understanding to bits_per_mux flags here is that one 32bits
register shall control 16 pins if every pin takes 2 bits for function
config, where we shall have dts data:
"pinctrl-single,function-mask=<0x3>". In this case, pcs->fmask is 0x3
for all pins for we have only one copy of pcs->fmask in driver. If we
want to configure pin to gpio that controlled by bit[3:2], we shall
have below value set with shifting mask to clear bit[3:2] first, then
set desired value to configure it as gpio.
                    data = pcs->read(pcs->base + offset) &
~(pcs->fmask << pin_pos);
                    data = pcs->read(pcs->base + offset) & ~(0x3 << 2);

>
> Regards,
>
> Tony
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