Re: [PATCH v2 02/17] regmap-irq: Add get_irq_reg to support unusual register layouts

[Matti Vaittinen]

Hi dee Ho peeps!

Sorry for the late reply.

pe 10. kesäk. 2022 klo 18.43 Aidan MacDonald
(aidanmacdonald.0x0@xxxxxxxxx) kirjoitti:
>
> Mark Brown <broonie@xxxxxxxxxx> writes:
>
> > On Tue, Jun 07, 2022 at 04:53:09PM +0100, Aidan MacDonald wrote:
> >
> >> -    if (!chip->sub_reg_offsets || !chip->not_fixed_stride) {
> >> +    if (chip->get_irq_reg) {
> >> +            reg = chip->get_irq_reg(base_reg, i);
> >> +    } else if (!chip->sub_reg_offsets || !chip->not_fixed_stride) {
> >
> > It seems like it would be cleaner and clearer to refactor things so that
> > we always have a get_irq_reg() with standard chips getting given a
> > default implementation which implements the current behaviour.
>
> I don't think that is a good way to clean things up. I only intended
> get_irq_reg() to be a quick hack to solve a problem; in my opinion it
> would be a poor abstraction to base the API around.
>
> What I'd suggest is something that will simplify regmap-irq. Instead of
> defining the base registers, etc. in the chip, introduce a new struct
> to describe a register group:
>
>     struct regmap_irq_reg_group {
>         unsigned int status_base;
>         unsigned int mask_base;
>         ...
>
>         unsigned int irq_reg_stride;
>
>         int num_regs;
>     };
>
> The idea is that the registers in a group are linearly mapped using the
> formula "base + (i * irq_reg_stride)". Then it's possible to allow for
> multiple register groups in regmap_irq_chip:
>
>     struct regmap_irq_chip {
>         const struct regmap_irq_reg_group *groups;
>         unsigned int num_groups;
>
>         unsigned int main_status_base;
>         unsigned int num_main_status_bits;
>         int num_main_regs;
>
>         ...
>     };
>
> It should be straightforward to fit existing chips into this model.
>
> - Chips that use a main status + sub-block IRQ layout will define
>   one register group for each sub-block and continue to describe the
>   location of the main status registers inside of regmap_irq_chip.
>   A group will only get polled if the corresponding main status bit
>   is set -- n'th group is polled if n'th bit is set.

Does this work for devices where a single main status bit can flag
IRQs in more than one sub-registers?

Best Regards
 -- Matti

-- 

Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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