[Letux-kernel] [PATCH v3 2/4] gpio: pca953x: add register definitions for pcal6524 and fix address calculation

Andy Shevchenko andy.shevchenko at gmail.com
Tue Apr 10 20:06:41 CEST 2018

On Tue, Apr 10, 2018 at 7:07 PM, H. Nikolaus Schaller <hns at goldelico.com> wrote:
> PCAL chips ("L" seems to stand for "latched") have additional
> registers starting at address 0x40 to control the latches,
> interrupt mask, pull-up and pull down etc.
> The constants are so far defined in a way that they fit for
> the pcal9555a when shifted by the number of banks, i.e. multiplied
> by 2.
> Now the pcal6524 has 3 banks which means the relative offset
> must be multiplied by 4 which gives a wrong result if not done
> carefully, since the base offset is already included in the offset.
> For the basic registers shared with all pca93xx/tca64xx chips
> there is no such offset.
> Therefore, we add code to adjust the register number for exended
> registers to the 24 bit accessor functions.
> And we add additional register offset constants (not yet used by
> the driver code) which are specific to the pcal6524.

First of all, as I said, please split this to two patches. Don't mix the things.

> +       /* adjust register address for pcal6524 */
> +       if (reg >= PCAL953X_OUT_STRENGTH)
> +               reg -= PCAL953X_OUT_STRENGTH >> 1;
> +

Give me some days to think about it.

With Best Regards,
Andy Shevchenko

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