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SubjectRe: [PATCH v2 2/5] gpio: pca953x: add register definitions for pcal6524 and fix address calculation
On Wed, Apr 4, 2018 at 10:00 PM, H. Nikolaus Schaller <hns@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 in this case.
>
> And we add additional register offset constants (not yet used by
> the driver code) which are specific to the pcal6524.

> -#define PCAL953X_IN_LATCH 34
> -#define PCAL953X_INT_MASK 37
> -#define PCAL953X_INT_STAT 38

I prefer either to change first all the rest to be 2 digit hex values
first, or leave decimal in this patch.

> +#define PCAL953X_OUT_STRENGTH 0x20
> +#define PCAL953X_IN_LATCH 0x22
> +#define PCAL953X_PULL_EN 0x23
> +#define PCAL953X_PULL_SEL 0x24
> +#define PCAL953X_INT_MASK 0x25
> +#define PCAL953X_INT_STAT 0x26
> +#define PCAL953X_OUT_CONF 0x27
> +
> +#define PCAL6524_INT_EDGE 0x28
> +#define PCAL6524_INT_CLR 0x2a
> +#define PCAL6524_IN_STATUS 0x2b
> +#define PCAL6524_OUT_INDCONF 0x2c
> +#define PCAL6524_DEBOUNCE 0x2d

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

I don't like this condition. Can we avoid relying on the register
offset in regard to some flag / compatible string / etc?

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

Ditto.

--
With Best Regards,
Andy Shevchenko

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