Re: [PATCH 4/9] gpio: regmap: add the .get_direction() callback

[Andrew Lunn <andrew@lunn.ch>]

On Wed, Jul 09, 2025 at 02:26:53PM +0300, Ioana Ciornei wrote:
> There are GPIO controllers such as the one present in the LX2160ARDB
> QIXIS CPLD which are single register fixed-direction. This cannot be
> modeled using the gpio-regmap as-is since there is no way to
> present the true direction of a GPIO line.
> 
> In order to make this use case possible, add a new callback to the
> gpio_config structure - .get_direction() - which can be used by user
> drivers to provide the fixed direction per GPIO line.
> 
> Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> ---
>  drivers/gpio/gpio-regmap.c  | 17 ++++++++++++++++-
>  include/linux/gpio/regmap.h |  3 +++
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> index 87c4225784cf..dac2acb26655 100644
> --- a/drivers/gpio/gpio-regmap.c
> +++ b/drivers/gpio/gpio-regmap.c
> @@ -32,6 +32,8 @@ struct gpio_regmap {
>  	unsigned int reg_dir_in_base;
>  	unsigned int reg_dir_out_base;
>  
> +	int (*get_direction)(struct gpio_regmap *gpio, unsigned int offset);
> +

This is not my area, so i will deffer to the GPIO
Maintainers. However, it is not clear to me what get_direction()
should return. Is it the current direction, or the supported
directions? Maybe it should be called get_fixed_direction()?

I then wounder how it will be implemented. Since it is fixed, it is
probably just a constant bitmap, and you look at the offset bit in
this batmap? At minimum a ready made helper could be provided, or
rather than have this op, just provide the bitmap, and gpio-regmap.c
can look at the bit in the bitmap?

	Andrew