linux-kernel - Re: [PATCH 1/1] pinctrl: sunxi: add GPIO get

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Message-ID: <CAGb2v64TYWbvs7mmpa87X28WWQpTi7O+VZSz-x8GmGhyadBegQ@mail.gmail.com>
Date: Wed, 11 Feb 2026 11:49:36 +0800
From: Chen-Yu Tsai <wens@...nel.org>
To: James Hilliard <james.hilliard1@...il.com>
Cc: linux-sunxi@...ts.linux.dev, linux-gpio@...r.kernel.org, 
	Linus Walleij <linusw@...nel.org>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Samuel Holland <samuel@...lland.org>, Bartosz Golaszewski <brgl@...nel.org>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] pinctrl: sunxi: add GPIO get_direction callback

On Wed, Feb 11, 2026 at 11:33 AM James Hilliard
<james.hilliard1@...il.com> wrote:

Ah, you beat me to it.

> Implement sunxi_pinctrl_gpio_get_direction() and wire it into
> the sunxi gpio_chip setup.

Can you also mention that without this, calls to gpiochip_get_direction()
cause a big warning?

> The new callback reads the pin mux register and compares the mux
> value against the pin descriptor gpio_in and gpio_out functions
> to report GPIO_LINE_DIRECTION_IN or GPIO_LINE_DIRECTION_OUT.
> If the pin is muxed to irq, report it as input.
>
> Signed-off-by: James Hilliard <james.hilliard1@...il.com>
> ---
>  drivers/pinctrl/sunxi/pinctrl-sunxi.c | 32 +++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> index 0fb057a07dcc..424f23be27b2 100644
> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> @@ -995,6 +995,37 @@ static int sunxi_pinctrl_gpio_direction_output(struct gpio_chip *chip,
>                                             chip->base + offset, false);
>  }
>
> +static int sunxi_pinctrl_gpio_get_direction(struct gpio_chip *chip,
> +                                           unsigned int offset)
> +{
> +       struct sunxi_pinctrl *pctl = gpiochip_get_data(chip);
> +       struct sunxi_desc_function *in, *out, *irq;
> +       u32 reg, shift, mask, val;
> +       u16 pin = chip->base + offset;
> +
> +       in = sunxi_pinctrl_desc_find_function_by_pin(pctl, pin, "gpio_in");
> +       out = sunxi_pinctrl_desc_find_function_by_pin(pctl, pin, "gpio_out");
> +       if (!in || !out)
> +               return -EINVAL;
> +
> +       irq = sunxi_pinctrl_desc_find_function_by_pin(pctl, pin, "irq");

This is less efficient, as you end up (linearly) searching the whole pin
array three times.

What I did in my version was implement a search based on pin and muxval.
I can send that out if it's OK with you.


ChenYu

> +
> +       sunxi_mux_reg(pctl, offset, &reg, &shift, &mask);
> +       val = (readl(pctl->membase + reg) & mask) >> shift;
> +
> +       if (val == in->muxval)
> +               return GPIO_LINE_DIRECTION_IN;
> +
> +       if (val == out->muxval)
> +               return GPIO_LINE_DIRECTION_OUT;
> +
> +       /* IRQ function is effectively input. */
> +       if (irq && val == irq->muxval)
> +               return GPIO_LINE_DIRECTION_IN;
> +
> +       return -EINVAL;
> +}
> +
>  static int sunxi_pinctrl_gpio_of_xlate(struct gpio_chip *gc,
>                                 const struct of_phandle_args *gpiospec,
>                                 u32 *flags)
> @@ -1603,6 +1634,7 @@ int sunxi_pinctrl_init_with_flags(struct platform_device *pdev,
>         pctl->chip->set_config = gpiochip_generic_config;
>         pctl->chip->direction_input = sunxi_pinctrl_gpio_direction_input;
>         pctl->chip->direction_output = sunxi_pinctrl_gpio_direction_output;
> +       pctl->chip->get_direction = sunxi_pinctrl_gpio_get_direction;
>         pctl->chip->get = sunxi_pinctrl_gpio_get;
>         pctl->chip->set = sunxi_pinctrl_gpio_set;
>         pctl->chip->of_xlate = sunxi_pinctrl_gpio_of_xlate;
> --
> 2.43.0
>