Not my area, but consider making the subject more specific, e.g.,
"add flag to set direction before value"
On Thu, Aug 21, 2025 at 12:18:57PM +0200, Marcos Del Sol Vives wrote:
> The Vortex86 family of SoCs need the direction set before the value, else
> writes to the DATA ports are ignored.
>
> This commit adds a new "flags" field plus a flag to change the default
> behaviour, which is to set first the direction and then the value.
This sounds like the default behavior is to set direction, then value.
But from the patch, it looks like:
- default: set value, then direction
- with GPIO_REGMAP_DIR_BEFORE_SET: set direction, then value
> Signed-off-by: Marcos Del Sol Vives <marcos@xxxxxxxx>
> ---
> drivers/gpio/gpio-regmap.c | 17 ++++++++++++++++-
> include/linux/gpio/regmap.h | 17 +++++++++++++++++
> 2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> index e8a32dfebdcb..24cefbd57637 100644
> --- a/drivers/gpio/gpio-regmap.c
> +++ b/drivers/gpio/gpio-regmap.c
> @@ -31,6 +31,7 @@ struct gpio_regmap {
> unsigned int reg_clr_base;
> unsigned int reg_dir_in_base;
> unsigned int reg_dir_out_base;
> + unsigned int flags;
>
> int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
> unsigned int offset, unsigned int *reg,
> @@ -196,7 +197,20 @@ static int gpio_regmap_direction_input(struct gpio_chip *chip,
> static int gpio_regmap_direction_output(struct gpio_chip *chip,
> unsigned int offset, int value)
> {
> - gpio_regmap_set(chip, offset, value);
> + struct gpio_regmap *gpio = gpiochip_get_data(chip);
> + int ret;
> +
> + if (gpio->flags & GPIO_REGMAP_DIR_BEFORE_SET) {
> + ret = gpio_regmap_set_direction(chip, offset, true);
> + if (ret)
> + return ret;
> +
> + return gpio_regmap_set(chip, offset, value);
> + }
> +
> + ret = gpio_regmap_set(chip, offset, value);
> + if (ret)
> + return ret;
>
> return gpio_regmap_set_direction(chip, offset, true);
> }
> @@ -247,6 +261,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
> gpio->reg_clr_base = config->reg_clr_base;
> gpio->reg_dir_in_base = config->reg_dir_in_base;
> gpio->reg_dir_out_base = config->reg_dir_out_base;
> + gpio->flags = config->flags;
>
> chip = &gpio->gpio_chip;
> chip->parent = config->parent;
> diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
> index c722c67668c6..aea107e71fec 100644
> --- a/include/linux/gpio/regmap.h
> +++ b/include/linux/gpio/regmap.h
> @@ -12,6 +12,20 @@ struct regmap;
> #define GPIO_REGMAP_ADDR_ZERO ((unsigned int)(-1))
> #define GPIO_REGMAP_ADDR(addr) ((addr) ? : GPIO_REGMAP_ADDR_ZERO)
>
> +
> +/**
> + * enum gpio_regmap_flags - flags to control GPIO operation
> + */
> +enum gpio_regmap_flags {
> + /**
> + * @GPIO_REGMAP_DIR_BEFORE_SET: when setting a pin as an output, set
> + * its direction before the value. The output value will be undefined
> + * for a short time which may have unwanted side effects, but some
> + * hardware requires this.
> + */
> + GPIO_REGMAP_DIR_BEFORE_SET = BIT(0),
> +};
> +
> /**
> * struct gpio_regmap_config - Description of a generic regmap gpio_chip.
> * @parent: The parent device
> @@ -23,6 +37,8 @@ struct regmap;
> * If not given, the name of the device is used.
> * @ngpio: (Optional) Number of GPIOs
> * @names: (Optional) Array of names for gpios
> + * @flags: (Optional) A bitmask of flags from
> + * &enum gpio_regmap_flags
> * @reg_dat_base: (Optional) (in) register base address
> * @reg_set_base: (Optional) set register base address
> * @reg_clr_base: (Optional) clear register base address
> @@ -68,6 +84,7 @@ struct gpio_regmap_config {
> const char *label;
> int ngpio;
> const char *const *names;
> + unsigned int flags;
>
> unsigned int reg_dat_base;
> unsigned int reg_set_base;
> --
> 2.34.1
>
