Re: [PATCH v3 1/2] gpio: regmap: Support sparsed fixed direction

[Alex Elder <elder@riscstar.com>]

On 5/11/26 2:43 PM, Linus Walleij wrote:
> On some regmapped GPIOs apparently only a sparser selection
> of the lines (not all) are actually fixed direction.
> 
> Support this situation by adding an optional bitmap indicating
> which GPIOs are actually fixed direction and which are not.
> 
> Cc: Alex Elder <elder@riscstar.com>
> Link: https://lore.kernel.org/linux-gpio/20260501155421.3329862-10-elder@riscstar.com/
> Tested-by: Alex Elder <elder@riscstar.com>
> Signed-off-by: Linus Walleij <linusw@kernel.org>

Reviewed-by: Alex Elder <elder@riscstar.com>


You renamed "test_direction_sparse" so I had to do that too, but
I tested this again as well.


> ---
>   drivers/gpio/gpio-regmap.c  | 37 +++++++++++++++++++++++++++++++++----
>   include/linux/gpio/regmap.h |  7 +++++++
>   2 files changed, 40 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> index 9ae4a41a2427..b3b4e77ec147 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 long *fixed_direction_mask;
>   	unsigned long *fixed_direction_output;
>   
>   #ifdef CONFIG_REGMAP_IRQ
> @@ -138,6 +139,20 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
>   	return regmap_write(gpio->regmap, reg, mask);
>   }
>   
> +static bool gpio_regmap_fixed_direction(struct gpio_regmap *gpio,
> +					unsigned int offset)
> +{
> +	if (!gpio->fixed_direction_output)
> +		return false;
> +
> +	/* In this case only some GPIOs are fixed as input/output */
> +	if (gpio->fixed_direction_mask &&
> +	    !test_bit(offset, gpio->fixed_direction_mask))
> +		return false;
> +
> +	return true;
> +}
> +
>   static int gpio_regmap_get_direction(struct gpio_chip *chip,
>   				     unsigned int offset)
>   {
> @@ -145,7 +160,7 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
>   	unsigned int base, val, reg, mask;
>   	int invert, ret;
>   
> -	if (gpio->fixed_direction_output) {
> +	if (gpio_regmap_fixed_direction(gpio, offset)) {
>   		if (test_bit(offset, gpio->fixed_direction_output))
>   			return GPIO_LINE_DIRECTION_OUT;
>   		else
> @@ -302,12 +317,23 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
>   			goto err_free_gpio;
>   	}
>   
> +	if (config->fixed_direction_mask) {
> +		gpio->fixed_direction_mask = bitmap_alloc(chip->ngpio,
> +							    GFP_KERNEL);
> +		if (!gpio->fixed_direction_mask) {
> +			ret = -ENOMEM;
> +			goto err_free_gpio;
> +		}
> +		bitmap_copy(gpio->fixed_direction_mask,
> +			    config->fixed_direction_mask, chip->ngpio);
> +	}
> +
>   	if (config->fixed_direction_output) {
>   		gpio->fixed_direction_output = bitmap_alloc(chip->ngpio,
>   							    GFP_KERNEL);
>   		if (!gpio->fixed_direction_output) {
>   			ret = -ENOMEM;
> -			goto err_free_gpio;
> +			goto err_free_bitmap_dirmask;
>   		}
>   		bitmap_copy(gpio->fixed_direction_output,
>   			    config->fixed_direction_output, chip->ngpio);
> @@ -329,7 +355,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
>   
>   	ret = gpiochip_add_data(chip, gpio);
>   	if (ret < 0)
> -		goto err_free_bitmap;
> +		goto err_free_bitmap_output;
>   
>   #ifdef CONFIG_REGMAP_IRQ
>   	if (config->regmap_irq_chip) {
> @@ -355,8 +381,10 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
>   
>   err_remove_gpiochip:
>   	gpiochip_remove(chip);
> -err_free_bitmap:
> +err_free_bitmap_output:
>   	bitmap_free(gpio->fixed_direction_output);
> +err_free_bitmap_dirmask:
> +	bitmap_free(gpio->fixed_direction_mask);
>   err_free_gpio:
>   	kfree(gpio);
>   	return ERR_PTR(ret);
> @@ -376,6 +404,7 @@ void gpio_regmap_unregister(struct gpio_regmap *gpio)
>   
>   	gpiochip_remove(&gpio->gpio_chip);
>   	bitmap_free(gpio->fixed_direction_output);
> +	bitmap_free(gpio->fixed_direction_mask);
>   	kfree(gpio);
>   }
>   EXPORT_SYMBOL_GPL(gpio_regmap_unregister);
> diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
> index 12d154732ca9..06255756710d 100644
> --- a/include/linux/gpio/regmap.h
> +++ b/include/linux/gpio/regmap.h
> @@ -38,6 +38,12 @@ struct regmap;
>    *			offset to a register/bitmask pair. If not
>    *			given the default gpio_regmap_simple_xlate()
>    *			is used.
> + * @fixed_direction_mask:
> + *			(Optional) Bitmap representing the GPIO lines that
> + *			make use of the @fixed_direction_output list to
> + *			enforce direction of the GPIO. If this is NULL
> + *			and @fixed_direction_output is defined, ALL GPIOs
> + *			are assumed to be fixed direction (out or in).
>    * @fixed_direction_output:
>    *			(Optional) Bitmap representing the fixed direction of
>    *			the GPIO lines. Useful when there are GPIO lines with a
> @@ -89,6 +95,7 @@ struct gpio_regmap_config {
>   	int reg_stride;
>   	int ngpio_per_reg;
>   	struct irq_domain *irq_domain;
> +	unsigned long *fixed_direction_mask;
>   	unsigned long *fixed_direction_output;
>   
>   #ifdef CONFIG_REGMAP_IRQ
>