[PATCH 01/12] gpio: mmio: use new GPIO line value setter callbacks

[Marek Szyprowski]

On 10.06.2025 14:33, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>
>
> struct gpio_chip now has callbacks for setting line values that return
> an integer, allowing to indicate failures. Convert the driver to using
> them.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>
> ---
>   drivers/gpio/gpio-mmio.c | 53 ++++++++++++++++++++++++++++++------------------
>   1 file changed, 33 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c
> index 4841e4ebe7a67d0f954e9a6f995ec5758f124edd..9169eccadb238efe944d494054b1e009f16eee7f 100644
> --- a/drivers/gpio/gpio-mmio.c
> +++ b/drivers/gpio/gpio-mmio.c
> @@ -211,11 +211,12 @@ static int bgpio_get_multiple_be(struct gpio_chip *gc, unsigned long *mask,
>   	return 0;
>   }
>   
> -static void bgpio_set_none(struct gpio_chip *gc, unsigned int gpio, int val)
> +static int bgpio_set_none(struct gpio_chip *gc, unsigned int gpio, int val)
>   {
> +	return 0;
>   }
>   
> -static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +static int bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
>   {
>   	unsigned long mask = bgpio_line2mask(gc, gpio);
>   	unsigned long flags;
> @@ -230,10 +231,12 @@ static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
>   	gc->write_reg(gc->reg_dat, gc->bgpio_data);
>   
>   	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +
> +	return 0;
>   }
>   
> -static void bgpio_set_with_clear(struct gpio_chip *gc, unsigned int gpio,
> -				 int val)
> +static int bgpio_set_with_clear(struct gpio_chip *gc, unsigned int gpio,
> +				int val)
>   {
>   	unsigned long mask = bgpio_line2mask(gc, gpio);
>   
> @@ -241,9 +244,11 @@ static void bgpio_set_with_clear(struct gpio_chip *gc, unsigned int gpio,
>   		gc->write_reg(gc->reg_set, mask);
>   	else
>   		gc->write_reg(gc->reg_clr, mask);
> +
> +	return 0;
>   }
>   
> -static void bgpio_set_set(struct gpio_chip *gc, unsigned int gpio, int val)
> +static int bgpio_set_set(struct gpio_chip *gc, unsigned int gpio, int val)
>   {
>   	unsigned long mask = bgpio_line2mask(gc, gpio);
>   	unsigned long flags;
> @@ -258,6 +263,8 @@ static void bgpio_set_set(struct gpio_chip *gc, unsigned int gpio, int val)
>   	gc->write_reg(gc->reg_set, gc->bgpio_data);
>   
>   	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
> +
> +	return 0;
>   }
>   
>   static void bgpio_multiple_get_masks(struct gpio_chip *gc,
> @@ -298,21 +305,25 @@ static void bgpio_set_multiple_single_reg(struct gpio_chip *gc,
>   	raw_spin_unlock_irqrestore(&gc->bgpio_lock, flags);
>   }
>   
> -static void bgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
> +static int bgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
>   			       unsigned long *bits)
>   {
>   	bgpio_set_multiple_single_reg(gc, mask, bits, gc->reg_dat);
> +
> +	return 0;
>   }
>   
> -static void bgpio_set_multiple_set(struct gpio_chip *gc, unsigned long *mask,
> -				   unsigned long *bits)
> +static int bgpio_set_multiple_set(struct gpio_chip *gc, unsigned long *mask,
> +				  unsigned long *bits)
>   {
>   	bgpio_set_multiple_single_reg(gc, mask, bits, gc->reg_set);
> +
> +	return 0;
>   }
>   
> -static void bgpio_set_multiple_with_clear(struct gpio_chip *gc,
> -					  unsigned long *mask,
> -					  unsigned long *bits)
> +static int bgpio_set_multiple_with_clear(struct gpio_chip *gc,
> +					 unsigned long *mask,
> +					 unsigned long *bits)
>   {
>   	unsigned long set_mask, clear_mask;
>   
> @@ -322,6 +333,8 @@ static void bgpio_set_multiple_with_clear(struct gpio_chip *gc,
>   		gc->write_reg(gc->reg_set, set_mask);
>   	if (clear_mask)
>   		gc->write_reg(gc->reg_clr, clear_mask);
> +
> +	return 0;
>   }
>   
>   static int bgpio_dir_return(struct gpio_chip *gc, unsigned int gpio, bool dir_out)
> @@ -510,18 +523,18 @@ static int bgpio_setup_io(struct gpio_chip *gc,
>   	if (set && clr) {
>   		gc->reg_set = set;
>   		gc->reg_clr = clr;
> -		gc->set = bgpio_set_with_clear;
> -		gc->set_multiple = bgpio_set_multiple_with_clear;
> +		gc->set_rv = bgpio_set_with_clear;
> +		gc->set_multiple_rv = bgpio_set_multiple_with_clear;
>   	} else if (set && !clr) {
>   		gc->reg_set = set;
> -		gc->set = bgpio_set_set;
> -		gc->set_multiple = bgpio_set_multiple_set;
> +		gc->set_rv = bgpio_set_set;
> +		gc->set_multiple_rv = bgpio_set_multiple_set;
>   	} else if (flags & BGPIOF_NO_OUTPUT) {
> -		gc->set = bgpio_set_none;
> -		gc->set_multiple = NULL;
> +		gc->set_rv = bgpio_set_none;
> +		gc->set_multiple_rv = NULL;
>   	} else {
> -		gc->set = bgpio_set;
> -		gc->set_multiple = bgpio_set_multiple;
> +		gc->set_rv = bgpio_set;
> +		gc->set_multiple_rv = bgpio_set_multiple;
>   	}
>   
>   	if (!(flags & BGPIOF_UNREADABLE_REG_SET) &&
> @@ -654,7 +667,7 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
>   	}
>   
>   	gc->bgpio_data = gc->read_reg(gc->reg_dat);
> -	if (gc->set == bgpio_set_set &&
> +	if (gc->set_rv == bgpio_set_set &&
>   			!(flags & BGPIOF_UNREADABLE_REG_SET))
>   		gc->bgpio_data = gc->read_reg(gc->reg_set);
>   


A few more changes are needed to avoid NULL pointer dereference 
(observed on RasbperrryPi5), because this driver calls ->set method 
internally:

diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c
index 9169eccadb23..57622f45d33e 100644
--- a/drivers/gpio/gpio-mmio.c
+++ b/drivers/gpio/gpio-mmio.c
@@ -362,7 +362,7 @@ static int bgpio_dir_out_err(struct gpio_chip *gc, 
unsigned int gpio,
  static int bgpio_simple_dir_out(struct gpio_chip *gc, unsigned int gpio,
                                 int val)
  {
-       gc->set(gc, gpio, val);
+       gc->set_rv(gc, gpio, val);

         return bgpio_dir_return(gc, gpio, true);
  }
@@ -427,14 +427,14 @@ static int bgpio_dir_out_dir_first(struct 
gpio_chip *gc, unsigned int gpio,
                                    int val)
  {
         bgpio_dir_out(gc, gpio, val);
-       gc->set(gc, gpio, val);
+       gc->set_rv(gc, gpio, val);
         return bgpio_dir_return(gc, gpio, true);
  }

  static int bgpio_dir_out_val_first(struct gpio_chip *gc, unsigned int 
gpio,
                                    int val)
  {
-       gc->set(gc, gpio, val);
+       gc->set_rv(gc, gpio, val);
         bgpio_dir_out(gc, gpio, val);
         return bgpio_dir_return(gc, gpio, true);
  }

Do You want a formal patch with the above changes, or will You just 
amend them to the updated patch?

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland