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[PATCH v3 05/10] gpio: regmap: add the .fixed_direction_output configuration parameter

Ioana Ciornei posted 10 patches 2 weeks, 1 day ago
There is a newer version of this series
[PATCH v3 05/10] gpio: regmap: add the .fixed_direction_output configuration parameter
Posted by Ioana Ciornei 2 weeks, 1 day ago 
There are GPIO controllers such as the one present in the LX2160ARDB
QIXIS FPGA which have fixed-direction input and output GPIO lines mixed
together in a single register. 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 configuration
parameter - fixed_direction_output - into the gpio_regmap_config
structure. This will enable user drivers to provide a bitmap that
represents the fixed direction of the GPIO lines.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
---
Changes in v2:
- Add the fixed_direction_output bitmap to the gpio_regmap_config
Changes in v3:
- Make a deep copy of the new bitmap.
- Remove the offset check against the ngpio.
- Added documentation for the new config field.

 drivers/gpio/gpio-regmap.c  | 18 ++++++++++++++++++
 include/linux/gpio/regmap.h |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index e8a32dfebdcb..9edd79b5c10e 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_output;
 
 	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
 			      unsigned int offset, unsigned int *reg,
@@ -129,6 +130,13 @@ 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 (test_bit(offset, gpio->fixed_direction_output))
+			return GPIO_LINE_DIRECTION_OUT;
+		else
+			return GPIO_LINE_DIRECTION_IN;
+	}
+
 	if (gpio->reg_dat_base && !gpio->reg_set_base)
 		return GPIO_LINE_DIRECTION_IN;
 	if (gpio->reg_set_base && !gpio->reg_dat_base)
@@ -277,6 +285,16 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 			return ERR_PTR(ret);
 	}
 
+	if (config->fixed_direction_output) {
+		gpio->fixed_direction_output = devm_bitmap_alloc(config->parent,
+								 chip->ngpio,
+								 GFP_KERNEL);
+		if (!gpio->fixed_direction_output)
+			return ERR_PTR(-ENOMEM);
+		bitmap_copy(gpio->fixed_direction_output,
+			    config->fixed_direction_output, chip->ngpio);
+	}
+
 	/* if not set, assume there is only one register */
 	gpio->ngpio_per_reg = config->ngpio_per_reg;
 	if (!gpio->ngpio_per_reg)
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index c722c67668c6..8d3d595bfdd3 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -37,6 +37,10 @@ struct regmap;
  *			offset to a register/bitmask pair. If not
  *			given the default gpio_regmap_simple_xlate()
  *			is used.
+ * @fixed_direction_output:
+ *			(Optional) Bitmap representing the fixed direction of
+ *			the GPIO lines. Useful when there are GPIO lines with a
+ *			fixed direction mixed together in the same register.
  * @drvdata:		(Optional) Pointer to driver specific data which is
  *			not used by gpio-remap but is provided "as is" to the
  *			driver callback(s).
@@ -78,6 +82,8 @@ struct gpio_regmap_config {
 	int ngpio_per_reg;
 	struct irq_domain *irq_domain;
 
+	unsigned long *fixed_direction_output;
+
 	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
 			      unsigned int offset, unsigned int *reg,
 			      unsigned int *mask);
-- 
2.25.1
Re: [PATCH v3 05/10] gpio: regmap: add the .fixed_direction_output configuration parameter
Posted by Bartosz Golaszewski 2 weeks ago 
On Wed, 17 Sep 2025 11:04:17 +0200, Ioana Ciornei <ioana.ciornei@nxp.com> said:
> There are GPIO controllers such as the one present in the LX2160ARDB
> QIXIS FPGA which have fixed-direction input and output GPIO lines mixed
> together in a single register. 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 configuration
> parameter - fixed_direction_output - into the gpio_regmap_config
> structure. This will enable user drivers to provide a bitmap that
> represents the fixed direction of the GPIO lines.
>
> Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> ---
> Changes in v2:
> - Add the fixed_direction_output bitmap to the gpio_regmap_config
> Changes in v3:
> - Make a deep copy of the new bitmap.
> - Remove the offset check against the ngpio.
> - Added documentation for the new config field.
>
>  drivers/gpio/gpio-regmap.c  | 18 ++++++++++++++++++
>  include/linux/gpio/regmap.h |  6 ++++++
>  2 files changed, 24 insertions(+)
>
> diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> index e8a32dfebdcb..9edd79b5c10e 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_output;
>
>  	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
>  			      unsigned int offset, unsigned int *reg,
> @@ -129,6 +130,13 @@ 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 (test_bit(offset, gpio->fixed_direction_output))
> +			return GPIO_LINE_DIRECTION_OUT;
> +		else
> +			return GPIO_LINE_DIRECTION_IN;
> +	}
> +
>  	if (gpio->reg_dat_base && !gpio->reg_set_base)
>  		return GPIO_LINE_DIRECTION_IN;
>  	if (gpio->reg_set_base && !gpio->reg_dat_base)
> @@ -277,6 +285,16 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
>  			return ERR_PTR(ret);
>  	}
>
> +	if (config->fixed_direction_output) {
> +		gpio->fixed_direction_output = devm_bitmap_alloc(config->parent,
> +								 chip->ngpio,
> +								 GFP_KERNEL);

Please don't use devres hidden in what is effectively a library function for
drivers. You have no guarantee this will always be used in probe or that the
life-time of this will end with the associated device's detach. Just use
a regular bitmap_alloc().

Bart

> +		if (!gpio->fixed_direction_output)
> +			return ERR_PTR(-ENOMEM);
> +		bitmap_copy(gpio->fixed_direction_output,
> +			    config->fixed_direction_output, chip->ngpio);
> +	}
> +
>  	/* if not set, assume there is only one register */
>  	gpio->ngpio_per_reg = config->ngpio_per_reg;
>  	if (!gpio->ngpio_per_reg)
> diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
> index c722c67668c6..8d3d595bfdd3 100644
> --- a/include/linux/gpio/regmap.h
> +++ b/include/linux/gpio/regmap.h
> @@ -37,6 +37,10 @@ struct regmap;
>   *			offset to a register/bitmask pair. If not
>   *			given the default gpio_regmap_simple_xlate()
>   *			is used.
> + * @fixed_direction_output:
> + *			(Optional) Bitmap representing the fixed direction of
> + *			the GPIO lines. Useful when there are GPIO lines with a
> + *			fixed direction mixed together in the same register.
>   * @drvdata:		(Optional) Pointer to driver specific data which is
>   *			not used by gpio-remap but is provided "as is" to the
>   *			driver callback(s).
> @@ -78,6 +82,8 @@ struct gpio_regmap_config {
>  	int ngpio_per_reg;
>  	struct irq_domain *irq_domain;
>
> +	unsigned long *fixed_direction_output;
> +
>  	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
>  			      unsigned int offset, unsigned int *reg,
>  			      unsigned int *mask);
> --
> 2.25.1
>
>
Re: [PATCH v3 05/10] gpio: regmap: add the .fixed_direction_output configuration parameter
Posted by Ioana Ciornei 1 week, 6 days ago 
On Thu, Sep 18, 2025 at 03:55:16AM -0700, Bartosz Golaszewski wrote:
> On Wed, 17 Sep 2025 11:04:17 +0200, Ioana Ciornei <ioana.ciornei@nxp.com> said:
> > There are GPIO controllers such as the one present in the LX2160ARDB
> > QIXIS FPGA which have fixed-direction input and output GPIO lines mixed
> > together in a single register. 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 configuration
> > parameter - fixed_direction_output - into the gpio_regmap_config
> > structure. This will enable user drivers to provide a bitmap that
> > represents the fixed direction of the GPIO lines.
> >
> > Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
> > ---
> > Changes in v2:
> > - Add the fixed_direction_output bitmap to the gpio_regmap_config
> > Changes in v3:
> > - Make a deep copy of the new bitmap.
> > - Remove the offset check against the ngpio.
> > - Added documentation for the new config field.
> >
> >  drivers/gpio/gpio-regmap.c  | 18 ++++++++++++++++++
> >  include/linux/gpio/regmap.h |  6 ++++++
> >  2 files changed, 24 insertions(+)
> >
> > diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
> > index e8a32dfebdcb..9edd79b5c10e 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_output;
> >
> >  	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
> >  			      unsigned int offset, unsigned int *reg,
> > @@ -129,6 +130,13 @@ 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 (test_bit(offset, gpio->fixed_direction_output))
> > +			return GPIO_LINE_DIRECTION_OUT;
> > +		else
> > +			return GPIO_LINE_DIRECTION_IN;
> > +	}
> > +
> >  	if (gpio->reg_dat_base && !gpio->reg_set_base)
> >  		return GPIO_LINE_DIRECTION_IN;
> >  	if (gpio->reg_set_base && !gpio->reg_dat_base)
> > @@ -277,6 +285,16 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
> >  			return ERR_PTR(ret);
> >  	}
> >
> > +	if (config->fixed_direction_output) {
> > +		gpio->fixed_direction_output = devm_bitmap_alloc(config->parent,
> > +								 chip->ngpio,
> > +								 GFP_KERNEL);
> 
> Please don't use devres hidden in what is effectively a library function for
> drivers. You have no guarantee this will always be used in probe or that the
> life-time of this will end with the associated device's detach. Just use
> a regular bitmap_alloc().

Ok, sure. I will switch to bitmap_alloc() and bitmap_free().

Ioana

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