linux-kernel - [PATCH 4/9] gpio: regmap: add the .get

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Message-Id: <20250709112658.1987608-5-ioana.ciornei@nxp.com>
Date: Wed,  9 Jul 2025 14:26:53 +0300
From: Ioana Ciornei <ioana.ciornei@....com>
To: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc: Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Shawn Guo <shawnguo@...nel.org>,
	Michael Walle <mwalle@...nel.org>,
	Lee Jones <lee@...nel.org>,
	Frank Li <Frank.Li@....com>
Subject: [PATCH 4/9] gpio: regmap: add the .get_direction() callback

There are GPIO controllers such as the one present in the LX2160ARDB
QIXIS CPLD which are single register fixed-direction. 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 callback to the
gpio_config structure - .get_direction() - which can be used by user
drivers to provide the fixed direction per GPIO line.

Signed-off-by: Ioana Ciornei <ioana.ciornei@....com>
---
 drivers/gpio/gpio-regmap.c  | 17 ++++++++++++++++-
 include/linux/gpio/regmap.h |  3 +++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 87c4225784cf..dac2acb26655 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -32,6 +32,8 @@ struct gpio_regmap {
 	unsigned int reg_dir_in_base;
 	unsigned int reg_dir_out_base;
 
+	int (*get_direction)(struct gpio_regmap *gpio, unsigned int offset);
+
 	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
 			      unsigned int offset, unsigned int *reg,
 			      unsigned int *mask);
@@ -129,6 +131,9 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 	unsigned int base, val, reg, mask;
 	int invert, ret;
 
+	if (gpio->get_direction)
+		return gpio->get_direction(gpio, offset);
+
 	if (gpio->reg_dat_base && !gpio->reg_set_base)
 		return GPIO_LINE_DIRECTION_IN;
 	if (gpio->reg_set_base && !gpio->reg_dat_base)
@@ -163,7 +168,16 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
 	unsigned int base, val, reg, mask;
-	int invert, ret;
+	int invert, ret, dir;
+
+	if (gpio->get_direction) {
+		dir = gpio->get_direction(gpio, offset);
+		if (dir == GPIO_LINE_DIRECTION_IN && output)
+			return -EOPNOTSUPP;
+		if (dir == GPIO_LINE_DIRECTION_OUT && !output)
+			return -EOPNOTSUPP;
+		return 0;
+	}
 
 	if (gpio->reg_dir_out_base) {
 		base = gpio_regmap_addr(gpio->reg_dir_out_base);
@@ -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->get_direction = config->get_direction;
 
 	chip = &gpio->gpio_chip;
 	chip->parent = config->parent;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index c722c67668c6..99fd973e61fa 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -37,6 +37,8 @@ struct regmap;
  *			offset to a register/bitmask pair. If not
  *			given the default gpio_regmap_simple_xlate()
  *			is used.
+ * @get_direction:	(Optional) Callback to the user driver to return the
+ *			fixed direction of the GPIO line
  * @drvdata:		(Optional) Pointer to driver specific data which is
  *			not used by gpio-remap but is provided "as is" to the
  *			driver callback(s).
@@ -81,6 +83,7 @@ struct gpio_regmap_config {
 	int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
 			      unsigned int offset, unsigned int *reg,
 			      unsigned int *mask);
+	int (*get_direction)(struct gpio_regmap *gpio, unsigned int offset);
 
 	void *drvdata;
 };
-- 
2.25.1