[PATCH v6 0/3] gpio: Add AD7768 GPIO support

[PATCH v6 0/3] gpio: Add AD7768 GPIO support

[Janani Sunil]

Add GPIO support for the Analog Devices AD7768 and AD7768-4
simultaneous sampling ADCs.

Datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/ad7768-ad7768-4.pdf

**Device Overview:**
The AD7768 and AD7768-4 provide five on-chip GPIO pins controlled
through registers shared with the parent IIO device. The GPIO driver is
registered as an auxiliary driver and shares the parent's regmap and
runtime power-management state.

**Features Implemented:**
- Use regmap_test_bits() for single-bit gpio-regmap value and direction
  reads.
- Add optional runtime PM support to gpio-regmap.
- Expose the five AD7768 GPIO pins through gpio-regmap.
- Read output GPIO values from the output-latch register while retaining
  input-state reads for input pins.
- Reserve GPIO4 when it is used to select the crystal or LVDS master
  clock source.

**Patch Summary:**
1. Use regmap_test_bits() for single-bit gpio-regmap reads.
2. Add optional runtime PM support to gpio-regmap.
3. Add the AD7768 GPIO auxiliary driver.

**Testing:**
The complete AD7768 driver was compiled and tested on the
EVAL-AD7768FMCZ using a Zedboard with a mainline kernel.

**Base:**
This series is based on the GPIO subsystem's gpio/for-next branch,
commit a2cfc48fee416f0ea78e7dc38acbf2ce072574cc

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
Changes in v6:
- Split the GPIO patches from the main AD7768 IIO series.
- Rebase onto gpio/for-next commit
  a2cfc48fee416f0ea78e7dc38acbf2ce072574cc.
- Adapt the gpio-regmap callbacks to the operation argument present in
  gpio/for-next.
- Align the gpio-regmap runtime-PM member layout with review feedback.
- Move GPIO valid-mask handling into the GPIO driver and reserve GPIO4
  there when it is used for crystal or LVDS clock selection.
- Link to v5: https://lore.kernel.org/r/20260828-ad7768-driver-v5-0-e33ca6f841a2@analog.com

---
Janani Sunil (3):
      gpio: regmap: Use regmap_test_bits() for single bit reads
      gpio: regmap: Add optional runtime PM support
      gpio: ad7768: Add AD7768 GPIO auxiliary driver

 drivers/gpio/Kconfig        |  12 +++++
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-ad7768.c  | 122 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/gpio/gpio-regmap.c  |  98 +++++++++++++++++++++++++++++------
 include/linux/gpio/regmap.h |   2 +
 5 files changed, 220 insertions(+), 15 deletions(-)
---
base-commit: a2cfc48fee416f0ea78e7dc38acbf2ce072574cc
change-id: 20260903-ad7768-gpio-4a19153b1470

Best regards,
-- 
Janani Sunil <janani.sunil@analog.com>

[PATCH v6 1/3] gpio: regmap: Use regmap_test_bits() for single bit reads

[Janani Sunil]

Use regmap_test_bits() when reading a single GPIO value from a normal
register and when reading the direction bit.

Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/gpio-regmap.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index fb21396e1d02..ae6fa42b00a4 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -95,11 +95,11 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 	if (ret)
 		return ret;
 
+	if (gpio->reg_dat_base != gpio->reg_set_base)
+		return regmap_test_bits(gpio->regmap, reg, mask);
+
 	/* ensure we don't spoil any register cache with pin input values */
-	if (gpio->reg_dat_base == gpio->reg_set_base)
-		ret = regmap_read_bypassed(gpio->regmap, reg, &val);
-	else
-		ret = regmap_read(gpio->regmap, reg, &val);
+	ret = regmap_read_bypassed(gpio->regmap, reg, &val);
 	if (ret)
 		return ret;
 
@@ -183,7 +183,7 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 				     unsigned int offset)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
-	unsigned int base, val, reg, mask;
+	unsigned int base, reg, mask;
 	int invert, ret;
 
 	if (gpio_regmap_fixed_direction(gpio, offset)) {
@@ -212,14 +212,14 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 	if (ret)
 		return ret;
 
-	ret = regmap_read(gpio->regmap, reg, &val);
-	if (ret)
+	ret = regmap_test_bits(gpio->regmap, reg, mask);
+	if (ret < 0)
 		return ret;
 
-	if (!!(val & mask) ^ invert)
+	if (ret ^ invert)
 		return GPIO_LINE_DIRECTION_OUT;
-	else
-		return GPIO_LINE_DIRECTION_IN;
+
+	return GPIO_LINE_DIRECTION_IN;
 }
 
 static int gpio_regmap_try_direction_fixed(struct gpio_regmap *gpio,

-- 
2.43.0

[PATCH v6 2/3] gpio: regmap: Add optional runtime PM support

[Janani Sunil]

Some gpio-regmap consumers share their regmap with a parent device that
may be runtime suspended. GPIO register accesses must resume that device
first.

Add an optional pm_dev field and acquire it before register translation
or access. Release it using runtime autosuspend after each operation.
Keep the device active across the complete direction-output sequence and
propagate failure when setting the initial output value.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/gpio-regmap.c  | 80 +++++++++++++++++++++++++++++++++++++++++----
 include/linux/gpio/regmap.h |  2 ++
 2 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index ae6fa42b00a4..2f5f45b84cc9 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -6,11 +6,13 @@
  */
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/compiler_attributes.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -23,6 +25,8 @@
 struct gpio_regmap {
 	struct device *parent;
 	struct regmap *regmap;
+	struct device *pm_dev;
+
 	struct gpio_chip gpio_chip;
 
 	int reg_stride;
@@ -79,6 +83,33 @@ static int gpio_regmap_simple_xlate(struct gpio_regmap *gpio,
 	return 0;
 }
 
+static int gpio_regmap_runtime_get(struct gpio_regmap *gpio)
+{
+	if (!gpio->pm_dev)
+		return 0;
+
+	return pm_runtime_get_active(gpio->pm_dev, RPM_TRANSPARENT);
+}
+
+static void gpio_regmap_runtime_put(struct gpio_regmap *gpio)
+{
+	if (!gpio->pm_dev)
+		return;
+
+	pm_runtime_put_autosuspend(gpio->pm_dev);
+}
+
+DEFINE_GUARD(gpio_regmap_runtime, struct gpio_regmap *,
+	     gpio_regmap_runtime_get(_T), gpio_regmap_runtime_put(_T))
+DEFINE_GUARD_COND(gpio_regmap_runtime, _try,
+		  gpio_regmap_runtime_get(_T), _RET == 0)
+
+#define GPIO_REGMAP_RUNTIME_ACQUIRE(_gpio, _var) \
+	ACQUIRE(gpio_regmap_runtime_try, _var)(_gpio)
+
+#define GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(_var_ptr) \
+	ACQUIRE_ERR(gpio_regmap_runtime, _var_ptr)
+
 static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
@@ -91,7 +122,13 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 	else
 		base = gpio_regmap_addr(gpio->reg_set_base);
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -114,7 +151,13 @@ static int gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
 	unsigned int reg, mask, mask_val;
 	int ret;
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -146,6 +189,11 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 	unsigned int base, reg, mask, value = 0;
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	if (val)
 		base = gpio_regmap_addr(gpio->reg_set_base);
 	else
@@ -208,7 +256,13 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_DIR_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_GET_DIR_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -262,7 +316,13 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
-	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_DIR_OP, base, offset, &reg, &mask);
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = gpio->reg_mask_xlate(gpio, GPIO_REGMAP_SET_DIR_OP, base, offset,
+				   &reg, &mask);
 	if (ret)
 		return ret;
 
@@ -293,6 +353,11 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	/*
 	 * First check if this is gonna work on a fixed direction line,
 	 * if it doesn't (i.e. this is a fixed input line), then do not
@@ -304,7 +369,9 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 			return ret;
 	}
 
-	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);
 }
@@ -399,6 +466,7 @@ 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->pm_dev = config->pm_dev;
 
 	chip = &gpio->gpio_chip;
 	chip->parent = config->parent;
@@ -406,7 +474,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	chip->base = -1;
 	chip->names = config->names;
 	chip->label = config->label ?: dev_name(config->parent);
-	chip->can_sleep = regmap_might_sleep(config->regmap);
+	chip->can_sleep = config->pm_dev || regmap_might_sleep(config->regmap);
 	chip->init_valid_mask = config->init_valid_mask;
 
 	chip->request = gpiochip_generic_request;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index 6f52c140e50d..6fe0877717cb 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -46,6 +46,7 @@ enum gpio_regmap_operation {
  * @parent:		The parent device
  * @regmap:		The regmap used to access the registers
  *			given, the name of the device is used
+ * @pm_dev:		(Optional) Device to use for runtime power management.
  * @fwnode:		(Optional) The firmware node.
  *			If not given, the fwnode of the parent is used.
  * @label:		(Optional) Descriptive name for GPIO controller.
@@ -117,6 +118,7 @@ enum gpio_regmap_operation {
 struct gpio_regmap_config {
 	struct device *parent;
 	struct regmap *regmap;
+	struct device *pm_dev;
 	struct fwnode_handle *fwnode;
 
 	const char *label;

-- 
2.43.0

Re: [PATCH v6 2/3] gpio: regmap: Add optional runtime PM support

[Michael Walle]

[-- Attachment #1: Type: text/plain, Size: 677 bytes --]

On Thu Sep 3, 2026 at 2:01 PM CEST, Janani Sunil wrote:
> Some gpio-regmap consumers share their regmap with a parent device that
> may be runtime suspended. GPIO register accesses must resume that device
> first.
>
> Add an optional pm_dev field and acquire it before register translation
> or access. Release it using runtime autosuspend after each operation.
> Keep the device active across the complete direction-output sequence and
> propagate failure when setting the initial output value.
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>

Reviewed-by: Michael Walle <mwalle@kernel.org>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 297 bytes --]

[PATCH v6 3/3] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Janani Sunil]

The AD7768 provides five GPIOs controlled through registers shared
with the parent IIO device. Register an auxiliary gpio-regmap driver
and use the parent device for runtime PM.

The device has separate input-state and output-latch registers. Add a
reg_mask_xlate() callback that checks the line direction and reads the
programmed output latch for output lines while retaining input-state
reads for input lines.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/Kconfig       |  12 +++++
 drivers/gpio/Makefile      |   1 +
 drivers/gpio/gpio-ad7768.c | 122 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 135 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index a48586bb8edb..07b7f8ab0ccb 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1818,6 +1818,18 @@ endmenu
 menu "Auxiliary Bus GPIO drivers"
 	depends on AUXILIARY_BUS
 
+config GPIO_AD7768
+	tristate "Analog Devices AD7768 GPIO support"
+	depends on AD7768
+	depends on GPIOLIB
+	select GPIO_REGMAP
+	help
+	  Say yes here to expose the AD7768 utility pins as GPIOs when the
+	  device tree node is marked as a GPIO controller.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called gpio-ad7768.
+
 config GPIO_LTC4283
 	tristate "Analog Devices LTC4283 GPIO support"
 	depends on SENSORS_LTC4283
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index dc9e6d643b5b..ce56e9b3f55d 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_GPIO_104_IDI_48)		+= gpio-104-idi-48.o
 obj-$(CONFIG_GPIO_104_IDIO_16)		+= gpio-104-idio-16.o
 obj-$(CONFIG_GPIO_74X164)		+= gpio-74x164.o
 obj-$(CONFIG_GPIO_74XX_MMIO)		+= gpio-74xx-mmio.o
+obj-$(CONFIG_GPIO_AD7768)		+= gpio-ad7768.o
 obj-$(CONFIG_GPIO_ADNP)			+= gpio-adnp.o
 obj-$(CONFIG_GPIO_ADP5520)		+= gpio-adp5520.o
 obj-$(CONFIG_GPIO_ADP5585)		+= gpio-adp5585.o
diff --git a/drivers/gpio/gpio-ad7768.c b/drivers/gpio/gpio-ad7768.c
new file mode 100644
index 000000000000..cac3a55e738d
--- /dev/null
+++ b/drivers/gpio/gpio-ad7768.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7768 GPIO auxiliary driver
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/bitmap.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/regmap.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define AD7768_REG_GPIO_CONTROL		0x0E
+#define   AD7768_GPIO_UGPIO_ENABLE	BIT(7)
+
+#define AD7768_REG_GPIO_WRITE		0x0F
+#define AD7768_REG_GPIO_READ		0x10
+
+#define AD7768_NUM_GPIOS		5
+#define AD7768_FILTER_GPIO		4
+
+static int ad7768_gpio_init_valid_mask(struct gpio_chip *gc,
+				       unsigned long *valid_mask,
+				       unsigned int ngpios)
+{
+	if (ngpios > AD7768_FILTER_GPIO &&
+	    device_property_match_string(gc->parent->parent, "clock-names",
+					 "mclk") < 0)
+		bitmap_clear(valid_mask, AD7768_FILTER_GPIO, 1);
+
+	return 0;
+}
+
+static int ad7768_gpio_reg_mask_xlate(struct gpio_regmap *gpio,
+				      enum gpio_regmap_operation op,
+				      unsigned int base, unsigned int offset,
+				      unsigned int *reg, unsigned int *mask)
+{
+	struct regmap *regmap = gpio_regmap_get_drvdata(gpio);
+	int ret;
+
+	*reg = base;
+	*mask = BIT(offset);
+
+	if (op != GPIO_REGMAP_GET_OP)
+		return 0;
+
+	/*
+	 * AD7768 has separate input-state and output-latch registers. For an
+	 * output line, report the programmed value from the output latch;
+	 * input lines continue to use the input-state register.
+	 */
+	ret = regmap_test_bits(regmap, AD7768_REG_GPIO_CONTROL, *mask);
+	if (ret < 0)
+		return ret;
+	if (ret)
+		*reg = AD7768_REG_GPIO_WRITE;
+
+	return 0;
+}
+
+static int ad7768_gpio_probe(struct auxiliary_device *adev,
+			     const struct auxiliary_device_id *id)
+{
+	struct gpio_regmap_config config;
+	struct device *dev = &adev->dev;
+	struct device *parent;
+	struct regmap *map;
+	int ret;
+
+	parent = dev->parent;
+	map = dev_get_regmap(parent, NULL);
+	if (!map)
+		return -ENODEV;
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(parent, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(map, AD7768_REG_GPIO_CONTROL, AD7768_GPIO_UGPIO_ENABLE);
+	if (ret)
+		return ret;
+
+	config = (struct gpio_regmap_config) {
+		.parent = dev,
+		.regmap = map,
+		.label = dev_name(parent),
+		.ngpio = AD7768_NUM_GPIOS,
+		.reg_dat_base = AD7768_REG_GPIO_READ,
+		.reg_set_base = AD7768_REG_GPIO_WRITE,
+		.reg_dir_out_base = AD7768_REG_GPIO_CONTROL,
+		.pm_dev = parent,
+		.reg_mask_xlate = ad7768_gpio_reg_mask_xlate,
+		.init_valid_mask = ad7768_gpio_init_valid_mask,
+		.drvdata = map,
+	};
+
+	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &config));
+}
+
+static const struct auxiliary_device_id ad7768_gpio_ids[] = {
+	{ .name = "ad7768.gpio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(auxiliary, ad7768_gpio_ids);
+
+static struct auxiliary_driver ad7768_gpio_driver = {
+	.probe = ad7768_gpio_probe,
+	.id_table = ad7768_gpio_ids,
+};
+module_auxiliary_driver(ad7768_gpio_driver);
+
+MODULE_AUTHOR("Janani Sunil <janani.sunil@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7768 GPIO auxiliary driver");
+MODULE_LICENSE("GPL");

-- 
2.43.0

Re: [PATCH v6 3/3] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Andy Shevchenko]

On Thu, Sep 03, 2026 at 02:01:28PM +0200, Janani Sunil wrote:
> The AD7768 provides five GPIOs controlled through registers shared
> with the parent IIO device. Register an auxiliary gpio-regmap driver
> and use the parent device for runtime PM.
> 
> The device has separate input-state and output-latch registers. Add a
> reg_mask_xlate() callback that checks the line direction and reads the
> programmed output latch for output lines while retaining input-state
> reads for input lines.

...

> +#include <linux/bitmap.h>

Hmm... as far as I can see this is an overkill and bitops.h should suffice.

...

> +static int ad7768_gpio_init_valid_mask(struct gpio_chip *gc,
> +				       unsigned long *valid_mask,
> +				       unsigned int ngpios)
> +{
> +	if (ngpios > AD7768_FILTER_GPIO &&
> +	    device_property_match_string(gc->parent->parent, "clock-names",
> +					 "mclk") < 0)
> +		bitmap_clear(valid_mask, AD7768_FILTER_GPIO, 1);

This is a single bit, we have __clear_bit() for that in bitops.h.

> +	return 0;
> +}

...

> +static int ad7768_gpio_probe(struct auxiliary_device *adev,
> +			     const struct auxiliary_device_id *id)
> +{
> +	struct gpio_regmap_config config;
> +	struct device *dev = &adev->dev;

> +	struct device *parent;

Assign it here, this callback must not be called with dev == NULL, so it's fine
to dereference it without validation.

	struct device *parent = dev->parent;

> +	struct regmap *map;
> +	int ret;

> +	parent = dev->parent;

And drop this.

> +	map = dev_get_regmap(parent, NULL);
> +	if (!map)
> +		return -ENODEV;
> +
> +	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(parent, pm);
> +	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_set_bits(map, AD7768_REG_GPIO_CONTROL, AD7768_GPIO_UGPIO_ENABLE);
> +	if (ret)
> +		return ret;
> +
> +	config = (struct gpio_regmap_config) {
> +		.parent = dev,
> +		.regmap = map,
> +		.label = dev_name(parent),
> +		.ngpio = AD7768_NUM_GPIOS,
> +		.reg_dat_base = AD7768_REG_GPIO_READ,
> +		.reg_set_base = AD7768_REG_GPIO_WRITE,
> +		.reg_dir_out_base = AD7768_REG_GPIO_CONTROL,
> +		.pm_dev = parent,
> +		.reg_mask_xlate = ad7768_gpio_reg_mask_xlate,
> +		.init_valid_mask = ad7768_gpio_init_valid_mask,
> +		.drvdata = map,
> +	};
> +
> +	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &config));
> +}

-- 
With Best Regards,
Andy Shevchenko