[PATCH v2 2/2] gpio: gpio-adg1414: New driver

[Kim Seer Paller <kimseer.paller@analog.com>]

The ADG1414 is a 9.5 Ω RON ±15 V/+12 V/±5 V iCMOS Serially-Controlled
Octal SPST Switches

Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
---
 MAINTAINERS                 |   1 +
 drivers/gpio/Kconfig        |  10 +++
 drivers/gpio/Makefile       |   1 +
 drivers/gpio/gpio-adg1414.c | 162 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 174 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 66d92be0f57daa9eabb48d7e53b6b2bea0c40863..65877ca70b7e929353798c5639bf38593241d83e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -503,6 +503,7 @@ M:	Kim Seer Paller <kimseer.paller@analog.com>
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/gpio/gpio-adg1414.yaml
+F:	drivers/gpio/gpio-adg1414.c
 
 ADM1025 HARDWARE MONITOR DRIVER
 M:	Jean Delvare <jdelvare@suse.com>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 98b4d1633b258b93d05ba66d53f647e7ec6ac364..4b797ddebd21bc879524f8504b343add2730c793 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1797,6 +1797,16 @@ config GPIO_74X164
 	  shift registers. This driver can be used to provide access
 	  to more GPIO outputs.
 
+config GPIO_ADG1414
+	tristate "ADG1414 Serially-Controlled Octal SPST Switches"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices ADG1414
+	  Serially-Controlled Octal SPST Switches
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called gpio-adg1414.
+
 config GPIO_MAX3191X
 	tristate "Maxim MAX3191x industrial serializer"
 	select CRC8
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index af3ba4d81b583842893ea69e677fbe2abf31bc7b..58d723cb32feebd35db13ae9cae5d232feba3f5b 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -24,6 +24,7 @@ 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-$(CONFIG_GPIO_ADG1414)		+= gpio-adg1414.o
 obj-$(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-adg1414.c b/drivers/gpio/gpio-adg1414.c
new file mode 100644
index 0000000000000000000000000000000000000000..91e07c38fb1c86162afd9cfcdf1d7cfcccb03234
--- /dev/null
+++ b/drivers/gpio/gpio-adg1414.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADG1414 Serially-Controlled Octal SPST Switches
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#define ADG1414_MAX_DEVICES		4
+
+struct adg1414_state {
+	struct spi_device *spi;
+	struct gpio_chip chip;
+	struct regmap *regmap;
+	struct mutex lock; /* protect sensor state */
+	u32 buf;
+
+	__be32 tx __aligned(ARCH_DMA_MINALIGN);
+};
+
+static int adg1414_spi_write(void *context, const void *data, size_t count)
+{
+	struct adg1414_state *st = context;
+
+	struct spi_transfer xfer = {
+		.tx_buf = &st->tx,
+		.len = count,
+	};
+
+	return spi_sync_transfer(st->spi, &xfer, 1);
+}
+
+static int adg1414_spi_read(void *context, const void *reg, size_t reg_size,
+			    void *val, size_t val_size)
+{
+	return 0;
+}
+
+static int adg1414_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct adg1414_state *st = gpiochip_get_data(chip);
+
+	guard(mutex)(&st->lock);
+
+	return st->buf & BIT(offset);
+}
+
+static void adg1414_set(struct gpio_chip *chip, unsigned int offset, int value)
+{
+	struct adg1414_state *st = gpiochip_get_data(chip);
+
+	guard(mutex)(&st->lock);
+
+	if (value)
+		st->buf |= BIT(offset);
+	else
+		st->buf &= ~BIT(offset);
+
+	st->tx = cpu_to_be32(st->buf << (32 - st->chip.ngpio));
+
+	adg1414_spi_write(st, 0, st->chip.ngpio / 8);
+}
+
+static const struct regmap_bus adg1414_regmap_bus = {
+	.write = adg1414_spi_write,
+	.read =	adg1414_spi_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static const struct regmap_config adg1414_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int adg1414_get_direction(struct gpio_chip *chip,
+				 unsigned int offset)
+{
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static int adg1414_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct adg1414_state *st;
+	struct gpio_desc *reset;
+	u32 num_devices;
+	int ret;
+
+	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	st->spi = spi;
+
+	st->regmap = devm_regmap_init(dev, &adg1414_regmap_bus, st,
+				      &adg1414_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(dev, PTR_ERR(st->regmap),
+				     "Failed to initialize regmap");
+
+	/* Use reset pin to reset the device */
+	reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(reset))
+		return dev_err_probe(dev, PTR_ERR(reset),
+				     "Failed to get reset gpio");
+
+	if (reset) {
+		fsleep(1);
+		gpiod_set_value_cansleep(reset, 0);
+	}
+
+	num_devices = 1;
+	ret = device_property_read_u32(dev, "#daisy-chained-devices",
+				       &num_devices);
+	if (!ret) {
+		if (!num_devices || num_devices > ADG1414_MAX_DEVICES)
+			return dev_err_probe(dev, ret,
+			       "Failed to get daisy-chained-devices property\n");
+	}
+
+	st->chip.label = "adg1414";
+	st->chip.parent = dev;
+	st->chip.get_direction = adg1414_get_direction;
+	st->chip.set = adg1414_set;
+	st->chip.get = adg1414_get;
+	st->chip.base = -1;
+	st->chip.ngpio =  num_devices * 8;
+	st->chip.can_sleep = true;
+
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
+	return devm_gpiochip_add_data(dev, &st->chip, st);
+}
+
+static const struct of_device_id adg1414_of_match[] = {
+	{ .compatible = "adi,adg1414-gpio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, adg1414_of_match);
+
+static struct spi_driver adg1414_driver = {
+	.driver = {
+		.name = "adg1414-gpio",
+		.of_match_table = adg1414_of_match,
+	},
+	.probe = adg1414_probe,
+};
+module_spi_driver(adg1414_driver);
+
+MODULE_AUTHOR("Kim Seer Paller <kimseer.paller@analog.com>");
+MODULE_DESCRIPTION("ADG1414 Serially-Controlled Octal SPST Switches");
+MODULE_LICENSE("GPL");

-- 
2.34.1