gpio: gpio-adg1414: add ADG1414

The ADG1414 is a set of octal, single-pole, single-throw (SPST) switches
controlled via a 3-wire serial interface. On resistance is matched
closely between switches and is very flat over the full signal range.
Each switch conducts equally well in both directions and the input
signal range extends to the supplies. Data is written to these devices
in the form of eight bits; each bit corresponds to one channel.

Signed-off-by: Kim Seer Paller <[email protected]>

Author: kseerp

drivers/gpio/Kconfig

@@ -1708,6 +1708,16 @@ config GPIO_74X164
 	  shift registers. This driver can be used to provide access
 	  to more GPIO outputs.
 
+config GPIO_ADG1414
+	tristate "ADG1414 SPST Switch Driver"
+	depends on GPIOLIB && SPI
+	help
+	  Say yes here to build support for Analog Devices ADG1414 SPST
+	  Switch Driver
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called gpio-adg1414.
+
 config GPIO_ADI_DAQ1
 	tristate "Analog Devices AD-FMCDAQ1-EBZ SPI-GPIO expander driver"
 	help

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_ADI_DAQ1)		+= gpio-adi-daq1.o
 obj-$(CONFIG_GPIO_ADNP)			+= gpio-adnp.o
 obj-$(CONFIG_GPIO_ADP5520)		+= gpio-adp5520.o

drivers/gpio/gpio-adg1414.c

@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADG1414 Serially-Controlled Octal SPST Switches Driver
+ *
+ * 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/spi/spi.h>
+
+#define ADG1414_MAX_DEVICES 4
+
+struct adg1414_state {
+	struct spi_device *spi;
+	struct gpio_chip chip;
+	/* lock to protect against multiple access to the device and shared data */
+	struct mutex lock;
+
+	u8 buffer[];
+};
+
+static int adg1414_write_config(struct adg1414_state *st)
+{
+	return spi_write(st->spi, st->buffer, st->chip.ngpio / 8);
+}
+
+static int adg1414_get_value(struct gpio_chip *chip, unsigned int offset)
+{
+	struct adg1414_state *st = gpiochip_get_data(chip);
+	u8 bank, pin;
+
+	guard(mutex)(&st->lock);
+	bank = (chip->ngpio / 8) - 1 - offset / 8;
+	pin = offset % 8;
+
+	return (st->buffer[bank] >> pin) & 0x1;
+}
+
+static void adg1414_set_value(struct gpio_chip *chip, unsigned int offset,
+			      int val)
+{
+	struct adg1414_state *st = gpiochip_get_data(chip);
+	u8 bank, pin;
+
+	guard(mutex)(&st->lock);
+	bank = (chip->ngpio / 8) - 1 - offset / 8;
+	pin = offset % 8;
+
+	if (val)
+		st->buffer[bank] |= BIT(pin);
+	else
+		st->buffer[bank] &= ~BIT(pin);
+
+	adg1414_write_config(st);
+}
+
+static void adg1414_set_multiple(struct gpio_chip *chip, unsigned long *mask,
+				 unsigned long *bits)
+{
+	struct adg1414_state *st = gpiochip_get_data(chip);
+	unsigned long offset, bankmask, bitmask;
+	size_t bank;
+
+	guard(mutex)(&st->lock);
+	for_each_set_clump8(offset, bankmask, mask, chip->ngpio) {
+		bank = (chip->ngpio / 8) - 1 - offset / 8;
+		bitmask = bitmap_get_value8(bits, offset) & bankmask;
+
+		st->buffer[bank] &= ~bankmask;
+		st->buffer[bank] |= bitmask;
+	}
+
+	adg1414_write_config(st);
+}
+
+static int adg1414_direction_output(struct gpio_chip *chip, unsigned int offset,
+				    int val)
+{
+	adg1414_set_value(chip, offset, val);
+	return 0;
+}
+
+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;
+
+	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 = devm_kzalloc(dev, sizeof(*st) + num_devices, GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	st->spi = spi;
+
+	/* 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);
+	}
+
+	st->chip.label = "adg1414";
+	st->chip.parent = dev;
+	st->chip.direction_output = adg1414_direction_output;
+	st->chip.set = adg1414_set_value;
+	st->chip.get = adg1414_get_value;
+	st->chip.set_multiple = adg1414_set_multiple;
+	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 <[email protected]>");
+MODULE_DESCRIPTION("ADG1414 Serially-Controlled Octal SPST Switches Driver");
+MODULE_LICENSE("GPL");