[PATCH v3 2/2] gpio: adg1712: add driver support

[Antoniu Miclaus <antoniu.miclaus@analog.com>]

Add driver support for the ADG1712, which contains four independent
single-pole/single-throw (SPST) switches and operates with a
low-voltage single supply range from +1.08V to +5.5V or a low-voltage
dual supply range from ±1.08V to ±2.75V.

The driver configures switches once at probe time based on device tree
properties and does not expose any userspace interface for runtime control.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
Changes in v3:
- Remove GPIO controller interface
- Configure switches from device tree at probe time only
- Add 'switch-states' property parsing
- Change from GPIOD_ASIS to GPIOD_OUT_LOW
---
 drivers/gpio/Kconfig        |  9 ++++
 drivers/gpio/Makefile       |  1 +
 drivers/gpio/gpio-adg1712.c | 87 +++++++++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+)
 create mode 100644 drivers/gpio/gpio-adg1712.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 7ee3afbc2b05..3fac05823eae 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -157,6 +157,15 @@ config GPIO_74XX_MMIO
 	    8 bits:	74244 (Input), 74273 (Output)
 	    16 bits:	741624 (Input), 7416374 (Output)
 
+config GPIO_ADG1712
+	tristate "Analog Devices ADG1712 quad SPST switch GPIO driver"
+	depends on GPIOLIB
+	help
+	  GPIO driver for Analog Devices ADG1712 quad single-pole,
+	  single-throw (SPST) switch. The driver provides a GPIO controller
+	  interface where each GPIO line controls one of the four independent
+	  analog switches on the ADG1712.
+
 config GPIO_ALTERA
 	tristate "Altera GPIO"
 	select GPIOLIB_IRQCHIP
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index ec296fa14bfd..9043d2d07a15 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -28,6 +28,7 @@ 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-$(CONFIG_GPIO_ADG1712)		+= gpio-adg1712.o
 obj-$(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-adg1712.c b/drivers/gpio/gpio-adg1712.c
new file mode 100644
index 000000000000..86f8645cf2ad
--- /dev/null
+++ b/drivers/gpio/gpio-adg1712.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices ADG1712 quad SPST switch driver
+ *
+ * Copyright 2025 Analog Devices Inc.
+ *
+ * Author: Antoniu Miclaus <antoniu.miclaus@analog.com>
+ */
+
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+
+#define ADG1712_NUM_SWITCHES	4
+
+struct adg1712 {
+	struct gpio_descs *switch_gpios;
+};
+
+static int adg1712_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct adg1712 *adg1712;
+	u32 switch_states[ADG1712_NUM_SWITCHES] = {0}; /* Default all switches off */
+	int ret, i;
+
+	adg1712 = devm_kzalloc(dev, sizeof(*adg1712), GFP_KERNEL);
+	if (!adg1712)
+		return -ENOMEM;
+
+	adg1712->switch_gpios = devm_gpiod_get_array(dev, "switch", GPIOD_OUT_LOW);
+	if (IS_ERR(adg1712->switch_gpios))
+		return dev_err_probe(dev, PTR_ERR(adg1712->switch_gpios),
+				     "failed to get switch gpios\n");
+
+	if (adg1712->switch_gpios->ndescs != ADG1712_NUM_SWITCHES)
+		return dev_err_probe(dev, -EINVAL,
+				     "expected %d gpios, got %d\n",
+				     ADG1712_NUM_SWITCHES,
+				     adg1712->switch_gpios->ndescs);
+
+	ret = device_property_read_u32_array(dev, "switch-states", switch_states,
+					     ADG1712_NUM_SWITCHES);
+	if (ret && ret != -EINVAL)
+		return dev_err_probe(dev, ret, "failed to read switch-states\n");
+
+	for (i = 0; i < ADG1712_NUM_SWITCHES; i++) {
+		if (switch_states[i] > 1) {
+			dev_warn(dev, "invalid switch state %u for switch %d, using 0\n",
+				 switch_states[i], i);
+			switch_states[i] = 0;
+		}
+
+		ret = gpiod_set_value_cansleep(adg1712->switch_gpios->desc[i],
+					       switch_states[i]);
+		if (ret)
+			return dev_err_probe(dev, ret, "failed to set switch %d\n", i);
+	}
+
+	platform_set_drvdata(pdev, adg1712);
+
+	dev_info(dev, "ADG1712 switch controller configured\n");
+
+	return 0;
+}
+
+static const struct of_device_id adg1712_dt_ids[] = {
+	{ .compatible = "adi,adg1712", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, adg1712_dt_ids);
+
+static struct platform_driver adg1712_driver = {
+	.driver = {
+		.name = "adg1712",
+		.of_match_table = adg1712_dt_ids,
+	},
+	.probe = adg1712_probe,
+};
+module_platform_driver(adg1712_driver);
+
+MODULE_DESCRIPTION("Analog Devices ADG1712 quad SPST switch driver");
+MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@analog.com>");
+MODULE_LICENSE("GPL");
-- 
2.43.0