gpio: Add Nuvoton NCT6694 GPIO support

This driver supports GPIO and IRQ functionality for NCT6694 MFD
device based on USB interface.

Reviewed-by: Linus Walleij <[e-mail]>
Acked-by: Bartosz Golaszewski <[e-mail]>
Signed-off-by: Ming Yu <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

MAINTAINERS

···
 NUVOTON NCT6694 MFD DRIVER
 M:	Ming Yu <[e-mail]>
 S:	Supported
+F:	drivers/gpio/gpio-nct6694.c
 F:	drivers/mfd/nct6694.c
 F:	include/linux/mfd/nct6694.h
 

drivers/gpio/Kconfig

···
 	  This driver can also be built as a module. If so, the module will be
 	  called gpio-max77759.
 
+config GPIO_NCT6694
+	tristate "Nuvoton NCT6694 GPIO controller support"
+	depends on MFD_NCT6694
+	select GENERIC_IRQ_CHIP
+	select GPIOLIB_IRQCHIP
+	help
+	  This driver supports 8 GPIO pins per bank that can all be interrupt
+	  sources.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called gpio-nct6694.
+
 config GPIO_PALMAS
 	tristate "TI PALMAS series PMICs GPIO"
 	depends on MFD_PALMAS

drivers/gpio/Makefile

···
 obj-$(CONFIG_GPIO_MVEBU)		+= gpio-mvebu.o
 obj-$(CONFIG_GPIO_MXC)			+= gpio-mxc.o
 obj-$(CONFIG_GPIO_MXS)			+= gpio-mxs.o
+obj-$(CONFIG_GPIO_NCT6694)		+= gpio-nct6694.o
 obj-$(CONFIG_GPIO_NOMADIK)		+= gpio-nomadik.o
 obj-$(CONFIG_GPIO_NPCM_SGPIO)		+= gpio-npcm-sgpio.o
 obj-$(CONFIG_GPIO_OCTEON)		+= gpio-octeon.o

drivers/gpio/gpio-nct6694.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 GPIO controller driver based on USB interface.
+ *
+ * Copyright (C) 2025 Nuvoton Technology Corp.
+ */
+
+#include <linux/bits.h>
+#include <linux/gpio/driver.h>
+#include <linux/idr.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/nct6694.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+/*
+ * USB command module type for NCT6694 GPIO controller.
+ * This defines the module type used for communication with the NCT6694
+ * GPIO controller over the USB interface.
+ */
+#define NCT6694_GPIO_MOD	0xFF
+
+#define NCT6694_GPIO_VER	0x90
+#define NCT6694_GPIO_VALID	0x110
+#define NCT6694_GPI_DATA	0x120
+#define NCT6694_GPO_DIR		0x170
+#define NCT6694_GPO_TYPE	0x180
+#define NCT6694_GPO_DATA	0x190
+
+#define NCT6694_GPI_STS		0x130
+#define NCT6694_GPI_CLR		0x140
+#define NCT6694_GPI_FALLING	0x150
+#define NCT6694_GPI_RISING	0x160
+
+#define NCT6694_NR_GPIO		8
+
+struct nct6694_gpio_data {
+	struct nct6694 *nct6694;
+	struct gpio_chip gpio;
+	struct mutex lock;
+	/* Protect irq operation */
+	struct mutex irq_lock;
+
+	unsigned char reg_val;
+	unsigned char irq_trig_falling;
+	unsigned char irq_trig_rising;
+
+	/* Current gpio group */
+	unsigned char group;
+	int irq;
+};
+
+static int nct6694_get_direction(struct gpio_chip *gpio, unsigned int offset)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	const struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPO_DIR + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	return !(BIT(offset) & data->reg_val);
+}
+
+static int nct6694_direction_input(struct gpio_chip *gpio, unsigned int offset)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	const struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPO_DIR + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	data->reg_val &= ~BIT(offset);
+
+	return nct6694_write_msg(data->nct6694, &cmd_hd, &data->reg_val);
+}
+
+static int nct6694_direction_output(struct gpio_chip *gpio,
+				    unsigned int offset, int val)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPO_DIR + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	/* Set direction to output */
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	data->reg_val |= BIT(offset);
+	ret = nct6694_write_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	/* Then set output level */
+	cmd_hd.offset = cpu_to_le16(NCT6694_GPO_DATA + data->group);
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	if (val)
+		data->reg_val |= BIT(offset);
+	else
+		data->reg_val &= ~BIT(offset);
+
+	return nct6694_write_msg(data->nct6694, &cmd_hd, &data->reg_val);
+}
+
+static int nct6694_get_value(struct gpio_chip *gpio, unsigned int offset)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPO_DIR + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	if (BIT(offset) & data->reg_val) {
+		cmd_hd.offset = cpu_to_le16(NCT6694_GPO_DATA + data->group);
+		ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+		if (ret < 0)
+			return ret;
+
+		return !!(BIT(offset) & data->reg_val);
+	}
+
+	cmd_hd.offset = cpu_to_le16(NCT6694_GPI_DATA + data->group);
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	return !!(BIT(offset) & data->reg_val);
+}
+
+static int nct6694_set_value(struct gpio_chip *gpio, unsigned int offset,
+			     int val)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	const struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPO_DATA + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	if (val)
+		data->reg_val |= BIT(offset);
+	else
+		data->reg_val &= ~BIT(offset);
+
+	return nct6694_write_msg(data->nct6694, &cmd_hd, &data->reg_val);
+}
+
+static int nct6694_set_config(struct gpio_chip *gpio, unsigned int offset,
+			      unsigned long config)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	const struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPO_TYPE + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+		data->reg_val |= BIT(offset);
+		break;
+	case PIN_CONFIG_DRIVE_PUSH_PULL:
+		data->reg_val &= ~BIT(offset);
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	return nct6694_write_msg(data->nct6694, &cmd_hd, &data->reg_val);
+}
+
+static int nct6694_init_valid_mask(struct gpio_chip *gpio,
+				   unsigned long *valid_mask,
+				   unsigned int ngpios)
+{
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	const struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPIO_VALID + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret < 0)
+		return ret;
+
+	*valid_mask = data->reg_val;
+
+	return ret;
+}
+
+static irqreturn_t nct6694_irq_handler(int irq, void *priv)
+{
+	struct nct6694_gpio_data *data = priv;
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPI_STS + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	unsigned char status;
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	if (ret)
+		return IRQ_NONE;
+
+	status = data->reg_val;
+
+	while (status) {
+		int bit = __ffs(status);
+
+		data->reg_val = BIT(bit);
+		handle_nested_irq(irq_find_mapping(data->gpio.irq.domain, bit));
+		status &= ~BIT(bit);
+		cmd_hd.offset = cpu_to_le16(NCT6694_GPI_CLR + data->group);
+		nct6694_write_msg(data->nct6694, &cmd_hd, &data->reg_val);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int nct6694_get_irq_trig(struct nct6694_gpio_data *data)
+{
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPI_FALLING + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(data->nct6694, &cmd_hd, &data->irq_trig_falling);
+	if (ret)
+		return ret;
+
+	cmd_hd.offset = cpu_to_le16(NCT6694_GPI_RISING + data->group);
+	return nct6694_read_msg(data->nct6694, &cmd_hd, &data->irq_trig_rising);
+}
+
+static void nct6694_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *gpio = irq_data_get_irq_chip_data(d);
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
+
+	gpiochip_disable_irq(gpio, hwirq);
+}
+
+static void nct6694_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *gpio = irq_data_get_irq_chip_data(d);
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
+
+	gpiochip_enable_irq(gpio, hwirq);
+}
+
+static int nct6694_irq_set_type(struct irq_data *d, unsigned int type)
+{
+	struct gpio_chip *gpio = irq_data_get_irq_chip_data(d);
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
+
+	guard(mutex)(&data->lock);
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		data->irq_trig_rising |= BIT(hwirq);
+		break;
+
+	case IRQ_TYPE_EDGE_FALLING:
+		data->irq_trig_falling |= BIT(hwirq);
+		break;
+
+	case IRQ_TYPE_EDGE_BOTH:
+		data->irq_trig_rising |= BIT(hwirq);
+		data->irq_trig_falling |= BIT(hwirq);
+		break;
+
+	default:
+		return -ENOTSUPP;
+	}
+
+	return 0;
+}
+
+static void nct6694_irq_bus_lock(struct irq_data *d)
+{
+	struct gpio_chip *gpio = irq_data_get_irq_chip_data(d);
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+
+	mutex_lock(&data->irq_lock);
+}
+
+static void nct6694_irq_bus_sync_unlock(struct irq_data *d)
+{
+	struct gpio_chip *gpio = irq_data_get_irq_chip_data(d);
+	struct nct6694_gpio_data *data = gpiochip_get_data(gpio);
+	struct nct6694_cmd_header cmd_hd = {
+		.mod = NCT6694_GPIO_MOD,
+		.offset = cpu_to_le16(NCT6694_GPI_FALLING + data->group),
+		.len = cpu_to_le16(sizeof(data->reg_val))
+	};
+
+	scoped_guard(mutex, &data->lock) {
+		nct6694_write_msg(data->nct6694, &cmd_hd, &data->irq_trig_falling);
+
+		cmd_hd.offset = cpu_to_le16(NCT6694_GPI_RISING + data->group);
+		nct6694_write_msg(data->nct6694, &cmd_hd, &data->irq_trig_rising);
+	}
+
+	mutex_unlock(&data->irq_lock);
+}
+
+static const struct irq_chip nct6694_irq_chip = {
+	.name			= "gpio-nct6694",
+	.irq_mask		= nct6694_irq_mask,
+	.irq_unmask		= nct6694_irq_unmask,
+	.irq_set_type		= nct6694_irq_set_type,
+	.irq_bus_lock		= nct6694_irq_bus_lock,
+	.irq_bus_sync_unlock	= nct6694_irq_bus_sync_unlock,
+	.flags			= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
+static void nct6694_irq_dispose_mapping(void *d)
+{
+	struct nct6694_gpio_data *data = d;
+
+	irq_dispose_mapping(data->irq);
+}
+
+static void nct6694_gpio_ida_free(void *d)
+{
+	struct nct6694_gpio_data *data = d;
+	struct nct6694 *nct6694 = data->nct6694;
+
+	ida_free(&nct6694->gpio_ida, data->group);
+}
+
+static int nct6694_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct nct6694 *nct6694 = dev_get_drvdata(dev->parent);
+	struct nct6694_gpio_data *data;
+	struct gpio_irq_chip *girq;
+	int ret, i;
+	char **names;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->nct6694 = nct6694;
+
+	ret = ida_alloc(&nct6694->gpio_ida, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+	data->group = ret;
+
+	ret = devm_add_action_or_reset(dev, nct6694_gpio_ida_free, data);
+	if (ret)
+		return ret;
+
+	names = devm_kcalloc(dev, NCT6694_NR_GPIO, sizeof(char *),
+			     GFP_KERNEL);
+	if (!names)
+		return -ENOMEM;
+
+	for (i = 0; i < NCT6694_NR_GPIO; i++) {
+		names[i] = devm_kasprintf(dev, GFP_KERNEL, "GPIO%X%d",
+					  data->group, i);
+		if (!names[i])
+			return -ENOMEM;
+	}
+
+	data->irq = irq_create_mapping(nct6694->domain,
+				       NCT6694_IRQ_GPIO0 + data->group);
+	if (!data->irq)
+		return -EINVAL;
+
+	ret = devm_add_action_or_reset(dev, nct6694_irq_dispose_mapping, data);
+	if (ret)
+		return ret;
+
+	data->gpio.names		= (const char * const*)names;
+	data->gpio.label		= pdev->name;
+	data->gpio.direction_input	= nct6694_direction_input;
+	data->gpio.get			= nct6694_get_value;
+	data->gpio.direction_output	= nct6694_direction_output;
+	data->gpio.set			= nct6694_set_value;
+	data->gpio.get_direction	= nct6694_get_direction;
+	data->gpio.set_config		= nct6694_set_config;
+	data->gpio.init_valid_mask	= nct6694_init_valid_mask;
+	data->gpio.base			= -1;
+	data->gpio.can_sleep		= false;
+	data->gpio.owner		= THIS_MODULE;
+	data->gpio.ngpio		= NCT6694_NR_GPIO;
+
+	platform_set_drvdata(pdev, data);
+
+	ret = devm_mutex_init(dev, &data->lock);
+	if (ret)
+		return ret;
+
+	ret = devm_mutex_init(dev, &data->irq_lock);
+	if (ret)
+		return ret;
+
+	ret = nct6694_get_irq_trig(data);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to get irq trigger type\n");
+		return ret;
+	}
+
+	girq = &data->gpio.irq;
+	gpio_irq_chip_set_chip(girq, &nct6694_irq_chip);
+	girq->parent_handler = NULL;
+	girq->num_parents = 0;
+	girq->parents = NULL;
+	girq->default_type = IRQ_TYPE_NONE;
+	girq->handler = handle_level_irq;
+	girq->threaded = true;
+
+	ret = devm_request_threaded_irq(dev, data->irq, NULL, nct6694_irq_handler,
+					IRQF_ONESHOT | IRQF_SHARED,
+					"gpio-nct6694", data);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to request irq\n");
+		return ret;
+	}
+
+	return devm_gpiochip_add_data(dev, &data->gpio, data);
+}
+
+static struct platform_driver nct6694_gpio_driver = {
+	.driver = {
+		.name	= "nct6694-gpio",
+	},
+	.probe		= nct6694_gpio_probe,
+};
+
+module_platform_driver(nct6694_gpio_driver);
+
+MODULE_DESCRIPTION("USB-GPIO controller driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <[e-mail]>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:nct6694-gpio");