1 files changed, 115 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-line-mux.c b/drivers/gpio/gpio-line-mux.c
new file mode 100644
index 000000000..b4452d956
--- /dev/null
+++ b/drivers/gpio/gpio-line-mux.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO line mux which acts as virtual gpiochip and provides a 1-to-many
+ * mapping between virtual GPIOs and a real GPIO + multiplexer.
+ *
+ * Copyright (c) 2025 Jonas Jelonek <jelonek.jonas@gmail.com>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/mutex.h>
+#include <linux/mux/consumer.h>
+#include <linux/platform_device.h>
+
+#define MUX_SELECT_DELAY_US	100
+
+struct gpio_lmux {
+	struct gpio_chip gc;
+	struct mux_control *mux;
+	struct gpio_desc *muxed_gpio;
+
+	u32 num_gpio_mux_states;
+	unsigned int gpio_mux_states[] __counted_by(num_gpio_mux_states);
+};
+
+static int gpio_lmux_gpio_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_lmux *glm = gpiochip_get_data(gc);
+	int ret;
+
+	ret = mux_control_select_delay(glm->mux, glm->gpio_mux_states[offset],
+				       MUX_SELECT_DELAY_US);
+	if (ret < 0)
+		return ret;
+
+	ret = gpiod_get_raw_value_cansleep(glm->muxed_gpio);
+	mux_control_deselect(glm->mux);
+	return ret;
+}
+
+static int gpio_lmux_gpio_get_direction(struct gpio_chip *gc,
+					unsigned int offset)
+{
+	return GPIO_LINE_DIRECTION_IN;
+}
+
+static int gpio_lmux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_lmux *glm;
+	unsigned int ngpio;
+	size_t size;
+	int ret;
+
+	ngpio = device_property_count_u32(dev, "gpio-line-mux-states");
+	if (!ngpio)
+		return -EINVAL;
+
+	size = struct_size(glm, gpio_mux_states, ngpio);
+	glm = devm_kzalloc(dev, size, GFP_KERNEL);
+	if (!glm)
+		return -ENOMEM;
+
+	glm->gc.base = -1;
+	glm->gc.can_sleep = true;
+	glm->gc.fwnode = dev_fwnode(dev);
+	glm->gc.label = dev_name(dev);
+	glm->gc.ngpio = ngpio;
+	glm->gc.owner = THIS_MODULE;
+	glm->gc.parent = dev;
+
+	glm->gc.get = gpio_lmux_gpio_get;
+	glm->gc.get_direction = gpio_lmux_gpio_get_direction;
+
+	glm->mux = devm_mux_control_get(dev, NULL);
+	if (IS_ERR(glm->mux))
+		return dev_err_probe(dev, PTR_ERR(glm->mux),
+				     "could not get mux controller\n");
+
+	glm->muxed_gpio = devm_gpiod_get(dev, "muxed", GPIOD_IN);
+	if (IS_ERR(glm->muxed_gpio))
+		return dev_err_probe(dev, PTR_ERR(glm->muxed_gpio),
+				     "could not get muxed-gpio\n");
+
+	glm->num_gpio_mux_states = ngpio;
+	ret = device_property_read_u32_array(dev, "gpio-line-mux-states",
+					     &glm->gpio_mux_states[0], ngpio);
+	if (ret)
+		return dev_err_probe(dev, ret, "could not get mux states\n");
+
+	ret = devm_gpiochip_add_data(dev, &glm->gc, glm);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to add gpiochip\n");
+
+	return 0;
+}
+
+static const struct of_device_id gpio_lmux_of_match[] = {
+	{ .compatible = "gpio-line-mux" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gpio_lmux_of_match);
+
+static struct platform_driver gpio_lmux_driver = {
+	.driver = {
+		.name = "gpio-line-mux",
+		.of_match_table = gpio_lmux_of_match,
+	},
+	.probe = gpio_lmux_probe,
+};
+module_platform_driver(gpio_lmux_driver);
+
+MODULE_AUTHOR("Jonas Jelonek <jelonek.jonas@gmail.com>");
+MODULE_DESCRIPTION("GPIO line mux driver");
+MODULE_LICENSE("GPL");