ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

13 files changed, 3282 insertions, 0 deletions

diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
new file mode 100644
index 000000000..6d2f66810
--- /dev/null
+++ b/drivers/i2c/muxes/Kconfig
@@ -0,0 +1,138 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Multiplexer I2C chip drivers configuration
+#
+
+menu "Multiplexer I2C Chip support"
+	depends on I2C_MUX
+
+config I2C_ARB_GPIO_CHALLENGE
+	tristate "GPIO-based I2C arbitration"
+	depends on GPIOLIB || COMPILE_TEST
+	depends on OF
+	help
+	  If you say yes to this option, support will be included for an
+	  I2C multimaster arbitration scheme using GPIOs and a challenge &
+	  response mechanism where masters have to claim the bus by asserting
+	  a GPIO.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-arb-gpio-challenge.
+
+config I2C_MUX_GPIO
+	tristate "GPIO-based I2C multiplexer"
+	depends on GPIOLIB
+	help
+	  If you say yes to this option, support will be included for a
+	  GPIO based I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which is controlled
+	  through GPIO pins.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-gpio.
+
+config I2C_MUX_GPMUX
+	tristate "General Purpose I2C multiplexer"
+	select MULTIPLEXER
+	depends on OF
+	help
+	  If you say yes to this option, support will be included for a
+	  general purpose I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which in turn is controlled
+	  by a MUX-controller from the MUX subsystem.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-gpmux.
+
+config I2C_MUX_LTC4306
+	tristate "LTC LTC4306/5 I2C multiplexer"
+	select GPIOLIB
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the Analog Devices
+	  LTC4306 or LTC4305 I2C mux/switch devices.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-ltc4306.
+
+config I2C_MUX_PCA9541
+	tristate "NXP PCA9541 I2C Master Selector"
+	help
+	  If you say yes here you get support for the NXP PCA9541
+	  I2C Master Selector.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-pca9541.
+
+config I2C_MUX_PCA954x
+	tristate "NXP PCA954x/PCA984x and Maxim MAX735x/MAX736x I2C Mux/switches"
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  If you say yes here you get support for NXP PCA954x/PCA984x
+	  and Maxim MAX735x/MAX736x I2C mux/switch devices.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-pca954x.
+
+config I2C_MUX_PINCTRL
+	tristate "pinctrl-based I2C multiplexer"
+	depends on PINCTRL
+	depends on OF
+	help
+	  If you say yes to this option, support will be included for an I2C
+	  multiplexer that uses the pinctrl subsystem, i.e. pin multiplexing.
+	  This is useful for SoCs whose I2C module's signals can be routed to
+	  different sets of pins at run-time.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-mux-pinctrl.
+
+config I2C_MUX_REG
+	tristate "Register-based I2C multiplexer"
+	depends on HAS_IOMEM
+	help
+	  If you say yes to this option, support will be included for a
+	  register based I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which is controlled
+	  by a single register.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-reg.
+
+config I2C_DEMUX_PINCTRL
+	tristate "pinctrl-based I2C demultiplexer"
+	depends on PINCTRL && OF
+	select OF_DYNAMIC
+	help
+	  If you say yes to this option, support will be included for an I2C
+	  demultiplexer that uses the pinctrl subsystem. This is useful if you
+	  want to change the I2C master at run-time depending on features.
+
+config I2C_MUX_MLXCPLD
+	tristate "Mellanox CPLD based I2C multiplexer"
+	help
+	  If you say yes to this option, support will be included for a
+	  CPLD based I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which is controlled
+	  by a CPLD register.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-mlxcpld.
+
+config I2C_MUX_MULE
+	tristate "Theobroma Systems Mule I2C device multiplexer"
+	depends on OF && SENSORS_AMC6821
+	help
+	  Mule is an MCU that emulates a set of I2C devices, among which
+	  devices that are reachable through an I2C-mux. The devices on the mux
+	  can be selected by writing the appropriate device number to an I2C
+	  configuration register.
+
+	  If you say yes to this option, support will be included for a
+	  Theobroma Systems Mule I2C multiplexer. This driver provides access to
+	  I2C devices connected on this mux.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-mule.
+
+endmenu
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
new file mode 100644
index 000000000..4b24f4951
--- /dev/null
+++ b/drivers/i2c/muxes/Makefile
@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for multiplexer I2C chip drivers.
+
+obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE)	+= i2c-arb-gpio-challenge.o
+
+obj-$(CONFIG_I2C_DEMUX_PINCTRL)		+= i2c-demux-pinctrl.o
+
+obj-$(CONFIG_I2C_MUX_GPIO)	+= i2c-mux-gpio.o
+obj-$(CONFIG_I2C_MUX_GPMUX)	+= i2c-mux-gpmux.o
+obj-$(CONFIG_I2C_MUX_LTC4306)	+= i2c-mux-ltc4306.o
+obj-$(CONFIG_I2C_MUX_MLXCPLD)	+= i2c-mux-mlxcpld.o
+obj-$(CONFIG_I2C_MUX_MULE)	+= i2c-mux-mule.o
+obj-$(CONFIG_I2C_MUX_PCA9541)	+= i2c-mux-pca9541.o
+obj-$(CONFIG_I2C_MUX_PCA954x)	+= i2c-mux-pca954x.o
+obj-$(CONFIG_I2C_MUX_PINCTRL)	+= i2c-mux-pinctrl.o
+obj-$(CONFIG_I2C_MUX_REG)	+= i2c-mux-reg.o
+
+ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/muxes/i2c-arb-gpio-challenge.c b/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
new file mode 100644
index 000000000..d6ef91b88
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * GPIO-based I2C Arbitration Using a Challenge & Response Mechanism
+ *
+ * Copyright (C) 2012 Google, Inc
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/kernel.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+
+/**
+ * struct i2c_arbitrator_data - Driver data for I2C arbitrator
+ *
+ * @our_gpio: GPIO descriptor we'll use to claim.
+ * @their_gpio: GPIO descriptor that the other side will use to claim.
+ * @slew_delay_us: microseconds to wait for a GPIO to go high.
+ * @wait_retry_us: we'll attempt another claim after this many microseconds.
+ * @wait_free_us: we'll give up after this many microseconds.
+ */
+
+struct i2c_arbitrator_data {
+	struct gpio_desc *our_gpio;
+	struct gpio_desc *their_gpio;
+	unsigned int slew_delay_us;
+	unsigned int wait_retry_us;
+	unsigned int wait_free_us;
+};
+
+
+/*
+ * i2c_arbitrator_select - claim the I2C bus
+ *
+ * Use the GPIO-based signalling protocol; return -EBUSY if we fail.
+ */
+static int i2c_arbitrator_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	const struct i2c_arbitrator_data *arb = i2c_mux_priv(muxc);
+	unsigned long stop_retry, stop_time;
+
+	/* Start a round of trying to claim the bus */
+	stop_time = jiffies + usecs_to_jiffies(arb->wait_free_us) + 1;
+	do {
+		/* Indicate that we want to claim the bus */
+		gpiod_set_value(arb->our_gpio, 1);
+		udelay(arb->slew_delay_us);
+
+		/* Wait for the other master to release it */
+		stop_retry = jiffies + usecs_to_jiffies(arb->wait_retry_us) + 1;
+		while (time_before(jiffies, stop_retry)) {
+			int gpio_val = gpiod_get_value(arb->their_gpio);
+
+			if (!gpio_val) {
+				/* We got it, so return */
+				return 0;
+			}
+
+			usleep_range(50, 200);
+		}
+
+		/* It didn't release, so give up, wait, and try again */
+		gpiod_set_value(arb->our_gpio, 0);
+
+		usleep_range(arb->wait_retry_us, arb->wait_retry_us * 2);
+	} while (time_before(jiffies, stop_time));
+
+	/* Give up, release our claim */
+	gpiod_set_value(arb->our_gpio, 0);
+	udelay(arb->slew_delay_us);
+	dev_err(muxc->dev, "Could not claim bus, timeout\n");
+	return -EBUSY;
+}
+
+/*
+ * i2c_arbitrator_deselect - release the I2C bus
+ *
+ * Release the I2C bus using the GPIO-based signalling protocol.
+ */
+static int i2c_arbitrator_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	const struct i2c_arbitrator_data *arb = i2c_mux_priv(muxc);
+
+	/* Release the bus and wait for the other master to notice */
+	gpiod_set_value(arb->our_gpio, 0);
+	udelay(arb->slew_delay_us);
+
+	return 0;
+}
+
+static int i2c_arbitrator_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *parent_np;
+	struct i2c_mux_core *muxc;
+	struct i2c_arbitrator_data *arb;
+	struct gpio_desc *dummy;
+	int ret;
+
+	/* We only support probing from device tree; no platform_data */
+	if (!np) {
+		dev_err(dev, "Cannot find device tree node\n");
+		return -ENODEV;
+	}
+	if (dev_get_platdata(dev)) {
+		dev_err(dev, "Platform data is not supported\n");
+		return -EINVAL;
+	}
+
+	muxc = i2c_mux_alloc(NULL, dev, 1, sizeof(*arb), I2C_MUX_ARBITRATOR,
+			     i2c_arbitrator_select, i2c_arbitrator_deselect);
+	if (!muxc)
+		return -ENOMEM;
+	arb = i2c_mux_priv(muxc);
+
+	platform_set_drvdata(pdev, muxc);
+
+	/* Request GPIOs, our GPIO as unclaimed to begin with */
+	arb->our_gpio = devm_gpiod_get(dev, "our-claim", GPIOD_OUT_LOW);
+	if (IS_ERR(arb->our_gpio)) {
+		dev_err(dev, "could not get \"our-claim\" GPIO (%ld)\n",
+			PTR_ERR(arb->our_gpio));
+		return PTR_ERR(arb->our_gpio);
+	}
+
+	arb->their_gpio = devm_gpiod_get(dev, "their-claim", GPIOD_IN);
+	if (IS_ERR(arb->their_gpio)) {
+		dev_err(dev, "could not get \"their-claim\" GPIO (%ld)\n",
+			PTR_ERR(arb->their_gpio));
+		return PTR_ERR(arb->their_gpio);
+	}
+
+	/* At the moment we only support a single two master (us + 1 other) */
+	dummy = devm_gpiod_get_index(dev, "their-claim", 1, GPIOD_IN);
+	if (!IS_ERR(dummy)) {
+		dev_err(dev, "Only one other master is supported\n");
+		return -EINVAL;
+	} else if (PTR_ERR(dummy) == -EPROBE_DEFER) {
+		return -EPROBE_DEFER;
+	}
+
+	/* Arbitration parameters */
+	if (of_property_read_u32(np, "slew-delay-us", &arb->slew_delay_us))
+		arb->slew_delay_us = 10;
+	if (of_property_read_u32(np, "wait-retry-us", &arb->wait_retry_us))
+		arb->wait_retry_us = 3000;
+	if (of_property_read_u32(np, "wait-free-us", &arb->wait_free_us))
+		arb->wait_free_us = 50000;
+
+	/* Find our parent */
+	parent_np = of_parse_phandle(np, "i2c-parent", 0);
+	if (!parent_np) {
+		dev_err(dev, "Cannot parse i2c-parent\n");
+		return -EINVAL;
+	}
+	muxc->parent = of_get_i2c_adapter_by_node(parent_np);
+	of_node_put(parent_np);
+	if (!muxc->parent) {
+		dev_err(dev, "Cannot find parent bus\n");
+		return -EPROBE_DEFER;
+	}
+
+	/* Actually add the mux adapter */
+	ret = i2c_mux_add_adapter(muxc, 0, 0);
+	if (ret)
+		i2c_put_adapter(muxc->parent);
+
+	return ret;
+}
+
+static void i2c_arbitrator_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+}
+
+static const struct of_device_id i2c_arbitrator_of_match[] = {
+	{ .compatible = "i2c-arb-gpio-challenge", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_arbitrator_of_match);
+
+static struct platform_driver i2c_arbitrator_driver = {
+	.probe	= i2c_arbitrator_probe,
+	.remove = i2c_arbitrator_remove,
+	.driver	= {
+		.name	= "i2c-arb-gpio-challenge",
+		.of_match_table = i2c_arbitrator_of_match,
+	},
+};
+
+module_platform_driver(i2c_arbitrator_driver);
+
+MODULE_DESCRIPTION("GPIO-based I2C Arbitration");
+MODULE_AUTHOR("Doug Anderson <dianders@chromium.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:i2c-arb-gpio-challenge");
diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
new file mode 100644
index 000000000..2403c0bf7
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -0,0 +1,327 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Pinctrl based I2C DeMultiplexer
+ *
+ * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * Copyright (C) 2015-16 by Renesas Electronics Corporation
+ *
+ * See the bindings doc for DTS setup and the sysfs doc for usage information.
+ * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
+ */
+
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+struct i2c_demux_pinctrl_chan {
+	struct device_node *parent_np;
+	struct i2c_adapter *parent_adap;
+	struct of_changeset chgset;
+};
+
+struct i2c_demux_pinctrl_priv {
+	int cur_chan;
+	int num_chan;
+	struct device *dev;
+	const char *bus_name;
+	struct i2c_adapter cur_adap;
+	struct i2c_algorithm algo;
+	struct i2c_demux_pinctrl_chan chan[] __counted_by(num_chan);
+};
+
+static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+	struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
+	struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
+
+	return __i2c_transfer(parent, msgs, num);
+}
+
+static u32 i2c_demux_functionality(struct i2c_adapter *adap)
+{
+	struct i2c_demux_pinctrl_priv *priv = adap->algo_data;
+	struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap;
+
+	return parent->algo->functionality(parent);
+}
+
+static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
+{
+	struct i2c_adapter *adap;
+	struct pinctrl *p;
+	int ret;
+
+	ret = of_changeset_apply(&priv->chan[new_chan].chgset);
+	if (ret)
+		goto err;
+
+	adap = of_get_i2c_adapter_by_node(priv->chan[new_chan].parent_np);
+	if (!adap) {
+		ret = -ENODEV;
+		goto err_with_revert;
+	}
+
+	/*
+	 * Check if there are pinctrl states at all. Note: we can't use
+	 * devm_pinctrl_get_select() because we need to distinguish between
+	 * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state().
+	 */
+	p = devm_pinctrl_get(adap->dev.parent);
+	if (IS_ERR(p)) {
+		ret = PTR_ERR(p);
+		/* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */
+		if (ret != -ENODEV)
+			goto err_with_put;
+	} else {
+		/* there are states. check and use them */
+		struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name);
+
+		if (IS_ERR(s)) {
+			ret = PTR_ERR(s);
+			goto err_with_put;
+		}
+		ret = pinctrl_select_state(p, s);
+		if (ret < 0)
+			goto err_with_put;
+	}
+
+	priv->chan[new_chan].parent_adap = adap;
+	priv->cur_chan = new_chan;
+
+	/* Now fill out current adapter structure. cur_chan must be up to date */
+	priv->algo.xfer = i2c_demux_master_xfer;
+	if (adap->algo->master_xfer_atomic)
+		priv->algo.xfer_atomic = i2c_demux_master_xfer;
+	priv->algo.functionality = i2c_demux_functionality;
+
+	snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name),
+		 "i2c-demux (master i2c-%d)", i2c_adapter_id(adap));
+	priv->cur_adap.owner = THIS_MODULE;
+	priv->cur_adap.algo = &priv->algo;
+	priv->cur_adap.algo_data = priv;
+	priv->cur_adap.dev.parent = &adap->dev;
+	priv->cur_adap.class = adap->class;
+	priv->cur_adap.retries = adap->retries;
+	priv->cur_adap.timeout = adap->timeout;
+	priv->cur_adap.quirks = adap->quirks;
+	priv->cur_adap.dev.of_node = priv->dev->of_node;
+	ret = i2c_add_adapter(&priv->cur_adap);
+	if (ret < 0)
+		goto err_with_put;
+
+	return 0;
+
+ err_with_put:
+	i2c_put_adapter(adap);
+ err_with_revert:
+	of_changeset_revert(&priv->chan[new_chan].chgset);
+ err:
+	dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret);
+	priv->cur_chan = -EINVAL;
+	return ret;
+}
+
+static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv)
+{
+	int ret, cur = priv->cur_chan;
+
+	if (cur < 0)
+		return 0;
+
+	i2c_del_adapter(&priv->cur_adap);
+	i2c_put_adapter(priv->chan[cur].parent_adap);
+
+	ret = of_changeset_revert(&priv->chan[cur].chgset);
+
+	priv->chan[cur].parent_adap = NULL;
+	priv->cur_chan = -EINVAL;
+
+	return ret;
+}
+
+static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan)
+{
+	int ret;
+
+	if (new_chan == priv->cur_chan)
+		return 0;
+
+	ret = i2c_demux_deactivate_master(priv);
+	if (ret)
+		return ret;
+
+	return i2c_demux_activate_master(priv, new_chan);
+}
+
+static ssize_t available_masters_show(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf)
+{
+	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
+	int count = 0, i;
+
+	for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++)
+		count += sysfs_emit_at(buf, count, "%d:%pOF%c",
+				       i, priv->chan[i].parent_np,
+				       i == priv->num_chan - 1 ? '\n' : ' ');
+
+	return count;
+}
+static DEVICE_ATTR_RO(available_masters);
+
+static ssize_t current_master_show(struct device *dev,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", priv->cur_chan);
+}
+
+static ssize_t current_master_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
+	unsigned int val;
+	int ret;
+
+	ret = kstrtouint(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val >= priv->num_chan)
+		return -EINVAL;
+
+	ret = i2c_demux_change_master(priv, val);
+
+	return ret < 0 ? ret : count;
+}
+static DEVICE_ATTR_RW(current_master);
+
+static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct i2c_demux_pinctrl_priv *priv;
+	struct property *props;
+	int num_chan, i, j, err;
+
+	num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL);
+	if (num_chan < 2) {
+		dev_err(&pdev->dev, "Need at least two I2C masters to switch\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, struct_size(priv, chan, num_chan),
+			    GFP_KERNEL);
+
+	props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
+
+	if (!priv || !props)
+		return -ENOMEM;
+
+	priv->num_chan = num_chan;
+
+	err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name);
+	if (err)
+		return err;
+
+	for (i = 0; i < num_chan; i++) {
+		struct device_node *adap_np;
+
+		adap_np = of_parse_phandle(np, "i2c-parent", i);
+		if (!adap_np) {
+			dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
+			err = -ENOENT;
+			goto err_rollback;
+		}
+		priv->chan[i].parent_np = adap_np;
+
+		props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL);
+		props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL);
+		if (!props[i].name || !props[i].value) {
+			err = -ENOMEM;
+			of_node_put(adap_np);
+			goto err_rollback;
+		}
+		props[i].length = 3;
+
+		of_changeset_init(&priv->chan[i].chgset);
+		of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
+	}
+
+	priv->dev = &pdev->dev;
+	platform_set_drvdata(pdev, priv);
+
+	pm_runtime_no_callbacks(&pdev->dev);
+
+	/* switch to first parent as active master */
+	err = i2c_demux_activate_master(priv, 0);
+	if (err)
+		goto err_rollback;
+
+	err = device_create_file(&pdev->dev, &dev_attr_available_masters);
+	if (err)
+		goto err_rollback_activation;
+
+	err = device_create_file(&pdev->dev, &dev_attr_current_master);
+	if (err)
+		goto err_rollback_available;
+
+	return 0;
+
+err_rollback_available:
+	device_remove_file(&pdev->dev, &dev_attr_available_masters);
+err_rollback_activation:
+	i2c_demux_deactivate_master(priv);
+err_rollback:
+	for (j = 0; j < i; j++) {
+		of_node_put(priv->chan[j].parent_np);
+		of_changeset_destroy(&priv->chan[j].chgset);
+	}
+
+	return err;
+}
+
+static void i2c_demux_pinctrl_remove(struct platform_device *pdev)
+{
+	struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
+	int i;
+
+	device_remove_file(&pdev->dev, &dev_attr_current_master);
+	device_remove_file(&pdev->dev, &dev_attr_available_masters);
+
+	i2c_demux_deactivate_master(priv);
+
+	for (i = 0; i < priv->num_chan; i++) {
+		of_node_put(priv->chan[i].parent_np);
+		of_changeset_destroy(&priv->chan[i].chgset);
+	}
+}
+
+static const struct of_device_id i2c_demux_pinctrl_of_match[] = {
+	{ .compatible = "i2c-demux-pinctrl", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match);
+
+static struct platform_driver i2c_demux_pinctrl_driver = {
+	.driver	= {
+		.name = "i2c-demux-pinctrl",
+		.of_match_table = i2c_demux_pinctrl_of_match,
+	},
+	.probe	= i2c_demux_pinctrl_probe,
+	.remove = i2c_demux_pinctrl_remove,
+};
+module_platform_driver(i2c_demux_pinctrl_driver);
+
+MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
+MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:i2c-demux-pinctrl");
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
new file mode 100644
index 000000000..9b46b84e8
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C multiplexer using GPIO API
+ *
+ * Peter Korsgaard <peter.korsgaard@barco.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/platform_data/i2c-mux-gpio.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct gpiomux {
+	struct i2c_mux_gpio_platform_data data;
+	int ngpios;
+	struct gpio_desc **gpios;
+};
+
+static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned int val)
+{
+	DECLARE_BITMAP(values, BITS_PER_TYPE(val));
+
+	values[0] = val;
+
+	gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
+}
+
+static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct gpiomux *mux = i2c_mux_priv(muxc);
+
+	i2c_mux_gpio_set(mux, chan);
+
+	if (mux->data.settle_time)
+		fsleep(mux->data.settle_time);
+
+	return 0;
+}
+
+static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct gpiomux *mux = i2c_mux_priv(muxc);
+
+	i2c_mux_gpio_set(mux, mux->data.idle);
+
+	return 0;
+}
+
+static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
+				 struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
+	struct device_node *np = dev->of_node;
+	struct device_node *adapter_np;
+	struct i2c_adapter *adapter = NULL;
+	struct fwnode_handle *child;
+	unsigned int *values;
+	int rc, i = 0;
+
+	if (is_of_node(fwnode)) {
+		if (!np)
+			return -ENODEV;
+
+		adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+		if (!adapter_np) {
+			dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+			return -ENODEV;
+		}
+		adapter = of_find_i2c_adapter_by_node(adapter_np);
+		of_node_put(adapter_np);
+
+	} else if (is_acpi_node(fwnode)) {
+		/*
+		 * In ACPI land the mux should be a direct child of the i2c
+		 * bus it muxes.
+		 */
+		acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
+
+		adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
+	}
+
+	if (!adapter)
+		return -EPROBE_DEFER;
+
+	mux->data.parent = i2c_adapter_id(adapter);
+	put_device(&adapter->dev);
+
+	mux->data.n_values = device_get_child_node_count(dev);
+	values = devm_kcalloc(dev,
+			      mux->data.n_values, sizeof(*mux->data.values),
+			      GFP_KERNEL);
+	if (!values) {
+		dev_err(dev, "Cannot allocate values array");
+		return -ENOMEM;
+	}
+
+	device_for_each_child_node(dev, child) {
+		if (is_of_node(child)) {
+			fwnode_property_read_u32(child, "reg", values + i);
+		} else if (is_acpi_node(child)) {
+			rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
+			if (rc) {
+				fwnode_handle_put(child);
+				return dev_err_probe(dev, rc, "Cannot get address\n");
+			}
+		}
+
+		i++;
+	}
+	mux->data.values = values;
+
+	if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
+		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
+
+	device_property_read_u32(dev, "settle-time-us", &mux->data.settle_time);
+
+	return 0;
+}
+
+static int i2c_mux_gpio_probe(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc;
+	struct gpiomux *mux;
+	struct i2c_adapter *parent;
+	struct i2c_adapter *root;
+	unsigned int initial_state;
+	int i, ngpios, ret;
+
+	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return -ENOMEM;
+
+	if (!dev_get_platdata(&pdev->dev)) {
+		ret = i2c_mux_gpio_probe_fw(mux, pdev);
+		if (ret < 0)
+			return ret;
+	} else {
+		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
+			sizeof(mux->data));
+	}
+
+	ngpios = gpiod_count(&pdev->dev, "mux");
+	if (ngpios <= 0) {
+		dev_err(&pdev->dev, "no valid gpios provided\n");
+		return ngpios ?: -EINVAL;
+	}
+	mux->ngpios = ngpios;
+
+	parent = i2c_get_adapter(mux->data.parent);
+	if (!parent)
+		return -EPROBE_DEFER;
+
+	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
+			     array_size(ngpios, sizeof(*mux->gpios)), 0,
+			     i2c_mux_gpio_select, NULL);
+	if (!muxc) {
+		ret = -ENOMEM;
+		goto alloc_failed;
+	}
+	mux->gpios = muxc->priv;
+	muxc->priv = mux;
+
+	platform_set_drvdata(pdev, muxc);
+
+	root = i2c_root_adapter(&parent->dev);
+
+	muxc->mux_locked = true;
+
+	if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
+		initial_state = mux->data.idle;
+		muxc->deselect = i2c_mux_gpio_deselect;
+	} else {
+		initial_state = mux->data.values[0];
+	}
+
+	for (i = 0; i < ngpios; i++) {
+		struct gpio_device *gdev;
+		struct device *dev;
+		struct gpio_desc *gpiod;
+		enum gpiod_flags flag;
+
+		if (initial_state & BIT(i))
+			flag = GPIOD_OUT_HIGH;
+		else
+			flag = GPIOD_OUT_LOW;
+		gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
+		if (IS_ERR(gpiod)) {
+			ret = PTR_ERR(gpiod);
+			goto alloc_failed;
+		}
+
+		mux->gpios[i] = gpiod;
+
+		if (!muxc->mux_locked)
+			continue;
+
+		gdev = gpiod_to_gpio_device(gpiod);
+		dev = gpio_device_to_device(gdev);
+		muxc->mux_locked = i2c_root_adapter(dev) == root;
+	}
+
+	if (muxc->mux_locked)
+		dev_info(&pdev->dev, "mux-locked i2c mux\n");
+
+	for (i = 0; i < mux->data.n_values; i++) {
+		u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
+
+		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i]);
+		if (ret)
+			goto add_adapter_failed;
+	}
+
+	dev_info(&pdev->dev, "%d port mux on %s adapter\n",
+		 mux->data.n_values, parent->name);
+
+	return 0;
+
+add_adapter_failed:
+	i2c_mux_del_adapters(muxc);
+alloc_failed:
+	i2c_put_adapter(parent);
+
+	return ret;
+}
+
+static void i2c_mux_gpio_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+}
+
+static const struct of_device_id i2c_mux_gpio_of_match[] = {
+	{ .compatible = "i2c-mux-gpio", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
+
+static struct platform_driver i2c_mux_gpio_driver = {
+	.probe	= i2c_mux_gpio_probe,
+	.remove = i2c_mux_gpio_remove,
+	.driver	= {
+		.name	= "i2c-mux-gpio",
+		.of_match_table = i2c_mux_gpio_of_match,
+	},
+};
+
+module_platform_driver(i2c_mux_gpio_driver);
+
+MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
+MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-mux-gpio");
diff --git a/drivers/i2c/muxes/i2c-mux-gpmux.c b/drivers/i2c/muxes/i2c-mux-gpmux.c
new file mode 100644
index 000000000..ab8e11661
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-gpmux.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * General Purpose I2C multiplexer
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ *
+ * Author: Peter Rosin <peda@axentia.se>
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/mux/consumer.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+struct mux {
+	struct mux_control *control;
+
+	bool do_not_deselect;
+};
+
+static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct mux *mux = i2c_mux_priv(muxc);
+	int ret;
+
+	ret = mux_control_select(mux->control, chan);
+	mux->do_not_deselect = ret < 0;
+
+	return ret;
+}
+
+static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct mux *mux = i2c_mux_priv(muxc);
+
+	if (mux->do_not_deselect)
+		return 0;
+
+	return mux_control_deselect(mux->control);
+}
+
+static struct i2c_adapter *mux_parent_adapter(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct device_node *parent_np;
+	struct i2c_adapter *parent;
+
+	parent_np = of_parse_phandle(np, "i2c-parent", 0);
+	if (!parent_np) {
+		dev_err(dev, "Cannot parse i2c-parent\n");
+		return ERR_PTR(-ENODEV);
+	}
+	parent = of_get_i2c_adapter_by_node(parent_np);
+	of_node_put(parent_np);
+	if (!parent)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	return parent;
+}
+
+static const struct of_device_id i2c_mux_of_match[] = {
+	{ .compatible = "i2c-mux", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
+
+static int i2c_mux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *child;
+	struct i2c_mux_core *muxc;
+	struct mux *mux;
+	struct i2c_adapter *parent;
+	int children;
+	int ret;
+
+	if (!np)
+		return -ENODEV;
+
+	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return -ENOMEM;
+
+	mux->control = devm_mux_control_get(dev, NULL);
+	if (IS_ERR(mux->control))
+		return dev_err_probe(dev, PTR_ERR(mux->control),
+				     "failed to get control-mux\n");
+
+	parent = mux_parent_adapter(dev);
+	if (IS_ERR(parent))
+		return dev_err_probe(dev, PTR_ERR(parent),
+				     "failed to get i2c-parent adapter\n");
+
+	children = of_get_child_count(np);
+
+	muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
+			     i2c_mux_select, i2c_mux_deselect);
+	if (!muxc) {
+		ret = -ENOMEM;
+		goto err_parent;
+	}
+	muxc->priv = mux;
+
+	platform_set_drvdata(pdev, muxc);
+
+	muxc->mux_locked = of_property_read_bool(np, "mux-locked");
+
+	for_each_child_of_node(np, child) {
+		u32 chan;
+
+		ret = of_property_read_u32(child, "reg", &chan);
+		if (ret < 0) {
+			dev_err(dev, "no reg property for node '%pOFn'\n",
+				child);
+			goto err_children;
+		}
+
+		if (chan >= mux_control_states(mux->control)) {
+			dev_err(dev, "invalid reg %u\n", chan);
+			ret = -EINVAL;
+			goto err_children;
+		}
+
+		ret = i2c_mux_add_adapter(muxc, 0, chan);
+		if (ret)
+			goto err_children;
+	}
+
+	dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
+
+	return 0;
+
+err_children:
+	of_node_put(child);
+	i2c_mux_del_adapters(muxc);
+err_parent:
+	i2c_put_adapter(parent);
+
+	return ret;
+}
+
+static void i2c_mux_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+}
+
+static struct platform_driver i2c_mux_driver = {
+	.probe	= i2c_mux_probe,
+	.remove = i2c_mux_remove,
+	.driver	= {
+		.name	= "i2c-mux-gpmux",
+		.of_match_table = i2c_mux_of_match,
+	},
+};
+module_platform_driver(i2c_mux_driver);
+
+MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
+MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/i2c/muxes/i2c-mux-ltc4306.c b/drivers/i2c/muxes/i2c-mux-ltc4306.c
new file mode 100644
index 000000000..18228f5b8
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-ltc4306.c
@@ -0,0 +1,317 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Linear Technology LTC4306 and LTC4305 I2C multiplexer/switch
+ *
+ * Copyright (C) 2017 Analog Devices Inc.
+ *
+ * Based on: i2c-mux-pca954x.c
+ *
+ * Datasheet: http://cds.linear.com/docs/en/datasheet/4306.pdf
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c-mux.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define LTC4305_MAX_NCHANS 2
+#define LTC4306_MAX_NCHANS 4
+
+#define LTC_REG_STATUS	0x0
+#define LTC_REG_CONFIG	0x1
+#define LTC_REG_MODE	0x2
+#define LTC_REG_SWITCH	0x3
+
+#define LTC_DOWNSTREAM_ACCL_EN	BIT(6)
+#define LTC_UPSTREAM_ACCL_EN	BIT(7)
+
+#define LTC_GPIO_ALL_INPUT	0xC0
+#define LTC_SWITCH_MASK		0xF0
+
+enum ltc_type {
+	ltc_4305,
+	ltc_4306,
+};
+
+struct chip_desc {
+	u8 nchans;
+	u8 num_gpios;
+};
+
+struct ltc4306 {
+	struct regmap *regmap;
+	struct gpio_chip gpiochip;
+	const struct chip_desc *chip;
+};
+
+static const struct chip_desc chips[] = {
+	[ltc_4305] = {
+		.nchans = LTC4305_MAX_NCHANS,
+	},
+	[ltc_4306] = {
+		.nchans = LTC4306_MAX_NCHANS,
+		.num_gpios = 2,
+	},
+};
+
+static bool ltc4306_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg == LTC_REG_CONFIG;
+}
+
+static const struct regmap_config ltc4306_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LTC_REG_SWITCH,
+	.volatile_reg = ltc4306_is_volatile_reg,
+	.cache_type = REGCACHE_FLAT,
+};
+
+static int ltc4306_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(data->regmap, LTC_REG_CONFIG, &val);
+	if (ret < 0)
+		return ret;
+
+	return !!(val & BIT(1 - offset));
+}
+
+static int ltc4306_gpio_set(struct gpio_chip *chip, unsigned int offset,
+			    int value)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+
+	return regmap_update_bits(data->regmap, LTC_REG_CONFIG,
+				  BIT(5 - offset), value ? BIT(5 - offset) : 0);
+}
+
+static int ltc4306_gpio_get_direction(struct gpio_chip *chip,
+				      unsigned int offset)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(data->regmap, LTC_REG_MODE, &val);
+	if (ret < 0)
+		return ret;
+
+	return !!(val & BIT(7 - offset));
+}
+
+static int ltc4306_gpio_direction_input(struct gpio_chip *chip,
+					unsigned int offset)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+
+	return regmap_update_bits(data->regmap, LTC_REG_MODE,
+				  BIT(7 - offset), BIT(7 - offset));
+}
+
+static int ltc4306_gpio_direction_output(struct gpio_chip *chip,
+					 unsigned int offset, int value)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+
+	ltc4306_gpio_set(chip, offset, value);
+	return regmap_update_bits(data->regmap, LTC_REG_MODE,
+				  BIT(7 - offset), 0);
+}
+
+static int ltc4306_gpio_set_config(struct gpio_chip *chip,
+				   unsigned int offset, unsigned long config)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+	unsigned int val;
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+		val = 0;
+		break;
+	case PIN_CONFIG_DRIVE_PUSH_PULL:
+		val = BIT(4 - offset);
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	return regmap_update_bits(data->regmap, LTC_REG_MODE,
+				  BIT(4 - offset), val);
+}
+
+static int ltc4306_gpio_init(struct ltc4306 *data)
+{
+	struct device *dev = regmap_get_device(data->regmap);
+
+	if (!data->chip->num_gpios)
+		return 0;
+
+	data->gpiochip.label = dev_name(dev);
+	data->gpiochip.base = -1;
+	data->gpiochip.ngpio = data->chip->num_gpios;
+	data->gpiochip.parent = dev;
+	data->gpiochip.can_sleep = true;
+	data->gpiochip.get_direction = ltc4306_gpio_get_direction;
+	data->gpiochip.direction_input = ltc4306_gpio_direction_input;
+	data->gpiochip.direction_output = ltc4306_gpio_direction_output;
+	data->gpiochip.get = ltc4306_gpio_get;
+	data->gpiochip.set = ltc4306_gpio_set;
+	data->gpiochip.set_config = ltc4306_gpio_set_config;
+	data->gpiochip.owner = THIS_MODULE;
+
+	/* gpiolib assumes all GPIOs default input */
+	regmap_write(data->regmap, LTC_REG_MODE, LTC_GPIO_ALL_INPUT);
+
+	return devm_gpiochip_add_data(dev, &data->gpiochip, data);
+}
+
+static int ltc4306_select_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct ltc4306 *data = i2c_mux_priv(muxc);
+
+	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
+				  LTC_SWITCH_MASK, BIT(7 - chan));
+}
+
+static int ltc4306_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct ltc4306 *data = i2c_mux_priv(muxc);
+
+	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
+				  LTC_SWITCH_MASK, 0);
+}
+
+static const struct i2c_device_id ltc4306_id[] = {
+	{ .name = "ltc4305", .driver_data = ltc_4305 },
+	{ .name = "ltc4306", .driver_data = ltc_4306 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc4306_id);
+
+static const struct of_device_id ltc4306_of_match[] = {
+	{ .compatible = "lltc,ltc4305", .data = &chips[ltc_4305] },
+	{ .compatible = "lltc,ltc4306", .data = &chips[ltc_4306] },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ltc4306_of_match);
+
+static int ltc4306_probe(struct i2c_client *client)
+{
+	struct i2c_adapter *adap = client->adapter;
+	const struct chip_desc *chip;
+	struct i2c_mux_core *muxc;
+	struct ltc4306 *data;
+	struct gpio_desc *gpio;
+	bool idle_disc;
+	unsigned int val = 0;
+	int num, ret;
+
+	chip = of_device_get_match_data(&client->dev);
+
+	if (!chip)
+		chip = &chips[i2c_match_id(ltc4306_id, client)->driver_data];
+
+	idle_disc = device_property_read_bool(&client->dev,
+					      "i2c-mux-idle-disconnect");
+
+	muxc = i2c_mux_alloc(adap, &client->dev,
+			     chip->nchans, sizeof(*data),
+			     I2C_MUX_LOCKED, ltc4306_select_mux,
+			     idle_disc ? ltc4306_deselect_mux : NULL);
+	if (!muxc)
+		return -ENOMEM;
+	data = i2c_mux_priv(muxc);
+	data->chip = chip;
+
+	i2c_set_clientdata(client, muxc);
+
+	data->regmap = devm_regmap_init_i2c(client, &ltc4306_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		ret = PTR_ERR(data->regmap);
+		dev_err(&client->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	/* Reset and enable the mux if an enable GPIO is specified. */
+	gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+
+	if (gpio) {
+		udelay(1);
+		gpiod_set_value(gpio, 1);
+	}
+
+	/*
+	 * Write the mux register at addr to verify
+	 * that the mux is in fact present. This also
+	 * initializes the mux to disconnected state.
+	 */
+	if (regmap_write(data->regmap, LTC_REG_SWITCH, 0) < 0) {
+		dev_warn(&client->dev, "probe failed\n");
+		return -ENODEV;
+	}
+
+	if (device_property_read_bool(&client->dev,
+				      "ltc,downstream-accelerators-enable"))
+		val |= LTC_DOWNSTREAM_ACCL_EN;
+
+	if (device_property_read_bool(&client->dev,
+				      "ltc,upstream-accelerators-enable"))
+		val |= LTC_UPSTREAM_ACCL_EN;
+
+	if (regmap_write(data->regmap, LTC_REG_CONFIG, val) < 0)
+		return -ENODEV;
+
+	ret = ltc4306_gpio_init(data);
+	if (ret < 0)
+		return ret;
+
+	/* Now create an adapter for each channel */
+	for (num = 0; num < chip->nchans; num++) {
+		ret = i2c_mux_add_adapter(muxc, 0, num);
+		if (ret) {
+			i2c_mux_del_adapters(muxc);
+			return ret;
+		}
+	}
+
+	dev_info(&client->dev,
+		 "registered %d multiplexed busses for I2C switch %s\n",
+		 num, client->name);
+
+	return 0;
+}
+
+static void ltc4306_remove(struct i2c_client *client)
+{
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+	i2c_mux_del_adapters(muxc);
+}
+
+static struct i2c_driver ltc4306_driver = {
+	.driver		= {
+		.name	= "ltc4306",
+		.of_match_table = ltc4306_of_match,
+	},
+	.probe		= ltc4306_probe,
+	.remove		= ltc4306_remove,
+	.id_table	= ltc4306_id,
+};
+
+module_i2c_driver(ltc4306_driver);
+
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Linear Technology LTC4306, LTC4305 I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/i2c/muxes/i2c-mux-mlxcpld.c b/drivers/i2c/muxes/i2c-mux-mlxcpld.c
new file mode 100644
index 000000000..1c2debcf3
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-mlxcpld.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/*
+ * Mellanox i2c mux driver
+ *
+ * Copyright (C) 2016-2020 Mellanox Technologies
+ */
+
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_data/mlxcpld.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+/* mlxcpld_mux - mux control structure:
+ * @last_val - last selected register value or -1 if mux deselected
+ * @client - I2C device client
+ * @pdata: platform data
+ */
+struct mlxcpld_mux {
+	int last_val;
+	struct i2c_client *client;
+	struct mlxcpld_mux_plat_data pdata;
+};
+
+/* MUX logic description.
+ * Driver can support different mux control logic, according to CPLD
+ * implementation.
+ *
+ * Connectivity schema.
+ *
+ * i2c-mlxcpld                                 Digital               Analog
+ * driver
+ * *--------*                                 * -> mux1 (virt bus2) -> mux -> |
+ * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |
+ * | bridge | bus 1                 *---------*                               |
+ * | logic  |---------------------> * mux reg *                               |
+ * | in CPLD|                       *---------*                               |
+ * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |
+ *     |        driver                   |                                    |
+ *     |        *---------------*        |                              Devices
+ *     |        * CPLD (i2c bus)* select |
+ *     |        * registers for *--------*
+ *     |        * mux selection * deselect
+ *     |        *---------------*
+ *     |                 |
+ * <-------->     <----------->
+ * i2c cntrl      Board cntrl reg
+ * reg space      space (mux select,
+ *                IO, LED, WD, info)
+ *
+ */
+
+/* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
+ * for this as they will try to lock adapter a second time.
+ */
+static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
+				 struct mlxcpld_mux *mux, u32 val)
+{
+	struct i2c_client *client = mux->client;
+	union i2c_smbus_data data;
+	struct i2c_msg msg;
+	u8 buf[3];
+
+	switch (mux->pdata.reg_size) {
+	case 1:
+		data.byte = val;
+		return __i2c_smbus_xfer(adap, client->addr, client->flags,
+					I2C_SMBUS_WRITE, mux->pdata.sel_reg_addr,
+					I2C_SMBUS_BYTE_DATA, &data);
+	case 2:
+		buf[0] = mux->pdata.sel_reg_addr >> 8;
+		buf[1] = mux->pdata.sel_reg_addr;
+		buf[2] = val;
+		msg.addr = client->addr;
+		msg.buf = buf;
+		msg.len = mux->pdata.reg_size + 1;
+		msg.flags = 0;
+		return __i2c_transfer(adap, &msg, 1);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
+	u32 regval = chan;
+	int err = 0;
+
+	if (mux->pdata.reg_size == 1)
+		regval += 1;
+
+	/* Only select the channel if its different from the last channel */
+	if (mux->last_val != regval) {
+		err = mlxcpld_mux_reg_write(muxc->parent, mux, regval);
+		mux->last_val = err < 0 ? -1 : regval;
+	}
+
+	return err;
+}
+
+static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
+
+	/* Deselect active channel */
+	mux->last_val = -1;
+
+	return mlxcpld_mux_reg_write(muxc->parent, mux, 0);
+}
+
+/* Probe/reomove functions */
+static int mlxcpld_mux_probe(struct platform_device *pdev)
+{
+	struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&pdev->dev);
+	struct i2c_client *client = to_i2c_client(pdev->dev.parent);
+	struct i2c_mux_core *muxc;
+	struct mlxcpld_mux *data;
+	int num, err;
+	u32 func;
+
+	if (!pdata)
+		return -EINVAL;
+
+	switch (pdata->reg_size) {
+	case 1:
+		func = I2C_FUNC_SMBUS_WRITE_BYTE_DATA;
+		break;
+	case 2:
+		func = I2C_FUNC_I2C;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (!i2c_check_functionality(client->adapter, func))
+		return -ENODEV;
+
+	muxc = i2c_mux_alloc(client->adapter, &pdev->dev, pdata->num_adaps,
+			     sizeof(*data), 0, mlxcpld_mux_select_chan,
+			     mlxcpld_mux_deselect);
+	if (!muxc)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, muxc);
+	data = i2c_mux_priv(muxc);
+	data->client = client;
+	memcpy(&data->pdata, pdata, sizeof(*pdata));
+	data->last_val = -1; /* force the first selection */
+
+	/* Create an adapter for each channel. */
+	for (num = 0; num < pdata->num_adaps; num++) {
+		err = i2c_mux_add_adapter(muxc, 0, pdata->chan_ids[num]);
+		if (err)
+			goto virt_reg_failed;
+	}
+
+	/* Notify caller when all channels' adapters are created. */
+	if (pdata->completion_notify)
+		pdata->completion_notify(pdata->handle, muxc->parent, muxc->adapter);
+
+	return 0;
+
+virt_reg_failed:
+	i2c_mux_del_adapters(muxc);
+	return err;
+}
+
+static void mlxcpld_mux_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+}
+
+static struct platform_driver mlxcpld_mux_driver = {
+	.driver = {
+		.name = "i2c-mux-mlxcpld",
+	},
+	.probe = mlxcpld_mux_probe,
+	.remove = mlxcpld_mux_remove,
+};
+
+module_platform_driver(mlxcpld_mux_driver);
+
+MODULE_AUTHOR("Michael Shych <michaels@mellanox.com>");
+MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("platform:i2c-mux-mlxcpld");
diff --git a/drivers/i2c/muxes/i2c-mux-mule.c b/drivers/i2c/muxes/i2c-mux-mule.c
new file mode 100644
index 000000000..d3b32b794
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-mule.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Theobroma Systems Mule I2C device multiplexer
+ *
+ * Copyright (C) 2024 Theobroma Systems Design und Consulting GmbH
+ */
+
+#include <linux/i2c-mux.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#define MULE_I2C_MUX_CONFIG_REG  0xff
+#define MULE_I2C_MUX_DEFAULT_DEV 0x0
+
+struct mule_i2c_reg_mux {
+	struct regmap *regmap;
+};
+
+static int mule_i2c_mux_select(struct i2c_mux_core *muxc, u32 dev)
+{
+	struct mule_i2c_reg_mux *mux = muxc->priv;
+
+	return regmap_write(mux->regmap, MULE_I2C_MUX_CONFIG_REG, dev);
+}
+
+static int mule_i2c_mux_deselect(struct i2c_mux_core *muxc, u32 dev)
+{
+	return mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV);
+}
+
+static void mule_i2c_mux_remove(void *data)
+{
+	struct i2c_mux_core *muxc = data;
+
+	i2c_mux_del_adapters(muxc);
+
+	mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV);
+}
+
+static int mule_i2c_mux_probe(struct platform_device *pdev)
+{
+	struct device *mux_dev = &pdev->dev;
+	struct mule_i2c_reg_mux *priv;
+	struct i2c_client *client;
+	struct i2c_mux_core *muxc;
+	unsigned int readback;
+	int ndev, ret;
+	bool old_fw;
+
+	/* Count devices on the mux */
+	ndev = of_get_child_count(mux_dev->of_node);
+	dev_dbg(mux_dev, "%d devices on the mux\n", ndev);
+
+	client = to_i2c_client(mux_dev->parent);
+
+	muxc = i2c_mux_alloc(client->adapter, mux_dev, ndev, sizeof(*priv),
+			     I2C_MUX_LOCKED, mule_i2c_mux_select, mule_i2c_mux_deselect);
+	if (!muxc)
+		return -ENOMEM;
+
+	priv = i2c_mux_priv(muxc);
+
+	priv->regmap = dev_get_regmap(mux_dev->parent, NULL);
+	if (!priv->regmap)
+		return dev_err_probe(mux_dev, -ENODEV,
+				     "No parent i2c register map\n");
+
+	platform_set_drvdata(pdev, muxc);
+
+	/*
+	 * MULE_I2C_MUX_DEFAULT_DEV is guaranteed to exist on all old and new
+	 * mule fw. Mule fw without mux support will accept write ops to the
+	 * config register, but readback returns 0xff (register not updated).
+	 */
+	ret = mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV);
+	if (ret)
+		return dev_err_probe(mux_dev, ret,
+				     "Failed to write config register\n");
+
+	ret = regmap_read(priv->regmap, MULE_I2C_MUX_CONFIG_REG, &readback);
+	if (ret)
+		return dev_err_probe(mux_dev, ret,
+				     "Failed to read config register\n");
+
+	old_fw = (readback != MULE_I2C_MUX_DEFAULT_DEV);
+
+	ret = devm_add_action_or_reset(mux_dev, mule_i2c_mux_remove, muxc);
+	if (ret)
+		return dev_err_probe(mux_dev, ret,
+				     "Failed to register mux remove\n");
+
+	/* Create device adapters */
+	for_each_child_of_node_scoped(mux_dev->of_node, dev) {
+		u32 reg;
+
+		ret = of_property_read_u32(dev, "reg", &reg);
+		if (ret)
+			return dev_err_probe(mux_dev, ret,
+					     "No reg property found for %s\n",
+					     of_node_full_name(dev));
+
+		if (old_fw && reg != 0) {
+			dev_warn(mux_dev,
+				 "Mux is not supported, please update Mule FW\n");
+			continue;
+		}
+
+		ret = mule_i2c_mux_select(muxc, reg);
+		if (ret) {
+			dev_warn(mux_dev,
+				 "Device %d not supported, please update Mule FW\n", reg);
+			continue;
+		}
+
+		ret = i2c_mux_add_adapter(muxc, 0, reg);
+		if (ret)
+			return ret;
+	}
+
+	mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV);
+
+	return 0;
+}
+
+static const struct of_device_id mule_i2c_mux_of_match[] = {
+	{ .compatible = "tsd,mule-i2c-mux", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mule_i2c_mux_of_match);
+
+static struct platform_driver mule_i2c_mux_driver = {
+	.driver = {
+		.name	= "mule-i2c-mux",
+		.of_match_table = mule_i2c_mux_of_match,
+	},
+	.probe		= mule_i2c_mux_probe,
+};
+
+module_platform_driver(mule_i2c_mux_driver);
+
+MODULE_AUTHOR("Farouk Bouabid <farouk.bouabid@cherry.de>");
+MODULE_DESCRIPTION("I2C mux driver for Theobroma Systems Mule");
+MODULE_LICENSE("GPL");
diff --git a/drivers/i2c/muxes/i2c-mux-pca9541.c b/drivers/i2c/muxes/i2c-mux-pca9541.c
new file mode 100644
index 000000000..9a59129bc
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-pca9541.c
@@ -0,0 +1,348 @@
+/*
+ * I2C multiplexer driver for PCA9541 bus master selector
+ *
+ * Copyright (c) 2010 Ericsson AB.
+ *
+ * Author: Guenter Roeck <linux@roeck-us.net>
+ *
+ * Derived from:
+ *  pca954x.c
+ *
+ *  Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ *  Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*
+ * The PCA9541 is a bus master selector. It supports two I2C masters connected
+ * to a single slave bus.
+ *
+ * Before each bus transaction, a master has to acquire bus ownership. After the
+ * transaction is complete, bus ownership has to be released. This fits well
+ * into the I2C multiplexer framework, which provides select and release
+ * functions for this purpose. For this reason, this driver is modeled as
+ * single-channel I2C bus multiplexer.
+ *
+ * This driver assumes that the two bus masters are controlled by two different
+ * hosts. If a single host controls both masters, platform code has to ensure
+ * that only one of the masters is instantiated at any given time.
+ */
+
+#define PCA9541_CONTROL		0x01
+#define PCA9541_ISTAT		0x02
+
+#define PCA9541_CTL_MYBUS	BIT(0)
+#define PCA9541_CTL_NMYBUS	BIT(1)
+#define PCA9541_CTL_BUSON	BIT(2)
+#define PCA9541_CTL_NBUSON	BIT(3)
+#define PCA9541_CTL_BUSINIT	BIT(4)
+#define PCA9541_CTL_TESTON	BIT(6)
+#define PCA9541_CTL_NTESTON	BIT(7)
+
+#define PCA9541_ISTAT_INTIN	BIT(0)
+#define PCA9541_ISTAT_BUSINIT	BIT(1)
+#define PCA9541_ISTAT_BUSOK	BIT(2)
+#define PCA9541_ISTAT_BUSLOST	BIT(3)
+#define PCA9541_ISTAT_MYTEST	BIT(6)
+#define PCA9541_ISTAT_NMYTEST	BIT(7)
+
+#define BUSON		(PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
+#define MYBUS		(PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
+#define mybus(x)	(!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
+#define busoff(x)	(!((x) & BUSON) || ((x) & BUSON) == BUSON)
+
+/* arbitration retry delays, in us */
+#define SELECT_DELAY_SHORT	50
+#define SELECT_DELAY_LONG	1000
+
+struct pca9541 {
+	struct i2c_client *client;
+	unsigned long select_timeout;
+	unsigned long arb_timeout;
+};
+
+static const struct i2c_device_id pca9541_id[] = {
+	{ .name = "pca9541" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, pca9541_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pca9541_of_match[] = {
+	{ .compatible = "nxp,pca9541" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pca9541_of_match);
+#endif
+
+/*
+ * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ * as they will try to lock the adapter a second time.
+ */
+static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val)
+{
+	struct i2c_adapter *adap = client->adapter;
+	union i2c_smbus_data data = { .byte = val };
+
+	return __i2c_smbus_xfer(adap, client->addr, client->flags,
+				I2C_SMBUS_WRITE, command,
+				I2C_SMBUS_BYTE_DATA, &data);
+}
+
+/*
+ * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ * as they will try to lock adapter a second time.
+ */
+static int pca9541_reg_read(struct i2c_client *client, u8 command)
+{
+	struct i2c_adapter *adap = client->adapter;
+	union i2c_smbus_data data;
+	int ret;
+
+	ret = __i2c_smbus_xfer(adap, client->addr, client->flags,
+			       I2C_SMBUS_READ, command,
+			       I2C_SMBUS_BYTE_DATA, &data);
+
+	return ret ?: data.byte;
+}
+
+/*
+ * Arbitration management functions
+ */
+
+/* Release bus. Also reset NTESTON and BUSINIT if it was set. */
+static void pca9541_release_bus(struct i2c_client *client)
+{
+	int reg;
+
+	reg = pca9541_reg_read(client, PCA9541_CONTROL);
+	if (reg >= 0 && !busoff(reg) && mybus(reg))
+		pca9541_reg_write(client, PCA9541_CONTROL,
+				  (reg & PCA9541_CTL_NBUSON) >> 1);
+}
+
+/*
+ * Arbitration is defined as a two-step process. A bus master can only activate
+ * the slave bus if it owns it; otherwise it has to request ownership first.
+ * This multi-step process ensures that access contention is resolved
+ * gracefully.
+ *
+ * Bus	Ownership	Other master	Action
+ * state		requested access
+ * ----------------------------------------------------
+ * off	-		yes		wait for arbitration timeout or
+ *					for other master to drop request
+ * off	no		no		take ownership
+ * off	yes		no		turn on bus
+ * on	yes		-		done
+ * on	no		-		wait for arbitration timeout or
+ *					for other master to release bus
+ *
+ * The main contention point occurs if the slave bus is off and both masters
+ * request ownership at the same time. In this case, one master will turn on
+ * the slave bus, believing that it owns it. The other master will request
+ * bus ownership. Result is that the bus is turned on, and master which did
+ * _not_ own the slave bus before ends up owning it.
+ */
+
+/* Control commands per PCA9541 datasheet */
+static const u8 pca9541_control[16] = {
+	4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1
+};
+
+/*
+ * Channel arbitration
+ *
+ * Return values:
+ *  <0: error
+ *  0 : bus not acquired
+ *  1 : bus acquired
+ */
+static int pca9541_arbitrate(struct i2c_client *client)
+{
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+	struct pca9541 *data = i2c_mux_priv(muxc);
+	int reg;
+
+	reg = pca9541_reg_read(client, PCA9541_CONTROL);
+	if (reg < 0)
+		return reg;
+
+	if (busoff(reg)) {
+		int istat;
+		/*
+		 * Bus is off. Request ownership or turn it on unless
+		 * other master requested ownership.
+		 */
+		istat = pca9541_reg_read(client, PCA9541_ISTAT);
+		if (!(istat & PCA9541_ISTAT_NMYTEST)
+		    || time_is_before_eq_jiffies(data->arb_timeout)) {
+			/*
+			 * Other master did not request ownership,
+			 * or arbitration timeout expired. Take the bus.
+			 */
+			pca9541_reg_write(client,
+					  PCA9541_CONTROL,
+					  pca9541_control[reg & 0x0f]
+					  | PCA9541_CTL_NTESTON);
+			data->select_timeout = SELECT_DELAY_SHORT;
+		} else {
+			/*
+			 * Other master requested ownership.
+			 * Set extra long timeout to give it time to acquire it.
+			 */
+			data->select_timeout = SELECT_DELAY_LONG * 2;
+		}
+	} else if (mybus(reg)) {
+		/*
+		 * Bus is on, and we own it. We are done with acquisition.
+		 * Reset NTESTON and BUSINIT, then return success.
+		 */
+		if (reg & (PCA9541_CTL_NTESTON | PCA9541_CTL_BUSINIT))
+			pca9541_reg_write(client,
+					  PCA9541_CONTROL,
+					  reg & ~(PCA9541_CTL_NTESTON
+						  | PCA9541_CTL_BUSINIT));
+		return 1;
+	} else {
+		/*
+		 * Other master owns the bus.
+		 * If arbitration timeout has expired, force ownership.
+		 * Otherwise request it.
+		 */
+		data->select_timeout = SELECT_DELAY_LONG;
+		if (time_is_before_eq_jiffies(data->arb_timeout)) {
+			dev_warn(&client->dev,
+				 "Arbitration timeout on I2C bus, forcing bus ownership\n");
+
+			/* Time is up, take the bus and reset it. */
+			pca9541_reg_write(client,
+					  PCA9541_CONTROL,
+					  pca9541_control[reg & 0x0f]
+					  | PCA9541_CTL_BUSINIT
+					  | PCA9541_CTL_NTESTON);
+		} else {
+			/* Request bus ownership if needed */
+			if (!(reg & PCA9541_CTL_NTESTON))
+				pca9541_reg_write(client,
+						  PCA9541_CONTROL,
+						  reg | PCA9541_CTL_NTESTON);
+		}
+	}
+	return 0;
+}
+
+static int pca9541_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct pca9541 *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+	int ret;
+	unsigned long timeout = jiffies + (2 * client->adapter->timeout);
+		/* give up after this time */
+
+	data->arb_timeout = jiffies + client->adapter->timeout;
+		/* force bus ownership after this time */
+
+	do {
+		ret = pca9541_arbitrate(client);
+		if (ret)
+			return ret < 0 ? ret : 0;
+
+		if (data->select_timeout == SELECT_DELAY_SHORT)
+			udelay(data->select_timeout);
+		else
+			msleep(data->select_timeout / 1000);
+	} while (time_is_after_eq_jiffies(timeout));
+	dev_warn(&client->dev, "Failed to acquire I2C bus, timed out\n");
+
+	return -ETIMEDOUT;
+}
+
+static int pca9541_release_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct pca9541 *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+
+	pca9541_release_bus(client);
+	return 0;
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca9541_probe(struct i2c_client *client)
+{
+	struct i2c_adapter *adap = client->adapter;
+	struct i2c_mux_core *muxc;
+	struct pca9541 *data;
+	int ret;
+
+	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	/*
+	 * I2C accesses are unprotected here.
+	 * We have to lock the I2C segment before releasing the bus.
+	 */
+	i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
+	pca9541_release_bus(client);
+	i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
+
+	/* Create mux adapter */
+
+	muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
+			     I2C_MUX_ARBITRATOR,
+			     pca9541_select_chan, pca9541_release_chan);
+	if (!muxc)
+		return -ENOMEM;
+
+	data = i2c_mux_priv(muxc);
+	data->client = client;
+
+	i2c_set_clientdata(client, muxc);
+
+	ret = i2c_mux_add_adapter(muxc, 0, 0);
+	if (ret)
+		return ret;
+
+	dev_info(&client->dev, "registered master selector for I2C %s\n",
+		 client->name);
+
+	return 0;
+}
+
+static void pca9541_remove(struct i2c_client *client)
+{
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+	i2c_mux_del_adapters(muxc);
+}
+
+static struct i2c_driver pca9541_driver = {
+	.driver = {
+		   .name = "pca9541",
+		   .of_match_table = of_match_ptr(pca9541_of_match),
+		   },
+	.probe = pca9541_probe,
+	.remove = pca9541_remove,
+	.id_table = pca9541_id,
+};
+
+module_i2c_driver(pca9541_driver);
+
+MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
+MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
new file mode 100644
index 000000000..8fca709ed
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -0,0 +1,717 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * I2C multiplexer
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This module supports the PCA954x and PCA984x series of I2C multiplexer/switch
+ * chips made by NXP Semiconductors.
+ * This includes the:
+ *	 PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547,
+ *	 PCA9548, PCA9846, PCA9847, PCA9848 and PCA9849.
+ *
+ * It's also compatible to Maxims MAX735x I2C switch chips, which are controlled
+ * as the NXP PCA9548 and the MAX736x chips that act like the PCA9544.
+ *
+ * This includes the:
+ *	 MAX7356, MAX7357, MAX7358, MAX7367, MAX7368 and MAX7369
+ *
+ * These chips are all controlled via the I2C bus itself, and all have a
+ * single 8-bit register. The upstream "parent" bus fans out to two,
+ * four, or eight downstream busses or channels; which of these
+ * are selected is determined by the chip type and register contents. A
+ * mux can select only one sub-bus at a time; a switch can select any
+ * combination simultaneously.
+ *
+ * Based on:
+ *	pca954x.c from Kumar Gala <galak@kernel.crashing.org>
+ * Copyright (C) 2006
+ *
+ * Based on:
+ *	pca954x.c from Ken Harrenstien
+ * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
+ *
+ * Based on:
+ *	i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
+ * and
+ *	pca9540.c from Jean Delvare <jdelvare@suse.de>.
+ */
+
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <dt-bindings/mux/mux.h>
+
+#define PCA954X_MAX_NCHANS 8
+
+#define PCA954X_IRQ_OFFSET 4
+
+/*
+ * MAX7357's configuration register is writeable after POR, but
+ * can be locked by setting the basic mode bit. MAX7358 configuration
+ * register is locked by default and needs to be unlocked first.
+ * The configuration register holds the following settings:
+ */
+#define MAX7357_CONF_INT_ENABLE			BIT(0)
+#define MAX7357_CONF_FLUSH_OUT			BIT(1)
+#define MAX7357_CONF_RELEASE_INT		BIT(2)
+#define MAX7357_CONF_DISCON_SINGLE_CHAN		BIT(4)
+#define MAX7357_CONF_PRECONNECT_TEST		BIT(7)
+
+#define MAX7357_POR_DEFAULT_CONF		MAX7357_CONF_INT_ENABLE
+
+enum pca_type {
+	max_7356,
+	max_7357,
+	max_7358,
+	max_7367,
+	max_7368,
+	max_7369,
+	pca_9540,
+	pca_9542,
+	pca_9543,
+	pca_9544,
+	pca_9545,
+	pca_9546,
+	pca_9547,
+	pca_9548,
+	pca_9846,
+	pca_9847,
+	pca_9848,
+	pca_9849,
+};
+
+struct chip_desc {
+	u8 nchans;
+	u8 enable;	/* used for muxes only */
+	u8 has_irq;
+	enum muxtype {
+		pca954x_ismux = 0,
+		pca954x_isswi
+	} muxtype;
+	struct i2c_device_identity id;
+};
+
+struct pca954x {
+	const struct chip_desc *chip;
+
+	u8 last_chan;		/* last register value */
+	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
+	s32 idle_state;
+
+	struct i2c_client *client;
+
+	struct irq_domain *irq;
+	unsigned int irq_mask;
+	raw_spinlock_t lock;
+	struct regulator *supply;
+
+	struct gpio_desc *reset_gpio;
+	struct reset_control *reset_cont;
+};
+
+/* Provide specs for the MAX735x, PCA954x and PCA984x types we know about */
+static const struct chip_desc chips[] = {
+	[max_7356] = {
+		.nchans = 8,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[max_7357] = {
+		.nchans = 8,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+		/*
+		 * No interrupt controller support. The interrupt
+		 * provides information about stuck channels.
+		 */
+	},
+	[max_7358] = {
+		.nchans = 8,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+		/*
+		 * No interrupt controller support. The interrupt
+		 * provides information about stuck channels.
+		 */
+	},
+	[max_7367] = {
+		.nchans = 4,
+		.muxtype = pca954x_isswi,
+		.has_irq = 1,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[max_7368] = {
+		.nchans = 4,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[max_7369] = {
+		.nchans = 4,
+		.enable = 0x4,
+		.muxtype = pca954x_ismux,
+		.has_irq = 1,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9540] = {
+		.nchans = 2,
+		.enable = 0x4,
+		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9542] = {
+		.nchans = 2,
+		.enable = 0x4,
+		.has_irq = 1,
+		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9543] = {
+		.nchans = 2,
+		.has_irq = 1,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9544] = {
+		.nchans = 4,
+		.enable = 0x4,
+		.has_irq = 1,
+		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9545] = {
+		.nchans = 4,
+		.has_irq = 1,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9546] = {
+		.nchans = 4,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9547] = {
+		.nchans = 8,
+		.enable = 0x8,
+		.muxtype = pca954x_ismux,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9548] = {
+		.nchans = 8,
+		.muxtype = pca954x_isswi,
+		.id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
+	},
+	[pca_9846] = {
+		.nchans = 4,
+		.muxtype = pca954x_isswi,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x10b,
+		},
+	},
+	[pca_9847] = {
+		.nchans = 8,
+		.enable = 0x8,
+		.muxtype = pca954x_ismux,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x108,
+		},
+	},
+	[pca_9848] = {
+		.nchans = 8,
+		.muxtype = pca954x_isswi,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x10a,
+		},
+	},
+	[pca_9849] = {
+		.nchans = 4,
+		.enable = 0x4,
+		.muxtype = pca954x_ismux,
+		.id = {
+			.manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
+			.part_id = 0x109,
+		},
+	},
+};
+
+static const struct i2c_device_id pca954x_id[] = {
+	{ .name = "max7356", .driver_data = max_7356 },
+	{ .name = "max7357", .driver_data = max_7357 },
+	{ .name = "max7358", .driver_data = max_7358 },
+	{ .name = "max7367", .driver_data = max_7367 },
+	{ .name = "max7368", .driver_data = max_7368 },
+	{ .name = "max7369", .driver_data = max_7369 },
+	{ .name = "pca9540", .driver_data = pca_9540 },
+	{ .name = "pca9542", .driver_data = pca_9542 },
+	{ .name = "pca9543", .driver_data = pca_9543 },
+	{ .name = "pca9544", .driver_data = pca_9544 },
+	{ .name = "pca9545", .driver_data = pca_9545 },
+	{ .name = "pca9546", .driver_data = pca_9546 },
+	{ .name = "pca9547", .driver_data = pca_9547 },
+	{ .name = "pca9548", .driver_data = pca_9548 },
+	{ .name = "pca9846", .driver_data = pca_9846 },
+	{ .name = "pca9847", .driver_data = pca_9847 },
+	{ .name = "pca9848", .driver_data = pca_9848 },
+	{ .name = "pca9849", .driver_data = pca_9849 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pca954x_id);
+
+static const struct of_device_id pca954x_of_match[] = {
+	{ .compatible = "maxim,max7356", .data = &chips[max_7356] },
+	{ .compatible = "maxim,max7357", .data = &chips[max_7357] },
+	{ .compatible = "maxim,max7358", .data = &chips[max_7358] },
+	{ .compatible = "maxim,max7367", .data = &chips[max_7367] },
+	{ .compatible = "maxim,max7368", .data = &chips[max_7368] },
+	{ .compatible = "maxim,max7369", .data = &chips[max_7369] },
+	{ .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
+	{ .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
+	{ .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
+	{ .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
+	{ .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
+	{ .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
+	{ .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
+	{ .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
+	{ .compatible = "nxp,pca9846", .data = &chips[pca_9846] },
+	{ .compatible = "nxp,pca9847", .data = &chips[pca_9847] },
+	{ .compatible = "nxp,pca9848", .data = &chips[pca_9848] },
+	{ .compatible = "nxp,pca9849", .data = &chips[pca_9849] },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pca954x_of_match);
+
+/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
+   for this as they will try to lock adapter a second time */
+static int pca954x_reg_write(struct i2c_adapter *adap,
+			     struct i2c_client *client, u8 val)
+{
+	union i2c_smbus_data dummy;
+
+	return __i2c_smbus_xfer(adap, client->addr, client->flags,
+				I2C_SMBUS_WRITE, val,
+				I2C_SMBUS_BYTE, &dummy);
+}
+
+static u8 pca954x_regval(struct pca954x *data, u8 chan)
+{
+	/* We make switches look like muxes, not sure how to be smarter. */
+	if (data->chip->muxtype == pca954x_ismux)
+		return chan | data->chip->enable;
+	else
+		return 1 << chan;
+}
+
+static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct pca954x *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+	u8 regval;
+	int ret = 0;
+
+	regval = pca954x_regval(data, chan);
+	/* Only select the channel if its different from the last channel */
+	if (data->last_chan != regval) {
+		ret = pca954x_reg_write(muxc->parent, client, regval);
+		data->last_chan = ret < 0 ? 0 : regval;
+	}
+
+	return ret;
+}
+
+static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct pca954x *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+	s32 idle_state;
+
+	idle_state = READ_ONCE(data->idle_state);
+	if (idle_state >= 0)
+		/* Set the mux back to a predetermined channel */
+		return pca954x_select_chan(muxc, idle_state);
+
+	if (idle_state == MUX_IDLE_DISCONNECT) {
+		/* Deselect active channel */
+		data->last_chan = 0;
+		return pca954x_reg_write(muxc->parent, client,
+					 data->last_chan);
+	}
+
+	/* otherwise leave as-is */
+
+	return 0;
+}
+
+static ssize_t idle_state_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+	struct pca954x *data = i2c_mux_priv(muxc);
+
+	return sprintf(buf, "%d\n", READ_ONCE(data->idle_state));
+}
+
+static ssize_t idle_state_store(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+	struct pca954x *data = i2c_mux_priv(muxc);
+	int val;
+	int ret;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val != MUX_IDLE_AS_IS && val != MUX_IDLE_DISCONNECT &&
+	    (val < 0 || val >= data->chip->nchans))
+		return -EINVAL;
+
+	i2c_lock_bus(muxc->parent, I2C_LOCK_SEGMENT);
+
+	WRITE_ONCE(data->idle_state, val);
+	/*
+	 * Set the mux into a state consistent with the new
+	 * idle_state.
+	 */
+	if (data->last_chan || val != MUX_IDLE_DISCONNECT)
+		ret = pca954x_deselect_mux(muxc, 0);
+
+	i2c_unlock_bus(muxc->parent, I2C_LOCK_SEGMENT);
+
+	return ret < 0 ? ret : count;
+}
+
+static DEVICE_ATTR_RW(idle_state);
+
+static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
+{
+	struct pca954x *data = dev_id;
+	unsigned long pending;
+	int ret, i;
+
+	ret = i2c_smbus_read_byte(data->client);
+	if (ret < 0)
+		return IRQ_NONE;
+
+	pending = (ret >> PCA954X_IRQ_OFFSET) & (BIT(data->chip->nchans) - 1);
+	for_each_set_bit(i, &pending, data->chip->nchans)
+		handle_nested_irq(irq_find_mapping(data->irq, i));
+
+	return IRQ_RETVAL(pending);
+}
+
+static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
+{
+	if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
+		return -EINVAL;
+	return 0;
+}
+
+static struct irq_chip pca954x_irq_chip = {
+	.name = "i2c-mux-pca954x",
+	.irq_set_type = pca954x_irq_set_type,
+};
+
+static int pca954x_irq_setup(struct i2c_mux_core *muxc)
+{
+	struct pca954x *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+	int c, irq;
+
+	if (!data->chip->has_irq || client->irq <= 0)
+		return 0;
+
+	raw_spin_lock_init(&data->lock);
+
+	data->irq = irq_domain_create_linear(dev_fwnode(&client->dev), data->chip->nchans,
+					     &irq_domain_simple_ops, data);
+	if (!data->irq)
+		return -ENODEV;
+
+	for (c = 0; c < data->chip->nchans; c++) {
+		irq = irq_create_mapping(data->irq, c);
+		if (!irq) {
+			dev_err(&client->dev, "failed irq create map\n");
+			return -EINVAL;
+		}
+		irq_set_chip_data(irq, data);
+		irq_set_chip_and_handler(irq, &pca954x_irq_chip,
+			handle_simple_irq);
+	}
+
+	return 0;
+}
+
+static void pca954x_cleanup(struct i2c_mux_core *muxc)
+{
+	struct pca954x *data = i2c_mux_priv(muxc);
+	int c, irq;
+
+	regulator_disable(data->supply);
+
+	if (data->irq) {
+		for (c = 0; c < data->chip->nchans; c++) {
+			irq = irq_find_mapping(data->irq, c);
+			irq_dispose_mapping(irq);
+		}
+		irq_domain_remove(data->irq);
+	}
+	i2c_mux_del_adapters(muxc);
+}
+
+static int pca954x_init(struct i2c_client *client, struct pca954x *data)
+{
+	int ret;
+
+	if (data->idle_state >= 0)
+		data->last_chan = pca954x_regval(data, data->idle_state);
+	else
+		data->last_chan = 0; /* Disconnect multiplexer */
+
+	if (device_is_compatible(&client->dev, "maxim,max7357")) {
+		if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+			u8 conf = MAX7357_POR_DEFAULT_CONF;
+			/*
+			 * The interrupt signal is shared with the reset pin. Release the
+			 * interrupt after 1.6 seconds to allow using the pin as reset.
+			 */
+			conf |= MAX7357_CONF_RELEASE_INT;
+
+			if (device_property_read_bool(&client->dev, "maxim,isolate-stuck-channel"))
+				conf |= MAX7357_CONF_DISCON_SINGLE_CHAN;
+			if (device_property_read_bool(&client->dev,
+						      "maxim,send-flush-out-sequence"))
+				conf |= MAX7357_CONF_FLUSH_OUT;
+			if (device_property_read_bool(&client->dev,
+						      "maxim,preconnection-wiggle-test-enable"))
+				conf |= MAX7357_CONF_PRECONNECT_TEST;
+
+			ret = i2c_smbus_write_byte_data(client, data->last_chan, conf);
+		} else {
+			dev_warn(&client->dev, "Write byte data not supported."
+				 "Cannot enable enhanced mode features\n");
+			ret = i2c_smbus_write_byte(client, data->last_chan);
+		}
+	} else {
+		ret = i2c_smbus_write_byte(client, data->last_chan);
+	}
+
+	if (ret < 0)
+		data->last_chan = 0;
+
+	return ret;
+}
+
+static int pca954x_get_reset(struct device *dev, struct pca954x *data)
+{
+	data->reset_cont = devm_reset_control_get_optional_shared(dev, NULL);
+	if (IS_ERR(data->reset_cont))
+		return dev_err_probe(dev, PTR_ERR(data->reset_cont),
+				     "Failed to get reset\n");
+	else if (data->reset_cont)
+		return 0;
+
+	/*
+	 * fallback to legacy reset-gpios
+	 */
+	data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(data->reset_gpio)) {
+		return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
+				     "Failed to get reset gpio");
+	}
+
+	return 0;
+}
+
+static void pca954x_reset_deassert(struct pca954x *data)
+{
+	if (data->reset_cont)
+		reset_control_deassert(data->reset_cont);
+	else
+		gpiod_set_value_cansleep(data->reset_gpio, 0);
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca954x_probe(struct i2c_client *client)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(client);
+	struct i2c_adapter *adap = client->adapter;
+	struct device *dev = &client->dev;
+	struct i2c_mux_core *muxc;
+	struct pca954x *data;
+	int num;
+	int ret;
+
+	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
+		return -ENODEV;
+
+	muxc = i2c_mux_alloc(adap, dev, PCA954X_MAX_NCHANS, sizeof(*data), 0,
+			     pca954x_select_chan, pca954x_deselect_mux);
+	if (!muxc)
+		return -ENOMEM;
+	data = i2c_mux_priv(muxc);
+
+	i2c_set_clientdata(client, muxc);
+	data->client = client;
+
+	data->supply = devm_regulator_get(dev, "vdd");
+	if (IS_ERR(data->supply))
+		return dev_err_probe(dev, PTR_ERR(data->supply),
+				"Failed to request regulator\n");
+
+	ret = regulator_enable(data->supply);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to enable vdd supply\n");
+
+	ret = pca954x_get_reset(dev, data);
+	if (ret)
+		goto fail_cleanup;
+
+	if (data->reset_cont || data->reset_gpio) {
+		udelay(1);
+		pca954x_reset_deassert(data);
+		/* Give the chip some time to recover. */
+		udelay(1);
+	}
+
+	data->chip = device_get_match_data(dev);
+	if (!data->chip)
+		data->chip = &chips[id->driver_data];
+
+	if (data->chip->id.manufacturer_id != I2C_DEVICE_ID_NONE) {
+		struct i2c_device_identity id;
+
+		ret = i2c_get_device_id(client, &id);
+		if (ret && ret != -EOPNOTSUPP)
+			goto fail_cleanup;
+
+		if (!ret &&
+		    (id.manufacturer_id != data->chip->id.manufacturer_id ||
+		     id.part_id != data->chip->id.part_id)) {
+			dev_warn(dev, "unexpected device id %03x-%03x-%x\n",
+				 id.manufacturer_id, id.part_id,
+				 id.die_revision);
+			ret = -ENODEV;
+			goto fail_cleanup;
+		}
+	}
+
+	data->idle_state = MUX_IDLE_AS_IS;
+	if (device_property_read_u32(dev, "idle-state", &data->idle_state)) {
+		if (device_property_read_bool(dev, "i2c-mux-idle-disconnect"))
+			data->idle_state = MUX_IDLE_DISCONNECT;
+	}
+
+	/*
+	 * Write the mux register at addr to verify
+	 * that the mux is in fact present. This also
+	 * initializes the mux to a channel
+	 * or disconnected state.
+	 */
+	ret = pca954x_init(client, data);
+	if (ret < 0) {
+		dev_warn(dev, "probe failed\n");
+		ret = -ENODEV;
+		goto fail_cleanup;
+	}
+
+	ret = pca954x_irq_setup(muxc);
+	if (ret)
+		goto fail_cleanup;
+
+	/* Now create an adapter for each channel */
+	for (num = 0; num < data->chip->nchans; num++) {
+		ret = i2c_mux_add_adapter(muxc, 0, num);
+		if (ret)
+			goto fail_cleanup;
+	}
+
+	if (data->irq) {
+		ret = devm_request_threaded_irq(dev, data->client->irq,
+						NULL, pca954x_irq_handler,
+						IRQF_ONESHOT | IRQF_SHARED,
+						"pca954x", data);
+		if (ret)
+			goto fail_cleanup;
+	}
+
+	/*
+	 * The attr probably isn't going to be needed in most cases,
+	 * so don't fail completely on error.
+	 */
+	device_create_file(dev, &dev_attr_idle_state);
+
+	dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
+		 num, data->chip->muxtype == pca954x_ismux
+				? "mux" : "switch", client->name);
+
+	return 0;
+
+fail_cleanup:
+	pca954x_cleanup(muxc);
+	return ret;
+}
+
+static void pca954x_remove(struct i2c_client *client)
+{
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+	device_remove_file(&client->dev, &dev_attr_idle_state);
+
+	pca954x_cleanup(muxc);
+}
+
+static int pca954x_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+	struct pca954x *data = i2c_mux_priv(muxc);
+	int ret;
+
+	ret = pca954x_init(client, data);
+	if (ret < 0)
+		dev_err(&client->dev, "failed to verify mux presence\n");
+
+	return ret;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
+
+static struct i2c_driver pca954x_driver = {
+	.driver		= {
+		.name	= "pca954x",
+		.pm	= pm_sleep_ptr(&pca954x_pm),
+		.of_match_table = pca954x_of_match,
+	},
+	.probe		= pca954x_probe,
+	.remove		= pca954x_remove,
+	.id_table	= pca954x_id,
+};
+
+module_i2c_driver(pca954x_driver);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c
new file mode 100644
index 000000000..fc686a350
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C multiplexer using pinctrl API
+ *
+ * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include "../../pinctrl/core.h"
+
+struct i2c_mux_pinctrl {
+	struct pinctrl *pinctrl;
+	struct pinctrl_state *states[];
+};
+
+static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);
+
+	return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
+}
+
+static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	return i2c_mux_pinctrl_select(muxc, muxc->num_adapters);
+}
+
+static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
+	struct pinctrl_state *state)
+{
+	struct i2c_adapter *root = NULL;
+	struct pinctrl_setting *setting;
+	struct i2c_adapter *pin_root;
+
+	list_for_each_entry(setting, &state->settings, node) {
+		pin_root = i2c_root_adapter(setting->pctldev->dev);
+		if (!pin_root)
+			return NULL;
+		if (!root)
+			root = pin_root;
+		else if (root != pin_root)
+			return NULL;
+	}
+
+	return root;
+}
+
+static struct i2c_adapter *i2c_mux_pinctrl_parent_adapter(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct device_node *parent_np;
+	struct i2c_adapter *parent;
+
+	parent_np = of_parse_phandle(np, "i2c-parent", 0);
+	if (!parent_np) {
+		dev_err(dev, "Cannot parse i2c-parent\n");
+		return ERR_PTR(-ENODEV);
+	}
+	parent = of_get_i2c_adapter_by_node(parent_np);
+	of_node_put(parent_np);
+	if (!parent)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	return parent;
+}
+
+static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct i2c_mux_core *muxc;
+	struct i2c_mux_pinctrl *mux;
+	struct i2c_adapter *parent;
+	struct i2c_adapter *root;
+	int num_names, i, ret;
+	const char *name;
+
+	num_names = of_property_count_strings(np, "pinctrl-names");
+	if (num_names < 0) {
+		dev_err(dev, "Cannot parse pinctrl-names: %d\n",
+			num_names);
+		return num_names;
+	}
+
+	parent = i2c_mux_pinctrl_parent_adapter(dev);
+	if (IS_ERR(parent))
+		return PTR_ERR(parent);
+
+	muxc = i2c_mux_alloc(parent, dev, num_names,
+			     struct_size(mux, states, num_names),
+			     0, i2c_mux_pinctrl_select, NULL);
+	if (!muxc) {
+		ret = -ENOMEM;
+		goto err_put_parent;
+	}
+	mux = i2c_mux_priv(muxc);
+
+	platform_set_drvdata(pdev, muxc);
+
+	mux->pinctrl = devm_pinctrl_get(dev);
+	if (IS_ERR(mux->pinctrl)) {
+		ret = PTR_ERR(mux->pinctrl);
+		dev_err(dev, "Cannot get pinctrl: %d\n", ret);
+		goto err_put_parent;
+	}
+
+	for (i = 0; i < num_names; i++) {
+		ret = of_property_read_string_index(np, "pinctrl-names", i,
+						    &name);
+		if (ret < 0) {
+			dev_err(dev, "Cannot parse pinctrl-names: %d\n", ret);
+			goto err_put_parent;
+		}
+
+		mux->states[i] = pinctrl_lookup_state(mux->pinctrl, name);
+		if (IS_ERR(mux->states[i])) {
+			ret = PTR_ERR(mux->states[i]);
+			dev_err(dev, "Cannot look up pinctrl state %s: %d\n",
+				name, ret);
+			goto err_put_parent;
+		}
+
+		if (strcmp(name, "idle"))
+			continue;
+
+		if (i != num_names - 1) {
+			dev_err(dev, "idle state must be last\n");
+			ret = -EINVAL;
+			goto err_put_parent;
+		}
+		muxc->deselect = i2c_mux_pinctrl_deselect;
+	}
+
+	root = i2c_root_adapter(&muxc->parent->dev);
+
+	muxc->mux_locked = true;
+	for (i = 0; i < num_names; i++) {
+		if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
+			muxc->mux_locked = false;
+			break;
+		}
+	}
+	if (muxc->mux_locked)
+		dev_info(dev, "mux-locked i2c mux\n");
+
+	/* Do not add any adapter for the idle state (if it's there at all). */
+	for (i = 0; i < num_names - !!muxc->deselect; i++) {
+		ret = i2c_mux_add_adapter(muxc, 0, i);
+		if (ret)
+			goto err_del_adapter;
+	}
+
+	return 0;
+
+err_del_adapter:
+	i2c_mux_del_adapters(muxc);
+err_put_parent:
+	i2c_put_adapter(parent);
+
+	return ret;
+}
+
+static void i2c_mux_pinctrl_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+}
+
+static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
+	{ .compatible = "i2c-mux-pinctrl", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
+
+static struct platform_driver i2c_mux_pinctrl_driver = {
+	.driver	= {
+		.name	= "i2c-mux-pinctrl",
+		.of_match_table = i2c_mux_pinctrl_of_match,
+	},
+	.probe	= i2c_mux_pinctrl_probe,
+	.remove = i2c_mux_pinctrl_remove,
+};
+module_platform_driver(i2c_mux_pinctrl_driver);
+
+MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
+MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:i2c-mux-pinctrl");
diff --git a/drivers/i2c/muxes/i2c-mux-reg.c b/drivers/i2c/muxes/i2c-mux-reg.c
new file mode 100644
index 000000000..13da75710
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-reg.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun  <yorksun@freescale.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_data/i2c-mux-reg.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct regmux {
+	struct i2c_mux_reg_platform_data data;
+};
+
+static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
+{
+	if (!mux->data.reg)
+		return -EINVAL;
+
+	/*
+	 * Write to the register, followed by a read to ensure the write is
+	 * completed on a "posted" bus, for example PCI or write buffers.
+	 * The endianness of reading doesn't matter and the return data
+	 * is not used.
+	 */
+	switch (mux->data.reg_size) {
+	case 4:
+		if (mux->data.little_endian)
+			iowrite32(chan_id, mux->data.reg);
+		else
+			iowrite32be(chan_id, mux->data.reg);
+		if (!mux->data.write_only)
+			ioread32(mux->data.reg);
+		break;
+	case 2:
+		if (mux->data.little_endian)
+			iowrite16(chan_id, mux->data.reg);
+		else
+			iowrite16be(chan_id, mux->data.reg);
+		if (!mux->data.write_only)
+			ioread16(mux->data.reg);
+		break;
+	case 1:
+		iowrite8(chan_id, mux->data.reg);
+		if (!mux->data.write_only)
+			ioread8(mux->data.reg);
+		break;
+	}
+
+	return 0;
+}
+
+static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct regmux *mux = i2c_mux_priv(muxc);
+
+	return i2c_mux_reg_set(mux, chan);
+}
+
+static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct regmux *mux = i2c_mux_priv(muxc);
+
+	if (mux->data.idle_in_use)
+		return i2c_mux_reg_set(mux, mux->data.idle);
+
+	return 0;
+}
+
+static int i2c_mux_reg_probe_fw(struct regmux *mux, struct device *dev)
+{
+	struct fwnode_handle *fwnode, *child;
+	struct i2c_adapter *adapter;
+	unsigned *values;
+	int ret, i = 0;
+
+	if (!dev_fwnode(dev))
+		return -ENODEV;
+
+	fwnode = fwnode_find_reference(dev_fwnode(dev), "i2c-parent", 0);
+	if (IS_ERR(fwnode)) {
+		dev_err(dev, "missing 'i2c-parent' property\n");
+		return -ENODEV;
+	}
+
+	adapter = i2c_find_adapter_by_fwnode(fwnode);
+	fwnode_handle_put(fwnode);
+	if (!adapter)
+		return -EPROBE_DEFER;
+
+	mux->data.parent = i2c_adapter_id(adapter);
+	put_device(&adapter->dev);
+
+	mux->data.n_values = device_get_child_node_count(dev);
+	if (device_property_read_bool(dev, "little-endian")) {
+		mux->data.little_endian = true;
+	} else if (device_property_read_bool(dev, "big-endian")) {
+		mux->data.little_endian = false;
+	} else {
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
+	defined(__LITTLE_ENDIAN)
+		mux->data.little_endian = true;
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
+	defined(__BIG_ENDIAN)
+		mux->data.little_endian = false;
+#else
+#error Endianness not defined?
+#endif
+	}
+	mux->data.write_only = device_property_read_bool(dev, "write-only");
+
+	values = devm_kcalloc(dev, mux->data.n_values, sizeof(*mux->data.values),
+			      GFP_KERNEL);
+	if (!values)
+		return -ENOMEM;
+
+	device_for_each_child_node(dev, child) {
+		if (is_acpi_device_node(child)) {
+			ret = acpi_get_local_address(ACPI_HANDLE_FWNODE(child),
+						     &values[i]);
+			if (ret) {
+				fwnode_handle_put(child);
+				return dev_err_probe(dev, ret,
+						     "Cannot get address\n");
+			}
+		} else {
+			fwnode_property_read_u32(child, "reg", &values[i]);
+		}
+
+		i++;
+	}
+	mux->data.values = values;
+
+	if (!device_property_read_u32(dev, "idle-state", &mux->data.idle))
+		mux->data.idle_in_use = true;
+
+	return 0;
+}
+
+static int i2c_mux_reg_probe(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc;
+	struct regmux *mux;
+	struct i2c_adapter *parent;
+	struct resource *res;
+	int i, ret, nr;
+
+	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return -ENOMEM;
+
+	if (dev_get_platdata(&pdev->dev)) {
+		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
+			sizeof(mux->data));
+	} else {
+		ret = i2c_mux_reg_probe_fw(mux, &pdev->dev);
+		if (ret < 0)
+			return dev_err_probe(&pdev->dev, ret,
+					     "Error parsing firmware description\n");
+	}
+
+	if (!mux->data.reg) {
+		mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+		if (IS_ERR(mux->data.reg))
+			return PTR_ERR(mux->data.reg);
+		mux->data.reg_size = resource_size(res);
+	}
+
+	if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
+	    mux->data.reg_size != 1) {
+		dev_err(&pdev->dev, "Invalid register size\n");
+		return -EINVAL;
+	}
+
+	parent = i2c_get_adapter(mux->data.parent);
+	if (!parent)
+		return -EPROBE_DEFER;
+
+	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
+			     i2c_mux_reg_select, NULL);
+	if (!muxc) {
+		ret = -ENOMEM;
+		goto err_put_parent;
+	}
+	muxc->priv = mux;
+
+	platform_set_drvdata(pdev, muxc);
+
+	if (mux->data.idle_in_use)
+		muxc->deselect = i2c_mux_reg_deselect;
+
+	for (i = 0; i < mux->data.n_values; i++) {
+		nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
+
+		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i]);
+		if (ret)
+			goto err_del_mux_adapters;
+	}
+
+	dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
+		 mux->data.n_values, muxc->parent->name);
+
+	return 0;
+
+err_del_mux_adapters:
+	i2c_mux_del_adapters(muxc);
+err_put_parent:
+	i2c_put_adapter(parent);
+
+	return ret;
+}
+
+static void i2c_mux_reg_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+}
+
+static const struct of_device_id i2c_mux_reg_of_match[] = {
+	{ .compatible = "i2c-mux-reg", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
+
+static struct platform_driver i2c_mux_reg_driver = {
+	.probe	= i2c_mux_reg_probe,
+	.remove = i2c_mux_reg_remove,
+	.driver	= {
+		.name	= "i2c-mux-reg",
+		.of_match_table = i2c_mux_reg_of_match,
+	},
+};
+
+module_platform_driver(i2c_mux_reg_driver);
+
+MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
+MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-mux-reg");