Merge branch '2020-10-28-mux-driver-framework'

- Add a framework for mux drivers

21 files changed, 1461 insertions, 1 deletions

diff --git a/Kconfig b/Kconfig
index 990353800f..c94b10e9fa 100644
--- a/Kconfig
+++ b/Kconfig
@@ -196,7 +196,7 @@ config SYS_MALLOC_F_LEN
 	hex "Size of malloc() pool before relocation"
 	depends on SYS_MALLOC_F
 	default 0x1000 if AM33XX
-	default 0x2800 if SANDBOX
+	default 0x4000 if SANDBOX
 	default 0x2000 if (ARCH_IMX8 || ARCH_IMX8M || ARCH_MX7 || \
 			   ARCH_MX7ULP || ARCH_MX6 || ARCH_MX5 || \
 			   ARCH_LS1012A || ARCH_LS1021A || ARCH_LS1043A || \
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index fa84b2c10f..70ccb4951a 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -3,6 +3,7 @@
 #include <dt-bindings/gpio/gpio.h>
 #include <dt-bindings/gpio/sandbox-gpio.h>
 #include <dt-bindings/pinctrl/sandbox-pinmux.h>
+#include <dt-bindings/mux/mux.h>
 
 / {
 	model = "sandbox";
@@ -133,6 +134,12 @@
 		interrupts-extended = <&irq 3 0>;
 		acpi,name = "GHIJ";
 		phandle-value = <&gpio_c 10>, <0xFFFFFFFF 20>, <&gpio_a 30>;
+
+		mux-controls = <&muxcontroller0 0>, <&muxcontroller0 1>,
+			       <&muxcontroller0 2>, <&muxcontroller0 3>,
+			       <&muxcontroller1>;
+		mux-control-names = "mux0", "mux1", "mux2", "mux3", "mux4";
+		mux-syscon = <&syscon3>;
 	};
 
 	junk {
@@ -170,6 +177,9 @@
 		compatible = "denx,u-boot-fdt-test";
 		ping-expect = <3>;
 		ping-add = <3>;
+
+		mux-controls = <&muxcontroller0 0>;
+		mux-control-names = "mux0";
 	};
 
 	phy_provider0: gen_phy@0 {
@@ -884,6 +894,29 @@
 			0x58 8>;
 	};
 
+	syscon3: syscon@3 {
+		compatible = "simple-mfd", "syscon";
+		reg = <0x000100 0x10>;
+
+		muxcontroller0: a-mux-controller {
+			compatible = "mmio-mux";
+			#mux-control-cells = <1>;
+
+			mux-reg-masks = <0x0 0x30>, /* 0: reg 0x0, bits 5:4 */
+					<0xc 0x1E>, /* 1: reg 0xc, bits 4:1 */
+					<0x4 0xFF>; /* 2: reg 0x4, bits 7:0 */
+			idle-states = <MUX_IDLE_AS_IS>, <0x02>, <0x73>;
+			u-boot,mux-autoprobe;
+		};
+	};
+
+	muxcontroller1: emul-mux-controller {
+		compatible = "mux-emul";
+		#mux-control-cells = <0>;
+		u-boot,mux-autoprobe;
+		idle-state = <0xabcd>;
+	};
+
 	timer@0 {
 		compatible = "sandbox,timer";
 		clock-frequency = <1000000>;
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 11f299da2b..58864f6448 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1081,6 +1081,12 @@ config CMD_MTD
 	help
 	  MTD commands support.
 
+config CMD_MUX
+	bool "mux"
+	depends on MULTIPLEXER
+	help
+	 List, select, and deselect mux controllers on the fly.
+
 config CMD_NAND
 	bool "nand"
 	default y if NAND_SUNXI
diff --git a/cmd/Makefile b/cmd/Makefile
index da4e0600b2..0cbee6c2f8 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -105,6 +105,7 @@ obj-$(CONFIG_CMD_CLONE) += clone.o
 ifneq ($(CONFIG_CMD_NAND)$(CONFIG_CMD_SF),)
 obj-y += legacy-mtd-utils.o
 endif
+obj-$(CONFIG_CMD_MUX) += mux.o
 obj-$(CONFIG_CMD_NAND) += nand.o
 obj-$(CONFIG_CMD_NET) += net.o
 obj-$(CONFIG_CMD_NVEDIT_EFI) += nvedit_efi.o
diff --git a/cmd/mux.c b/cmd/mux.c
new file mode 100644
index 0000000000..833266f08b
--- /dev/null
+++ b/cmd/mux.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * List, select, and deselect mux controllers on the fly.
+ *
+ * Copyright (c) 2020 Texas Instruments Inc.
+ * Author: Pratyush Yadav <p.yadav@ti.com>
+ */
+
+#include <common.h>
+#include <command.h>
+#include <errno.h>
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <mux.h>
+#include <mux-internal.h>
+#include <linux/err.h>
+#include <dt-bindings/mux/mux.h>
+
+#define COLUMN_SIZE 16
+
+/*
+ * Print a member of a column. The total size of the text printed, including
+ * trailing whitespace, will always be COLUMN_SIZE.
+ */
+#define PRINT_COLUMN(fmt, args...) do {					\
+	char buf[COLUMN_SIZE + 1];					\
+	snprintf(buf, COLUMN_SIZE + 1, fmt, ##args);			\
+	printf("%-*s", COLUMN_SIZE, buf);				\
+} while (0)
+
+/*
+ * Find a mux based on its device name in argv[1] and index in the chip in
+ * argv[2].
+ */
+static struct mux_control *cmd_mux_find(char *const argv[])
+{
+	struct udevice *dev;
+	struct mux_chip *chip;
+	int ret;
+	unsigned long id;
+
+	ret = strict_strtoul(argv[2], 10, &id);
+	if (ret)
+		return ERR_PTR(ret);
+
+	ret = uclass_get_device_by_name(UCLASS_MUX, argv[1], &dev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	chip = dev_get_uclass_priv(dev);
+	if (!chip)
+		return ERR_PTR(ret);
+
+	if (id >= chip->controllers)
+		return ERR_PTR(-EINVAL);
+
+	return &chip->mux[id];
+}
+
+/*
+ * Print the details of a mux. The columns printed correspond to: "Selected",
+ * "Current State", "Idle State", and "Num States".
+ */
+static void print_mux(struct mux_control *mux)
+{
+	PRINT_COLUMN("%s", mux->in_use ? "yes" : "no");
+
+	if (mux->cached_state == MUX_IDLE_AS_IS)
+		PRINT_COLUMN("%s", "unknown");
+	else
+		PRINT_COLUMN("0x%x", mux->cached_state);
+
+	if (mux->idle_state == MUX_IDLE_AS_IS)
+		PRINT_COLUMN("%s", "as-is");
+	else if (mux->idle_state == MUX_IDLE_DISCONNECT)
+		PRINT_COLUMN("%s", "disconnect");
+	else
+		PRINT_COLUMN("0x%x", mux->idle_state);
+
+	PRINT_COLUMN("0x%x", mux->states);
+
+	printf("\n");
+}
+
+static int do_mux_list(struct cmd_tbl *cmdtp, int flag, int argc,
+		       char *const argv[])
+{
+	struct udevice *dev;
+	struct mux_chip *chip;
+	int j;
+
+	for (uclass_first_device(UCLASS_MUX, &dev);
+	     dev;
+	     uclass_next_device(&dev)) {
+		chip = dev_get_uclass_priv(dev);
+		if (!chip) {
+			dev_err(dev, "can't find mux chip\n");
+			continue;
+		}
+
+		printf("%s:\n", dev->name);
+
+		printf("    ");
+		PRINT_COLUMN("ID");
+		PRINT_COLUMN("Selected");
+		PRINT_COLUMN("Current State");
+		PRINT_COLUMN("Idle State");
+		PRINT_COLUMN("Num States");
+		printf("\n");
+		for (j = 0; j < chip->controllers; j++) {
+			printf("    ");
+			PRINT_COLUMN("%d", j);
+			print_mux(&chip->mux[j]);
+		}
+		printf("\n");
+	}
+
+	return 0;
+}
+
+static int do_mux_select(struct cmd_tbl *cmdtp, int flag, int argc,
+			 char *const argv[])
+{
+	struct mux_control *mux;
+	int ret;
+	unsigned long state;
+
+	if (argc != 4)
+		return CMD_RET_USAGE;
+
+	mux = cmd_mux_find(argv);
+	if (IS_ERR_OR_NULL(mux)) {
+		printf("Failed to find the specified mux\n");
+		return CMD_RET_FAILURE;
+	}
+
+	ret = strict_strtoul(argv[3], 16, &state);
+	if (ret) {
+		printf("Invalid state\n");
+		return CMD_RET_FAILURE;
+	}
+
+	ret = mux_control_select(mux, state);
+	if (ret) {
+		printf("Failed to select requested state\n");
+		return CMD_RET_FAILURE;
+	}
+
+	return CMD_RET_SUCCESS;
+}
+
+static int do_mux_deselect(struct cmd_tbl *cmdtp, int flag, int argc,
+			   char *const argv[])
+{
+	struct mux_control *mux;
+	int ret;
+
+	if (argc != 3)
+		return CMD_RET_USAGE;
+
+	mux = cmd_mux_find(argv);
+	if (IS_ERR_OR_NULL(mux)) {
+		printf("Failed to find the specified mux\n");
+		return CMD_RET_FAILURE;
+	}
+
+	ret = mux_control_deselect(mux);
+	if (ret) {
+		printf("Failed to deselect mux\n");
+		return CMD_RET_FAILURE;
+	}
+
+	return CMD_RET_SUCCESS;
+}
+
+static char mux_help_text[] =
+	"list - List all Muxes and their states\n"
+	"select <chip> <id> <state> - Select the given mux state\n"
+	"deselect <chip> <id> - Deselect the given mux and reset it to its idle state";
+
+U_BOOT_CMD_WITH_SUBCMDS(mux, "List, select, and deselect muxes", mux_help_text,
+			U_BOOT_SUBCMD_MKENT(list, 1, 1, do_mux_list),
+			U_BOOT_SUBCMD_MKENT(select, 4, 0, do_mux_select),
+			U_BOOT_SUBCMD_MKENT(deselect, 3, 0, do_mux_deselect));
diff --git a/common/board_r.c b/common/board_r.c
index 9b2fec701a..b9217b2e27 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -46,6 +46,7 @@
 #include <miiphy.h>
 #endif
 #include <mmc.h>
+#include <mux.h>
 #include <nand.h>
 #include <of_live.h>
 #include <onenand_uboot.h>
@@ -341,6 +342,17 @@ static int initr_dm_devices(void)
 			return ret;
 	}
 
+	if (IS_ENABLED(CONFIG_MULTIPLEXER)) {
+		/*
+		 * Initialize the multiplexer controls to their default state.
+		 * This must be done early as other drivers may unknowingly
+		 * rely on it.
+		 */
+		ret = dm_mux_init();
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index b15b1889e0..3043208b4b 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -55,6 +55,7 @@ CONFIG_CMD_GPT_RENAME=y
 CONFIG_CMD_IDE=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_LSBLK=y
+CONFIG_CMD_MUX=y
 CONFIG_CMD_OSD=y
 CONFIG_CMD_PCI=y
 CONFIG_CMD_READ=y
@@ -179,6 +180,8 @@ CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_SST=y
 CONFIG_SPI_FLASH_WINBOND=y
+CONFIG_MULTIPLEXER=y
+CONFIG_MUX_MMIO=y
 CONFIG_DM_ETH=y
 CONFIG_NVME=y
 CONFIG_PCI=y
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 613669cb38..ed8a39c994 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -64,6 +64,8 @@ source "drivers/mmc/Kconfig"
 
 source "drivers/mtd/Kconfig"
 
+source "drivers/mux/Kconfig"
+
 source "drivers/net/Kconfig"
 
 source "drivers/nvme/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index 9eb51453e5..33f1d536cd 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_$(SPL_TPL_)INPUT) += input/
 obj-$(CONFIG_$(SPL_TPL_)LED) += led/
 obj-$(CONFIG_$(SPL_TPL_)MMC_SUPPORT) += mmc/
 obj-y += mtd/
+obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux/
 obj-$(CONFIG_$(SPL_TPL_)PCH_SUPPORT) += pch/
 obj-$(CONFIG_$(SPL_TPL_)PCI) += pci/
 obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
new file mode 100644
index 0000000000..f15ee4f833
--- /dev/null
+++ b/drivers/mux/Kconfig
@@ -0,0 +1,25 @@
+menu "Multiplexer drivers"
+
+config MULTIPLEXER
+	bool "Multiplexer Support"
+	depends on DM
+	help
+	 The mux framework is a minimalistic subsystem that handles multiplexer
+	 controllers. It provides the same API as Linux and mux drivers should
+	 be portable with a minimum effort.
+
+if MULTIPLEXER
+
+config MUX_MMIO
+	bool "MMIO register bitfield-controlled Multiplexer"
+	depends on MULTIPLEXER && SYSCON
+	help
+	  MMIO register bitfield-controlled Multiplexer controller.
+
+	  The driver builds multiplexer controllers for bitfields in a syscon
+	  register. For N bit wide bitfields, there will be 2^N possible
+	  multiplexer states.
+
+endif
+
+endmenu
diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
new file mode 100644
index 0000000000..78ebf04c7a
--- /dev/null
+++ b/drivers/mux/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# (C) Copyright 2019
+# Jean-Jacques Hiblot <jjhiblot@ti.com>
+
+obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
+obj-$(CONFIG_$(SPL_)MUX_MMIO) += mmio.o
diff --git a/drivers/mux/mmio.c b/drivers/mux/mmio.c
new file mode 100644
index 0000000000..b9868505a3
--- /dev/null
+++ b/drivers/mux/mmio.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MMIO register bitfield-controlled multiplexer driver
+ * Based on the linux mmio multiplexer driver
+ *
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
+ * Copyright (C) 2019 Texas Instrument, Jean-jacques Hiblot <jjhiblot@ti.com>
+ */
+#include <common.h>
+#include <dm.h>
+#include <mux-internal.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <dm/device.h>
+#include <dm/device_compat.h>
+#include <dm/read.h>
+#include <dm/devres.h>
+#include <dt-bindings/mux/mux.h>
+#include <linux/bitops.h>
+
+static int mux_mmio_set(struct mux_control *mux, int state)
+{
+	struct regmap_field **fields = dev_get_priv(mux->dev);
+
+	return regmap_field_write(fields[mux_control_get_index(mux)], state);
+}
+
+static const struct mux_control_ops mux_mmio_ops = {
+	.set = mux_mmio_set,
+};
+
+static const struct udevice_id mmio_mux_of_match[] = {
+	{ .compatible = "mmio-mux" },
+	{ /* sentinel */ },
+};
+
+static int mmio_mux_probe(struct udevice *dev)
+{
+	struct regmap_field **fields;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+	struct regmap *regmap;
+	u32 *mux_reg_masks;
+	u32 *idle_states;
+	int num_fields;
+	int ret;
+	int i;
+
+	regmap = syscon_node_to_regmap(dev_ofnode(dev->parent));
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(dev, "failed to get regmap: %d\n", ret);
+		return ret;
+	}
+
+	num_fields = dev_read_size(dev, "mux-reg-masks");
+	if (num_fields < 0)
+		return log_msg_ret("mux-reg-masks missing", -EINVAL);
+
+	num_fields /= sizeof(u32);
+	if (num_fields == 0 || num_fields % 2)
+		ret = -EINVAL;
+	num_fields = num_fields / 2;
+
+	ret = mux_alloc_controllers(dev, num_fields);
+	if (ret < 0)
+		return log_msg_ret("mux_alloc_controllers", ret);
+
+	fields = devm_kmalloc(dev, num_fields * sizeof(*fields), __GFP_ZERO);
+	if (!fields)
+		return -ENOMEM;
+	dev->priv = fields;
+
+	mux_reg_masks = devm_kmalloc(dev, num_fields * 2 * sizeof(u32),
+				     __GFP_ZERO);
+	if (!mux_reg_masks)
+		return -ENOMEM;
+
+	ret = dev_read_u32_array(dev, "mux-reg-masks", mux_reg_masks,
+				 num_fields * 2);
+	if (ret < 0)
+		return log_msg_ret("mux-reg-masks read", ret);
+
+	idle_states = devm_kmalloc(dev, num_fields * sizeof(u32), __GFP_ZERO);
+	if (!idle_states)
+		return -ENOMEM;
+
+	ret = dev_read_u32_array(dev, "idle-states", idle_states, num_fields);
+	if (ret < 0) {
+		log_err("idle-states");
+		devm_kfree(dev, idle_states);
+		idle_states = NULL;
+	}
+
+	for (i = 0; i < num_fields; i++) {
+		struct mux_control *mux = &mux_chip->mux[i];
+		struct reg_field field;
+		u32 reg, mask;
+		int bits;
+
+		reg = mux_reg_masks[2 * i];
+		mask = mux_reg_masks[2 * i + 1];
+
+		field.reg = reg;
+		field.msb = fls(mask) - 1;
+		field.lsb = ffs(mask) - 1;
+
+		if (mask != GENMASK(field.msb, field.lsb))
+			return log_msg_ret("invalid mask", -EINVAL);
+
+		fields[i] = devm_regmap_field_alloc(dev, regmap, field);
+		if (IS_ERR(fields[i])) {
+			ret = PTR_ERR(fields[i]);
+			return log_msg_ret("regmap_field_alloc", ret);
+		}
+
+		bits = 1 + field.msb - field.lsb;
+		mux->states = 1 << bits;
+
+		if (!idle_states)
+			continue;
+
+		if (idle_states[i] != MUX_IDLE_AS_IS &&
+		    idle_states[i] >= mux->states)
+			return log_msg_ret("idle-states range", -EINVAL);
+
+		mux->idle_state = idle_states[i];
+	}
+
+	devm_kfree(dev, mux_reg_masks);
+	if (idle_states)
+		devm_kfree(dev, idle_states);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(mmio_mux) = {
+	.name = "mmio-mux",
+	.id = UCLASS_MUX,
+	.of_match = mmio_mux_of_match,
+	.probe = mmio_mux_probe,
+	.ops = &mux_mmio_ops,
+};
diff --git a/drivers/mux/mux-uclass.c b/drivers/mux/mux-uclass.c
new file mode 100644
index 0000000000..a35c3d9c94
--- /dev/null
+++ b/drivers/mux/mux-uclass.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Multiplexer subsystem
+ *
+ * Based on the linux multiplexer framework
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mux-internal.h>
+#include <dm/device-internal.h>
+#include <dm/device_compat.h>
+#include <dm/devres.h>
+#include <dt-bindings/mux/mux.h>
+#include <linux/bug.h>
+
+/*
+ * The idle-as-is "state" is not an actual state that may be selected, it
+ * only implies that the state should not be changed. So, use that state
+ * as indication that the cached state of the multiplexer is unknown.
+ */
+#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
+
+/**
+ * mux_control_ops() - Get the mux_control ops.
+ * @dev: The client device.
+ *
+ * Return: A pointer to the 'mux_control_ops' of the device.
+ */
+static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
+{
+	return (const struct mux_control_ops *)dev->driver->ops;
+}
+
+/**
+ * mux_control_set() - Set the state of the given mux controller.
+ * @mux: A multiplexer control
+ * @state: The new requested state.
+ *
+ * Return: 0 if OK, or a negative error code.
+ */
+static int mux_control_set(struct mux_control *mux, int state)
+{
+	int ret = mux_dev_ops(mux->dev)->set(mux, state);
+
+	mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
+
+	return ret;
+}
+
+unsigned int mux_control_states(struct mux_control *mux)
+{
+	return mux->states;
+}
+
+/**
+ * __mux_control_select() - Select the given multiplexer state.
+ * @mux: The mux-control to request a change of state from.
+ * @state: The new requested state.
+ *
+ * Try to set the mux to the requested state. If not, try to revert if
+ * appropriate.
+ */
+static int __mux_control_select(struct mux_control *mux, int state)
+{
+	int ret;
+
+	if (WARN_ON(state < 0 || state >= mux->states))
+		return -EINVAL;
+
+	if (mux->cached_state == state)
+		return 0;
+
+	ret = mux_control_set(mux, state);
+	if (ret >= 0)
+		return 0;
+
+	/* The mux update failed, try to revert if appropriate... */
+	if (mux->idle_state != MUX_IDLE_AS_IS)
+		mux_control_set(mux, mux->idle_state);
+
+	return ret;
+}
+
+int mux_control_select(struct mux_control *mux, unsigned int state)
+{
+	int ret;
+
+	if (mux->in_use)
+		return -EBUSY;
+
+	ret = __mux_control_select(mux, state);
+
+	if (ret < 0)
+		return ret;
+
+	mux->in_use = true;
+
+	return 0;
+}
+
+int mux_control_deselect(struct mux_control *mux)
+{
+	int ret = 0;
+
+	if (mux->idle_state != MUX_IDLE_AS_IS &&
+	    mux->idle_state != mux->cached_state)
+		ret = mux_control_set(mux, mux->idle_state);
+
+	mux->in_use = false;
+
+	return ret;
+}
+
+static int mux_of_xlate_default(struct mux_chip *mux_chip,
+				struct ofnode_phandle_args *args,
+				struct mux_control **muxp)
+{
+	struct mux_control *mux;
+	int id;
+
+	log_debug("%s(muxp=%p)\n", __func__, muxp);
+
+	if (args->args_count > 1) {
+		debug("Invaild args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	if (args->args_count)
+		id = args->args[0];
+	else
+		id = 0;
+
+	if (id >= mux_chip->controllers) {
+		pr_err("bad mux controller %u specified in %s\n",
+			id, ofnode_get_name(args->node));
+		return -ERANGE;
+	}
+
+	mux = &mux_chip->mux[id];
+	mux->id = id;
+	*muxp = mux;
+	return 0;
+}
+
+/**
+ * mux_get_by_indexed_prop() - Get a mux control by integer index
+ * @dev: The client device.
+ * @prop_name: Name of the device tree property.
+ * @index: The index of the mux to get
+ * @mux: A pointer to the 'mux_control' struct to initialize.
+ *
+ * Return: 0 of OK, -errno otherwise.
+ */
+static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
+				   int index, struct mux_control **mux)
+{
+	int ret;
+	struct ofnode_phandle_args args;
+	struct udevice *dev_mux;
+	const struct mux_control_ops *ops;
+	struct mux_chip *mux_chip;
+
+	log_debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);
+
+	ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
+					 0, index, &args);
+	if (ret) {
+		debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
+	if (ret) {
+		debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	mux_chip = dev_get_uclass_priv(dev_mux);
+
+	ops = mux_dev_ops(dev_mux);
+	if (ops->of_xlate)
+		ret = ops->of_xlate(mux_chip, &args, mux);
+	else
+		ret = mux_of_xlate_default(mux_chip, &args, mux);
+	if (ret) {
+		debug("of_xlate() failed: %d\n", ret);
+		return ret;
+	}
+	(*mux)->dev = dev_mux;
+
+	return 0;
+}
+
+int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
+{
+	return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
+}
+
+int mux_control_get(struct udevice *dev, const char *name,
+		    struct mux_control **mux)
+{
+	int index;
+
+	debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);
+
+	index = dev_read_stringlist_search(dev, "mux-control-names", name);
+	if (index < 0) {
+		debug("fdt_stringlist_search() failed: %d\n", index);
+		return index;
+	}
+
+	return mux_get_by_index(dev, index, mux);
+}
+
+void mux_control_put(struct mux_control *mux)
+{
+	mux_control_deselect(mux);
+}
+
+/**
+ * devm_mux_control_release() - Release the given managed mux.
+ * @dev: The client device.
+ * @res: Pointer to the mux to be released.
+ *
+ * This function is called by devres to release the mux. It reverses the
+ * effects of mux_control_get().
+ */
+static void devm_mux_control_release(struct udevice *dev, void *res)
+{
+	mux_control_put(*(struct mux_control **)res);
+}
+
+struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
+{
+	int rc;
+	struct mux_control **mux;
+
+	mux = devres_alloc(devm_mux_control_release,
+			   sizeof(struct mux_control *), __GFP_ZERO);
+	if (unlikely(!mux))
+		return ERR_PTR(-ENOMEM);
+
+	rc = mux_control_get(dev, id, mux);
+	if (rc)
+		return ERR_PTR(rc);
+
+	devres_add(dev, mux);
+	return *mux;
+}
+
+int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
+{
+	int i;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+
+	mux_chip->mux = devm_kmalloc(dev,
+				     sizeof(struct mux_control) * controllers,
+				     __GFP_ZERO);
+	if (!mux_chip->mux)
+		return -ENOMEM;
+
+	mux_chip->controllers = controllers;
+
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		mux->dev = dev;
+		mux->cached_state = MUX_CACHE_UNKNOWN;
+		mux->idle_state = MUX_IDLE_AS_IS;
+		mux->in_use = false;
+		mux->id = i;
+	}
+
+	return 0;
+}
+
+static int mux_uclass_post_probe(struct udevice *dev)
+{
+	int i, ret;
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+
+	/* Set all mux controllers to their idle state. */
+	for (i = 0; i < mux_chip->controllers; ++i) {
+		struct mux_control *mux = &mux_chip->mux[i];
+
+		if (mux->idle_state == mux->cached_state)
+			continue;
+
+		ret = mux_control_set(mux, mux->idle_state);
+		if (ret < 0) {
+			dev_err(dev, "unable to set idle state\n");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+int dm_mux_init(void)
+{
+	struct uclass *uc;
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_get(UCLASS_MUX, &uc);
+	if (ret < 0) {
+		log_debug("unable to get MUX uclass\n");
+		return ret;
+	}
+	uclass_foreach_dev(dev, uc) {
+		if (dev_read_bool(dev, "u-boot,mux-autoprobe")) {
+			ret = device_probe(dev);
+			if (ret)
+				log_debug("unable to probe device %s\n",
+					  dev->name);
+		}
+	}
+
+	return 0;
+}
+
+UCLASS_DRIVER(mux) = {
+	.id		= UCLASS_MUX,
+	.name		= "mux",
+	.post_probe	= mux_uclass_post_probe,
+	.per_device_auto_alloc_size = sizeof(struct mux_chip),
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index 88f10c4622..17542de2f3 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -71,6 +71,7 @@ enum uclass_id {
 	UCLASS_MMC,		/* SD / MMC card or chip */
 	UCLASS_MOD_EXP,		/* RSA Mod Exp device */
 	UCLASS_MTD,		/* Memory Technology Device (MTD) device */
+	UCLASS_MUX,		/* Multiplexer device */
 	UCLASS_NOP,		/* No-op devices */
 	UCLASS_NORTHBRIDGE,	/* Intel Northbridge / SDRAM controller */
 	UCLASS_NVME,		/* NVM Express device */
diff --git a/include/dt-bindings/mux/mux.h b/include/dt-bindings/mux/mux.h
new file mode 100644
index 0000000000..042719218d
--- /dev/null
+++ b/include/dt-bindings/mux/mux.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This header provides constants for most Multiplexer bindings.
+ *
+ * Most Multiplexer bindings specify an idle state. In most cases, the
+ * the multiplexer can be left as is when idle, and in some cases it can
+ * disconnect the input/output and leave the multiplexer in a high
+ * impedance state.
+ */
+
+#ifndef _DT_BINDINGS_MUX_MUX_H
+#define _DT_BINDINGS_MUX_MUX_H
+
+#define MUX_IDLE_AS_IS      (-1)
+#define MUX_IDLE_DISCONNECT (-2)
+
+#endif
diff --git a/include/mux-internal.h b/include/mux-internal.h
new file mode 100644
index 0000000000..93e3a5cdd7
--- /dev/null
+++ b/include/mux-internal.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Based on the linux multiplexer framework
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#ifndef _MUX_INTERNAL_H
+#define _MUX_INTERNAL_H
+
+/* See mux.h for background documentation. */
+
+struct ofnode_phandle_args;
+
+/**
+ * struct mux_chip -	Represents a chip holding mux controllers.
+ * @controllers:	Number of mux controllers handled by the chip.
+ * @mux:		Array of mux controllers that are handled.
+ *
+ * This a per-device uclass-private data.
+ */
+struct mux_chip {
+	unsigned int controllers;
+	struct mux_control *mux;
+};
+
+/**
+ * struct mux_control_ops -	Mux controller operations for a mux chip.
+ * @set:			Set the state of the given mux controller.
+ */
+struct mux_control_ops {
+	/**
+	 * set - Apply a state to a multiplexer control
+	 *
+	 * @mux:	A multiplexer control
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*set)(struct mux_control *mux, int state);
+
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) multiplexer
+	 * specifier.
+	 *
+	 * If this function pointer is set to NULL, the multiplexer core will
+	 * use a default implementation, which assumes #mux-control-cells = <1>
+	 * and that the DT cell contains a simple integer channel ID.
+	 *
+	 * @dev_mux:	The multiplexer device. A single device may handle
+	 *              several multiplexer controls.
+	 * @args:	The multiplexer specifier values from device tree.
+	 * @muxp:	(out) A multiplexer control
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*of_xlate)(struct mux_chip *dev_mux,
+			struct ofnode_phandle_args *args,
+			struct mux_control **muxp);
+};
+
+/**
+ * struct mux_control -	Represents a mux controller.
+ * @in_use:		Whether the mux controller is in use or not.
+ * @dev:		The client device.
+ * @cached_state:	The current mux controller state, or -1 if none.
+ * @states:		The number of mux controller states.
+ * @idle_state:		The mux controller state to use when inactive, or one
+ *			of MUX_IDLE_AS_IS and MUX_IDLE_DISCONNECT.
+ * @id:			The index of the mux controller within the mux chip
+ *			it is a part of.
+ *
+ * Mux drivers may only change @states and @idle_state, and may only do so
+ * between allocation and registration of the mux controller. Specifically,
+ * @cached_state is internal to the mux core and should never be written by
+ * mux drivers.
+ */
+struct mux_control {
+	bool	in_use;
+	struct udevice *dev;
+	int cached_state;
+	unsigned int states;
+	int idle_state;
+	int id;
+};
+
+/**
+ * mux_control_get_index() - Get the index of the given mux controller
+ * @mux:		The mux-control to get the index for.
+ *
+ * Return: The index of the mux controller within the mux chip the mux
+ * controller is a part of.
+ */
+static inline unsigned int mux_control_get_index(struct mux_control *mux)
+{
+	return mux->id;
+}
+
+/**
+ * mux_alloc_controllers() - Allocate the given number of mux controllers.
+ * @dev:		The client device.
+ * controllers:		Number of controllers to allocate.
+ *
+ * Return: 0 of OK, -errno otherwise.
+ */
+int mux_alloc_controllers(struct udevice *dev, unsigned int controllers);
+
+#endif
diff --git a/include/mux.h b/include/mux.h
new file mode 100644
index 0000000000..23844f480a
--- /dev/null
+++ b/include/mux.h
@@ -0,0 +1,159 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Based on the linux multiplexer framework
+ *
+ * At its core, a multiplexer (or mux), also known as a data selector, is a
+ * device that selects between several analog or digital input signals and
+ * forwards it to a single output line. This notion can be extended to work
+ * with buses, like a I2C bus multiplexer for example.
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#ifndef _MUX_H_
+#define _MUX_H_
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct udevice;
+struct mux_control;
+
+#if CONFIG_IS_ENABLED(MULTIPLEXER)
+/**
+ * mux_control_states() - Query the number of multiplexer states.
+ * @mux: The mux-control to query.
+ *
+ * Return: The number of multiplexer states.
+ */
+unsigned int mux_control_states(struct mux_control *mux);
+
+/**
+ * mux_control_select() - Select the given multiplexer state.
+ * @mux: The mux-control to request a change of state from.
+ * @state: The new requested state.
+ *
+ * On successfully selecting the mux-control state, it will be locked until
+ * there is a call to mux_control_deselect(). If the mux-control is already
+ * selected when mux_control_select() is called, the function will indicate
+ * -EBUSY
+ *
+ * Therefore, make sure to call mux_control_deselect() when the operation is
+ * complete and the mux-control is free for others to use, but do not call
+ * mux_control_deselect() if mux_control_select() fails.
+ *
+ * Return: 0 when the mux-control state has the requested state or a negative
+ * errno on error.
+ */
+int __must_check mux_control_select(struct mux_control *mux,
+				    unsigned int state);
+#define mux_control_try_select(mux) mux_control_select(mux)
+
+/**
+ * mux_control_deselect() - Deselect the previously selected multiplexer state.
+ * @mux: The mux-control to deselect.
+ *
+ * It is required that a single call is made to mux_control_deselect() for
+ * each and every successful call made to either of mux_control_select() or
+ * mux_control_try_select().
+ *
+ * Return: 0 on success and a negative errno on error. An error can only
+ * occur if the mux has an idle state. Note that even if an error occurs, the
+ * mux-control is unlocked and is thus free for the next access.
+ */
+int mux_control_deselect(struct mux_control *mux);
+
+/**
+ * mux_get_by_index() = Get a mux by integer index.
+ * @dev: The client device.
+ * @index: The index of the mux to get.
+ * @mux: A pointer to the 'mux_control' struct to initialize.
+ *
+ * This looks up and initializes a mux. The index is relative to the client
+ * device.
+ *
+ * Return: 0 if OK, or a negative error code.
+ */
+int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux);
+
+/**
+ * mux_control_get() - Get the mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ * @mux: A pointer to the mux-control pointer.
+ *
+ * Return: 0 of OK, or a negative error code.
+ */
+int mux_control_get(struct udevice *dev, const char *name,
+		    struct mux_control **mux);
+
+/**
+ * mux_control_put() - Put away the mux-control for good.
+ * @mux: The mux-control to put away.
+ *
+ * mux_control_put() reverses the effects of mux_control_get().
+ */
+void mux_control_put(struct mux_control *mux);
+
+/**
+ * devm_mux_control_get() - Get the mux-control for a device, with resource
+ *			    management.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *devm_mux_control_get(struct udevice *dev,
+					 const char *mux_name);
+/**
+ * dm_mux_init() - Initialize the multiplexer controls to their default state.
+ *
+ * Return: 0 if OK, -errno otherwise.
+ */
+int dm_mux_init(void);
+
+#else
+unsigned int mux_control_states(struct mux_control *mux)
+{
+	return -ENOSYS;
+}
+
+int __must_check mux_control_select(struct mux_control *mux,
+				    unsigned int state)
+{
+	return -ENOSYS;
+}
+
+#define mux_control_try_select(mux) mux_control_select(mux)
+
+int mux_control_deselect(struct mux_control *mux)
+{
+	return -ENOSYS;
+}
+
+struct mux_control *mux_control_get(struct udevice *dev, const char *mux_name)
+{
+	return NULL;
+}
+
+void mux_control_put(struct mux_control *mux)
+{
+}
+
+struct mux_control *devm_mux_control_get(struct udevice *dev,
+					 const char *mux_name)
+{
+	return NULL;
+}
+
+int dm_mux_init(void)
+{
+	return -ENOSYS;
+}
+#endif
+
+#endif
diff --git a/test/dm/Makefile b/test/dm/Makefile
index e2b0798388..8b3d77e34e 100644
--- a/test/dm/Makefile
+++ b/test/dm/Makefile
@@ -34,6 +34,7 @@ obj-y += irq.o
 obj-$(CONFIG_LED) += led.o
 obj-$(CONFIG_DM_MAILBOX) += mailbox.o
 obj-$(CONFIG_DM_MMC) += mmc.o
+obj-$(CONFIG_CMD_MUX) += mux-cmd.o
 obj-y += fdtdec.o
 obj-y += ofnode.o
 obj-y += ofread.o
@@ -57,6 +58,8 @@ obj-$(CONFIG_DM_SPI_FLASH) += sf.o
 obj-$(CONFIG_SMEM) += smem.o
 obj-$(CONFIG_DM_SPI) += spi.o
 obj-y += syscon.o
+obj-$(CONFIG_MUX_MMIO) += mux-mmio.o
+obj-$(CONFIG_MULTIPLEXER) += mux-emul.o
 obj-$(CONFIG_DM_USB) += usb.o
 obj-$(CONFIG_DM_PMIC) += pmic.o
 obj-$(CONFIG_DM_REGULATOR) += regulator.o
diff --git a/test/dm/mux-cmd.c b/test/dm/mux-cmd.c
new file mode 100644
index 0000000000..11c237b5da
--- /dev/null
+++ b/test/dm/mux-cmd.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Texas Instruments Inc.
+ * Pratyush Yadav <p.yadav@ti.com>
+ */
+#include <common.h>
+#include <dm.h>
+#include <mux.h>
+#include <mux-internal.h>
+#include <dt-bindings/mux/mux.h>
+#include <asm/test.h>
+#include <dm/test.h>
+#include <test/ut.h>
+#include <console.h>
+#include <rand.h>
+
+#define BUF_SIZE		256
+
+/* Test 'mux list' */
+static int dm_test_cmd_mux_list(struct unit_test_state *uts)
+{
+	char str[BUF_SIZE], *tok;
+	struct udevice *dev;
+	struct mux_chip *chip;
+	struct mux_control *mux;
+	int i;
+	unsigned long val;
+
+	sandbox_set_enable_memio(true);
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_MUX, "a-mux-controller",
+					      &dev));
+	chip = dev_get_uclass_priv(dev);
+	ut_assertnonnull(chip);
+
+	run_command("mux list", 0);
+	ut_assert_nextline("a-mux-controller:");
+
+	/*
+	 * Check the table header to make sure we are not out of sync with the
+	 * code in the command. If we are, catch it early.
+	 */
+	console_record_readline(str, BUF_SIZE);
+	tok = strtok(str, " ");
+	ut_asserteq_str("ID", tok);
+
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("Selected", tok);
+
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("Current", tok);
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("State", tok);
+
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("Idle", tok);
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("State", tok);
+
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("Num", tok);
+	tok = strtok(NULL, " ");
+	ut_asserteq_str("States", tok);
+
+	for (i = 0; i < chip->controllers; i++) {
+		mux = &chip->mux[i];
+
+		console_record_readline(str, BUF_SIZE);
+
+		/*
+		 * Check if the ID printed matches with the ID of the chip we
+		 * have.
+		 */
+		tok = strtok(str, " ");
+		ut_assertok(strict_strtoul(tok, 10, &val));
+		ut_asserteq(i, val);
+
+		/* Check if mux selection state matches. */
+		tok = strtok(NULL, " ");
+		if (mux->in_use) {
+			ut_asserteq_str("yes", tok);
+		} else {
+			ut_asserteq_str("no", tok);
+		}
+
+		/* Check if the current state matches. */
+		tok = strtok(NULL, " ");
+		if (mux->cached_state == MUX_IDLE_AS_IS) {
+			ut_asserteq_str("unknown", tok);
+		} else {
+			ut_assertok(strict_strtoul(tok, 16, &val));
+			ut_asserteq(mux->cached_state, val);
+		}
+
+		/* Check if the idle state matches */
+		tok = strtok(NULL, " ");
+		if (mux->idle_state == MUX_IDLE_AS_IS) {
+			ut_asserteq_str("as-is", tok);
+		} else {
+			ut_assertok(strict_strtoul(tok, 16, &val));
+			ut_asserteq(mux->idle_state, val);
+		}
+
+		/* Check if the number of states matches */
+		tok = strtok(NULL, " ");
+		ut_assertok(strict_strtoul(tok, 16, &val));
+		ut_asserteq(mux->states, val);
+	}
+
+	return 0;
+}
+DM_TEST(dm_test_cmd_mux_list, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
+
+static int dm_test_cmd_mux_select(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	struct mux_chip *chip;
+	struct mux_control *mux;
+	char cmd[BUF_SIZE];
+	unsigned int i, state;
+
+	sandbox_set_enable_memio(true);
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_MUX, "a-mux-controller",
+					      &dev));
+	chip = dev_get_uclass_priv(dev);
+	ut_assertnonnull(chip);
+
+	srand(get_ticks() + rand());
+	for (i = 0; i < chip->controllers; i++) {
+		mux = &chip->mux[i];
+
+		state = rand() % mux->states;
+
+		snprintf(cmd, BUF_SIZE, "mux select a-mux-controller %x %x", i,
+			 state);
+		run_command(cmd, 0);
+		ut_asserteq(!!mux->in_use, true);
+		ut_asserteq(state, mux->cached_state);
+
+		ut_assertok(mux_control_deselect(mux));
+	}
+
+	return 0;
+}
+DM_TEST(dm_test_cmd_mux_select, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
+
+static int dm_test_cmd_mux_deselect(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	struct mux_chip *chip;
+	struct mux_control *mux;
+	char cmd[BUF_SIZE];
+	unsigned int i, state;
+
+	sandbox_set_enable_memio(true);
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_MUX, "a-mux-controller",
+					      &dev));
+	chip = dev_get_uclass_priv(dev);
+	ut_assertnonnull(chip);
+
+	srand(get_ticks() + rand());
+	for (i = 0; i < chip->controllers; i++) {
+		mux = &chip->mux[i];
+
+		state = rand() % mux->states;
+		ut_assertok(mux_control_select(mux, state));
+
+		snprintf(cmd, BUF_SIZE, "mux deselect a-mux-controller %d", i);
+		run_command(cmd, 0);
+		ut_asserteq(!!mux->in_use, false);
+	}
+
+	return 0;
+}
+DM_TEST(dm_test_cmd_mux_deselect, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
diff --git a/test/dm/mux-emul.c b/test/dm/mux-emul.c
new file mode 100644
index 0000000000..141fd4d908
--- /dev/null
+++ b/test/dm/mux-emul.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com/
+ * Pratyush Yadav <p.yadav@ti.com>
+ */
+#include <common.h>
+#include <dm.h>
+#include <mux.h>
+#include <mux-internal.h>
+#include <dm/test.h>
+#include <test/ut.h>
+
+struct mux_emul_priv {
+	u32 state;
+};
+
+static int mux_emul_set(struct mux_control *mux, int state)
+{
+	struct mux_emul_priv *priv = dev_get_priv(mux->dev);
+
+	priv->state = state;
+	return 0;
+}
+
+static int mux_emul_probe(struct udevice *dev)
+{
+	struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
+	struct mux_control *mux;
+	u32 idle_state;
+	int ret;
+
+	ret = mux_alloc_controllers(dev, 1);
+	if (ret < 0)
+		return ret;
+
+	mux = &mux_chip->mux[0];
+
+	ret = dev_read_u32(dev, "idle-state", &idle_state);
+	if (ret)
+		return ret;
+
+	mux->idle_state = idle_state;
+	mux->states = 0x100000;
+
+	return 0;
+}
+
+static const struct mux_control_ops mux_emul_ops = {
+	.set = mux_emul_set,
+};
+
+static const struct udevice_id mux_emul_of_match[] = {
+	{ .compatible = "mux-emul" },
+	{ /* sentinel */ },
+};
+
+U_BOOT_DRIVER(emul_mux) = {
+	.name = "mux-emul",
+	.id = UCLASS_MUX,
+	.of_match = mux_emul_of_match,
+	.ops = &mux_emul_ops,
+	.probe = mux_emul_probe,
+	.priv_auto_alloc_size = sizeof(struct mux_emul_priv),
+};
+
+static int dm_test_mux_emul_default_state(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	struct mux_control *mux;
+	struct mux_emul_priv *priv;
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "a-test",
+					      &dev));
+	ut_assertok(mux_control_get(dev, "mux4", &mux));
+
+	priv = dev_get_priv(mux->dev);
+
+	ut_asserteq(0xabcd, priv->state);
+
+	return 0;
+}
+DM_TEST(dm_test_mux_emul_default_state, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
+
+static int dm_test_mux_emul_select_deselect(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	struct mux_control *mux;
+	struct mux_emul_priv *priv;
+
+	gd->flags &= ~(GD_FLG_SILENT | GD_FLG_RECORD);
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "a-test",
+					      &dev));
+	ut_assertok(mux_control_get(dev, "mux4", &mux));
+
+	priv = dev_get_priv(mux->dev);
+
+	ut_assertok(mux_control_select(mux, 0x1234));
+	ut_asserteq(priv->state, 0x1234);
+
+	ut_assertok(mux_control_deselect(mux));
+	ut_asserteq(priv->state, 0xabcd);
+
+	return 0;
+}
+DM_TEST(dm_test_mux_emul_select_deselect, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
diff --git a/test/dm/mux-mmio.c b/test/dm/mux-mmio.c
new file mode 100644
index 0000000000..fd353d8b15
--- /dev/null
+++ b/test/dm/mux-mmio.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
+ * Jean-Jacques Hiblot <jjhiblot@ti.com>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mux.h>
+#include <regmap.h>
+#include <syscon.h>
+#include <asm/test.h>
+#include <dm/test.h>
+#include <dm/device-internal.h>
+#include <test/ut.h>
+
+static int dm_test_mux_mmio_select(struct unit_test_state *uts)
+{
+	struct udevice *dev, *dev_b;
+	struct regmap *map;
+	struct mux_control *ctl0_a, *ctl0_b;
+	struct mux_control *ctl1;
+	struct mux_control *ctl_err;
+	u32 val;
+	int i;
+
+	sandbox_set_enable_memio(true);
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "a-test",
+					      &dev));
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "b-test",
+					      &dev_b));
+	map = syscon_regmap_lookup_by_phandle(dev, "mux-syscon");
+	ut_assertok_ptr(map);
+	ut_assert(map);
+
+	ut_assertok(mux_control_get(dev, "mux0", &ctl0_a));
+	ut_assertok(mux_control_get(dev, "mux1", &ctl1));
+	ut_asserteq(-ERANGE, mux_control_get(dev, "mux3", &ctl_err));
+	ut_asserteq(-ENODATA, mux_control_get(dev, "dummy", &ctl_err));
+	ut_assertok(mux_control_get(dev_b, "mux0", &ctl0_b));
+
+	for (i = 0; i < mux_control_states(ctl0_a); i++) {
+		/* Select a new state and verify the value in the regmap. */
+		ut_assertok(mux_control_select(ctl0_a, i));
+		ut_assertok(regmap_read(map, 0, &val));
+		ut_asserteq(i, (val & 0x30) >> 4);
+		/*
+		 * Deselect the mux and verify that the value in the regmap
+		 * reflects the idle state (fixed to MUX_IDLE_AS_IS).
+		 */
+		ut_assertok(mux_control_deselect(ctl0_a));
+		ut_assertok(regmap_read(map, 0, &val));
+		ut_asserteq(i, (val & 0x30) >> 4);
+	}
+
+	for (i = 0; i < mux_control_states(ctl1); i++) {
+		/* Select a new state and verify the value in the regmap. */
+		ut_assertok(mux_control_select(ctl1, i));
+		ut_assertok(regmap_read(map, 0xc, &val));
+		ut_asserteq(i, (val & 0x1E) >> 1);
+		/*
+		 * Deselect the mux and verify that the value in the regmap
+		 * reflects the idle state (fixed to 2).
+		 */
+		ut_assertok(mux_control_deselect(ctl1));
+		ut_assertok(regmap_read(map, 0xc, &val));
+		ut_asserteq(2, (val & 0x1E) >> 1);
+	}
+
+	/* Try unbalanced selection/deselection. */
+	ut_assertok(mux_control_select(ctl0_a, 0));
+	ut_asserteq(-EBUSY, mux_control_select(ctl0_a, 1));
+	ut_asserteq(-EBUSY, mux_control_select(ctl0_a, 0));
+	ut_assertok(mux_control_deselect(ctl0_a));
+
+	/* Try concurrent selection. */
+	ut_assertok(mux_control_select(ctl0_a, 0));
+	ut_assert(mux_control_select(ctl0_b, 0));
+	ut_assertok(mux_control_deselect(ctl0_a));
+	ut_assertok(mux_control_select(ctl0_b, 0));
+	ut_assert(mux_control_select(ctl0_a, 0));
+	ut_assertok(mux_control_deselect(ctl0_b));
+	ut_assertok(mux_control_select(ctl0_a, 0));
+	ut_assertok(mux_control_deselect(ctl0_a));
+
+	return 0;
+}
+DM_TEST(dm_test_mux_mmio_select, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
+
+/* Test that managed API for mux work correctly */
+static int dm_test_devm_mux_mmio(struct unit_test_state *uts)
+{
+	struct udevice *dev, *dev_b;
+	struct mux_control *ctl0_a, *ctl0_b;
+	struct mux_control *ctl1;
+	struct mux_control *ctl_err;
+
+	sandbox_set_enable_memio(true);
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "a-test",
+					      &dev));
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "b-test",
+					      &dev_b));
+
+	ctl0_a = devm_mux_control_get(dev, "mux0");
+	ut_assertok_ptr(ctl0_a);
+	ut_assert(ctl0_a);
+	ctl1 = devm_mux_control_get(dev, "mux1");
+	ut_assertok_ptr(ctl1);
+	ut_assert(ctl1);
+	ctl_err = devm_mux_control_get(dev, "mux3");
+	ut_asserteq(-ERANGE, PTR_ERR(ctl_err));
+	ctl_err = devm_mux_control_get(dev, "dummy");
+	ut_asserteq(-ENODATA, PTR_ERR(ctl_err));
+
+	ctl0_b = devm_mux_control_get(dev_b, "mux0");
+	ut_assertok_ptr(ctl0_b);
+	ut_assert(ctl0_b);
+
+	/* Try concurrent selection. */
+	ut_assertok(mux_control_select(ctl0_a, 0));
+	ut_assert(mux_control_select(ctl0_b, 0));
+	ut_assertok(mux_control_deselect(ctl0_a));
+	ut_assertok(mux_control_select(ctl0_b, 0));
+	ut_assert(mux_control_select(ctl0_a, 0));
+	ut_assertok(mux_control_deselect(ctl0_b));
+
+	/* Remove one device and check that the mux is released. */
+	ut_assertok(mux_control_select(ctl0_a, 0));
+	ut_assert(mux_control_select(ctl0_b, 0));
+	device_remove(dev, DM_REMOVE_NORMAL);
+	ut_assertok(mux_control_select(ctl0_b, 0));
+
+	device_remove(dev_b, DM_REMOVE_NORMAL);
+	return 0;
+}
+DM_TEST(dm_test_devm_mux_mmio, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);