diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 6a3fd2d75f96..c2183eb0775f 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2170,6 +2170,14 @@ config SGI_MFD_IOC3
 	  If you have an SGI Origin, Octane, or a PCI IOC3 card,
 	  then say Y. Otherwise say N.
 
+config MFD_IEI_WT61P803_PUZZLE
+	tristate "IEI WT61P803 PUZZLE MCU driver"
+	depends on SERIAL_DEV_BUS
+	help
+	  IEI WT61P803 PUZZLE is a system power management microcontroller
+	  used for fan control, temperature sensor reading, LED control
+	  and system identification.
+
 config MFD_INTEL_M10_BMC
 	tristate "Intel MAX 10 Board Management Controller"
 	depends on SPI_MASTER
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 8116c19d5fd4..42b9767ec37a 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -236,6 +236,7 @@ obj-$(CONFIG_MFD_DLN2)		+= dln2.o
 obj-$(CONFIG_MFD_RT4831)	+= rt4831.o
 obj-$(CONFIG_MFD_RT5033)	+= rt5033.o
 obj-$(CONFIG_MFD_SKY81452)	+= sky81452.o
+obj-$(CONFIG_MFD_IEI_WT61P803_PUZZLE)	+= iei-wt61p803-puzzle.o
 
 intel-soc-pmic-objs		:= intel_soc_pmic_core.o intel_soc_pmic_crc.o
 obj-$(CONFIG_INTEL_SOC_PMIC)	+= intel-soc-pmic.o
diff --git a/drivers/mfd/iei-wt61p803-puzzle.c b/drivers/mfd/iei-wt61p803-puzzle.c
new file mode 100644
index 000000000000..596ecbc65627
--- /dev/null
+++ b/drivers/mfd/iei-wt61p803-puzzle.c
@@ -0,0 +1,908 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* IEI WT61P803 PUZZLE MCU Driver
+ * System management microcontroller for fan control, temperature sensor reading,
+ * LED control and system identification on IEI Puzzle series ARM-based appliances.
+ *
+ * Copyright (C) 2020 Sartura Ltd.
+ * Author: Luka Kovacic <luka.kovacic@sartura.hr>
+ */
+
+#include <linux/atomic.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/iei-wt61p803-puzzle.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/property.h>
+#include <linux/sched.h>
+#include <linux/serdev.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <asm/unaligned.h>
+
+/* start, payload and XOR checksum at end */
+#define IEI_WT61P803_PUZZLE_MAX_COMMAND_LENGTH	(1 + 20 + 1)
+#define IEI_WT61P803_PUZZLE_RESP_BUF_SIZE	512
+
+#define IEI_WT61P803_PUZZLE_MAC_LENGTH			17
+#define IEI_WT61P803_PUZZLE_SN_LENGTH			36
+#define IEI_WT61P803_PUZZLE_VERSION_LENGTH		 6
+#define IEI_WT61P803_PUZZLE_BUILD_INFO_LENGTH		16
+#define IEI_WT61P803_PUZZLE_PROTOCOL_VERSION_LENGTH	 8
+#define IEI_WT61P803_PUZZLE_NB_MAC			 8
+
+/* Use HZ as a timeout value throughout the driver */
+#define IEI_WT61P803_PUZZLE_GENERAL_TIMEOUT HZ
+
+enum iei_wt61p803_puzzle_attribute_type {
+	IEI_WT61P803_PUZZLE_VERSION,
+	IEI_WT61P803_PUZZLE_BUILD_INFO,
+	IEI_WT61P803_PUZZLE_BOOTLOADER_MODE,
+	IEI_WT61P803_PUZZLE_PROTOCOL_VERSION,
+	IEI_WT61P803_PUZZLE_SERIAL_NUMBER,
+	IEI_WT61P803_PUZZLE_MAC_ADDRESS,
+	IEI_WT61P803_PUZZLE_AC_RECOVERY_STATUS,
+	IEI_WT61P803_PUZZLE_POWER_LOSS_RECOVERY,
+	IEI_WT61P803_PUZZLE_POWER_STATUS,
+};
+
+struct iei_wt61p803_puzzle_device_attribute {
+	struct device_attribute dev_attr;
+	enum iei_wt61p803_puzzle_attribute_type type;
+	u8 index;
+};
+
+/**
+ * struct iei_wt61p803_puzzle_mcu_status - MCU flags state
+ * @ac_recovery_status_flag:	AC Recovery Status Flag
+ * @power_loss_recovery:	System recovery after power loss
+ * @power_status:		System Power-on Method
+ */
+struct iei_wt61p803_puzzle_mcu_status {
+	u8 ac_recovery_status_flag;
+	u8 power_loss_recovery;
+	u8 power_status;
+};
+
+/**
+ * struct iei_wt61p803_puzzle_reply - MCU reply
+ * @size:	Size of the MCU reply
+ * @data:	Full MCU reply buffer
+ * @state:	Current state of the packet
+ * @received:	Was the response fullfilled
+ */
+struct iei_wt61p803_puzzle_reply {
+	size_t size;
+	unsigned char data[IEI_WT61P803_PUZZLE_RESP_BUF_SIZE];
+	struct completion received;
+};
+
+/**
+ * struct iei_wt61p803_puzzle_mcu_version - MCU version status
+ * @version:		Primary firmware version
+ * @build_info:		Build date and time
+ * @bootloader_mode:	Status of the MCU operation
+ * @protocol_version:	MCU communication protocol version
+ * @serial_number:	Device factory serial number
+ * @mac_address:	Device factory MAC addresses
+ *
+ * Last element of arrays is reserved for '\0'.
+ */
+struct iei_wt61p803_puzzle_mcu_version {
+	char version[IEI_WT61P803_PUZZLE_VERSION_LENGTH + 1];
+	char build_info[IEI_WT61P803_PUZZLE_BUILD_INFO_LENGTH + 1];
+	bool bootloader_mode;
+	char protocol_version[IEI_WT61P803_PUZZLE_PROTOCOL_VERSION_LENGTH + 1];
+	char serial_number[IEI_WT61P803_PUZZLE_SN_LENGTH + 1];
+	char mac_address[IEI_WT61P803_PUZZLE_NB_MAC][IEI_WT61P803_PUZZLE_MAC_LENGTH + 1];
+};
+
+/**
+ * struct iei_wt61p803_puzzle - IEI WT61P803 PUZZLE MCU Driver
+ * @serdev:		Pointer to underlying serdev device
+ * @dev:		Pointer to underlying dev device
+ * @reply_lock:		Reply mutex lock
+ * @reply:		Pointer to the iei_wt61p803_puzzle_reply struct
+ * @version:		MCU version related data
+ * @status:		MCU status related data
+ * @response_buffer	Command response buffer allocation
+ * @lock		General member mutex lock
+ */
+struct iei_wt61p803_puzzle {
+	struct serdev_device *serdev;
+	struct device *dev;
+	struct mutex reply_lock; /* lock to prevent multiple firmware calls */
+	struct iei_wt61p803_puzzle_reply *reply;
+	struct iei_wt61p803_puzzle_mcu_version version;
+	struct iei_wt61p803_puzzle_mcu_status status;
+	unsigned char response_buffer[IEI_WT61P803_PUZZLE_BUF_SIZE];
+	struct mutex lock; /* lock to protect response buffer */
+};
+
+static unsigned char iei_wt61p803_puzzle_checksum(unsigned char *buf, size_t len)
+{
+	unsigned char checksum = 0;
+	size_t i;
+
+	for (i = 0; i < len; i++)
+		checksum ^= buf[i];
+	return checksum;
+}
+
+static int iei_wt61p803_puzzle_process_resp(struct iei_wt61p803_puzzle *mcu,
+					    const unsigned char *raw_resp_data, size_t size)
+{
+	unsigned char checksum;
+
+	/* Check the incoming frame header */
+	if (!(raw_resp_data[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_START ||
+	      raw_resp_data[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_START_OTHER ||
+	     (raw_resp_data[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM &&
+	      raw_resp_data[1] == IEI_WT61P803_PUZZLE_CMD_EEPROM_READ))) {
+		if (mcu->reply->size + size >= sizeof(mcu->reply->data))
+			return -EIO;
+
+		/* Append the frame to existing data */
+		memcpy(mcu->reply->data + mcu->reply->size, raw_resp_data, size);
+		mcu->reply->size += size;
+	} else {
+		if (size >= sizeof(mcu->reply->data))
+			return -EIO;
+
+		/* Start processing a new frame */
+		memcpy(mcu->reply->data, raw_resp_data, size);
+		mcu->reply->size = size;
+	}
+
+	checksum = iei_wt61p803_puzzle_checksum(mcu->reply->data, mcu->reply->size - 1);
+	if (checksum != mcu->reply->data[mcu->reply->size - 1]) {
+		/* The checksum isn't matched yet, wait for new frames */
+		return size;
+	}
+
+	/* Received all the data */
+	complete(&mcu->reply->received);
+
+	return size;
+}
+
+static int iei_wt61p803_puzzle_recv_buf(struct serdev_device *serdev,
+					const unsigned char *data, size_t size)
+{
+	struct iei_wt61p803_puzzle *mcu = serdev_device_get_drvdata(serdev);
+	int ret;
+
+	ret = iei_wt61p803_puzzle_process_resp(mcu, data, size);
+	/* Return the number of processed bytes if function returns error,
+	 * discard the remaining incoming data, since the frame this data
+	 * belongs to is broken anyway
+	 */
+	if (ret < 0)
+		return size;
+
+	return ret;
+}
+
+static const struct serdev_device_ops iei_wt61p803_puzzle_serdev_device_ops = {
+	.receive_buf  = iei_wt61p803_puzzle_recv_buf,
+	.write_wakeup = serdev_device_write_wakeup,
+};
+
+/**
+ * iei_wt61p803_puzzle_write_command_watchdog() - Watchdog of the normal cmd
+ * @mcu: Pointer to the iei_wt61p803_puzzle core MFD struct
+ * @cmd: Pointer to the char array to send (size should be content + 1 (xor))
+ * @size: Size of the cmd char array
+ * @reply_data: Pointer to the reply/response data array (should be allocated)
+ * @reply_size: Pointer to size_t (size of reply_data)
+ * @retry_count: Number of times to retry sending the command to the MCU
+ */
+int iei_wt61p803_puzzle_write_command_watchdog(struct iei_wt61p803_puzzle *mcu,
+					       unsigned char *cmd, size_t size,
+					       unsigned char *reply_data,
+					       size_t *reply_size, int retry_count)
+{
+	struct device *dev = &mcu->serdev->dev;
+	int ret, i;
+
+	for (i = 0; i < retry_count; i++) {
+		ret = iei_wt61p803_puzzle_write_command(mcu, cmd, size,
+							reply_data, reply_size);
+		if (ret != -ETIMEDOUT)
+			return ret;
+	}
+
+	dev_err(dev, "Command response timed out. Retries: %d\n", retry_count);
+
+	return -ETIMEDOUT;
+}
+EXPORT_SYMBOL_GPL(iei_wt61p803_puzzle_write_command_watchdog);
+
+/**
+ * iei_wt61p803_puzzle_write_command() - Send a structured command to the MCU
+ * @mcu: Pointer to the iei_wt61p803_puzzle core MFD struct
+ * @cmd: Pointer to the char array to send (size should be content + 1 (xor))
+ * @size: Size of the cmd char array
+ * @reply_data: Pointer to the reply/response data array (should be allocated)
+ *
+ * Sends a structured command to the MCU.
+ */
+int iei_wt61p803_puzzle_write_command(struct iei_wt61p803_puzzle *mcu,
+				      unsigned char *cmd, size_t size,
+				      unsigned char *reply_data,
+				      size_t *reply_size)
+{
+	struct device *dev = &mcu->serdev->dev;
+	int ret;
+
+	if (size <= 1 || size > IEI_WT61P803_PUZZLE_MAX_COMMAND_LENGTH)
+		return -EINVAL;
+
+	mutex_lock(&mcu->reply_lock);
+
+	cmd[size - 1] = iei_wt61p803_puzzle_checksum(cmd, size - 1);
+
+	/* Initialize reply struct */
+	reinit_completion(&mcu->reply->received);
+	mcu->reply->size = 0;
+	usleep_range(2000, 10000);
+	serdev_device_write_flush(mcu->serdev);
+	ret = serdev_device_write_buf(mcu->serdev, cmd, size);
+	if (ret < 0)
+		goto exit;
+
+	serdev_device_wait_until_sent(mcu->serdev, IEI_WT61P803_PUZZLE_GENERAL_TIMEOUT);
+	ret = wait_for_completion_timeout(&mcu->reply->received,
+					  IEI_WT61P803_PUZZLE_GENERAL_TIMEOUT);
+	if (ret == 0) {
+		dev_err(dev, "Command reply receive timeout\n");
+		ret = -ETIMEDOUT;
+		goto exit;
+	}
+
+	*reply_size = mcu->reply->size;
+	/* Copy the received data, as it will not be available after a new frame is received */
+	memcpy(reply_data, mcu->reply->data, mcu->reply->size);
+	ret = 0;
+exit:
+	mutex_unlock(&mcu->reply_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iei_wt61p803_puzzle_write_command);
+
+static int iei_wt61p803_puzzle_buzzer(struct iei_wt61p803_puzzle *mcu, bool long_beep)
+{
+	unsigned char *resp_buf = mcu->response_buffer;
+	unsigned char buzzer_cmd[4] = {};
+	size_t reply_size;
+	int ret;
+
+	buzzer_cmd[0] = IEI_WT61P803_PUZZLE_CMD_HEADER_START;
+	buzzer_cmd[1] = IEI_WT61P803_PUZZLE_CMD_FUNCTION_SINGLE;
+	buzzer_cmd[2] = long_beep ? '3' : '2'; /* Buzzer 1.5 / 0.5 second beep */
+
+	mutex_lock(&mcu->lock);
+	ret = iei_wt61p803_puzzle_write_command(mcu, buzzer_cmd, sizeof(buzzer_cmd),
+						resp_buf, &reply_size);
+	if (ret)
+		goto exit;
+
+	if (reply_size != 3) {
+		ret = -EIO;
+		goto exit;
+	}
+
+	if (!(resp_buf[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_START &&
+	      resp_buf[1] == IEI_WT61P803_PUZZLE_CMD_RESPONSE_OK &&
+	      resp_buf[2] == IEI_WT61P803_PUZZLE_CHECKSUM_RESPONSE_OK)) {
+		ret = -EPROTO;
+		goto exit;
+	}
+exit:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_get_version(struct iei_wt61p803_puzzle *mcu)
+{
+	unsigned char version_cmd[3] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_START_OTHER,
+		IEI_WT61P803_PUZZLE_CMD_OTHER_VERSION,
+	};
+	unsigned char build_info_cmd[3] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_START_OTHER,
+		IEI_WT61P803_PUZZLE_CMD_OTHER_BUILD,
+	};
+	unsigned char bootloader_mode_cmd[3] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_START_OTHER,
+		IEI_WT61P803_PUZZLE_CMD_OTHER_BOOTLOADER_MODE,
+	};
+	unsigned char protocol_version_cmd[3] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_START_OTHER,
+		IEI_WT61P803_PUZZLE_CMD_OTHER_PROTOCOL_VERSION,
+	};
+	unsigned char *rb = mcu->response_buffer;
+	size_t reply_size;
+	int ret;
+
+	mutex_lock(&mcu->lock);
+
+	ret = iei_wt61p803_puzzle_write_command(mcu, version_cmd, sizeof(version_cmd),
+						rb, &reply_size);
+	if (ret)
+		goto err;
+	if (reply_size < 7) {
+		ret = -EIO;
+		goto err;
+	}
+	sprintf(mcu->version.version, "v%c.%.3s", rb[2], &rb[3]);
+
+	ret = iei_wt61p803_puzzle_write_command(mcu, build_info_cmd,
+						sizeof(build_info_cmd),	rb,
+						&reply_size);
+	if (ret)
+		goto err;
+	if (reply_size < 15) {
+		ret = -EIO;
+		goto err;
+	}
+	sprintf(mcu->version.build_info, "%c%c/%c%c/%.4s %c%c:%c%c",
+		rb[8], rb[9], rb[6], rb[7], &rb[2], rb[10], rb[11],
+		rb[12], rb[13]);
+
+	ret = iei_wt61p803_puzzle_write_command(mcu, bootloader_mode_cmd,
+						sizeof(bootloader_mode_cmd), rb,
+						&reply_size);
+	if (ret)
+		goto err;
+	if (reply_size < 4) {
+		ret = -EIO;
+		goto err;
+	}
+	if (rb[2] == IEI_WT61P803_PUZZLE_CMD_OTHER_MODE_APPS)
+		mcu->version.bootloader_mode = false;
+	else if (rb[2] == IEI_WT61P803_PUZZLE_CMD_OTHER_MODE_BOOTLOADER)
+		mcu->version.bootloader_mode = true;
+
+	ret = iei_wt61p803_puzzle_write_command(mcu, protocol_version_cmd,
+						sizeof(protocol_version_cmd), rb,
+						&reply_size);
+	if (ret)
+		goto err;
+	if (reply_size < 9) {
+		ret = -EIO;
+		goto err;
+	}
+	sprintf(mcu->version.protocol_version, "v%c.%c%c%c%c%c",
+		rb[7], rb[6], rb[5], rb[4], rb[3], rb[2]);
+err:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_get_mcu_status(struct iei_wt61p803_puzzle *mcu)
+{
+	unsigned char mcu_status_cmd[5] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_START,
+		IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER,
+		IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_STATUS,
+		IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_STATUS,
+	};
+	unsigned char *resp_buf = mcu->response_buffer;
+	size_t reply_size;
+	int ret;
+
+	mutex_lock(&mcu->lock);
+	ret = iei_wt61p803_puzzle_write_command(mcu, mcu_status_cmd, sizeof(mcu_status_cmd),
+						resp_buf, &reply_size);
+	if (ret)
+		goto exit;
+	if (reply_size < 20) {
+		ret = -EIO;
+		goto exit;
+	}
+
+	/* Response format:
+	 * (IDX	RESPONSE)
+	 * 0	@
+	 * 1	O
+	 * 2	S
+	 * 3	S
+	 * ...
+	 * 5	AC Recovery Status Flag
+	 * ...
+	 * 10	Power Loss Recovery
+	 * ...
+	 * 19	Power Status (system power on method)
+	 * 20	XOR checksum
+	 */
+	if (resp_buf[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_START &&
+	    resp_buf[1] == IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER &&
+	    resp_buf[2] == IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_STATUS &&
+	    resp_buf[3] == IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_STATUS) {
+		mcu->status.ac_recovery_status_flag = resp_buf[5];
+		mcu->status.power_loss_recovery = resp_buf[10];
+		mcu->status.power_status = resp_buf[19];
+	}
+exit:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_get_serial_number(struct iei_wt61p803_puzzle *mcu)
+{
+	unsigned char *resp_buf = mcu->response_buffer;
+	unsigned char serial_number_cmd[5] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
+		IEI_WT61P803_PUZZLE_CMD_EEPROM_READ,
+		0x00,	/* EEPROM read address */
+		0x24,	/* Data length */
+	};
+	size_t reply_size;
+	int ret;
+
+	mutex_lock(&mcu->lock);
+	ret = iei_wt61p803_puzzle_write_command(mcu, serial_number_cmd,
+						sizeof(serial_number_cmd),
+						resp_buf, &reply_size);
+	if (ret)
+		goto err;
+
+	if (reply_size < IEI_WT61P803_PUZZLE_SN_LENGTH + 4) {
+		ret = -EIO;
+		goto err;
+	}
+
+	sprintf(mcu->version.serial_number, "%.*s",
+		IEI_WT61P803_PUZZLE_SN_LENGTH, resp_buf + 4);
+err:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_write_serial_number(struct iei_wt61p803_puzzle *mcu,
+						   unsigned char serial_number[36])
+{
+	unsigned char *resp_buf = mcu->response_buffer;
+	unsigned char serial_number_header[4] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
+		IEI_WT61P803_PUZZLE_CMD_EEPROM_WRITE,
+		0x00,	/* EEPROM write address */
+		0xC,	/* Data length */
+	};
+	unsigned char serial_number_cmd[4 + 12 + 1]; /* header, serial number, XOR checksum */
+	int ret, sn_counter;
+	size_t reply_size;
+
+	/* The MCU can only handle 22 byte messages, send the S/N in 12 byte chunks */
+	mutex_lock(&mcu->lock);
+	for (sn_counter = 0; sn_counter < 3; sn_counter++) {
+		serial_number_header[2] = 0x0 + 0xC * sn_counter;
+
+		memcpy(serial_number_cmd, serial_number_header, sizeof(serial_number_header));
+		memcpy(serial_number_cmd + sizeof(serial_number_header),
+		       serial_number + 0xC * sn_counter, 0xC);
+
+		ret = iei_wt61p803_puzzle_write_command(mcu, serial_number_cmd,
+							sizeof(serial_number_cmd),
+							resp_buf, &reply_size);
+		if (ret)
+			goto err;
+		if (reply_size != 3) {
+			ret = -EIO;
+			goto err;
+		}
+		if (!(resp_buf[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_START &&
+		      resp_buf[1] == IEI_WT61P803_PUZZLE_CMD_RESPONSE_OK &&
+		      resp_buf[2] == IEI_WT61P803_PUZZLE_CHECKSUM_RESPONSE_OK)) {
+			ret = -EPROTO;
+			goto err;
+		}
+	}
+
+	sprintf(mcu->version.serial_number, "%.*s",
+		IEI_WT61P803_PUZZLE_SN_LENGTH, serial_number);
+err:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_get_mac_address(struct iei_wt61p803_puzzle *mcu, int index)
+{
+	unsigned char *resp_buf = mcu->response_buffer;
+	unsigned char mac_address_cmd[5] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
+		IEI_WT61P803_PUZZLE_CMD_EEPROM_READ,
+		0x00,	/* EEPROM read address */
+		0x11,	/* Data length */
+	};
+	size_t reply_size;
+	int ret;
+
+	mutex_lock(&mcu->lock);
+	mac_address_cmd[2] = 0x24 + 0x11 * index;
+
+	ret = iei_wt61p803_puzzle_write_command(mcu, mac_address_cmd,
+						sizeof(mac_address_cmd),
+						resp_buf, &reply_size);
+	if (ret)
+		goto err;
+
+	if (reply_size < 22) {
+		ret = -EIO;
+		goto err;
+	}
+
+	sprintf(mcu->version.mac_address[index], "%.*s",
+		IEI_WT61P803_PUZZLE_MAC_LENGTH, resp_buf + 4);
+err:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int
+iei_wt61p803_puzzle_write_mac_address(struct iei_wt61p803_puzzle *mcu,
+				      unsigned char mac_address[IEI_WT61P803_PUZZLE_MAC_LENGTH],
+				      int mac_address_idx)
+{
+	unsigned char mac_address_cmd[4 + IEI_WT61P803_PUZZLE_MAC_LENGTH + 1];
+	unsigned char *resp_buf = mcu->response_buffer;
+	unsigned char mac_address_header[4] = {
+		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
+		IEI_WT61P803_PUZZLE_CMD_EEPROM_WRITE,
+		0x00,	/* EEPROM write address */
+		0x11,	/* Data length */
+	};
+	size_t reply_size;
+	int ret;
+
+	if (mac_address_idx < 0 || mac_address_idx >= IEI_WT61P803_PUZZLE_NB_MAC)
+		return -EINVAL;
+
+	mac_address_header[2] = 0x24 + 0x11 * mac_address_idx;
+
+	/* Concat mac_address_header, mac_address to mac_address_cmd */
+	memcpy(mac_address_cmd, mac_address_header, sizeof(mac_address_header));
+	memcpy(mac_address_cmd + sizeof(mac_address_header), mac_address,
+	       IEI_WT61P803_PUZZLE_MAC_LENGTH);
+
+	mutex_lock(&mcu->lock);
+	ret = iei_wt61p803_puzzle_write_command(mcu, mac_address_cmd,
+						sizeof(mac_address_cmd),
+						resp_buf, &reply_size);
+	if (ret)
+		goto err;
+	if (reply_size != 3) {
+		ret = -EIO;
+		goto err;
+	}
+	if (!(resp_buf[0] == IEI_WT61P803_PUZZLE_CMD_HEADER_START &&
+	      resp_buf[1] == IEI_WT61P803_PUZZLE_CMD_RESPONSE_OK &&
+	      resp_buf[2] == IEI_WT61P803_PUZZLE_CHECKSUM_RESPONSE_OK)) {
+		ret = -EPROTO;
+		goto err;
+	}
+
+	sprintf(mcu->version.mac_address[mac_address_idx], "%.*s",
+		IEI_WT61P803_PUZZLE_MAC_LENGTH, mac_address);
+err:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_write_power_loss_recovery(struct iei_wt61p803_puzzle *mcu,
+							 int power_loss_recovery_action)
+{
+	unsigned char *resp_buf = mcu->response_buffer;
+	unsigned char power_loss_recovery_cmd[5] = {};
+	size_t reply_size;
+	int ret;
+
+	if (power_loss_recovery_action < 0 || power_loss_recovery_action > 4)
+		return -EINVAL;
+
+	power_loss_recovery_cmd[0] = IEI_WT61P803_PUZZLE_CMD_HEADER_START;
+	power_loss_recovery_cmd[1] = IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER;
+	power_loss_recovery_cmd[2] = IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_POWER_LOSS;
+	power_loss_recovery_cmd[3] = hex_asc[power_loss_recovery_action];
+
+	mutex_lock(&mcu->lock);
+	ret = iei_wt61p803_puzzle_write_command(mcu, power_loss_recovery_cmd,
+						sizeof(power_loss_recovery_cmd),
+						resp_buf, &reply_size);
+	if (ret)
+		goto exit;
+	mcu->status.power_loss_recovery = power_loss_recovery_action;
+exit:
+	mutex_unlock(&mcu->lock);
+	return ret;
+}
+
+#define to_puzzle_dev_attr(_attr) \
+	container_of(_attr, struct iei_wt61p803_puzzle_device_attribute, dev_attr)
+
+static ssize_t show_output(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev);
+	struct iei_wt61p803_puzzle_device_attribute *pattr = to_puzzle_dev_attr(attr);
+	int ret;
+
+	switch (pattr->type) {
+	case IEI_WT61P803_PUZZLE_VERSION:
+		return scnprintf(buf, PAGE_SIZE, "%s\n", mcu->version.version);
+	case IEI_WT61P803_PUZZLE_BUILD_INFO:
+		return scnprintf(buf, PAGE_SIZE, "%s\n", mcu->version.build_info);
+	case IEI_WT61P803_PUZZLE_BOOTLOADER_MODE:
+		return scnprintf(buf, PAGE_SIZE, "%d\n", mcu->version.bootloader_mode);
+	case IEI_WT61P803_PUZZLE_PROTOCOL_VERSION:
+		return scnprintf(buf, PAGE_SIZE, "%s\n", mcu->version.protocol_version);
+	case IEI_WT61P803_PUZZLE_SERIAL_NUMBER:
+		ret = iei_wt61p803_puzzle_get_serial_number(mcu);
+		if (!ret)
+			ret = scnprintf(buf, PAGE_SIZE, "%s\n", mcu->version.serial_number);
+		else
+			ret = 0;
+		return ret;
+	case IEI_WT61P803_PUZZLE_MAC_ADDRESS:
+		ret = iei_wt61p803_puzzle_get_mac_address(mcu, pattr->index);
+		if (!ret)
+			ret = scnprintf(buf, PAGE_SIZE, "%s\n",
+					mcu->version.mac_address[pattr->index]);
+		else
+			ret = 0;
+		return ret;
+	case IEI_WT61P803_PUZZLE_AC_RECOVERY_STATUS:
+	case IEI_WT61P803_PUZZLE_POWER_LOSS_RECOVERY:
+	case IEI_WT61P803_PUZZLE_POWER_STATUS:
+		ret = iei_wt61p803_puzzle_get_mcu_status(mcu);
+		if (ret)
+			return ret;
+
+		mutex_lock(&mcu->lock);
+		switch (pattr->type) {
+		case IEI_WT61P803_PUZZLE_AC_RECOVERY_STATUS:
+			ret = scnprintf(buf, PAGE_SIZE, "%x\n",
+					mcu->status.ac_recovery_status_flag);
+			break;
+		case IEI_WT61P803_PUZZLE_POWER_LOSS_RECOVERY:
+			ret = scnprintf(buf, PAGE_SIZE, "%x\n", mcu->status.power_loss_recovery);
+			break;
+		case IEI_WT61P803_PUZZLE_POWER_STATUS:
+			ret = scnprintf(buf, PAGE_SIZE, "%x\n", mcu->status.power_status);
+			break;
+		default:
+			ret = 0;
+			break;
+		}
+		mutex_unlock(&mcu->lock);
+		return ret;
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+static ssize_t store_output(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t len)
+{
+	unsigned char serial_number[IEI_WT61P803_PUZZLE_SN_LENGTH];
+	unsigned char mac_address[IEI_WT61P803_PUZZLE_MAC_LENGTH];
+	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev);
+	struct iei_wt61p803_puzzle_device_attribute *pattr = to_puzzle_dev_attr(attr);
+	int power_loss_recovery_action = 0;
+	int ret;
+
+	switch (pattr->type) {
+	case IEI_WT61P803_PUZZLE_SERIAL_NUMBER:
+		if (len != (size_t)(IEI_WT61P803_PUZZLE_SN_LENGTH + 1))
+			return -EINVAL;
+		memcpy(serial_number, buf, sizeof(serial_number));
+		ret = iei_wt61p803_puzzle_write_serial_number(mcu, serial_number);
+		if (ret)
+			return ret;
+		return len;
+	case IEI_WT61P803_PUZZLE_MAC_ADDRESS:
+		if (len != (size_t)(IEI_WT61P803_PUZZLE_MAC_LENGTH + 1))
+			return -EINVAL;
+
+		memcpy(mac_address, buf, sizeof(mac_address));
+
+		if (strlen(attr->attr.name) != 13)
+			return -EIO;
+
+		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, pattr->index);
+		if (ret)
+			return ret;
+		return len;
+	case IEI_WT61P803_PUZZLE_POWER_LOSS_RECOVERY:
+		ret = kstrtoint(buf, 10, &power_loss_recovery_action);
+		if (ret)
+			return ret;
+		ret = iei_wt61p803_puzzle_write_power_loss_recovery(mcu,
+								    power_loss_recovery_action);
+		if (ret)
+			return ret;
+		return len;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+#define IEI_WT61P803_PUZZLE_ATTR(_name, _mode, _show, _store, _type, _index) \
+	struct iei_wt61p803_puzzle_device_attribute dev_attr_##_name = \
+		{ .dev_attr	= __ATTR(_name, _mode, _show, _store), \
+		  .type		= _type, \
+		  .index	= _index }
+
+#define IEI_WT61P803_PUZZLE_ATTR_RO(_name, _type, _id) \
+	IEI_WT61P803_PUZZLE_ATTR(_name, 0444, show_output, NULL, _type, _id)
+
+#define IEI_WT61P803_PUZZLE_ATTR_RW(_name, _type, _id) \
+	IEI_WT61P803_PUZZLE_ATTR(_name, 0644, show_output, store_output, _type, _id)
+
+static IEI_WT61P803_PUZZLE_ATTR_RO(version, IEI_WT61P803_PUZZLE_VERSION, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RO(build_info, IEI_WT61P803_PUZZLE_BUILD_INFO, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RO(bootloader_mode, IEI_WT61P803_PUZZLE_BOOTLOADER_MODE, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RO(protocol_version, IEI_WT61P803_PUZZLE_PROTOCOL_VERSION, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RW(serial_number, IEI_WT61P803_PUZZLE_SERIAL_NUMBER, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_0, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_1, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 1);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_2, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 2);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_3, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 3);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_4, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 4);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_5, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 5);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_6, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 6);
+static IEI_WT61P803_PUZZLE_ATTR_RW(mac_address_7, IEI_WT61P803_PUZZLE_MAC_ADDRESS, 7);
+static IEI_WT61P803_PUZZLE_ATTR_RO(ac_recovery_status, IEI_WT61P803_PUZZLE_AC_RECOVERY_STATUS, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RW(power_loss_recovery, IEI_WT61P803_PUZZLE_POWER_LOSS_RECOVERY, 0);
+static IEI_WT61P803_PUZZLE_ATTR_RO(power_status, IEI_WT61P803_PUZZLE_POWER_STATUS, 0);
+
+static struct attribute *iei_wt61p803_puzzle_attrs[] = {
+	&dev_attr_version.dev_attr.attr,
+	&dev_attr_build_info.dev_attr.attr,
+	&dev_attr_bootloader_mode.dev_attr.attr,
+	&dev_attr_protocol_version.dev_attr.attr,
+	&dev_attr_serial_number.dev_attr.attr,
+	&dev_attr_mac_address_0.dev_attr.attr,
+	&dev_attr_mac_address_1.dev_attr.attr,
+	&dev_attr_mac_address_2.dev_attr.attr,
+	&dev_attr_mac_address_3.dev_attr.attr,
+	&dev_attr_mac_address_4.dev_attr.attr,
+	&dev_attr_mac_address_5.dev_attr.attr,
+	&dev_attr_mac_address_6.dev_attr.attr,
+	&dev_attr_mac_address_7.dev_attr.attr,
+	&dev_attr_ac_recovery_status.dev_attr.attr,
+	&dev_attr_power_loss_recovery.dev_attr.attr,
+	&dev_attr_power_status.dev_attr.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(iei_wt61p803_puzzle);
+
+static int iei_wt61p803_puzzle_sysfs_create(struct device *dev,
+					    struct iei_wt61p803_puzzle *mcu)
+{
+	int ret;
+
+	ret = sysfs_create_groups(&mcu->dev->kobj, iei_wt61p803_puzzle_groups);
+	if (ret)
+		mfd_remove_devices(mcu->dev);
+
+	return ret;
+}
+
+static int iei_wt61p803_puzzle_sysfs_remove(struct device *dev,
+					    struct iei_wt61p803_puzzle *mcu)
+{
+	/* Remove sysfs groups */
+	sysfs_remove_groups(&mcu->dev->kobj, iei_wt61p803_puzzle_groups);
+	mfd_remove_devices(mcu->dev);
+
+	return 0;
+}
+
+static int iei_wt61p803_puzzle_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct iei_wt61p803_puzzle *mcu;
+	u32 baud;
+	int ret;
+
+	/* Read the baud rate from 'current-speed', because the MCU supports different rates */
+	if (device_property_read_u32(dev, "current-speed", &baud)) {
+		dev_err(dev,
+			"'current-speed' is not specified in device node\n");
+		return -EINVAL;
+	}
+	dev_dbg(dev, "Driver baud rate: %d\n", baud);
+
+	/* Allocate the memory */
+	mcu = devm_kzalloc(dev, sizeof(*mcu), GFP_KERNEL);
+	if (!mcu)
+		return -ENOMEM;
+
+	mcu->reply = devm_kzalloc(dev, sizeof(*mcu->reply), GFP_KERNEL);
+	if (!mcu->reply)
+		return -ENOMEM;
+
+	/* Initialize device struct data */
+	mcu->serdev = serdev;
+	mcu->dev = dev;
+	init_completion(&mcu->reply->received);
+	mutex_init(&mcu->reply_lock);
+	mutex_init(&mcu->lock);
+
+	/* Setup UART interface */
+	serdev_device_set_drvdata(serdev, mcu);
+	serdev_device_set_client_ops(serdev, &iei_wt61p803_puzzle_serdev_device_ops);
+	ret = devm_serdev_device_open(dev, serdev);
+	if (ret)
+		return ret;
+	serdev_device_set_baudrate(serdev, baud);
+	serdev_device_set_flow_control(serdev, false);
+	ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
+	if (ret) {
+		dev_err(dev, "Failed to set parity\n");
+		return ret;
+	}
+
+	ret = iei_wt61p803_puzzle_get_version(mcu);
+	if (ret)
+		return ret;
+
+	dev_dbg(dev, "MCU version: %s\n", mcu->version.version);
+	dev_dbg(dev, "MCU firmware build info: %s\n", mcu->version.build_info);
+	dev_dbg(dev, "MCU in bootloader mode: %s\n",
+		mcu->version.bootloader_mode ? "true" : "false");
+	dev_dbg(dev, "MCU protocol version: %s\n", mcu->version.protocol_version);
+
+	if (device_property_read_bool(dev, "enable-beep")) {
+		ret = iei_wt61p803_puzzle_buzzer(mcu, false);
+		if (ret)
+			return ret;
+	}
+
+	ret = iei_wt61p803_puzzle_sysfs_create(dev, mcu);
+	if (ret)
+		return ret;
+
+	return devm_of_platform_populate(dev);
+}
+
+static void iei_wt61p803_puzzle_remove(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev);
+
+	iei_wt61p803_puzzle_sysfs_remove(dev, mcu);
+}
+
+static const struct of_device_id iei_wt61p803_puzzle_dt_ids[] = {
+	{ .compatible = "iei,wt61p803-puzzle" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, iei_wt61p803_puzzle_dt_ids);
+
+static struct serdev_device_driver iei_wt61p803_puzzle_drv = {
+	.probe			= iei_wt61p803_puzzle_probe,
+	.remove			= iei_wt61p803_puzzle_remove,
+	.driver = {
+		.name		= "iei-wt61p803-puzzle",
+		.of_match_table	= iei_wt61p803_puzzle_dt_ids,
+	},
+};
+
+module_serdev_device_driver(iei_wt61p803_puzzle_drv);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Luka Kovacic <luka.kovacic@sartura.hr>");
+MODULE_DESCRIPTION("IEI WT61P803 PUZZLE MCU Driver");
diff --git a/include/linux/mfd/iei-wt61p803-puzzle.h b/include/linux/mfd/iei-wt61p803-puzzle.h
new file mode 100644
index 000000000000..7f2da5887dae
--- /dev/null
+++ b/include/linux/mfd/iei-wt61p803-puzzle.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* IEI WT61P803 PUZZLE MCU Driver
+ * System management microcontroller for fan control, temperature sensor reading,
+ * LED control and system identification on IEI Puzzle series ARM-based appliances.
+ *
+ * Copyright (C) 2020 Sartura Ltd.
+ * Author: Luka Kovacic <luka.kovacic@sartura.hr>
+ */
+
+#ifndef _MFD_IEI_WT61P803_PUZZLE_H_
+#define _MFD_IEI_WT61P803_PUZZLE_H_
+
+#define IEI_WT61P803_PUZZLE_BUF_SIZE 512
+
+/* Command magic numbers */
+#define IEI_WT61P803_PUZZLE_CMD_HEADER_START		0x40 /* @ */
+#define IEI_WT61P803_PUZZLE_CMD_HEADER_START_OTHER	0x25 /* % */
+#define IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM		0xF7
+
+#define IEI_WT61P803_PUZZLE_CMD_RESPONSE_OK		0x30 /* 0 */
+#define IEI_WT61P803_PUZZLE_CHECKSUM_RESPONSE_OK	0x70
+
+#define IEI_WT61P803_PUZZLE_CMD_EEPROM_READ		0xA1
+#define IEI_WT61P803_PUZZLE_CMD_EEPROM_WRITE		0xA0
+
+#define IEI_WT61P803_PUZZLE_CMD_OTHER_VERSION		0x56 /* V */
+#define IEI_WT61P803_PUZZLE_CMD_OTHER_BUILD		0x42 /* B */
+#define IEI_WT61P803_PUZZLE_CMD_OTHER_BOOTLOADER_MODE	0x4D /* M */
+#define IEI_WT61P803_PUZZLE_CMD_OTHER_MODE_BOOTLOADER	0x30
+#define IEI_WT61P803_PUZZLE_CMD_OTHER_MODE_APPS		0x31
+#define IEI_WT61P803_PUZZLE_CMD_OTHER_PROTOCOL_VERSION	0x50 /* P */
+
+#define IEI_WT61P803_PUZZLE_CMD_FUNCTION_SINGLE		0x43 /* C */
+#define IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER		0x4F /* O */
+#define IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_STATUS	0x53 /* S */
+#define IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_POWER_LOSS 0x41 /* A */
+
+#define IEI_WT61P803_PUZZLE_CMD_LED			0x52 /* R */
+#define IEI_WT61P803_PUZZLE_CMD_LED_POWER		0x31 /* 1 */
+
+#define IEI_WT61P803_PUZZLE_CMD_TEMP			0x54 /* T */
+#define IEI_WT61P803_PUZZLE_CMD_TEMP_ALL		0x41 /* A */
+
+#define IEI_WT61P803_PUZZLE_CMD_FAN			0x46 /* F */
+#define IEI_WT61P803_PUZZLE_CMD_FAN_PWM_READ		0x5A /* Z */
+#define IEI_WT61P803_PUZZLE_CMD_FAN_PWM_WRITE		0x57 /* W */
+#define IEI_WT61P803_PUZZLE_CMD_FAN_PWM_BASE		0x30
+#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM_BASE		0x41 /* A */
+
+#define IEI_WT61P803_PUZZLE_CMD_FAN_PWM(x) (IEI_WT61P803_PUZZLE_CMD_FAN_PWM_BASE + (x)) /* 0 - 1 */
+#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM(x) (IEI_WT61P803_PUZZLE_CMD_FAN_RPM_BASE + (x)) /* 0 - 5 */
+
+struct iei_wt61p803_puzzle_mcu_version;
+struct iei_wt61p803_puzzle_reply;
+struct iei_wt61p803_puzzle;
+
+int iei_wt61p803_puzzle_write_command_watchdog(struct iei_wt61p803_puzzle *mcu,
+					       unsigned char *cmd, size_t size,
+					       unsigned char *reply_data, size_t *reply_size,
+					       int retry_count);
+
+int iei_wt61p803_puzzle_write_command(struct iei_wt61p803_puzzle *mcu,
+				      unsigned char *cmd, size_t size,
+				      unsigned char *reply_data, size_t *reply_size);
+
+#endif /* _MFD_IEI_WT61P803_PUZZLE_H_ */
