From 692cfa85272dd12995b427c0a7a585ced5d54f32 Mon Sep 17 00:00:00 2001
From: Luka Kovacic <luka.kovacic () sartura ! hr>
Date: Tue, 24 Aug 2021 12:44:33 +0000
Subject: [PATCH 2/7] drivers: mfd: Add a driver for IEI WT61P803 PUZZLE MCU

Add a driver for the IEI WT61P803 PUZZLE microcontroller, used in some
IEI Puzzle series devices. The microcontroller controls system power,
temperature sensors, fans and LEDs.

This driver implements the core functionality for device communication
over the system serial (serdev bus). It handles MCU messages and the
internal MCU properties. Some properties can be managed over sysfs.

Signed-off-by: Luka Kovacic <luka.kovacic@sartura.hr>
Signed-off-by: Pavo Banicevic <pavo.banicevic@sartura.hr>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Robert Marko <robert.marko@sartura.hr>
---
 drivers/mfd/Kconfig                     |   9 +
 drivers/mfd/Makefile                    |   1 +
 drivers/mfd/iei-wt61p803-puzzle.c       | 908 ++++++++++++++++++++++++
 include/linux/mfd/iei-wt61p803-puzzle.h |  66 ++
 4 files changed, 984 insertions(+)
 create mode 100644 drivers/mfd/iei-wt61p803-puzzle.c
 create mode 100644 include/linux/mfd/iei-wt61p803-puzzle.h

--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2274,6 +2274,15 @@ 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
+	select MFD_CORE
+	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_CORE
         tristate
         select MFD_CORE
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -244,6 +244,7 @@ obj-$(CONFIG_MFD_RT4831)	+= rt4831.o
 obj-$(CONFIG_MFD_RT5033)	+= rt5033.o
 obj-$(CONFIG_MFD_RT5120)	+= rt5120.o
 obj-$(CONFIG_MFD_SKY81452)	+= sky81452.o
+obj-$(CONFIG_MFD_IEI_WT61P803_PUZZLE)  += iei-wt61p803-puzzle.o
 
 obj-$(CONFIG_INTEL_SOC_PMIC)		+= intel_soc_pmic_crc.o
 obj-$(CONFIG_INTEL_SOC_PMIC_BXTWC)	+= intel_soc_pmic_bxtwc.o
--- /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");
--- /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_ */
