Re: [PATCH v2 2/7] drivers: mfd: Add a driver for iEi WT61P803 PUZZLE MCU

[Marek Behun]

On Sat, 26 Sep 2020 15:55:09 +0200
Luka Kovacic <luka.kovacic@xxxxxxxxxx> wrote:

> 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.
> 

Hi Luka,

this patch produces some checkpatch warnings, some of them are
reasonable.

My thought below:

> Signed-off-by: Luka Kovacic <luka.kovacic@xxxxxxxxxx>
> Cc: Luka Perkov <luka.perkov@xxxxxxxxxx>
> Cc: Robert Marko <robert.marko@xxxxxxxxxx>
> ---
>  drivers/mfd/Kconfig                     |    8 +
>  drivers/mfd/Makefile                    |    1 +
>  drivers/mfd/iei-wt61p803-puzzle.c       | 1069 +++++++++++++++++++++++
>  include/linux/mfd/iei-wt61p803-puzzle.h |   69 ++
>  4 files changed, 1147 insertions(+)
>  create mode 100644 drivers/mfd/iei-wt61p803-puzzle.c
>  create mode 100644 include/linux/mfd/iei-wt61p803-puzzle.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 33df0837ab41..b1588845894e 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -2118,5 +2118,13 @@ 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.
> +
>  endmenu
>  endif
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index a60e5f835283..33b88023a68d 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -236,6 +236,7 @@ obj-$(CONFIG_MFD_HI655X_PMIC)   += hi655x-pmic.o
>  obj-$(CONFIG_MFD_DLN2)		+= dln2.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..5cba010ac9b9
> --- /dev/null
> +++ b/drivers/mfd/iei-wt61p803-puzzle.c
> @@ -0,0 +1,1069 @@
> +// 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@xxxxxxxxxx>
> + */
> +
> +#include <asm/unaligned.h>
> +#include <linux/atomic.h>
> +#include <linux/delay.h>
> +#include <linux/delay.h>
> +#include <linux/export.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/iei-wt61p803-puzzle.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/property.h>
> +#include <linux/sched.h>
> +#include <linux/serdev.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +
> +#define IEI_WT61P803_PUZZLE_MAX_COMMAND_LENGTH	(20 + 2)
> +#define IEI_WT61P803_PUZZLE_RESP_BUF_SIZE	512
> +
> +/* Use HZ as a timeout value throughout the driver */
> +#define IEI_WT61P803_PUZZLE_GENERAL_TIMEOUT HZ
> +
> +/**
> + * 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;
> +};
> +
> +/**
> + * enum iei_wt61p803_puzzle_reply_state - State of the reply
> + * @FRAME_OK:		The frame was completely processed/received
> + * @FRAME_PROCESSING:	First bytes were received, but the frame isn't complete
> + * @FRAME_STRUCT_EMPTY:	The frame struct is empty, no data was received
> + * @FRAME_TIMEOUT:	The frame processing timed out, communication failed
> + *
> + * Describes the general state of the frame that is currently being received.
> + */
> +enum iei_wt61p803_puzzle_reply_state {
> +	FRAME_OK = 0x00,
> +	FRAME_PROCESSING = 0x01,
> +	FRAME_STRUCT_EMPTY = 0xFF,
> +	FRAME_TIMEOUT = 0xFE
> +};
> +
> +/**
> + * 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;
> +	u8 state;
> +	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
> + */
> +struct iei_wt61p803_puzzle_mcu_version {
> +	const char *version;
> +	const char *build_info;
> +	bool bootloader_mode;
> +	const char *protocol_version;
> +	const char *serial_number;
> +	const char *mac_address[8];

You use devm_kasprintf below for these, but such variables have limited
and often small length. The mac_address array could for example be:
	char mac_address[8][18];
Can serial number be longer than 32 bytes? What about the other members?
I believe it would be better, to avoid unnecesarry allocations, to
change this.

> +};
> +
> +/**
> + * struct iei_wt61p803_puzzle - iEi WT61P803 PUZZLE MCU Driver
> + *
> + * @serdev:		Pointer to underlying serdev device
> + * @kobj:		Pointer to kobject (sysfs)
> + * @reply_lock:		Reply mutex lock
> + * @bus_lock:		Bus 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 kobject *kobj;
> +	struct mutex reply_lock;
> +	struct mutex bus_lock;
> +	struct iei_wt61p803_puzzle_reply *reply;
> +	struct iei_wt61p803_puzzle_mcu_version version;
> +	struct iei_wt61p803_puzzle_mcu_status status;
> +	unsigned char *response_buffer;
> +	struct mutex lock;
> +};
> +
> +unsigned char iei_wt61p803_puzzle_checksum(unsigned char *buf, size_t len)
> +{
> +	unsigned char checksum = 0;
> +	unsigned int i;
> +
> +	for (i = 0; i < len; i++)
> +		checksum ^= buf[i];
> +
> +	return checksum;
> +}

This function should be static.
And maybe for the whole driver: s/unsigned char/u8/

> +
> +static int iei_wt61p803_puzzle_process_resp(struct iei_wt61p803_puzzle *mcu,
> +		unsigned char *raw_resp_data, size_t size)
> +{
> +	struct device *dev = &mcu->serdev->dev;
> +
> +	unsigned char checksum;

Empty line between declarations?

> +
> +	mutex_lock(&mcu->reply_lock);
> +
> +	/* 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))) {
> +
> +		/* Frame header is not correct, check whether to append */
> +		if (mcu->reply->state != FRAME_PROCESSING) {
> +			dev_err(dev, "Invalid frame header and state (0x%x)", mcu->reply->state);
> +			mutex_unlock(&mcu->reply_lock);
> +			return -EIO;
> +		}
> +
> +		/* Append the frame to existing data */
> +		memcpy(mcu->reply->data+mcu->reply->size, raw_resp_data, size);
> +		mcu->reply->size += size;
> +	} else {
> +		/* Start processing a new frame */
> +		memcpy(mcu->reply->data, raw_resp_data, size);
> +		mcu->reply->size = size;
> +		mcu->reply->state = FRAME_PROCESSING;
> +	}
> +
> +	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 */
> +		mutex_unlock(&mcu->reply_lock);
> +		return (int)size;
> +	}
> +
> +	/* Received all the data */
> +	mcu->reply->state = FRAME_OK;
> +	complete(&mcu->reply->received);
> +
> +	mutex_unlock(&mcu->reply_lock);
> +
> +	return (int)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, (unsigned char *)data, size);
> +
> +	/* Return the number of processed bytes if function returns error */
> +	if (ret < 0)
> +		return (int)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, "%s: Command response timed out. Retries: %d", __func__,
> +			retry_count);

The indentation here is weird, I would put the retry_count at the
position one to the right after dev_err(. But this is not important.

> +
> +	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;
> +	int len = (int)size;

Some kernel maintainers like reverse christmas tree order of variable
declaration. I find it better to read. If you would like to try:
	struct device *dev = &mcu->serdev->dev;
	int len = (int)size;
	int ret;

> +
> +	if (size > IEI_WT61P803_PUZZLE_MAX_COMMAND_LENGTH)
> +		return -EINVAL;
> +
> +	cmd[len - 1] = iei_wt61p803_puzzle_checksum(cmd, size);
> +
> +	mutex_lock(&mcu->bus_lock);
> +	mutex_lock(&mcu->reply_lock);
> +
> +	if (!mcu->reply) {
> +		ret = -EFAULT;
> +		goto exit;
> +	}
> +
> +	/* Initialize reply struct */
> +	reinit_completion(&mcu->reply->received);
> +	mcu->reply->state = FRAME_STRUCT_EMPTY;
> +	mcu->reply->size = 0;
> +	mutex_unlock(&mcu->reply_lock);
> +
> +	ret = serdev_device_write(mcu->serdev, cmd, len, IEI_WT61P803_PUZZLE_GENERAL_TIMEOUT);
> +
> +	if (ret < 0) {
> +		mutex_unlock(&mcu->bus_lock);
> +		return ret;
> +	}
> +
> +	if (!wait_for_completion_timeout(&mcu->reply->received,
> +				IEI_WT61P803_PUZZLE_GENERAL_TIMEOUT)) {
> +		dev_err(dev, "Command reply receive timeout\n");
> +		mutex_lock(&mcu->reply_lock);
> +		reinit_completion(&mcu->reply->received);
> +		mcu->reply->state = FRAME_TIMEOUT;
> +
> +		ret = -ETIMEDOUT;
> +		goto exit;
> +	}
> +
> +	mutex_lock(&mcu->reply_lock);
> +
> +	if (!mcu->reply) {
> +		ret = -EFAULT;
> +		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);
> +	mutex_unlock(&mcu->bus_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iei_wt61p803_puzzle_write_command);
> +
> +int iei_wt61p803_puzzle_buzzer(struct iei_wt61p803_puzzle *mcu, bool long_beep)
> +{
> +	unsigned char buzzer_short_cmd[4] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_START,
> +		IEI_WT61P803_PUZZLE_CMD_FUNCTION_SINGLE,
> +		'2'
> +	}; /* Buzzer 0.5 sec */
> +	unsigned char buzzer_long_cmd[4] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_START,
> +		IEI_WT61P803_PUZZLE_CMD_FUNCTION_SINGLE,
> +		'3'
> +	}; /* Buzzer 1.5 sec */
> +	unsigned char *resp_buf = mcu->response_buffer;
> +	size_t reply_size = 0;
> +	int ret;
> +
> +	mutex_lock(&mcu->lock);
> +	ret = iei_wt61p803_puzzle_write_command(mcu,
> +			long_beep ? buzzer_long_cmd : buzzer_short_cmd, 4,
> +			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)) {

Again weird indentation here, I would do

	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;
> +}
> +
> +int iei_wt61p803_puzzle_get_version(struct iei_wt61p803_puzzle *mcu)
> +{
> +	struct device *dev = &mcu->serdev->dev;
> +	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 = 0;
> +	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;
> +	}
> +	mcu->version.version = devm_kasprintf(dev, GFP_KERNEL, "v%c.%c%c%c",
> +				rb[2], rb[3], rb[4], rb[5]);
> +
> +	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;
> +	}
> +	mcu->version.build_info = devm_kasprintf(dev, GFP_KERNEL,
> +			"%c%c/%c%c/%c%c%c%c %c%c:%c%c",
> +			rb[8], rb[9], rb[6], rb[7], rb[2],
> +			rb[3], rb[4], rb[5], 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;
> +	}
> +	mcu->version.protocol_version = devm_kasprintf(dev, GFP_KERNEL,
> +			"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;
> +}
> +
> +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 = 0;
> +	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;
> +}
> +
> +int iei_wt61p803_puzzle_get_serial_number(struct iei_wt61p803_puzzle *mcu)
> +{
> +	struct device *dev = &mcu->serdev->dev;
> +	unsigned char serial_number_cmd[5] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
> +		IEI_WT61P803_PUZZLE_CMD_EEPROM_READ,
> +		0x00,
> +		0x24
> +	};
> +	unsigned char *resp_buf = mcu->response_buffer;
> +	size_t reply_size = 0;
> +	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;
> +
> +	mcu->version.serial_number = devm_kasprintf(dev, GFP_KERNEL, "%.*s",
> +			(int)reply_size - 5, resp_buf + 4);
> +err:
> +	mutex_unlock(&mcu->lock);
> +	return ret;
> +
> +}
> +
> +int iei_wt61p803_puzzle_write_serial_number(struct iei_wt61p803_puzzle *mcu,
> +		unsigned char serial_number[36])
> +{
> +	struct device *dev = &mcu->serdev->dev;
> +	unsigned char serial_number_header[4] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
> +		IEI_WT61P803_PUZZLE_CMD_EEPROM_WRITE,
> +		0x00,
> +		0xC
> +	};
> +	unsigned char *resp_buf = mcu->response_buffer;
> +	unsigned char serial_number_cmd[4+12+1]; /* header, serial number chunk, XOR checksum */
> +	int ret, sn_counter;
> +	size_t reply_size = 0;
> +
> +	/* The MCU can only handle 22 byte messages, send the S/N in 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, 4);
> +		memcpy(serial_number_cmd + 4, serial_number + (0xC) * sn_counter, 0xC);
> +
> +		serial_number_cmd[sizeof(serial_number_cmd) - 1] = 0;
> +
> +		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;
> +		}
> +	}
> +
> +	mcu->version.serial_number = devm_kasprintf(dev, GFP_KERNEL, "%.*s",
> +			36, serial_number);
> +err:
> +	mutex_unlock(&mcu->lock);
> +	return ret;
> +}
> +
> +int iei_wt61p803_puzzle_get_mac_addresses(struct iei_wt61p803_puzzle *mcu)
> +{
> +	struct device *dev = &mcu->serdev->dev;
> +	unsigned char mac_address_cmd[5] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
> +		IEI_WT61P803_PUZZLE_CMD_EEPROM_READ,
> +		0x00,
> +		0x11
> +	};
> +	unsigned char *resp_buf = mcu->response_buffer;
> +	int ret, mac_counter;
> +	size_t reply_size = 0;
> +
> +	mutex_lock(&mcu->lock);
> +	for (mac_counter = 0; mac_counter < 8; mac_counter++) {
> +		mac_address_cmd[2] = 0x24 + (0x11) * mac_counter;
> +		mac_address_cmd[4] = 0x00;
> +
> +		ret = iei_wt61p803_puzzle_write_command(mcu, mac_address_cmd,
> +				sizeof(mac_address_cmd), resp_buf, &reply_size);
> +		if (ret)
> +			continue;
> +
> +		if (reply_size < 22) {
> +			ret = -EIO;
> +			goto err;
> +		}
> +
> +		mcu->version.mac_address[mac_counter] = devm_kasprintf(dev,
> +				GFP_KERNEL, "%.*s", (int)reply_size - 5,
> +				resp_buf + 4);
> +	}
> +err:
> +	mutex_unlock(&mcu->lock);
> +	return ret;
> +}
> +
> +int iei_wt61p803_puzzle_write_mac_address(struct iei_wt61p803_puzzle *mcu,
> +		unsigned char mac_address[17], int mac_address_idx)
> +{
> +	struct device *dev = &mcu->serdev->dev;
> +	unsigned char mac_address_header[4] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_EEPROM,
> +		IEI_WT61P803_PUZZLE_CMD_EEPROM_WRITE,
> +		0x00,
> +		0x11
> +	};
> +	unsigned char mac_address_cmd[4+17+1]; /* header, MAC address, XOR checksum*/
> +	unsigned char *resp_buf = mcu->response_buffer;
> +	size_t reply_size = 0;
> +	int ret;
> +
> +	if (!(mac_address_idx < 8))
> +		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, 4);
> +	memcpy(mac_address_cmd + 4, mac_address, 17);
> +
> +	mac_address_cmd[sizeof(mac_address_cmd) - 1] = 0;
> +
> +	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;
> +	}
> +
> +	mcu->version.mac_address[mac_address_idx] = devm_kasprintf(dev,
> +			GFP_KERNEL, "%.*s", 17, mac_address);
> +err:
> +	mutex_unlock(&mcu->lock);
> +	return ret;
> +}
> +
> +int iei_wt61p803_puzzle_write_power_loss_recovery(struct iei_wt61p803_puzzle *mcu,
> +		int power_loss_recovery_action)
> +{
> +	unsigned char power_loss_recovery_cmd[5] = {
> +		IEI_WT61P803_PUZZLE_CMD_HEADER_START,
> +		IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER,
> +		IEI_WT61P803_PUZZLE_CMD_FUNCTION_OTHER_POWER_LOSS,
> +		'0'
> +	};
> +	unsigned char *resp_buf = mcu->response_buffer;
> +	size_t reply_size = 0;
> +	unsigned char cmd_buf[2];
> +	int ret;
> +
> +	if (power_loss_recovery_action < 0 || power_loss_recovery_action > 4)
> +		return -EINVAL;
> +
> +	ret = snprintf(cmd_buf, sizeof(cmd_buf), "%d", power_loss_recovery_action);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Modify the command with the action index */
> +	power_loss_recovery_cmd[3] = cmd_buf[0];
> +
> +	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 sysfs_container(dev) \
> +	(container_of((dev)->kobj.parent, struct device, kobj))
> +
> +static ssize_t version_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	return sprintf(buf, "%s\n", mcu->version.version);
> +}
> +static DEVICE_ATTR_RO(version);
> +
> +static ssize_t build_info_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	return sprintf(buf, "%s\n", mcu->version.build_info);
> +}
> +static DEVICE_ATTR_RO(build_info);
> +
> +static ssize_t bootloader_mode_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	return sprintf(buf, "%d\n", mcu->version.bootloader_mode);
> +}
> +static DEVICE_ATTR_RO(bootloader_mode);
> +
> +static ssize_t protocol_version_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	return sprintf(buf, "%s\n", mcu->version.protocol_version);
> +}
> +static DEVICE_ATTR_RO(protocol_version);
> +
> +static ssize_t serial_number_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +	int ret;
> +
> +	mutex_lock(&mcu->lock);
> +	ret = sprintf(buf, "%s\n", mcu->version.serial_number);
> +	mutex_unlock(&mcu->lock);
> +
> +	return ret;
> +}
> +static ssize_t serial_number_store(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf, size_t count)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +	unsigned char serial_number[36];
> +	int ret;
> +
> +	/* Check whether the serial number is 36 characters long + null */
> +	if ((int)count != 36 + 1)
> +		return -EINVAL;
> +
> +	/* Copy 36 characters from the buffer to serial_number */
> +	memcpy(serial_number, (unsigned char *)buf, 36);
> +
> +	ret = iei_wt61p803_puzzle_write_serial_number(mcu, serial_number);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +static DEVICE_ATTR_RW(serial_number);
> +
> +static ssize_t mac_address_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +	int ret;
> +
> +	mutex_lock(&mcu->lock);
> +	if (!strcmp(attr->attr.name, "mac_address_0"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[0]);
> +	else if (!strcmp(attr->attr.name, "mac_address_1"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[1]);
> +	else if (!strcmp(attr->attr.name, "mac_address_2"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[2]);
> +	else if (!strcmp(attr->attr.name, "mac_address_3"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[3]);
> +	else if (!strcmp(attr->attr.name, "mac_address_4"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[4]);
> +	else if (!strcmp(attr->attr.name, "mac_address_5"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[5]);
> +	else if (!strcmp(attr->attr.name, "mac_address_6"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[6]);
> +	else if (!strcmp(attr->attr.name, "mac_address_7"))
> +		ret = sprintf(buf, "%s\n", mcu->version.mac_address[7]);
> +	else
> +		ret = sprintf(buf, "\n");

WHYYYYY?

	int idx;

	if (strlen(attr->attr.name) != 13)
		return -EIO;

	idx = attr->attr.name[12] - '0';
	if (idx < 0 || idx > 7)
		return -EIO;
	ret = sprintf(buf, "%s\n", mcu->version.mac_address[idx]);

> +	mutex_unlock(&mcu->lock);
> +
> +	return ret;
> +}
> +static ssize_t mac_address_store(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf, size_t count)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +	unsigned char mac_address[17];
> +	int ret;
> +
> +	if ((int)count != 17 + 1)
> +		return -EINVAL;
> +
> +	memcpy(mac_address, (unsigned char *)buf, 17);
> +
> +	if (!strcmp(attr->attr.name, "mac_address_0"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 0);
> +	else if (!strcmp(attr->attr.name, "mac_address_1"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 1);
> +	else if (!strcmp(attr->attr.name, "mac_address_2"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 2);
> +	else if (!strcmp(attr->attr.name, "mac_address_3"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 3);
> +	else if (!strcmp(attr->attr.name, "mac_address_4"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 4);
> +	else if (!strcmp(attr->attr.name, "mac_address_5"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 5);
> +	else if (!strcmp(attr->attr.name, "mac_address_6"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 6);
> +	else if (!strcmp(attr->attr.name, "mac_address_7"))
> +		ret = iei_wt61p803_puzzle_write_mac_address(mcu, mac_address, 7);
> +	if (ret)
> +		return ret;
> +

Similar to above.

> +	return count;
> +}
> +static DEVICE_ATTR(mac_address_0, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_1, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_2, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_3, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_4, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_5, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_6, 0644, mac_address_show, mac_address_store);
> +static DEVICE_ATTR(mac_address_7, 0644, mac_address_show, mac_address_store);
> +
> +static ssize_t ac_recovery_status_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	int ret;
> +
> +	ret = iei_wt61p803_puzzle_get_mcu_status(mcu);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&mcu->lock);
> +	ret = sprintf(buf, "%x\n", mcu->status.ac_recovery_status_flag);
> +	mutex_unlock(&mcu->lock);
> +
> +	return ret;
> +}
> +static DEVICE_ATTR_RO(ac_recovery_status);
> +
> +static ssize_t power_loss_recovery_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	int ret;
> +
> +	ret = iei_wt61p803_puzzle_get_mcu_status(mcu);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&mcu->lock);
> +	ret = sprintf(buf, "%x\n", mcu->status.power_loss_recovery);
> +	mutex_unlock(&mcu->lock);
> +
> +	return ret;
> +}
> +static ssize_t power_loss_recovery_store(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf, size_t count)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	int ret;
> +	long power_loss_recovery_action = 0;
> +
> +	ret = kstrtol(buf, 10, &power_loss_recovery_action);
> +	if (ret)
> +		return ret;
> +
> +	ret = iei_wt61p803_puzzle_write_power_loss_recovery(mcu,
> +			(int)power_loss_recovery_action);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +static DEVICE_ATTR_RW(power_loss_recovery);
> +
> +static ssize_t power_status_show(struct device *dev,
> +	struct device_attribute *attr, char *buf)
> +{
> +	struct device *dev_container = sysfs_container(dev);
> +	struct iei_wt61p803_puzzle *mcu = dev_get_drvdata(dev_container);
> +
> +	int ret;
> +
> +	ret = iei_wt61p803_puzzle_get_mcu_status(mcu);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&mcu->lock);
> +	ret = sprintf(buf, "%x\n", mcu->status.power_status);
> +	mutex_unlock(&mcu->lock);
> +
> +	return ret;
> +}
> +static DEVICE_ATTR_RO(power_status);
> +
> +static struct attribute *iei_wt61p803_puzzle_attrs[] = {
> +	&dev_attr_version.attr,
> +	&dev_attr_build_info.attr,
> +	&dev_attr_bootloader_mode.attr,
> +	&dev_attr_protocol_version.attr,
> +	&dev_attr_serial_number.attr,
> +	&dev_attr_mac_address_0.attr,
> +	&dev_attr_mac_address_1.attr,
> +	&dev_attr_mac_address_2.attr,
> +	&dev_attr_mac_address_3.attr,
> +	&dev_attr_mac_address_4.attr,
> +	&dev_attr_mac_address_5.attr,
> +	&dev_attr_mac_address_6.attr,
> +	&dev_attr_mac_address_7.attr,
> +	&dev_attr_ac_recovery_status.attr,
> +	&dev_attr_power_loss_recovery.attr,
> +	&dev_attr_power_status.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(iei_wt61p803_puzzle);
> +
> +static int iei_wt61p803_puzzle_sysfs_create(struct device *dev,
> +		struct iei_wt61p803_puzzle *mcu)
> +{
> +	int ret;
> +
> +	mcu->kobj = kobject_create_and_add("iei_wt61p803_puzzle_core", &dev->kobj);
> +	if (!mcu->kobj)
> +		return -ENOMEM;
> +
> +	ret = sysfs_create_groups(mcu->kobj, iei_wt61p803_puzzle_groups);
> +	if (ret) {
> +		kobject_del(mcu->kobj);
> +		kobject_put(mcu->kobj);
> +		mcu->kobj = NULL;
> +	}
> +
> +	return ret;
> +}
> +
> +static int iei_wt61p803_puzzle_sysfs_remove(struct device *dev,
> +		struct iei_wt61p803_puzzle *mcu)
> +{
> +	/* Remove sysfs groups */
> +	sysfs_remove_groups(mcu->kobj, iei_wt61p803_puzzle_groups);
> +
> +	/* Remove the kobject */
> +	kobject_del(mcu->kobj);
> +	kobject_put(mcu->kobj);
> +	mcu->kobj = NULL;
> +
> +	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_info(dev, "Driver baud rate: %d", 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;
> +
> +	mcu->reply->data = devm_kzalloc(dev, IEI_WT61P803_PUZZLE_RESP_BUF_SIZE,
> +			GFP_KERNEL);
> +	if (!mcu->reply->data)
> +		return -ENOMEM;
> +
> +	mcu->response_buffer = devm_kzalloc(dev, IEI_WT61P803_PUZZLE_BUF_SIZE,
> +			GFP_KERNEL);
> +	if (!mcu->response_buffer)
> +		return -ENOMEM;
> +
> +	/* Initialize device struct data */
> +	mcu->serdev = serdev;
> +	init_completion(&mcu->reply->received);
> +	mutex_init(&mcu->reply_lock);
> +	mutex_init(&mcu->bus_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");
> +		return ret;
> +	}
> +
> +	ret = iei_wt61p803_puzzle_get_version(mcu);
> +	if (ret)
> +		return ret;
> +
> +	ret = iei_wt61p803_puzzle_get_mac_addresses(mcu);
> +	if (ret)
> +		return ret;
> +
> +	ret = iei_wt61p803_puzzle_get_serial_number(mcu);
> +	if (ret)
> +		return ret;
> +
> +	dev_info(dev, "MCU version: %s", mcu->version.version);
> +	dev_info(dev, "MCU firmware build info: %s", mcu->version.build_info);
> +	dev_info(dev, "MCU in bootloader mode: %s",
> +			mcu->version.bootloader_mode ? "true" : "false");
> +	dev_info(dev, "MCU protocol version: %s", 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);
> +
> +	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");
> +MODULE_AUTHOR("Luka Kovacic <luka.kovacic@xxxxxxxxxx>");
> +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..633ceb1d00e3
> --- /dev/null
> +++ b/include/linux/mfd/iei-wt61p803-puzzle.h
> @@ -0,0 +1,69 @@
> +/* 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@xxxxxxxxxx>
> + */
> +
> +#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_0		0x30
> +#define IEI_WT61P803_PUZZLE_CMD_FAN_PWM_1		0x31
> +#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_RPM_0		0x41 /* A */
> +#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM_1		0x42 /* B */
> +#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM_2		0x43 /* C */
> +#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM_3		0x44 /* D */
> +#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM_4		0x45 /* E */
> +#define IEI_WT61P803_PUZZLE_CMD_FAN_RPM_5		0x46 /* F */
> +
> +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_ */

Marek