drivers/hwmon/pmbus/max20830.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Hardware monitoring driver for Analog Devices MAX20830
 *
 * Copyright (C) 2026 Analog Devices, Inc.
 */

#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/string.h>
#include "pmbus.h"

#define MAX20830_IC_DEVICE_ID_LENGTH	9

static struct pmbus_driver_info max20830_info = {
	.pages = 1,
	.format[PSC_VOLTAGE_IN] = linear,
	.format[PSC_VOLTAGE_OUT] = linear,
	.format[PSC_CURRENT_OUT] = linear,
	.format[PSC_TEMPERATURE] = linear,
	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
		PMBUS_HAVE_TEMP |
		PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_IOUT |
		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
};

static int max20830_probe(struct i2c_client *client)
{
	u8 buf[I2C_SMBUS_BLOCK_MAX + 1] = {};
	int ret;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BLOCK_DATA) &&
	    !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
		return -ENODEV;

	/*
	 * Use i2c_smbus_read_block_data() if supported, otherwise fall back
	 * to i2c_smbus_read_i2c_block_data() to support I2C controllers
	 * which do not support SMBus block reads.
	 */
	if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BLOCK_DATA)) {
		/* Reads 9 Data bytes from MAX20830 */
		ret = i2c_smbus_read_block_data(client, PMBUS_IC_DEVICE_ID, buf);
		if (ret < 0)
			return dev_err_probe(&client->dev, ret,
					     "Failed to read IC_DEVICE_ID\n");
	} else {
		/* Reads 1 length byte + 9 Data bytes from MAX20830 */
		ret = i2c_smbus_read_i2c_block_data(client, PMBUS_IC_DEVICE_ID,
						    MAX20830_IC_DEVICE_ID_LENGTH + 1,
						    buf);
		if (ret < 0)
			return dev_err_probe(&client->dev, ret,
					     "Failed to read IC_DEVICE_ID\n");
		/*
		 * Moves data forward, removing the length byte, this is to
		 * match the format of i2c_smbus_read_block_data().
		 * Also adjust return value to reflect length byte removal.
		 */
		memmove(buf, buf + 1, MAX20830_IC_DEVICE_ID_LENGTH);
		ret = ret - 1;
	}

	/*
	 * MAX20830 IC_DEVICE_ID sends string data "MAX20830\0".
	 * Return value should at least be 9 bytes of data.
	 */
	if (ret < MAX20830_IC_DEVICE_ID_LENGTH)
		return dev_err_probe(&client->dev, -ENODEV,
				     "IC_DEVICE_ID too short: expected at least 9 bytes, got %d\n",
				     ret);

	/* 9 bytes of data, buf[0]-buf[7] = "MAX20830", buf[8] = '\0' */
	buf[MAX20830_IC_DEVICE_ID_LENGTH - 1] = '\0';
	if (strncmp(buf, "MAX20830", MAX20830_IC_DEVICE_ID_LENGTH - 1))
		return dev_err_probe(&client->dev, -ENODEV,
				     "Unsupported device: '%s'\n", buf);

	return pmbus_do_probe(client, &max20830_info);
}

static const struct i2c_device_id max20830_id[] = {
	{"max20830"},
	{ }
};
MODULE_DEVICE_TABLE(i2c, max20830_id);

static const struct of_device_id max20830_of_match[] = {
	{ .compatible = "adi,max20830" },
	{ }
};
MODULE_DEVICE_TABLE(of, max20830_of_match);

static struct i2c_driver max20830_driver = {
	.driver = {
		.name = "max20830",
		.of_match_table = max20830_of_match,
	},
	.probe = max20830_probe,
	.id_table = max20830_id,
};

module_i2c_driver(max20830_driver);

MODULE_AUTHOR("Alexis Czezar Torreno <alexisczezar.torreno@analog.com>");
MODULE_DESCRIPTION("PMBus driver for Analog Devices MAX20830");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PMBUS");