// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hardware monitoring driver for Maxim MAX6620
 *
 * Originally from L. Grunenberg.
 * (C) 2012 by L. Grunenberg <contact@lgrunenberg.de>
 *
 * Copyright (c) 2021 Dell Inc. or its subsidiaries. All Rights Reserved.
 *
 * based on code written by :
 * 2007 by Hans J. Koch <hjk@hansjkoch.de>
 * John Morris <john.morris@spirentcom.com>
 * Copyright (c) 2003 Spirent Communications
 * and Claus Gindhart <claus.gindhart@kontron.com>
 *
 * This module has only been tested with the MAX6620 chip.
 *
 * The datasheet was last seen at:
 *
 *        http://pdfserv.maxim-ic.com/en/ds/MAX6620.pdf
 *
 */

#include <linux/bits.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/slab.h>

/*
 * MAX 6620 registers
 */

#define MAX6620_REG_CONFIG	0x00
#define MAX6620_REG_FAULT	0x01
#define MAX6620_REG_CONF_FAN0	0x02
#define MAX6620_REG_CONF_FAN1	0x03
#define MAX6620_REG_CONF_FAN2	0x04
#define MAX6620_REG_CONF_FAN3	0x05
#define MAX6620_REG_DYN_FAN0	0x06
#define MAX6620_REG_DYN_FAN1	0x07
#define MAX6620_REG_DYN_FAN2	0x08
#define MAX6620_REG_DYN_FAN3	0x09
#define MAX6620_REG_TACH0	0x10
#define MAX6620_REG_TACH1	0x12
#define MAX6620_REG_TACH2	0x14
#define MAX6620_REG_TACH3	0x16
#define MAX6620_REG_VOLT0	0x18
#define MAX6620_REG_VOLT1	0x1A
#define MAX6620_REG_VOLT2	0x1C
#define MAX6620_REG_VOLT3	0x1E
#define MAX6620_REG_TAR0	0x20
#define MAX6620_REG_TAR1	0x22
#define MAX6620_REG_TAR2	0x24
#define MAX6620_REG_TAR3	0x26
#define MAX6620_REG_DAC0	0x28
#define MAX6620_REG_DAC1	0x2A
#define MAX6620_REG_DAC2	0x2C
#define MAX6620_REG_DAC3	0x2E

/*
 * Config register bits
 */

#define MAX6620_CFG_RUN		BIT(7)
#define MAX6620_CFG_POR		BIT(6)
#define MAX6620_CFG_TIMEOUT	BIT(5)
#define MAX6620_CFG_FULLFAN	BIT(4)
#define MAX6620_CFG_OSC		BIT(3)
#define MAX6620_CFG_WD_MASK	(BIT(2) | BIT(1))
#define MAX6620_CFG_WD_2	BIT(1)
#define MAX6620_CFG_WD_6	BIT(2)
#define MAX6620_CFG_WD10	(BIT(2) | BIT(1))
#define MAX6620_CFG_WD		BIT(0)

/*
 * Failure status register bits
 */

#define MAX6620_FAIL_TACH0	BIT(4)
#define MAX6620_FAIL_TACH1	BIT(5)
#define MAX6620_FAIL_TACH2	BIT(6)
#define MAX6620_FAIL_TACH3	BIT(7)
#define MAX6620_FAIL_MASK0	BIT(0)
#define MAX6620_FAIL_MASK1	BIT(1)
#define MAX6620_FAIL_MASK2	BIT(2)
#define MAX6620_FAIL_MASK3	BIT(3)

#define MAX6620_CLOCK_FREQ	8192 /* Clock frequency in Hz */
#define MAX6620_PULSE_PER_REV	2 /* Tachometer pulses per revolution */

/* Minimum and maximum values of the FAN-RPM */
#define FAN_RPM_MIN	240
#define FAN_RPM_MAX	30000

static const u8 config_reg[] = {
	MAX6620_REG_CONF_FAN0,
	MAX6620_REG_CONF_FAN1,
	MAX6620_REG_CONF_FAN2,
	MAX6620_REG_CONF_FAN3,
};

static const u8 dyn_reg[] = {
	MAX6620_REG_DYN_FAN0,
	MAX6620_REG_DYN_FAN1,
	MAX6620_REG_DYN_FAN2,
	MAX6620_REG_DYN_FAN3,
};

static const u8 tach_reg[] = {
	MAX6620_REG_TACH0,
	MAX6620_REG_TACH1,
	MAX6620_REG_TACH2,
	MAX6620_REG_TACH3,
};

static const u8 target_reg[] = {
	MAX6620_REG_TAR0,
	MAX6620_REG_TAR1,
	MAX6620_REG_TAR2,
	MAX6620_REG_TAR3,
};

/*
 * Client data (each client gets its own)
 */

struct max6620_data {
	struct i2c_client *client;
	struct mutex update_lock;
	bool valid; /* false until following fields are valid */
	unsigned long last_updated; /* in jiffies */

	/* register values */
	u8 fancfg[4];
	u8 fandyn[4];
	u8 fault;
	u16 tach[4];
	u16 target[4];
};

static u8 max6620_fan_div_from_reg(u8 val)
{
	return BIT((val & 0xE0) >> 5);
}

static u16 max6620_fan_rpm_to_tach(u8 div, int rpm)
{
	return (60 * div * MAX6620_CLOCK_FREQ) / (rpm * MAX6620_PULSE_PER_REV);
}

static int max6620_fan_tach_to_rpm(u8 div, u16 tach)
{
	return (60 * div * MAX6620_CLOCK_FREQ) / (tach * MAX6620_PULSE_PER_REV);
}

static int max6620_update_device(struct device *dev)
{
	struct max6620_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int i;
	int ret = 0;

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
		for (i = 0; i < 4; i++) {
			ret = i2c_smbus_read_byte_data(client, config_reg[i]);
			if (ret < 0)
				goto error;
			data->fancfg[i] = ret;

			ret = i2c_smbus_read_byte_data(client, dyn_reg[i]);
			if (ret < 0)
				goto error;
			data->fandyn[i] = ret;

			ret = i2c_smbus_read_byte_data(client, tach_reg[i]);
			if (ret < 0)
				goto error;
			data->tach[i] = (ret << 3) & 0x7f8;
			ret = i2c_smbus_read_byte_data(client, tach_reg[i] + 1);
			if (ret < 0)
				goto error;
			data->tach[i] |= (ret >> 5) & 0x7;

			ret = i2c_smbus_read_byte_data(client, target_reg[i]);
			if (ret < 0)
				goto error;
			data->target[i] = (ret << 3) & 0x7f8;
			ret = i2c_smbus_read_byte_data(client, target_reg[i] + 1);
			if (ret < 0)
				goto error;
			data->target[i] |= (ret >> 5) & 0x7;
		}

		/*
		 * Alarms are cleared on read in case the condition that
		 * caused the alarm is removed. Keep the value latched here
		 * for providing the register through different alarm files.
		 */
		ret = i2c_smbus_read_byte_data(client, MAX6620_REG_FAULT);
		if (ret < 0)
			goto error;
		data->fault |= (ret >> 4) & (ret & 0x0F);

		data->last_updated = jiffies;
		data->valid = true;
	}

error:
	mutex_unlock(&data->update_lock);
	return ret;
}

static umode_t
max6620_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
		   int channel)
{
	switch (type) {
	case hwmon_fan:
		switch (attr) {
		case hwmon_fan_alarm:
		case hwmon_fan_input:
			return 0444;
		case hwmon_fan_div:
		case hwmon_fan_target:
			return 0644;
		default:
			break;
		}
		break;
	default:
		break;
	}

	return 0;
}

static int
max6620_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	     int channel, long *val)
{
	struct max6620_data *data;
	struct i2c_client *client;
	int ret;
	u8 div;
	u8 val1;
	u8 val2;

	ret = max6620_update_device(dev);
	if (ret < 0)
		return ret;
	data = dev_get_drvdata(dev);
	client = data->client;

	switch (type) {
	case hwmon_fan:
		switch (attr) {
		case hwmon_fan_alarm:
			mutex_lock(&data->update_lock);
			*val = !!(data->fault & BIT(channel));

			/* Setting TACH count to re-enable fan fault detection */
			if (*val == 1) {
				val1 = (data->target[channel] >> 3) & 0xff;
				val2 = (data->target[channel] << 5) & 0xe0;
				ret = i2c_smbus_write_byte_data(client,
								target_reg[channel], val1);
				if (ret < 0) {
					mutex_unlock(&data->update_lock);
					return ret;
				}
				ret = i2c_smbus_write_byte_data(client,
								target_reg[channel] + 1, val2);
				if (ret < 0) {
					mutex_unlock(&data->update_lock);
					return ret;
				}

				data->fault &= ~BIT(channel);
			}
			mutex_unlock(&data->update_lock);

			break;
		case hwmon_fan_div:
			*val = max6620_fan_div_from_reg(data->fandyn[channel]);
			break;
		case hwmon_fan_input:
			if (data->tach[channel] == 0) {
				*val = 0;
			} else {
				div = max6620_fan_div_from_reg(data->fandyn[channel]);
				*val = max6620_fan_tach_to_rpm(div, data->tach[channel]);
			}
			break;
		case hwmon_fan_target:
			if (data->target[channel] == 0) {
				*val = 0;
			} else {
				div = max6620_fan_div_from_reg(data->fandyn[channel]);
				*val = max6620_fan_tach_to_rpm(div, data->target[channel]);
			}
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;

	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int
max6620_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
	      int channel, long val)
{
	struct max6620_data *data;
	struct i2c_client *client;
	int ret;
	u8 div;
	u16 tach;
	u8 val1;
	u8 val2;

	ret = max6620_update_device(dev);
	if (ret < 0)
		return ret;
	data = dev_get_drvdata(dev);
	client = data->client;
	mutex_lock(&data->update_lock);

	switch (type) {
	case hwmon_fan:
		switch (attr) {
		case hwmon_fan_div:
			switch (val) {
			case 1:
				div = 0;
				break;
			case 2:
				div = 1;
				break;
			case 4:
				div = 2;
				break;
			case 8:
				div = 3;
				break;
			case 16:
				div = 4;
				break;
			case 32:
				div = 5;
				break;
			default:
				ret = -EINVAL;
				goto error;
			}
			data->fandyn[channel] &= 0x1F;
			data->fandyn[channel] |= div << 5;
			ret = i2c_smbus_write_byte_data(client, dyn_reg[channel],
							data->fandyn[channel]);
			break;
		case hwmon_fan_target:
			val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
			div = max6620_fan_div_from_reg(data->fandyn[channel]);
			tach = max6620_fan_rpm_to_tach(div, val);
			val1 = (tach >> 3) & 0xff;
			val2 = (tach << 5) & 0xe0;
			ret = i2c_smbus_write_byte_data(client, target_reg[channel], val1);
			if (ret < 0)
				break;
			ret = i2c_smbus_write_byte_data(client, target_reg[channel] + 1, val2);
			if (ret < 0)
				break;

			/* Setting TACH count re-enables fan fault detection */
			data->fault &= ~BIT(channel);

			break;
		default:
			ret = -EOPNOTSUPP;
			break;
		}
		break;

	default:
		ret = -EOPNOTSUPP;
		break;
	}

error:
	mutex_unlock(&data->update_lock);
	return ret;
}

static const struct hwmon_channel_info * const max6620_info[] = {
	HWMON_CHANNEL_INFO(fan,
			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
			   HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM),
	NULL
};

static const struct hwmon_ops max6620_hwmon_ops = {
	.read = max6620_read,
	.write = max6620_write,
	.is_visible = max6620_is_visible,
};

static const struct hwmon_chip_info max6620_chip_info = {
	.ops = &max6620_hwmon_ops,
	.info = max6620_info,
};

static int max6620_init_client(struct max6620_data *data)
{
	struct i2c_client *client = data->client;
	int config;
	int err;
	int i;
	int reg;

	config = i2c_smbus_read_byte_data(client, MAX6620_REG_CONFIG);
	if (config < 0) {
		dev_err(&client->dev, "Error reading config, aborting.\n");
		return config;
	}

	/*
	 * Set bit 4, disable other fans from going full speed on a fail
	 * failure.
	 */
	err = i2c_smbus_write_byte_data(client, MAX6620_REG_CONFIG, config | 0x10);
	if (err < 0) {
		dev_err(&client->dev, "Config write error, aborting.\n");
		return err;
	}

	for (i = 0; i < 4; i++) {
		reg = i2c_smbus_read_byte_data(client, config_reg[i]);
		if (reg < 0)
			return reg;
		data->fancfg[i] = reg;

		/* Enable RPM mode */
		data->fancfg[i] |= 0xa8;
		err = i2c_smbus_write_byte_data(client, config_reg[i], data->fancfg[i]);
		if (err < 0)
			return err;

		/* 2 counts (001) and Rate change 100 (0.125 secs) */
		data->fandyn[i] = 0x30;
		err = i2c_smbus_write_byte_data(client, dyn_reg[i], data->fandyn[i]);
		if (err < 0)
			return err;
	}
	return 0;
}

static int max6620_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct max6620_data *data;
	struct device *hwmon_dev;
	int err;

	data = devm_kzalloc(dev, sizeof(struct max6620_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->client = client;
	mutex_init(&data->update_lock);

	err = max6620_init_client(data);
	if (err)
		return err;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
							 data,
							 &max6620_chip_info,
							 NULL);

	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id max6620_id[] = {
	{ "max6620" },
	{ }
};
MODULE_DEVICE_TABLE(i2c, max6620_id);

static struct i2c_driver max6620_driver = {
	.class		= I2C_CLASS_HWMON,
	.driver = {
		.name	= "max6620",
	},
	.probe		= max6620_probe,
	.id_table	= max6620_id,
};

module_i2c_driver(max6620_driver);

MODULE_AUTHOR("Lucas Grunenberg");
MODULE_DESCRIPTION("MAX6620 sensor driver");
MODULE_LICENSE("GPL");