// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller
 *
 * Copyright (c) 2014 Guenter Roeck
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/regmap.h>

/* chip registers */
#define LTC4260_CONTROL 0x00
#define LTC4260_ALERT   0x01
#define LTC4260_STATUS  0x02
#define LTC4260_FAULT   0x03
#define LTC4260_SENSE   0x04
#define LTC4260_SOURCE  0x05
#define LTC4260_ADIN    0x06

/*
 * Fault register bits
 */
#define FAULT_OV        (1 << 0)
#define FAULT_UV        (1 << 1)
#define FAULT_OC        (1 << 2)
#define FAULT_POWER_BAD (1 << 3)
#define FAULT_FET_SHORT (1 << 5)

/* Return the voltage from the given register in mV or mA */
static int ltc4260_get_value(struct device *dev, u8 reg)
{
        struct regmap *regmap = dev_get_drvdata(dev);
        unsigned int val;
        int ret;

        ret = regmap_read(regmap, reg, &val);
        if (ret < 0)
                return ret;

        switch (reg) {
        case LTC4260_ADIN:
                /* 10 mV resolution. Convert to mV. */
                val = val * 10;
                break;
        case LTC4260_SOURCE:
                /* 400 mV resolution. Convert to mV. */
                val = val * 400;
                break;
        case LTC4260_SENSE:
                /*
                 * 300 uV resolution. Convert to current as measured with
                 * an 1 mOhm sense resistor, in mA. If a different sense
                 * resistor is installed, calculate the actual current by
                 * dividing the reported current by the sense resistor value
                 * in mOhm.
                 */
                val = val * 300;
                break;
        default:
                return -EINVAL;
        }

        return val;
}

static ssize_t ltc4260_value_show(struct device *dev,
                                  struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        int value;

        value = ltc4260_get_value(dev, attr->index);
        if (value < 0)
                return value;
        return sysfs_emit(buf, "%d\n", value);
}

static ssize_t ltc4260_bool_show(struct device *dev,
                                 struct device_attribute *da, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct regmap *regmap = dev_get_drvdata(dev);
        unsigned int fault;
        int ret;

        ret = regmap_read(regmap, LTC4260_FAULT, &fault);
        if (ret < 0)
                return ret;

        fault &= attr->index;
        if (fault)              /* Clear reported faults in chip register */
                regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0);

        return sysfs_emit(buf, "%d\n", !!fault);
}

/* Voltages */
static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4260_value, LTC4260_SOURCE);
static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4260_value, LTC4260_ADIN);

/*
 * Voltage alarms
 * UV/OV faults are associated with the input voltage, and the POWER BAD and
 * FET SHORT faults are associated with the output voltage.
 */
static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4260_bool, FAULT_UV);
static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4260_bool, FAULT_OV);
static SENSOR_DEVICE_ATTR_RO(in2_alarm, ltc4260_bool,
                             FAULT_POWER_BAD | FAULT_FET_SHORT);

/* Current (via sense resistor) */
static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4260_value, LTC4260_SENSE);

/* Overcurrent alarm */
static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4260_bool, FAULT_OC);

static struct attribute *ltc4260_attrs[] = {
        &sensor_dev_attr_in1_input.dev_attr.attr,
        &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
        &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
        &sensor_dev_attr_in2_input.dev_attr.attr,
        &sensor_dev_attr_in2_alarm.dev_attr.attr,

        &sensor_dev_attr_curr1_input.dev_attr.attr,
        &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,

        NULL,
};
ATTRIBUTE_GROUPS(ltc4260);

static const struct regmap_config ltc4260_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = LTC4260_ADIN,
};

static int ltc4260_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct regmap *regmap;

        regmap = devm_regmap_init_i2c(client, &ltc4260_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(dev, "failed to allocate register map\n");
                return PTR_ERR(regmap);
        }

        /* Clear faults */
        regmap_write(regmap, LTC4260_FAULT, 0x00);

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           regmap,
                                                           ltc4260_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ltc4260_id[] = {
        {"ltc4260"},
        { }
};

MODULE_DEVICE_TABLE(i2c, ltc4260_id);

static struct i2c_driver ltc4260_driver = {
        .driver = {
                   .name = "ltc4260",
                   },
        .probe = ltc4260_probe,
        .id_table = ltc4260_id,
};

module_i2c_driver(ltc4260_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("LTC4260 driver");
MODULE_LICENSE("GPL");