// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) 2011 David George <david.george@ska.ac.za>
 *
 * based on adm1021.c
 * some credit to Christoph Scheurer, but largely a rewrite
 */

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

/* Addresses to scan */
static const unsigned short max1668_addr_list[] = {
        0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, 0x4c, 0x4d, 0x4e, I2C_CLIENT_END };

/* max1668 registers */

#define MAX1668_REG_TEMP(nr)    (nr)
#define MAX1668_REG_STAT1       0x05
#define MAX1668_REG_STAT2       0x06
#define MAX1668_REG_MAN_ID      0xfe
#define MAX1668_REG_DEV_ID      0xff

/* limits */

/* high limits */
#define MAX1668_REG_LIMH(nr)    (0x08 + 2 * (nr))
/* read low limits */
#define MAX1668_REG_LIML(nr)    (0x09 + 2 * (nr))

/* manufacturer and device ID Constants */
#define MAN_ID_MAXIM            0x4d
#define DEV_ID_MAX1668          0x3
#define DEV_ID_MAX1805          0x5
#define DEV_ID_MAX1989          0xb

/* read only mode module parameter */
static bool read_only;
module_param(read_only, bool, 0);
MODULE_PARM_DESC(read_only, "Don't set any values, read only mode");

struct max1668_data {
        struct regmap *regmap;
        int channels;
};

static int max1668_read(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long *val)
{
        struct max1668_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;
        u32 regs[2] = { MAX1668_REG_STAT1, MAX1668_REG_TEMP(channel) };
        u8 regvals[2];
        u32 regval;
        int ret;

        switch (attr) {
        case hwmon_temp_input:
                ret = regmap_read(regmap, MAX1668_REG_TEMP(channel), &regval);
                if (ret)
                        return ret;
                *val = sign_extend32(regval, 7) * 1000;
                break;
        case hwmon_temp_min:
                ret = regmap_read(regmap, MAX1668_REG_LIML(channel), &regval);
                if (ret)
                        return ret;
                *val = sign_extend32(regval, 7) * 1000;
                break;
        case hwmon_temp_max:
                ret = regmap_read(regmap, MAX1668_REG_LIMH(channel), &regval);
                if (ret)
                        return ret;
                *val = sign_extend32(regval, 7) * 1000;
                break;
        case hwmon_temp_min_alarm:
                ret = regmap_read(regmap,
                                  channel ? MAX1668_REG_STAT2 : MAX1668_REG_STAT1,
                                  &regval);
                if (ret)
                        return ret;
                if (channel)
                        *val = !!(regval & BIT(9 - channel * 2));
                else
                        *val = !!(regval & BIT(5));
                break;
        case hwmon_temp_max_alarm:
                ret = regmap_read(regmap,
                                  channel ? MAX1668_REG_STAT2 : MAX1668_REG_STAT1,
                                  &regval);
                if (ret)
                        return ret;
                if (channel)
                        *val = !!(regval & BIT(8 - channel * 2));
                else
                        *val = !!(regval & BIT(6));
                break;
        case hwmon_temp_fault:
                ret = regmap_multi_reg_read(regmap, regs, regvals, 2);
                if (ret)
                        return ret;
                *val = !!((regvals[0] & BIT(4)) && regvals[1] == 127);
                break;
        default:
                return -EOPNOTSUPP;
        }
        return 0;
}

static int max1668_write(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long val)
{
        struct max1668_data *data = dev_get_drvdata(dev);
        struct regmap *regmap = data->regmap;

        val = clamp_val(val / 1000, -128, 127);

        switch (attr) {
        case hwmon_temp_min:
                return regmap_write(regmap, MAX1668_REG_LIML(channel), val);
        case hwmon_temp_max:
                return regmap_write(regmap, MAX1668_REG_LIMH(channel), val);
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t max1668_is_visible(const void *_data, enum hwmon_sensor_types type,
                                  u32 attr, int channel)
{
        const struct max1668_data *data = _data;

        if (channel >= data->channels)
                return 0;

        switch (attr) {
        case hwmon_temp_min:
        case hwmon_temp_max:
                return read_only ? 0444 : 0644;
        case hwmon_temp_input:
        case hwmon_temp_min_alarm:
        case hwmon_temp_max_alarm:
                return 0444;
        case hwmon_temp_fault:
                if (channel)
                        return 0444;
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_channel_info * const max1668_info[] = {
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
                           HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
                           HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
                           HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
                           HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
                           HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
                           HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
                           HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
                           HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
                           HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
                           HWMON_T_FAULT),
        NULL
};

static const struct hwmon_ops max1668_hwmon_ops = {
        .is_visible = max1668_is_visible,
        .read = max1668_read,
        .write = max1668_write,
};

static const struct hwmon_chip_info max1668_chip_info = {
        .ops = &max1668_hwmon_ops,
        .info = max1668_info,
};

/* Return 0 if detection is successful, -ENODEV otherwise */
static int max1668_detect(struct i2c_client *client,
                          struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = client->adapter;
        const char *type_name;
        int man_id, dev_id;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
                return -ENODEV;

        /* Check for unsupported part */
        man_id = i2c_smbus_read_byte_data(client, MAX1668_REG_MAN_ID);
        if (man_id != MAN_ID_MAXIM)
                return -ENODEV;

        dev_id = i2c_smbus_read_byte_data(client, MAX1668_REG_DEV_ID);
        if (dev_id < 0)
                return -ENODEV;

        type_name = NULL;
        if (dev_id == DEV_ID_MAX1668)
                type_name = "max1668";
        else if (dev_id == DEV_ID_MAX1805)
                type_name = "max1805";
        else if (dev_id == DEV_ID_MAX1989)
                type_name = "max1989";

        if (!type_name)
                return -ENODEV;

        strscpy(info->type, type_name, I2C_NAME_SIZE);

        return 0;
}

/* regmap */

static int max1668_reg_read(void *context, unsigned int reg, unsigned int *val)
{
        int ret;

        ret = i2c_smbus_read_byte_data(context, reg);
        if (ret < 0)
                return ret;

        *val = ret;
        return 0;
}

static int max1668_reg_write(void *context, unsigned int reg, unsigned int val)
{
        return i2c_smbus_write_byte_data(context, reg + 11, val);
}

static bool max1668_regmap_is_volatile(struct device *dev, unsigned int reg)
{
        return reg <= MAX1668_REG_STAT2;
}

static bool max1668_regmap_is_writeable(struct device *dev, unsigned int reg)
{
        return reg > MAX1668_REG_STAT2 && reg <= MAX1668_REG_LIML(4);
}

static const struct regmap_config max1668_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .cache_type = REGCACHE_MAPLE,
        .volatile_reg = max1668_regmap_is_volatile,
        .writeable_reg = max1668_regmap_is_writeable,
};

static const struct regmap_bus max1668_regmap_bus = {
        .reg_write = max1668_reg_write,
        .reg_read = max1668_reg_read,
};

static int max1668_probe(struct i2c_client *client)
{
        struct i2c_adapter *adapter = client->adapter;
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct max1668_data *data;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
                return -ENODEV;

        data = devm_kzalloc(dev, sizeof(struct max1668_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->regmap = devm_regmap_init(dev, &max1668_regmap_bus, client,
                                        &max1668_regmap_config);
        if (IS_ERR(data->regmap))
                return PTR_ERR(data->regmap);

        data->channels = (uintptr_t)i2c_get_match_data(client);

        hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
                                                         &max1668_chip_info, NULL);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id max1668_id[] = {
        { "max1668", 5 },
        { "max1805", 3 },
        { "max1989", 5 },
        { }
};
MODULE_DEVICE_TABLE(i2c, max1668_id);

/* This is the driver that will be inserted */
static struct i2c_driver max1668_driver = {
        .class = I2C_CLASS_HWMON,
        .driver = {
                  .name = "max1668",
                  },
        .probe = max1668_probe,
        .id_table = max1668_id,
        .detect = max1668_detect,
        .address_list = max1668_addr_list,
};

module_i2c_driver(max1668_driver);

MODULE_AUTHOR("David George <david.george@ska.ac.za>");
MODULE_DESCRIPTION("MAX1668 remote temperature sensor driver");
MODULE_LICENSE("GPL");