// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * isl28022.c - driver for Renesas ISL28022 power monitor chip monitoring
 *
 * Copyright (c) 2023 Carsten Spieß <mail@carsten-spiess.de>
 */

#include <linux/debugfs.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>

/* ISL28022 registers */
#define ISL28022_REG_CONFIG     0x00
#define ISL28022_REG_SHUNT      0x01
#define ISL28022_REG_BUS        0x02
#define ISL28022_REG_POWER      0x03
#define ISL28022_REG_CURRENT    0x04
#define ISL28022_REG_CALIB      0x05
#define ISL28022_REG_SHUNT_THR  0x06
#define ISL28022_REG_BUS_THR    0x07
#define ISL28022_REG_INT        0x08
#define ISL28022_REG_AUX        0x09
#define ISL28022_REG_MAX        ISL28022_REG_AUX

/* ISL28022 config flags */
/* mode flags */
#define ISL28022_MODE_SHIFT     0
#define ISL28022_MODE_MASK      0x0007

#define ISL28022_MODE_PWR_DOWN  0x0
#define ISL28022_MODE_TRG_S     0x1
#define ISL28022_MODE_TRG_B     0x2
#define ISL28022_MODE_TRG_SB    0x3
#define ISL28022_MODE_ADC_OFF   0x4
#define ISL28022_MODE_CONT_S    0x5
#define ISL28022_MODE_CONT_B    0x6
#define ISL28022_MODE_CONT_SB   0x7

/* shunt ADC settings */
#define ISL28022_SADC_SHIFT     3
#define ISL28022_SADC_MASK      0x0078

#define ISL28022_BADC_SHIFT     7
#define ISL28022_BADC_MASK      0x0780

#define ISL28022_ADC_12         0x0     /* 12 bit ADC */
#define ISL28022_ADC_13         0x1     /* 13 bit ADC */
#define ISL28022_ADC_14         0x2     /* 14 bit ADC */
#define ISL28022_ADC_15         0x3     /* 15 bit ADC */
#define ISL28022_ADC_15_1       0x8     /* 15 bit ADC, 1 sample */
#define ISL28022_ADC_15_2       0x9     /* 15 bit ADC, 2 samples */
#define ISL28022_ADC_15_4       0xA     /* 15 bit ADC, 4 samples */
#define ISL28022_ADC_15_8       0xB     /* 15 bit ADC, 8 samples */
#define ISL28022_ADC_15_16      0xC     /* 15 bit ADC, 16 samples */
#define ISL28022_ADC_15_32      0xD     /* 15 bit ADC, 32 samples */
#define ISL28022_ADC_15_64      0xE     /* 15 bit ADC, 64 samples */
#define ISL28022_ADC_15_128     0xF     /* 15 bit ADC, 128 samples */

/* shunt voltage range */
#define ISL28022_PG_SHIFT       11
#define ISL28022_PG_MASK        0x1800

#define ISL28022_PG_40          0x0     /* +/-40 mV */
#define ISL28022_PG_80          0x1     /* +/-80 mV */
#define ISL28022_PG_160         0x2     /* +/-160 mV */
#define ISL28022_PG_320         0x3     /* +/-3200 mV */

/* bus voltage range */
#define ISL28022_BRNG_SHIFT     13
#define ISL28022_BRNG_MASK      0x6000

#define ISL28022_BRNG_16        0x0     /* 16 V */
#define ISL28022_BRNG_32        0x1     /* 32 V */
#define ISL28022_BRNG_60        0x3     /* 60 V */

/* reset */
#define ISL28022_RESET          0x8000

struct isl28022_data {
        struct regmap           *regmap;
        u32                     shunt;
        u32                     gain;
        u32                     average;
};

static int isl28022_read_in(struct device *dev, u32 attr, int channel, long *val)
{
        struct isl28022_data *data = dev_get_drvdata(dev);
        unsigned int regval;
        int err;
        u16 sign_bit;

        switch (channel) {
        case 0:
                switch (attr) {
                case hwmon_in_input:
                        err = regmap_read(data->regmap,
                                          ISL28022_REG_BUS, &regval);
                        if (err < 0)
                                return err;
                        /* driver supports only 60V mode (BRNG 11) */
                        *val = (long)(((u16)regval) & 0xFFFC);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        case 1:
                switch (attr) {
                case hwmon_in_input:
                        err = regmap_read(data->regmap,
                                          ISL28022_REG_SHUNT, &regval);
                        if (err < 0)
                                return err;
                        switch (data->gain) {
                        case 8:
                                sign_bit = (regval >> 15) & 0x01;
                                *val = (long)((((u16)regval) & 0x7FFF) -
                                        (sign_bit * 32768)) / 100;
                                break;
                        case 4:
                                sign_bit = (regval >> 14) & 0x01;
                                *val = (long)((((u16)regval) & 0x3FFF) -
                                        (sign_bit * 16384)) / 100;
                                break;
                        case 2:
                                sign_bit = (regval >> 13) & 0x01;
                                *val = (long)((((u16)regval) & 0x1FFF) -
                                        (sign_bit * 8192)) / 100;
                                break;
                        case 1:
                                sign_bit = (regval >> 12) & 0x01;
                                *val = (long)((((u16)regval) & 0x0FFF) -
                                        (sign_bit * 4096)) / 100;
                                break;
                        }
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int isl28022_read_current(struct device *dev, u32 attr, long *val)
{
        struct isl28022_data *data = dev_get_drvdata(dev);
        unsigned int regval;
        int err;
        u16 sign_bit;

        switch (attr) {
        case hwmon_curr_input:
                err = regmap_read(data->regmap,
                                  ISL28022_REG_CURRENT, &regval);
                if (err < 0)
                        return err;
                sign_bit = (regval >> 15) & 0x01;
                *val = (((long)(((u16)regval) & 0x7FFF) - (sign_bit * 32768)) *
                        1250L * (long)data->gain) / (long)data->shunt;
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int isl28022_read_power(struct device *dev, u32 attr, long *val)
{
        struct isl28022_data *data = dev_get_drvdata(dev);
        unsigned int regval;
        int err;

        switch (attr) {
        case hwmon_power_input:
                err = regmap_read(data->regmap,
                                  ISL28022_REG_POWER, &regval);
                if (err < 0)
                        return err;
                *val = ((51200000L * ((long)data->gain)) /
                        (long)data->shunt) * (long)regval;
                break;
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int isl28022_read(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long *val)
{
        switch (type) {
        case hwmon_in:
                return isl28022_read_in(dev, attr, channel, val);
        case hwmon_curr:
                return isl28022_read_current(dev, attr, val);
        case hwmon_power:
                return isl28022_read_power(dev, attr, val);
        default:
                return -EOPNOTSUPP;
        }
        return 0;
}

static umode_t isl28022_is_visible(const void *data, enum hwmon_sensor_types type,
                                   u32 attr, int channel)
{
        switch (type) {
        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_power:
                switch (attr) {
                case hwmon_power_input:
                        return 0444;
                default:
                        break;
                }
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_channel_info *isl28022_info[] = {
        HWMON_CHANNEL_INFO(in,
                           HWMON_I_INPUT,       /* channel 0: bus voltage (mV) */
                           HWMON_I_INPUT),      /* channel 1: shunt voltage (mV) */
        HWMON_CHANNEL_INFO(curr,
                           HWMON_C_INPUT),      /* channel 1: current (mA) */
        HWMON_CHANNEL_INFO(power,
                           HWMON_P_INPUT),      /* channel 1: power (µW) */
        NULL
};

static const struct hwmon_ops isl28022_hwmon_ops = {
        .is_visible = isl28022_is_visible,
        .read = isl28022_read,
};

static const struct hwmon_chip_info isl28022_chip_info = {
        .ops = &isl28022_hwmon_ops,
        .info = isl28022_info,
};

static bool isl28022_is_writeable_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case ISL28022_REG_CONFIG:
        case ISL28022_REG_CALIB:
        case ISL28022_REG_SHUNT_THR:
        case ISL28022_REG_BUS_THR:
        case ISL28022_REG_INT:
        case ISL28022_REG_AUX:
                return true;
        }

        return false;
}

static bool isl28022_is_volatile_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case ISL28022_REG_CONFIG:
        case ISL28022_REG_SHUNT:
        case ISL28022_REG_BUS:
        case ISL28022_REG_POWER:
        case ISL28022_REG_CURRENT:
        case ISL28022_REG_INT:
        case ISL28022_REG_AUX:
                return true;
        }
        return true;
}

static const struct regmap_config isl28022_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .max_register = ISL28022_REG_MAX,
        .writeable_reg = isl28022_is_writeable_reg,
        .volatile_reg = isl28022_is_volatile_reg,
        .val_format_endian = REGMAP_ENDIAN_BIG,
        .cache_type = REGCACHE_MAPLE,
        .use_single_read = true,
        .use_single_write = true,
};

static int shunt_voltage_show(struct seq_file *seqf, void *unused)
{
        struct isl28022_data *data = seqf->private;
        unsigned int regval;
        int err;

        err = regmap_read(data->regmap,
                          ISL28022_REG_SHUNT, &regval);
        if (err)
                return err;

        /* print shunt voltage in micro volt  */
        seq_printf(seqf, "%d\n", regval * 10);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(shunt_voltage);

/*
 * read property values and make consistency checks.
 *
 * following values for shunt range and resistor are allowed:
 *   40 mV -> gain 1, shunt min.  800 micro ohms
 *   80 mV -> gain 2, shunt min. 1600 micro ohms
 *  160 mV -> gain 4, shunt min. 3200 micro ohms
 *  320 mV -> gain 8, shunt min. 6400 micro ohms
 */
static int isl28022_read_properties(struct device *dev, struct isl28022_data *data)
{
        u32 val;
        int err;

        err = device_property_read_u32(dev, "shunt-resistor-micro-ohms", &val);
        if (err == -EINVAL)
                val = 10000;
        else if (err < 0)
                return err;
        data->shunt = val;

        err = device_property_read_u32(dev, "renesas,shunt-range-microvolt", &val);
        if (err == -EINVAL)
                val = 320000;
        else if (err < 0)
                return err;

        switch (val) {
        case 40000:
                data->gain = 1;
                if (data->shunt < 800)
                        goto shunt_invalid;
                break;
        case 80000:
                data->gain = 2;
                if (data->shunt < 1600)
                        goto shunt_invalid;
                break;
        case 160000:
                data->gain = 4;
                if (data->shunt < 3200)
                        goto shunt_invalid;
                break;
        case 320000:
                data->gain = 8;
                if (data->shunt < 6400)
                        goto shunt_invalid;
                break;
        default:
                return dev_err_probe(dev, -EINVAL,
                                     "renesas,shunt-range-microvolt invalid value %d\n",
                                     val);
        }

        err = device_property_read_u32(dev, "renesas,average-samples", &val);
        if (err == -EINVAL)
                val = 1;
        else if (err < 0)
                return err;
        if (val > 128 || hweight32(val) != 1)
                return dev_err_probe(dev, -EINVAL,
                                     "renesas,average-samples invalid value %d\n",
                                     val);

        data->average = val;

        return 0;

shunt_invalid:
        return dev_err_probe(dev, -EINVAL,
                             "renesas,shunt-resistor-microvolt invalid value %d\n",
                             data->shunt);
}

/*
 * write configuration and calibration registers
 *
 * The driver supports only shunt and bus continuous ADC mode at 15bit resolution
 * with averaging from 1 to 128 samples (pow of 2) on both channels.
 * Shunt voltage gain 1,2,4 or 8 is allowed.
 * The bus voltage range is 60V fixed.
 */
static int isl28022_config(struct isl28022_data *data)
{
        int err;
        u16 config;
        u16 calib;

        config = (ISL28022_MODE_CONT_SB << ISL28022_MODE_SHIFT) |
                        (ISL28022_BRNG_60 << ISL28022_BRNG_SHIFT) |
                        (__ffs(data->gain) << ISL28022_PG_SHIFT) |
                        ((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_SADC_SHIFT) |
                        ((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_BADC_SHIFT);

        calib = data->shunt ? 0x8000 / data->gain : 0;

        err = regmap_write(data->regmap, ISL28022_REG_CONFIG, config);
        if (err < 0)
                return err;

        return regmap_write(data->regmap, ISL28022_REG_CALIB, calib);
}

static int isl28022_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct isl28022_data *data;
        int err;

        if (!i2c_check_functionality(client->adapter,
                                     I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_WORD_DATA))
                return -ENODEV;

        data = devm_kzalloc(dev, sizeof(struct isl28022_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        err = isl28022_read_properties(dev, data);
        if (err)
                return err;

        data->regmap = devm_regmap_init_i2c(client, &isl28022_regmap_config);
        if (IS_ERR(data->regmap))
                return PTR_ERR(data->regmap);

        err = isl28022_config(data);
        if (err)
                return err;

        debugfs_create_file("shunt_voltage", 0444, client->debugfs, data, &shunt_voltage_fops);

        hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
                                                         data, &isl28022_chip_info, NULL);
        if (IS_ERR(hwmon_dev))
                return PTR_ERR(hwmon_dev);

        return 0;
}

static const struct i2c_device_id isl28022_ids[] = {
        { "isl28022" },
        { /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, isl28022_ids);

static const struct of_device_id __maybe_unused isl28022_of_match[] = {
        { .compatible = "renesas,isl28022"},
        { /* LIST END */ }
};
MODULE_DEVICE_TABLE(of, isl28022_of_match);

static struct i2c_driver isl28022_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "isl28022",
        },
        .probe  = isl28022_probe,
        .id_table       = isl28022_ids,
};
module_i2c_driver(isl28022_driver);

MODULE_AUTHOR("Carsten Spieß <mail@carsten-spiess.de>");
MODULE_DESCRIPTION("ISL28022 driver");
MODULE_LICENSE("GPL");