// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C client/driver for the Linear Technology LTC2941, LTC2942, LTC2943
 * and LTC2944 Battery Gas Gauge IC
 *
 * Copyright (C) 2014 Topic Embedded Systems
 *
 * Author: Auryn Verwegen
 * Author: Mike Looijmans
 */
#include <linux/devm-helpers.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/swab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/power_supply.h>
#include <linux/slab.h>

#define I16_MSB(x)                      ((x >> 8) & 0xFF)
#define I16_LSB(x)                      (x & 0xFF)

#define LTC294X_WORK_DELAY              10      /* Update delay in seconds */

#define LTC294X_MAX_VALUE               0xFFFF
#define LTC294X_MID_SUPPLY              0x7FFF

#define LTC2941_MAX_PRESCALER_EXP       7
#define LTC2943_MAX_PRESCALER_EXP       6

enum ltc294x_reg {
        LTC294X_REG_STATUS              = 0x00,
        LTC294X_REG_CONTROL             = 0x01,
        LTC294X_REG_ACC_CHARGE_MSB      = 0x02,
        LTC294X_REG_ACC_CHARGE_LSB      = 0x03,
        LTC294X_REG_CHARGE_THR_HIGH_MSB = 0x04,
        LTC294X_REG_CHARGE_THR_HIGH_LSB = 0x05,
        LTC294X_REG_CHARGE_THR_LOW_MSB  = 0x06,
        LTC294X_REG_CHARGE_THR_LOW_LSB  = 0x07,
        LTC294X_REG_VOLTAGE_MSB         = 0x08,
        LTC294X_REG_VOLTAGE_LSB         = 0x09,
        LTC2942_REG_TEMPERATURE_MSB     = 0x0C,
        LTC2942_REG_TEMPERATURE_LSB     = 0x0D,
        LTC2943_REG_CURRENT_MSB         = 0x0E,
        LTC2943_REG_CURRENT_LSB         = 0x0F,
        LTC2943_REG_TEMPERATURE_MSB     = 0x14,
        LTC2943_REG_TEMPERATURE_LSB     = 0x15,
};

enum ltc294x_id {
        LTC2941_ID,
        LTC2942_ID,
        LTC2943_ID,
        LTC2944_ID,
};

#define LTC2941_REG_STATUS_CHIP_ID      BIT(7)

#define LTC2942_REG_CONTROL_MODE_SCAN   (BIT(7) | BIT(6))
#define LTC2943_REG_CONTROL_MODE_SCAN   BIT(7)
#define LTC294X_REG_CONTROL_PRESCALER_MASK      (BIT(5) | BIT(4) | BIT(3))
#define LTC294X_REG_CONTROL_SHUTDOWN_MASK       (BIT(0))
#define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
        ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
#define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED        0
#define LTC294X_REG_CONTROL_ADC_DISABLE(x)      ((x) & ~(BIT(7) | BIT(6)))

struct ltc294x_info {
        struct i2c_client *client;      /* I2C Client pointer */
        struct power_supply *supply;    /* Supply pointer */
        struct power_supply_desc supply_desc;   /* Supply description */
        struct delayed_work work;       /* Work scheduler */
        enum ltc294x_id id;             /* Chip type */
        int charge;     /* Last charge register content */
        int r_sense;    /* mOhm */
        int Qlsb;       /* nAh */
};

static inline int convert_bin_to_uAh(
        const struct ltc294x_info *info, int Q)
{
        return ((Q * (info->Qlsb / 10))) / 100;
}

static inline int convert_uAh_to_bin(
        const struct ltc294x_info *info, int uAh)
{
        int Q;

        Q = (uAh * 100) / (info->Qlsb/10);
        return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
}

static int ltc294x_read_regs(struct i2c_client *client,
        enum ltc294x_reg reg, u8 *buf, int num_regs)
{
        int ret;
        struct i2c_msg msgs[2] = { };
        u8 reg_start = reg;

        msgs[0].addr    = client->addr;
        msgs[0].len     = 1;
        msgs[0].buf     = &reg_start;

        msgs[1].addr    = client->addr;
        msgs[1].len     = num_regs;
        msgs[1].buf     = buf;
        msgs[1].flags   = I2C_M_RD;

        ret = i2c_transfer(client->adapter, &msgs[0], 2);
        if (ret < 0) {
                dev_err(&client->dev, "ltc2941 read_reg(0x%x[%d]) failed: %pe\n",
                        reg, num_regs, ERR_PTR(ret));
                return ret;
        }

        dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
                __func__, reg, num_regs, *buf);

        return 0;
}

static int ltc294x_write_regs(struct i2c_client *client,
        enum ltc294x_reg reg, const u8 *buf, int num_regs)
{
        int ret;
        u8 reg_start = reg;

        ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
        if (ret < 0) {
                dev_err(&client->dev, "ltc2941 write_reg(0x%x[%d]) failed: %pe\n",
                        reg, num_regs, ERR_PTR(ret));
                return ret;
        }

        dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
                __func__, reg, num_regs, *buf);

        return 0;
}

static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
{
        int ret;
        u8 value;
        u8 control;

        /* Read status and control registers */
        ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
        if (ret < 0)
                return ret;

        control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
                                LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
        /* Put device into "monitor" mode */
        switch (info->id) {
        case LTC2942_ID:        /* 2942 measures every 2 sec */
                control |= LTC2942_REG_CONTROL_MODE_SCAN;
                break;
        case LTC2943_ID:
        case LTC2944_ID:        /* 2943 and 2944 measure every 10 sec */
                control |= LTC2943_REG_CONTROL_MODE_SCAN;
                break;
        default:
                break;
        }

        if (value != control) {
                ret = ltc294x_write_regs(info->client,
                        LTC294X_REG_CONTROL, &control, 1);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static int ltc294x_read_charge_register(const struct ltc294x_info *info,
                                        enum ltc294x_reg reg)
 {
        int ret;
        u8 datar[2];

        ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
        if (ret < 0)
                return ret;
        return (datar[0] << 8) + datar[1];
}

static int ltc294x_get_charge(const struct ltc294x_info *info,
                                enum ltc294x_reg reg, int *val)
{
        int value = ltc294x_read_charge_register(info, reg);

        if (value < 0)
                return value;
        /* When r_sense < 0, this counts up when the battery discharges */
        if (info->Qlsb < 0)
                value -= 0xFFFF;
        *val = convert_bin_to_uAh(info, value);
        return 0;
}

static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
{
        int ret;
        u8 dataw[2];
        u8 ctrl_reg;
        s32 value;

        value = convert_uAh_to_bin(info, val);
        /* Direction depends on how sense+/- were connected */
        if (info->Qlsb < 0)
                value += 0xFFFF;
        if ((value < 0) || (value > 0xFFFF)) /* input validation */
                return -EINVAL;

        /* Read control register */
        ret = ltc294x_read_regs(info->client,
                LTC294X_REG_CONTROL, &ctrl_reg, 1);
        if (ret < 0)
                return ret;
        /* Disable analog section */
        ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
        ret = ltc294x_write_regs(info->client,
                LTC294X_REG_CONTROL, &ctrl_reg, 1);
        if (ret < 0)
                return ret;
        /* Set new charge value */
        dataw[0] = I16_MSB(value);
        dataw[1] = I16_LSB(value);
        ret = ltc294x_write_regs(info->client,
                LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
        if (ret < 0)
                goto error_exit;
        /* Enable analog section */
error_exit:
        ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
        ret = ltc294x_write_regs(info->client,
                LTC294X_REG_CONTROL, &ctrl_reg, 1);

        return ret < 0 ? ret : 0;
}

static int ltc294x_set_charge_thr(const struct ltc294x_info *info,
                                        enum ltc294x_reg reg, int val)
{
        u8 dataw[2];
        s32 value;

        value = convert_uAh_to_bin(info, val);
        /* Direction depends on how sense+/- were connected */
        if (info->Qlsb < 0)
                value += 0xFFFF;
        if ((value < 0) || (value > 0xFFFF)) /* input validation */
                return -EINVAL;

        /* Set new charge value */
        dataw[0] = I16_MSB(value);
        dataw[1] = I16_LSB(value);
        return ltc294x_write_regs(info->client, reg, &dataw[0], 2);
}

static int ltc294x_get_charge_counter(
        const struct ltc294x_info *info, int *val)
{
        int value = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);

        if (value < 0)
                return value;
        value -= LTC294X_MID_SUPPLY;
        *val = convert_bin_to_uAh(info, value);
        return 0;
}

static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
{
        int ret;
        u8 datar[2];
        u32 value;

        ret = ltc294x_read_regs(info->client,
                LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
        value = (datar[0] << 8) | datar[1];
        switch (info->id) {
        case LTC2943_ID:
                value *= 23600 * 2;
                value /= 0xFFFF;
                value *= 1000 / 2;
                break;
        case LTC2944_ID:
                value *= 70800 / 5*4;
                value /= 0xFFFF;
                value *= 1000 * 5/4;
                break;
        default:
                value *= 6000 * 10;
                value /= 0xFFFF;
                value *= 1000 / 10;
                break;
        }
        *val = value;
        return ret;
}

static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
{
        int ret;
        u8 datar[2];
        s32 value;

        ret = ltc294x_read_regs(info->client,
                LTC2943_REG_CURRENT_MSB, &datar[0], 2);
        value = (datar[0] << 8) | datar[1];
        value -= 0x7FFF;
        if (info->id == LTC2944_ID)
                value *= 64000;
        else
                value *= 60000;
        /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
         * the formula below keeps everything in s32 range while preserving
         * enough digits */
        *val = 1000 * (value / (info->r_sense * 0x7FFF)); /* in uA */
        return ret;
}

static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
{
        enum ltc294x_reg reg;
        int ret;
        u8 datar[2];
        u32 value;

        if (info->id == LTC2942_ID) {
                reg = LTC2942_REG_TEMPERATURE_MSB;
                value = 6000;   /* Full-scale is 600 Kelvin */
        } else {
                reg = LTC2943_REG_TEMPERATURE_MSB;
                value = 5100;   /* Full-scale is 510 Kelvin */
        }
        ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
        value *= (datar[0] << 8) | datar[1];
        /* Convert to tenths of degree Celsius */
        *val = value / 0xFFFF - 2722;
        return ret;
}

static int ltc294x_get_property(struct power_supply *psy,
                                enum power_supply_property prop,
                                union power_supply_propval *val)
{
        struct ltc294x_info *info = power_supply_get_drvdata(psy);

        switch (prop) {
        case POWER_SUPPLY_PROP_CHARGE_FULL:
                return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_HIGH_MSB,
                                                &val->intval);
        case POWER_SUPPLY_PROP_CHARGE_EMPTY:
                return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_LOW_MSB,
                                                &val->intval);
        case POWER_SUPPLY_PROP_CHARGE_NOW:
                return ltc294x_get_charge(info, LTC294X_REG_ACC_CHARGE_MSB,
                                                &val->intval);
        case POWER_SUPPLY_PROP_CHARGE_COUNTER:
                return ltc294x_get_charge_counter(info, &val->intval);
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                return ltc294x_get_voltage(info, &val->intval);
        case POWER_SUPPLY_PROP_CURRENT_NOW:
                return ltc294x_get_current(info, &val->intval);
        case POWER_SUPPLY_PROP_TEMP:
                return ltc294x_get_temperature(info, &val->intval);
        default:
                return -EINVAL;
        }
}

static int ltc294x_set_property(struct power_supply *psy,
        enum power_supply_property psp,
        const union power_supply_propval *val)
{
        struct ltc294x_info *info = power_supply_get_drvdata(psy);

        switch (psp) {
        case POWER_SUPPLY_PROP_CHARGE_FULL:
                return ltc294x_set_charge_thr(info,
                        LTC294X_REG_CHARGE_THR_HIGH_MSB, val->intval);
        case POWER_SUPPLY_PROP_CHARGE_EMPTY:
                return ltc294x_set_charge_thr(info,
                        LTC294X_REG_CHARGE_THR_LOW_MSB, val->intval);
        case POWER_SUPPLY_PROP_CHARGE_NOW:
                return ltc294x_set_charge_now(info, val->intval);
        default:
                return -EPERM;
        }
}

static int ltc294x_property_is_writeable(
        struct power_supply *psy, enum power_supply_property psp)
{
        switch (psp) {
        case POWER_SUPPLY_PROP_CHARGE_FULL:
        case POWER_SUPPLY_PROP_CHARGE_EMPTY:
        case POWER_SUPPLY_PROP_CHARGE_NOW:
                return 1;
        default:
                return 0;
        }
}

static void ltc294x_update(struct ltc294x_info *info)
{
        int charge = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);

        if (charge != info->charge) {
                info->charge = charge;
                power_supply_changed(info->supply);
        }
}

static void ltc294x_work(struct work_struct *work)
{
        struct ltc294x_info *info;

        info = container_of(work, struct ltc294x_info, work.work);
        ltc294x_update(info);
        schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
}

static enum power_supply_property ltc294x_properties[] = {
        POWER_SUPPLY_PROP_CHARGE_COUNTER,
        POWER_SUPPLY_PROP_CHARGE_FULL,
        POWER_SUPPLY_PROP_CHARGE_EMPTY,
        POWER_SUPPLY_PROP_CHARGE_NOW,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_TEMP,
        POWER_SUPPLY_PROP_CURRENT_NOW,
};

static int ltc294x_i2c_probe(struct i2c_client *client)
{
        struct power_supply_config psy_cfg = {};
        struct ltc294x_info *info;
        struct device_node *np;
        int ret;
        u32 prescaler_exp;
        s32 r_sense;
        u8 status;

        info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
        if (info == NULL)
                return -ENOMEM;

        i2c_set_clientdata(client, info);

        np = of_node_get(client->dev.of_node);

        info->id = (enum ltc294x_id) (uintptr_t) of_device_get_match_data(
                                                        &client->dev);
        info->supply_desc.name = np->name;

        /* r_sense can be negative, when sense+ is connected to the battery
         * instead of the sense-. This results in reversed measurements. */
        ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
        if (ret < 0)
                return dev_err_probe(&client->dev, ret,
                        "Could not find lltc,resistor-sense in devicetree\n");
        info->r_sense = r_sense;

        ret = of_property_read_u32(np, "lltc,prescaler-exponent",
                &prescaler_exp);
        if (ret < 0) {
                dev_warn(&client->dev,
                        "lltc,prescaler-exponent not in devicetree\n");
                prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
        }

        if (info->id == LTC2943_ID) {
                if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
                        prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
                info->Qlsb = ((340 * 50000) / r_sense) >>
                             (12 - 2*prescaler_exp);
        } else {
                if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
                        prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
                info->Qlsb = ((85 * 50000) / r_sense) >>
                             (7 - prescaler_exp);
        }

        /* Read status register to check for LTC2942 */
        if (info->id == LTC2941_ID || info->id == LTC2942_ID) {
                ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                "Could not read status register\n");
                if (status & LTC2941_REG_STATUS_CHIP_ID)
                        info->id = LTC2941_ID;
                else
                        info->id = LTC2942_ID;
        }

        info->client = client;
        info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
        info->supply_desc.properties = ltc294x_properties;
        switch (info->id) {
        case LTC2944_ID:
        case LTC2943_ID:
                info->supply_desc.num_properties =
                        ARRAY_SIZE(ltc294x_properties);
                break;
        case LTC2942_ID:
                info->supply_desc.num_properties =
                        ARRAY_SIZE(ltc294x_properties) - 1;
                break;
        case LTC2941_ID:
        default:
                info->supply_desc.num_properties =
                        ARRAY_SIZE(ltc294x_properties) - 3;
                break;
        }
        info->supply_desc.get_property = ltc294x_get_property;
        info->supply_desc.set_property = ltc294x_set_property;
        info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
        info->supply_desc.external_power_changed        = NULL;

        psy_cfg.drv_data = info;

        ret = devm_delayed_work_autocancel(&client->dev, &info->work,
                                           ltc294x_work);
        if (ret)
                return ret;

        ret = ltc294x_reset(info, prescaler_exp);
        if (ret < 0)
                return dev_err_probe(&client->dev, ret,
                        "Communication with chip failed\n");

        info->supply = devm_power_supply_register(&client->dev,
                                                  &info->supply_desc, &psy_cfg);
        if (IS_ERR(info->supply))
                return dev_err_probe(&client->dev, PTR_ERR(info->supply),
                        "failed to register ltc2941\n");

        schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);

        return 0;
}

static void ltc294x_i2c_shutdown(struct i2c_client *client)
{
        struct ltc294x_info *info = i2c_get_clientdata(client);
        int ret;
        u8 value;
        u8 control;

        /* The LTC2941 does not need any special handling */
        if (info->id == LTC2941_ID)
                return;

        /* Read control register */
        ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
        if (ret < 0)
                return;

        /* Disable continuous ADC conversion as this drains the battery */
        control = LTC294X_REG_CONTROL_ADC_DISABLE(value);
        if (control != value)
                ltc294x_write_regs(info->client, LTC294X_REG_CONTROL,
                        &control, 1);
}

#ifdef CONFIG_PM_SLEEP

static int ltc294x_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct ltc294x_info *info = i2c_get_clientdata(client);

        cancel_delayed_work(&info->work);
        return 0;
}

static int ltc294x_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct ltc294x_info *info = i2c_get_clientdata(client);

        schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
        return 0;
}

static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
#define LTC294X_PM_OPS (&ltc294x_pm_ops)

#else
#define LTC294X_PM_OPS NULL
#endif /* CONFIG_PM_SLEEP */


static const struct i2c_device_id ltc294x_i2c_id[] = {
        { "ltc2941", LTC2941_ID, },
        { "ltc2942", LTC2942_ID, },
        { "ltc2943", LTC2943_ID, },
        { "ltc2944", LTC2944_ID, },
        { },
};
MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);

static const struct of_device_id ltc294x_i2c_of_match[] = {
        {
                .compatible = "lltc,ltc2941",
                .data = (void *)LTC2941_ID,
        },
        {
                .compatible = "lltc,ltc2942",
                .data = (void *)LTC2942_ID,
        },
        {
                .compatible = "lltc,ltc2943",
                .data = (void *)LTC2943_ID,
        },
        {
                .compatible = "lltc,ltc2944",
                .data = (void *)LTC2944_ID,
        },
        { },
};
MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);

static struct i2c_driver ltc294x_driver = {
        .driver = {
                .name   = "LTC2941",
                .of_match_table = ltc294x_i2c_of_match,
                .pm     = LTC294X_PM_OPS,
        },
        .probe          = ltc294x_i2c_probe,
        .shutdown       = ltc294x_i2c_shutdown,
        .id_table       = ltc294x_i2c_id,
};
module_i2c_driver(ltc294x_driver);

MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
MODULE_DESCRIPTION("LTC2941/LTC2942/LTC2943/LTC2944 Battery Gas Gauge IC driver");
MODULE_LICENSE("GPL");