/*
 * 1-Wire implementation for Maxim Semiconductor
 * MAX7211/MAX17215 standalone fuel gauge chip
 *
 * Copyright (C) 2017 Radioavionica Corporation
 * Author: Alex A. Mihaylov <minimumlaw@rambler.ru>
 *
 * Use consistent with the GNU GPL is permitted,
 * provided that this copyright notice is
 * preserved in its entirety in all copies and derived works.
 *
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/w1.h>
#include <linux/regmap.h>
#include <linux/power_supply.h>

#define W1_MAX1721X_FAMILY_ID           0x26
#define DEF_DEV_NAME_MAX17211           "MAX17211"
#define DEF_DEV_NAME_MAX17215           "MAX17215"
#define DEF_DEV_NAME_UNKNOWN            "UNKNOWN"
#define DEF_MFG_NAME                    "MAXIM"

#define PSY_MAX_NAME_LEN        32

/* Number of valid register addresses in W1 mode */
#define MAX1721X_MAX_REG_NR     0x1EF

/* Factory settings (nonvolatile registers) (W1 specific) */
#define MAX1721X_REG_NRSENSE    0x1CF   /* RSense in 10^-5 Ohm */
/* Strings */
#define MAX1721X_REG_MFG_STR    0x1CC
#define MAX1721X_REG_MFG_NUMB   3
#define MAX1721X_REG_DEV_STR    0x1DB
#define MAX1721X_REG_DEV_NUMB   5
/* HEX Strings */
#define MAX1721X_REG_SER_HEX    0x1D8

/* MAX172XX Output Registers for W1 chips */
#define MAX172XX_REG_STATUS     0x000   /* status reg */
#define MAX172XX_BAT_PRESENT    (1<<4)  /* battery connected bit */
#define MAX172XX_REG_DEVNAME    0x021   /* chip config */
#define MAX172XX_DEV_MASK       0x000F  /* chip type mask */
#define MAX172X1_DEV            0x0001
#define MAX172X5_DEV            0x0005
#define MAX172XX_REG_TEMP       0x008   /* Temperature */
#define MAX172XX_REG_BATT       0x0DA   /* Battery voltage */
#define MAX172XX_REG_CURRENT    0x00A   /* Actual current */
#define MAX172XX_REG_AVGCURRENT 0x00B   /* Average current */
#define MAX172XX_REG_REPSOC     0x006   /* Percentage of charge */
#define MAX172XX_REG_DESIGNCAP  0x018   /* Design capacity */
#define MAX172XX_REG_REPCAP     0x005   /* Average capacity */
#define MAX172XX_REG_TTE        0x011   /* Time to empty */
#define MAX172XX_REG_TTF        0x020   /* Time to full */

struct max17211_device_info {
        char name[PSY_MAX_NAME_LEN];
        struct power_supply *bat;
        struct power_supply_desc bat_desc;
        struct device *w1_dev;
        struct regmap *regmap;
        /* battery design format */
        unsigned int rsense; /* in tenths uOhm */
        char DeviceName[2 * MAX1721X_REG_DEV_NUMB + 1];
        char ManufacturerName[2 * MAX1721X_REG_MFG_NUMB + 1];
        char SerialNumber[13]; /* see get_sn_str() later for comment */
};

/* Convert regs value to power_supply units */

static inline int max172xx_time_to_ps(unsigned int reg)
{
        return reg * 5625 / 1000;       /* in sec. */
}

static inline int max172xx_percent_to_ps(unsigned int reg)
{
        return reg / 256;       /* in percent from 0 to 100 */
}

static inline int max172xx_voltage_to_ps(unsigned int reg)
{
        return reg * 1250;      /* in uV */
}

static inline int max172xx_capacity_to_ps(unsigned int reg)
{
        return reg * 500;       /* in uAh */
}

/*
 * Current and temperature is signed values, so unsigned regs
 * value must be converted to signed type
 */

static inline int max172xx_temperature_to_ps(unsigned int reg)
{
        int val = (int16_t)(reg);

        return val * 10 / 256; /* in tenths of deg. C */
}

/*
 * Calculating current registers resolution:
 *
 * RSense stored in 10^-5 Ohm, so measurement voltage must be
 * in 10^-11 Volts for get current in uA.
 * 16 bit current reg fullscale +/-51.2mV is 102400 uV.
 * So: 102400 / 65535 * 10^5 = 156252
 */
static inline int max172xx_current_to_voltage(unsigned int reg)
{
        int val = (int16_t)(reg);

        return val * 156252;
}


static inline struct max17211_device_info *
to_device_info(struct power_supply *psy)
{
        return power_supply_get_drvdata(psy);
}

static int max1721x_battery_get_property(struct power_supply *psy,
        enum power_supply_property psp,
        union power_supply_propval *val)
{
        struct max17211_device_info *info = to_device_info(psy);
        unsigned int reg = 0;
        int ret = 0;

        switch (psp) {
        case POWER_SUPPLY_PROP_PRESENT:
                /*
                 * POWER_SUPPLY_PROP_PRESENT will always readable via
                 * sysfs interface. Value return 0 if battery not
                 * present or unaccessible via W1.
                 */
                val->intval =
                        regmap_read(info->regmap, MAX172XX_REG_STATUS,
                        &reg) ? 0 : !(reg & MAX172XX_BAT_PRESENT);
                break;
        case POWER_SUPPLY_PROP_CAPACITY:
                ret = regmap_read(info->regmap, MAX172XX_REG_REPSOC, &reg);
                val->intval = max172xx_percent_to_ps(reg);
                break;
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                ret = regmap_read(info->regmap, MAX172XX_REG_BATT, &reg);
                val->intval = max172xx_voltage_to_ps(reg);
                break;
        case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
                ret = regmap_read(info->regmap, MAX172XX_REG_DESIGNCAP, &reg);
                val->intval = max172xx_capacity_to_ps(reg);
                break;
        case POWER_SUPPLY_PROP_CHARGE_AVG:
                ret = regmap_read(info->regmap, MAX172XX_REG_REPCAP, &reg);
                val->intval = max172xx_capacity_to_ps(reg);
                break;
        case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
                ret = regmap_read(info->regmap, MAX172XX_REG_TTE, &reg);
                val->intval = max172xx_time_to_ps(reg);
                break;
        case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:
                ret = regmap_read(info->regmap, MAX172XX_REG_TTF, &reg);
                val->intval = max172xx_time_to_ps(reg);
                break;
        case POWER_SUPPLY_PROP_TEMP:
                ret = regmap_read(info->regmap, MAX172XX_REG_TEMP, &reg);
                val->intval = max172xx_temperature_to_ps(reg);
                break;
        /* We need signed current, so must cast info->rsense to signed type */
        case POWER_SUPPLY_PROP_CURRENT_NOW:
                ret = regmap_read(info->regmap, MAX172XX_REG_CURRENT, &reg);
                val->intval =
                        max172xx_current_to_voltage(reg) / (int)info->rsense;
                break;
        case POWER_SUPPLY_PROP_CURRENT_AVG:
                ret = regmap_read(info->regmap, MAX172XX_REG_AVGCURRENT, &reg);
                val->intval =
                        max172xx_current_to_voltage(reg) / (int)info->rsense;
                break;
        /*
         * Strings already received and inited by probe.
         * We do dummy read for check battery still available.
         */
        case POWER_SUPPLY_PROP_MODEL_NAME:
                ret = regmap_read(info->regmap, MAX1721X_REG_DEV_STR, &reg);
                val->strval = info->DeviceName;
                break;
        case POWER_SUPPLY_PROP_MANUFACTURER:
                ret = regmap_read(info->regmap, MAX1721X_REG_MFG_STR, &reg);
                val->strval = info->ManufacturerName;
                break;
        case POWER_SUPPLY_PROP_SERIAL_NUMBER:
                ret = regmap_read(info->regmap, MAX1721X_REG_SER_HEX, &reg);
                val->strval = info->SerialNumber;
                break;
        default:
                ret = -EINVAL;
        }

        return ret;
}

static enum power_supply_property max1721x_battery_props[] = {
        /* int */
        POWER_SUPPLY_PROP_PRESENT,
        POWER_SUPPLY_PROP_CAPACITY,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
        POWER_SUPPLY_PROP_CHARGE_AVG,
        POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
        POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
        POWER_SUPPLY_PROP_TEMP,
        POWER_SUPPLY_PROP_CURRENT_NOW,
        POWER_SUPPLY_PROP_CURRENT_AVG,
        /* strings */
        POWER_SUPPLY_PROP_MODEL_NAME,
        POWER_SUPPLY_PROP_MANUFACTURER,
        POWER_SUPPLY_PROP_SERIAL_NUMBER,
};

static int get_string(struct max17211_device_info *info,
                        uint16_t reg, uint8_t nr, char *str)
{
        unsigned int val;

        if (!str || !(reg == MAX1721X_REG_MFG_STR ||
                        reg == MAX1721X_REG_DEV_STR))
                return -EFAULT;

        while (nr--) {
                if (regmap_read(info->regmap, reg++, &val))
                        return -EFAULT;
                *str++ = val>>8 & 0x00FF;
                *str++ = val & 0x00FF;
        }
        return 0;
}

/* Maxim say: Serial number is a hex string up to 12 hex characters */
static int get_sn_string(struct max17211_device_info *info, char *str)
{
        unsigned int val[3];

        if (!str)
                return -EFAULT;

        if (regmap_read(info->regmap, MAX1721X_REG_SER_HEX, &val[0]))
                return -EFAULT;
        if (regmap_read(info->regmap, MAX1721X_REG_SER_HEX + 1, &val[1]))
                return -EFAULT;
        if (regmap_read(info->regmap, MAX1721X_REG_SER_HEX + 2, &val[2]))
                return -EFAULT;

        snprintf(str, 13, "%04X%04X%04X", val[0], val[1], val[2]);
        return 0;
}

/*
 * MAX1721x registers description for w1-regmap
 */
static const struct regmap_range max1721x_allow_range[] = {
        regmap_reg_range(0, 0xDF),      /* volatile data */
        regmap_reg_range(0x180, 0x1DF), /* non-volatile memory */
        regmap_reg_range(0x1E0, 0x1EF), /* non-volatile history (unused) */
};

static const struct regmap_range max1721x_deny_range[] = {
        /* volatile data unused registers */
        regmap_reg_range(0x24, 0x26),
        regmap_reg_range(0x30, 0x31),
        regmap_reg_range(0x33, 0x34),
        regmap_reg_range(0x37, 0x37),
        regmap_reg_range(0x3B, 0x3C),
        regmap_reg_range(0x40, 0x41),
        regmap_reg_range(0x43, 0x44),
        regmap_reg_range(0x47, 0x49),
        regmap_reg_range(0x4B, 0x4C),
        regmap_reg_range(0x4E, 0xAF),
        regmap_reg_range(0xB1, 0xB3),
        regmap_reg_range(0xB5, 0xB7),
        regmap_reg_range(0xBF, 0xD0),
        regmap_reg_range(0xDB, 0xDB),
        /* hole between volatile and non-volatile registers */
        regmap_reg_range(0xE0, 0x17F),
};

static const struct regmap_access_table max1721x_regs = {
        .yes_ranges     = max1721x_allow_range,
        .n_yes_ranges   = ARRAY_SIZE(max1721x_allow_range),
        .no_ranges      = max1721x_deny_range,
        .n_no_ranges    = ARRAY_SIZE(max1721x_deny_range),
};

/*
 * Model Gauge M5 Algorithm output register
 * Volatile data (must not be cached)
 */
static const struct regmap_range max1721x_volatile_allow[] = {
        regmap_reg_range(0, 0xDF),
};

static const struct regmap_access_table max1721x_volatile_regs = {
        .yes_ranges     = max1721x_volatile_allow,
        .n_yes_ranges   = ARRAY_SIZE(max1721x_volatile_allow),
};

/*
 * W1-regmap config
 */
static const struct regmap_config max1721x_regmap_w1_config = {
        .reg_bits = 16,
        .val_bits = 16,
        .rd_table = &max1721x_regs,
        .volatile_table = &max1721x_volatile_regs,
        .max_register = MAX1721X_MAX_REG_NR,
};

static int devm_w1_max1721x_add_device(struct w1_slave *sl)
{
        struct power_supply_config psy_cfg = {};
        struct max17211_device_info *info;

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

        sl->family_data = (void *)info;
        info->w1_dev = &sl->dev;

        /*
         * power_supply class battery name translated from W1 slave device
         * unique ID (look like 26-0123456789AB) to "max1721x-0123456789AB\0"
         * so, 26 (device family) correspond to max1721x devices.
         * Device name still unique for any number of connected devices.
         */
        snprintf(info->name, sizeof(info->name),
                "max1721x-%012X", (unsigned int)sl->reg_num.id);
        info->bat_desc.name = info->name;

        /*
         * FixMe: battery device name exceed max len for thermal_zone device
         * name and translation to thermal_zone must be disabled.
         */
        info->bat_desc.no_thermal = true;
        info->bat_desc.type = POWER_SUPPLY_TYPE_BATTERY;
        info->bat_desc.properties = max1721x_battery_props;
        info->bat_desc.num_properties = ARRAY_SIZE(max1721x_battery_props);
        info->bat_desc.get_property = max1721x_battery_get_property;
        psy_cfg.drv_data = info;

        /* regmap init */
        info->regmap = devm_regmap_init_w1(info->w1_dev,
                                        &max1721x_regmap_w1_config);
        if (IS_ERR(info->regmap)) {
                int err = PTR_ERR(info->regmap);

                dev_err(info->w1_dev, "Failed to allocate register map: %d\n",
                        err);
                return err;
        }

        /* rsense init */
        info->rsense = 0;
        if (regmap_read(info->regmap, MAX1721X_REG_NRSENSE, &info->rsense)) {
                dev_err(info->w1_dev, "Can't read RSense. Hardware error.\n");
                return -ENODEV;
        }

        if (!info->rsense) {
                dev_warn(info->w1_dev, "RSense not calibrated, set 10 mOhms!\n");
                info->rsense = 1000; /* in regs in 10^-5 */
        }
        dev_info(info->w1_dev, "RSense: %d mOhms.\n", info->rsense / 100);

        if (get_string(info, MAX1721X_REG_MFG_STR,
                        MAX1721X_REG_MFG_NUMB, info->ManufacturerName)) {
                dev_err(info->w1_dev, "Can't read manufacturer. Hardware error.\n");
                return -ENODEV;
        }

        if (!info->ManufacturerName[0])
                strscpy(info->ManufacturerName, DEF_MFG_NAME,
                        2 * MAX1721X_REG_MFG_NUMB);

        if (get_string(info, MAX1721X_REG_DEV_STR,
                        MAX1721X_REG_DEV_NUMB, info->DeviceName)) {
                dev_err(info->w1_dev, "Can't read device. Hardware error.\n");
                return -ENODEV;
        }
        if (!info->DeviceName[0]) {
                unsigned int dev_name;

                if (regmap_read(info->regmap,
                                MAX172XX_REG_DEVNAME, &dev_name)) {
                        dev_err(info->w1_dev, "Can't read device name reg.\n");
                        return -ENODEV;
                }

                switch (dev_name & MAX172XX_DEV_MASK) {
                case MAX172X1_DEV:
                        strscpy(info->DeviceName, DEF_DEV_NAME_MAX17211,
                                2 * MAX1721X_REG_DEV_NUMB);
                        break;
                case MAX172X5_DEV:
                        strscpy(info->DeviceName, DEF_DEV_NAME_MAX17215,
                                2 * MAX1721X_REG_DEV_NUMB);
                        break;
                default:
                        strscpy(info->DeviceName, DEF_DEV_NAME_UNKNOWN,
                                2 * MAX1721X_REG_DEV_NUMB);
                }
        }

        if (get_sn_string(info, info->SerialNumber)) {
                dev_err(info->w1_dev, "Can't read serial. Hardware error.\n");
                return -ENODEV;
        }

        info->bat = devm_power_supply_register(&sl->dev, &info->bat_desc,
                                                &psy_cfg);
        if (IS_ERR(info->bat)) {
                dev_err(info->w1_dev, "failed to register battery\n");
                return PTR_ERR(info->bat);
        }

        return 0;
}

static const struct w1_family_ops w1_max1721x_fops = {
        .add_slave = devm_w1_max1721x_add_device,
};

static struct w1_family w1_max1721x_family = {
        .fid = W1_MAX1721X_FAMILY_ID,
        .fops = &w1_max1721x_fops,
};

module_w1_family(w1_max1721x_family);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alex A. Mihaylov <minimumlaw@rambler.ru>");
MODULE_DESCRIPTION("Maxim MAX17211/MAX17215 Fuel Gauge IC driver");
MODULE_ALIAS("w1-family-" __stringify(W1_MAX1721X_FAMILY_ID));