/*
 * INA2XX Current and Power Monitors
 *
 * Copyright 2015 Baylibre SAS.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Based on linux/drivers/iio/adc/ad7291.c
 * Copyright 2010-2011 Analog Devices Inc.
 *
 * Based on linux/drivers/hwmon/ina2xx.c
 * Copyright 2012 Lothar Felten <l-felten@ti.com>
 *
 * Licensed under the GPL-2 or later.
 *
 * IIO driver for INA219-220-226-230-231
 *
 * Configurable 7-bit I2C slave address from 0x40 to 0x4F
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/kfifo_buf.h>
#include <linux/iio/sysfs.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/util_macros.h>

#include <linux/platform_data/ina2xx.h>

/* INA2XX registers definition */
#define INA2XX_CONFIG                   0x00
#define INA2XX_SHUNT_VOLTAGE            0x01    /* readonly */
#define INA2XX_BUS_VOLTAGE              0x02    /* readonly */
#define INA2XX_POWER                    0x03    /* readonly */
#define INA2XX_CURRENT                  0x04    /* readonly */
#define INA2XX_CALIBRATION              0x05

#define INA226_ALERT_MASK               GENMASK(2, 1)
#define INA266_CVRF                     BIT(3)

#define INA2XX_MAX_REGISTERS            8

/* settings - depend on use case */
#define INA219_CONFIG_DEFAULT           0x399F  /* PGA=8 */
#define INA226_CONFIG_DEFAULT           0x4327
#define INA226_DEFAULT_AVG              4
#define INA226_DEFAULT_IT               1110

#define INA2XX_RSHUNT_DEFAULT           10000

/*
 * bit mask for reading the averaging setting in the configuration register
 * FIXME: use regmap_fields.
 */
#define INA2XX_MODE_MASK        GENMASK(3, 0)

#define INA226_AVG_MASK         GENMASK(11, 9)
#define INA226_SHIFT_AVG(val)   ((val) << 9)

/* Integration time for VBus */
#define INA226_ITB_MASK         GENMASK(8, 6)
#define INA226_SHIFT_ITB(val)   ((val) << 6)

/* Integration time for VShunt */
#define INA226_ITS_MASK         GENMASK(5, 3)
#define INA226_SHIFT_ITS(val)   ((val) << 3)

/* Cosmetic macro giving the sampling period for a full P=UxI cycle */
#define SAMPLING_PERIOD(c)      ((c->int_time_vbus + c->int_time_vshunt) \
                                 * c->avg)

static bool ina2xx_is_writeable_reg(struct device *dev, unsigned int reg)
{
        return (reg == INA2XX_CONFIG) || (reg > INA2XX_CURRENT);
}

static bool ina2xx_is_volatile_reg(struct device *dev, unsigned int reg)
{
        return (reg != INA2XX_CONFIG);
}

static inline bool is_signed_reg(unsigned int reg)
{
        return (reg == INA2XX_SHUNT_VOLTAGE) || (reg == INA2XX_CURRENT);
}

static const struct regmap_config ina2xx_regmap_config = {
        .reg_bits = 8,
        .val_bits = 16,
        .max_register = INA2XX_MAX_REGISTERS,
        .writeable_reg = ina2xx_is_writeable_reg,
        .volatile_reg = ina2xx_is_volatile_reg,
};

enum ina2xx_ids { ina219, ina226 };

struct ina2xx_config {
        u16 config_default;
        int calibration_factor;
        int shunt_div;
        int bus_voltage_shift;
        int bus_voltage_lsb;    /* uV */
        int power_lsb;          /* uW */
};

struct ina2xx_chip_info {
        struct regmap *regmap;
        struct task_struct *task;
        const struct ina2xx_config *config;
        struct mutex state_lock;
        unsigned int shunt_resistor;
        int avg;
        int int_time_vbus; /* Bus voltage integration time uS */
        int int_time_vshunt; /* Shunt voltage integration time uS */
        bool allow_async_readout;
};

static const struct ina2xx_config ina2xx_config[] = {
        [ina219] = {
                .config_default = INA219_CONFIG_DEFAULT,
                .calibration_factor = 40960000,
                .shunt_div = 100,
                .bus_voltage_shift = 3,
                .bus_voltage_lsb = 4000,
                .power_lsb = 20000,
        },
        [ina226] = {
                .config_default = INA226_CONFIG_DEFAULT,
                .calibration_factor = 5120000,
                .shunt_div = 400,
                .bus_voltage_shift = 0,
                .bus_voltage_lsb = 1250,
                .power_lsb = 25000,
        },
};

static int ina2xx_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2, long mask)
{
        int ret;
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);
        unsigned int regval;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = regmap_read(chip->regmap, chan->address, &regval);
                if (ret)
                        return ret;

                if (is_signed_reg(chan->address))
                        *val = (s16) regval;
                else
                        *val  = regval;

                return IIO_VAL_INT;

        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                *val = chip->avg;
                return IIO_VAL_INT;

        case IIO_CHAN_INFO_INT_TIME:
                *val = 0;
                if (chan->address == INA2XX_SHUNT_VOLTAGE)
                        *val2 = chip->int_time_vshunt;
                else
                        *val2 = chip->int_time_vbus;

                return IIO_VAL_INT_PLUS_MICRO;

        case IIO_CHAN_INFO_SAMP_FREQ:
                /*
                 * Sample freq is read only, it is a consequence of
                 * 1/AVG*(CT_bus+CT_shunt).
                 */
                *val = DIV_ROUND_CLOSEST(1000000, SAMPLING_PERIOD(chip));

                return IIO_VAL_INT;

        case IIO_CHAN_INFO_SCALE:
                switch (chan->address) {
                case INA2XX_SHUNT_VOLTAGE:
                        /* processed (mV) = raw/shunt_div */
                        *val2 = chip->config->shunt_div;
                        *val = 1;
                        return IIO_VAL_FRACTIONAL;

                case INA2XX_BUS_VOLTAGE:
                        /* processed (mV) = raw*lsb (uV) / (1000 << shift) */
                        *val = chip->config->bus_voltage_lsb;
                        *val2 = 1000 << chip->config->bus_voltage_shift;
                        return IIO_VAL_FRACTIONAL;

                case INA2XX_POWER:
                        /* processed (mW) = raw*lsb (uW) / 1000 */
                        *val = chip->config->power_lsb;
                        *val2 = 1000;
                        return IIO_VAL_FRACTIONAL;

                case INA2XX_CURRENT:
                        /* processed (mA) = raw (mA) */
                        *val = 1;
                        return IIO_VAL_INT;
                }
        }

        return -EINVAL;
}

/*
 * Available averaging rates for ina226. The indices correspond with
 * the bit values expected by the chip (according to the ina226 datasheet,
 * table 3 AVG bit settings, found at
 * http://www.ti.com/lit/ds/symlink/ina226.pdf.
 */
static const int ina226_avg_tab[] = { 1, 4, 16, 64, 128, 256, 512, 1024 };

static int ina226_set_average(struct ina2xx_chip_info *chip, unsigned int val,
                              unsigned int *config)
{
        int bits;

        if (val > 1024 || val < 1)
                return -EINVAL;

        bits = find_closest(val, ina226_avg_tab,
                            ARRAY_SIZE(ina226_avg_tab));

        chip->avg = ina226_avg_tab[bits];

        *config &= ~INA226_AVG_MASK;
        *config |= INA226_SHIFT_AVG(bits) & INA226_AVG_MASK;

        return 0;
}

/* Conversion times in uS */
static const int ina226_conv_time_tab[] = { 140, 204, 332, 588, 1100,
                                            2116, 4156, 8244 };

static int ina226_set_int_time_vbus(struct ina2xx_chip_info *chip,
                                    unsigned int val_us, unsigned int *config)
{
        int bits;

        if (val_us > 8244 || val_us < 140)
                return -EINVAL;

        bits = find_closest(val_us, ina226_conv_time_tab,
                            ARRAY_SIZE(ina226_conv_time_tab));

        chip->int_time_vbus = ina226_conv_time_tab[bits];

        *config &= ~INA226_ITB_MASK;
        *config |= INA226_SHIFT_ITB(bits) & INA226_ITB_MASK;

        return 0;
}

static int ina226_set_int_time_vshunt(struct ina2xx_chip_info *chip,
                                      unsigned int val_us, unsigned int *config)
{
        int bits;

        if (val_us > 8244 || val_us < 140)
                return -EINVAL;

        bits = find_closest(val_us, ina226_conv_time_tab,
                            ARRAY_SIZE(ina226_conv_time_tab));

        chip->int_time_vshunt = ina226_conv_time_tab[bits];

        *config &= ~INA226_ITS_MASK;
        *config |= INA226_SHIFT_ITS(bits) & INA226_ITS_MASK;

        return 0;
}

static int ina2xx_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val, int val2, long mask)
{
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);
        unsigned int config, tmp;
        int ret;

        if (iio_buffer_enabled(indio_dev))
                return -EBUSY;

        mutex_lock(&chip->state_lock);

        ret = regmap_read(chip->regmap, INA2XX_CONFIG, &config);
        if (ret)
                goto err;

        tmp = config;

        switch (mask) {
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                ret = ina226_set_average(chip, val, &tmp);
                break;

        case IIO_CHAN_INFO_INT_TIME:
                if (chan->address == INA2XX_SHUNT_VOLTAGE)
                        ret = ina226_set_int_time_vshunt(chip, val2, &tmp);
                else
                        ret = ina226_set_int_time_vbus(chip, val2, &tmp);
                break;

        default:
                ret = -EINVAL;
        }

        if (!ret && (tmp != config))
                ret = regmap_write(chip->regmap, INA2XX_CONFIG, tmp);
err:
        mutex_unlock(&chip->state_lock);

        return ret;
}

static ssize_t ina2xx_allow_async_readout_show(struct device *dev,
                                           struct device_attribute *attr,
                                           char *buf)
{
        struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));

        return sprintf(buf, "%d\n", chip->allow_async_readout);
}

static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t len)
{
        struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
        bool val;
        int ret;

        ret = strtobool((const char *) buf, &val);
        if (ret)
                return ret;

        chip->allow_async_readout = val;

        return len;
}

/*
 * Set current LSB to 1mA, shunt is in uOhms
 * (equation 13 in datasheet). We hardcode a Current_LSB
 * of 1.0 x10-6. The only remaining parameter is RShunt.
 * There is no need to expose the CALIBRATION register
 * to the user for now. But we need to reset this register
 * if the user updates RShunt after driver init, e.g upon
 * reading an EEPROM/Probe-type value.
 */
static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
{
        u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
                                   chip->shunt_resistor);

        return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
}

static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val)
{
        if (val <= 0 || val > chip->config->calibration_factor)
                return -EINVAL;

        chip->shunt_resistor = val;

        return 0;
}

static ssize_t ina2xx_shunt_resistor_show(struct device *dev,
                                          struct device_attribute *attr,
                                          char *buf)
{
        struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));

        return sprintf(buf, "%d\n", chip->shunt_resistor);
}

static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
                                           struct device_attribute *attr,
                                           const char *buf, size_t len)
{
        struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
        unsigned long val;
        int ret;

        ret = kstrtoul((const char *) buf, 10, &val);
        if (ret)
                return ret;

        ret = set_shunt_resistor(chip, val);
        if (ret)
                return ret;

        /* Update the Calibration register */
        ret = ina2xx_set_calibration(chip);
        if (ret)
                return ret;

        return len;
}

#define INA2XX_CHAN(_type, _index, _address) { \
        .type = (_type), \
        .address = (_address), \
        .indexed = 1, \
        .channel = (_index), \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
        | BIT(IIO_CHAN_INFO_SCALE), \
        .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
                                   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
        .scan_index = (_index), \
        .scan_type = { \
                .sign = 'u', \
                .realbits = 16, \
                .storagebits = 16, \
                .endianness = IIO_CPU, \
        } \
}

/*
 * Sampling Freq is a consequence of the integration times of
 * the Voltage channels.
 */
#define INA2XX_CHAN_VOLTAGE(_index, _address) { \
        .type = IIO_VOLTAGE, \
        .address = (_address), \
        .indexed = 1, \
        .channel = (_index), \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
                              BIT(IIO_CHAN_INFO_SCALE) | \
                              BIT(IIO_CHAN_INFO_INT_TIME), \
        .scan_index = (_index), \
        .scan_type = { \
                .sign = 'u', \
                .realbits = 16, \
                .storagebits = 16, \
                .endianness = IIO_LE, \
        } \
}

static const struct iio_chan_spec ina2xx_channels[] = {
        INA2XX_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
        INA2XX_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
        INA2XX_CHAN(IIO_POWER, 2, INA2XX_POWER),
        INA2XX_CHAN(IIO_CURRENT, 3, INA2XX_CURRENT),
        IIO_CHAN_SOFT_TIMESTAMP(4),
};

static int ina2xx_work_buffer(struct iio_dev *indio_dev)
{
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);
        unsigned short data[8];
        int bit, ret, i = 0;
        s64 time_a, time_b;
        unsigned int alert;

        time_a = iio_get_time_ns(indio_dev);

        /*
         * Because the timer thread and the chip conversion clock
         * are asynchronous, the period difference will eventually
         * result in reading V[k-1] again, or skip V[k] at time Tk.
         * In order to resync the timer with the conversion process
         * we check the ConVersionReadyFlag.
         * On hardware that supports using the ALERT pin to toggle a
         * GPIO a triggered buffer could be used instead.
         * For now, we pay for that extra read of the ALERT register
         */
        if (!chip->allow_async_readout)
                do {
                        ret = regmap_read(chip->regmap, INA226_ALERT_MASK,
                                          &alert);
                        if (ret < 0)
                                return ret;

                        alert &= INA266_CVRF;
                } while (!alert);

        /*
         * Single register reads: bulk_read will not work with ina226
         * as there is no auto-increment of the address register for
         * data length longer than 16bits.
         */
        for_each_set_bit(bit, indio_dev->active_scan_mask,
                         indio_dev->masklength) {
                unsigned int val;

                ret = regmap_read(chip->regmap,
                                  INA2XX_SHUNT_VOLTAGE + bit, &val);
                if (ret < 0)
                        return ret;

                data[i++] = val;
        }

        time_b = iio_get_time_ns(indio_dev);

        iio_push_to_buffers_with_timestamp(indio_dev,
                                           (unsigned int *)data, time_a);

        return (unsigned long)(time_b - time_a) / 1000;
};

static int ina2xx_capture_thread(void *data)
{
        struct iio_dev *indio_dev = data;
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);
        unsigned int sampling_us = SAMPLING_PERIOD(chip);
        int buffer_us;

        /*
         * Poll a bit faster than the chip internal Fs, in case
         * we wish to sync with the conversion ready flag.
         */
        if (!chip->allow_async_readout)
                sampling_us -= 200;

        do {
                buffer_us = ina2xx_work_buffer(indio_dev);
                if (buffer_us < 0)
                        return buffer_us;

                if (sampling_us > buffer_us)
                        udelay(sampling_us - buffer_us);

        } while (!kthread_should_stop());

        return 0;
}

static int ina2xx_buffer_enable(struct iio_dev *indio_dev)
{
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);
        unsigned int sampling_us = SAMPLING_PERIOD(chip);

        dev_dbg(&indio_dev->dev, "Enabling buffer w/ scan_mask %02x, freq = %d, avg =%u\n",
                (unsigned int)(*indio_dev->active_scan_mask),
                1000000 / sampling_us, chip->avg);

        dev_dbg(&indio_dev->dev, "Expected work period: %u us\n", sampling_us);
        dev_dbg(&indio_dev->dev, "Async readout mode: %d\n",
                chip->allow_async_readout);

        chip->task = kthread_run(ina2xx_capture_thread, (void *)indio_dev,
                                 "%s:%d-%uus", indio_dev->name, indio_dev->id,
                                 sampling_us);

        return PTR_ERR_OR_ZERO(chip->task);
}

static int ina2xx_buffer_disable(struct iio_dev *indio_dev)
{
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);

        if (chip->task) {
                kthread_stop(chip->task);
                chip->task = NULL;
        }

        return 0;
}

static const struct iio_buffer_setup_ops ina2xx_setup_ops = {
        .postenable = &ina2xx_buffer_enable,
        .predisable = &ina2xx_buffer_disable,
};

static int ina2xx_debug_reg(struct iio_dev *indio_dev,
                            unsigned reg, unsigned writeval, unsigned *readval)
{
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);

        if (!readval)
                return regmap_write(chip->regmap, reg, writeval);

        return regmap_read(chip->regmap, reg, readval);
}

/* Possible integration times for vshunt and vbus */
static IIO_CONST_ATTR_INT_TIME_AVAIL("0.000140 0.000204 0.000332 0.000588 0.001100 0.002116 0.004156 0.008244");

static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR,
                       ina2xx_allow_async_readout_show,
                       ina2xx_allow_async_readout_store, 0);

static IIO_DEVICE_ATTR(in_shunt_resistor, S_IRUGO | S_IWUSR,
                       ina2xx_shunt_resistor_show,
                       ina2xx_shunt_resistor_store, 0);

static struct attribute *ina2xx_attributes[] = {
        &iio_dev_attr_in_allow_async_readout.dev_attr.attr,
        &iio_const_attr_integration_time_available.dev_attr.attr,
        &iio_dev_attr_in_shunt_resistor.dev_attr.attr,
        NULL,
};

static const struct attribute_group ina2xx_attribute_group = {
        .attrs = ina2xx_attributes,
};

static const struct iio_info ina2xx_info = {
        .driver_module = THIS_MODULE,
        .attrs = &ina2xx_attribute_group,
        .read_raw = ina2xx_read_raw,
        .write_raw = ina2xx_write_raw,
        .debugfs_reg_access = ina2xx_debug_reg,
};

/* Initialize the configuration and calibration registers. */
static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
{
        int ret = regmap_write(chip->regmap, INA2XX_CONFIG, config);
        if (ret)
                return ret;

        return ina2xx_set_calibration(chip);
}

static int ina2xx_probe(struct i2c_client *client,
                        const struct i2c_device_id *id)
{
        struct ina2xx_chip_info *chip;
        struct iio_dev *indio_dev;
        struct iio_buffer *buffer;
        unsigned int val;
        int ret;

        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
        if (!indio_dev)
                return -ENOMEM;

        chip = iio_priv(indio_dev);

        /* This is only used for device removal purposes. */
        i2c_set_clientdata(client, indio_dev);

        chip->regmap = devm_regmap_init_i2c(client, &ina2xx_regmap_config);
        if (IS_ERR(chip->regmap)) {
                dev_err(&client->dev, "failed to allocate register map\n");
                return PTR_ERR(chip->regmap);
        }

        chip->config = &ina2xx_config[id->driver_data];

        mutex_init(&chip->state_lock);

        if (of_property_read_u32(client->dev.of_node,
                                 "shunt-resistor", &val) < 0) {
                struct ina2xx_platform_data *pdata =
                    dev_get_platdata(&client->dev);

                if (pdata)
                        val = pdata->shunt_uohms;
                else
                        val = INA2XX_RSHUNT_DEFAULT;
        }

        ret = set_shunt_resistor(chip, val);
        if (ret)
                return ret;

        /* Patch the current config register with default. */
        val = chip->config->config_default;

        if (id->driver_data == ina226) {
                ina226_set_average(chip, INA226_DEFAULT_AVG, &val);
                ina226_set_int_time_vbus(chip, INA226_DEFAULT_IT, &val);
                ina226_set_int_time_vshunt(chip, INA226_DEFAULT_IT, &val);
        }

        ret = ina2xx_init(chip, val);
        if (ret) {
                dev_err(&client->dev, "error configuring the device\n");
                return ret;
        }

        indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
        indio_dev->dev.parent = &client->dev;
        indio_dev->dev.of_node = client->dev.of_node;
        indio_dev->channels = ina2xx_channels;
        indio_dev->num_channels = ARRAY_SIZE(ina2xx_channels);
        indio_dev->name = id->name;
        indio_dev->info = &ina2xx_info;
        indio_dev->setup_ops = &ina2xx_setup_ops;

        buffer = devm_iio_kfifo_allocate(&indio_dev->dev);
        if (!buffer)
                return -ENOMEM;

        iio_device_attach_buffer(indio_dev, buffer);

        return iio_device_register(indio_dev);
}

static int ina2xx_remove(struct i2c_client *client)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct ina2xx_chip_info *chip = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);

        /* Powerdown */
        return regmap_update_bits(chip->regmap, INA2XX_CONFIG,
                                  INA2XX_MODE_MASK, 0);
}

static const struct i2c_device_id ina2xx_id[] = {
        {"ina219", ina219},
        {"ina220", ina219},
        {"ina226", ina226},
        {"ina230", ina226},
        {"ina231", ina226},
        {}
};
MODULE_DEVICE_TABLE(i2c, ina2xx_id);

static struct i2c_driver ina2xx_driver = {
        .driver = {
                   .name = KBUILD_MODNAME,
        },
        .probe = ina2xx_probe,
        .remove = ina2xx_remove,
        .id_table = ina2xx_id,
};
module_i2c_driver(ina2xx_driver);

MODULE_AUTHOR("Marc Titinger <marc.titinger@baylibre.com>");
MODULE_DESCRIPTION("Texas Instruments INA2XX ADC driver");
MODULE_LICENSE("GPL v2");