/*
 * MMC35240 - MEMSIC 3-axis Magnetic Sensor
 *
 * Copyright (c) 2015, Intel Corporation.
 *
 * This file is subject to the terms and conditions of version 2 of
 * the GNU General Public License.  See the file COPYING in the main
 * directory of this archive for more details.
 *
 * IIO driver for MMC35240 (7-bit I2C slave address 0x30).
 *
 * TODO: offset, ACPI, continuous measurement mode, PM
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/regmap.h>
#include <linux/acpi.h>
#include <linux/pm.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#define MMC35240_DRV_NAME "mmc35240"
#define MMC35240_REGMAP_NAME "mmc35240_regmap"

#define MMC35240_REG_XOUT_L     0x00
#define MMC35240_REG_XOUT_H     0x01
#define MMC35240_REG_YOUT_L     0x02
#define MMC35240_REG_YOUT_H     0x03
#define MMC35240_REG_ZOUT_L     0x04
#define MMC35240_REG_ZOUT_H     0x05

#define MMC35240_REG_STATUS     0x06
#define MMC35240_REG_CTRL0      0x07
#define MMC35240_REG_CTRL1      0x08

#define MMC35240_REG_ID         0x20

#define MMC35240_STATUS_MEAS_DONE_BIT   BIT(0)

#define MMC35240_CTRL0_REFILL_BIT       BIT(7)
#define MMC35240_CTRL0_RESET_BIT        BIT(6)
#define MMC35240_CTRL0_SET_BIT          BIT(5)
#define MMC35240_CTRL0_CMM_BIT          BIT(1)
#define MMC35240_CTRL0_TM_BIT           BIT(0)

/* output resolution bits */
#define MMC35240_CTRL1_BW0_BIT          BIT(0)
#define MMC35240_CTRL1_BW1_BIT          BIT(1)

#define MMC35240_CTRL1_BW_MASK   (MMC35240_CTRL1_BW0_BIT | \
                 MMC35240_CTRL1_BW1_BIT)
#define MMC35240_CTRL1_BW_SHIFT         0

#define MMC35240_WAIT_CHARGE_PUMP       50000   /* us */
#define MMC53240_WAIT_SET_RESET         1000    /* us */

/*
 * Memsic OTP process code piece is put here for reference:
 *
 * #define OTP_CONVERT(REG)  ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006
 * 1) For X axis, the COEFFICIENT is always 1.
 * 2) For Y axis, the COEFFICIENT is as below:
 *    f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) |
 *                                   (reg_data[2] >> 4)) + 1.0;
 * 3) For Z axis, the COEFFICIENT is as below:
 *    f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35;
 * We implemented the OTP logic into driver.
 */

/* scale = 1000 here for Y otp */
#define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6)

/* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */
#define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81)

#define MMC35240_X_COEFF(x)     (x)
#define MMC35240_Y_COEFF(y)     (y + 1000)
#define MMC35240_Z_COEFF(z)     (z + 13500)

#define MMC35240_OTP_START_ADDR         0x1B

enum mmc35240_resolution {
        MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */
        MMC35240_16_BITS_FAST,     /* 4.08 ms */
        MMC35240_14_BITS,          /* 2.16 ms */
        MMC35240_12_BITS,          /* 1.20 ms */
};

enum mmc35240_axis {
        AXIS_X = 0,
        AXIS_Y,
        AXIS_Z,
};

static const struct {
        int sens[3]; /* sensitivity per X, Y, Z axis */
        int nfo; /* null field output */
} mmc35240_props_table[] = {
        /* 16 bits, 125Hz ODR */
        {
                {1024, 1024, 1024},
                32768,
        },
        /* 16 bits, 250Hz ODR */
        {
                {1024, 1024, 770},
                32768,
        },
        /* 14 bits, 450Hz ODR */
        {
                {256, 256, 193},
                8192,
        },
        /* 12 bits, 800Hz ODR */
        {
                {64, 64, 48},
                2048,
        },
};

struct mmc35240_data {
        struct i2c_client *client;
        struct mutex mutex;
        struct regmap *regmap;
        enum mmc35240_resolution res;

        /* OTP compensation */
        int axis_coef[3];
        int axis_scale[3];
};

static const struct {
        int val;
        int val2;
} mmc35240_samp_freq[] = { {1, 500000},
                           {13, 0},
                           {25, 0},
                           {50, 0} };

static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50");

#define MMC35240_CHANNEL(_axis) { \
        .type = IIO_MAGN, \
        .modified = 1, \
        .channel2 = IIO_MOD_ ## _axis, \
        .address = AXIS_ ## _axis, \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
                        BIT(IIO_CHAN_INFO_SCALE), \
}

static const struct iio_chan_spec mmc35240_channels[] = {
        MMC35240_CHANNEL(X),
        MMC35240_CHANNEL(Y),
        MMC35240_CHANNEL(Z),
};

static struct attribute *mmc35240_attributes[] = {
        &iio_const_attr_sampling_frequency_available.dev_attr.attr,
        NULL
};

static const struct attribute_group mmc35240_attribute_group = {
        .attrs = mmc35240_attributes,
};

static int mmc35240_get_samp_freq_index(struct mmc35240_data *data,
                                        int val, int val2)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++)
                if (mmc35240_samp_freq[i].val == val &&
                    mmc35240_samp_freq[i].val2 == val2)
                        return i;
        return -EINVAL;
}

static int mmc35240_hw_set(struct mmc35240_data *data, bool set)
{
        int ret;
        u8 coil_bit;

        /*
         * Recharge the capacitor at VCAP pin, requested to be issued
         * before a SET/RESET command.
         */
        ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
                                 MMC35240_CTRL0_REFILL_BIT,
                                 MMC35240_CTRL0_REFILL_BIT);
        if (ret < 0)
                return ret;
        usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1);

        if (set)
                coil_bit = MMC35240_CTRL0_SET_BIT;
        else
                coil_bit = MMC35240_CTRL0_RESET_BIT;

        return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0,
                                  coil_bit, coil_bit);

}

static int mmc35240_init(struct mmc35240_data *data)
{
        int ret, y_convert, z_convert;
        unsigned int reg_id;
        u8 otp_data[6];

        ret = regmap_read(data->regmap, MMC35240_REG_ID, &reg_id);
        if (ret < 0) {
                dev_err(&data->client->dev, "Error reading product id\n");
                return ret;
        }

        dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id);

        /*
         * make sure we restore sensor characteristics, by doing
         * a SET/RESET sequence, the axis polarity being naturally
         * aligned after RESET
         */
        ret = mmc35240_hw_set(data, true);
        if (ret < 0)
                return ret;
        usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1);

        ret = mmc35240_hw_set(data, false);
        if (ret < 0)
                return ret;

        /* set default sampling frequency */
        ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
                                 MMC35240_CTRL1_BW_MASK,
                                 data->res << MMC35240_CTRL1_BW_SHIFT);
        if (ret < 0)
                return ret;

        ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR,
                               (u8 *)otp_data, sizeof(otp_data));
        if (ret < 0)
                return ret;

        y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) |
                                           (otp_data[2] >> 4));
        z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f);

        data->axis_coef[0] = MMC35240_X_COEFF(1);
        data->axis_coef[1] = MMC35240_Y_COEFF(y_convert);
        data->axis_coef[2] = MMC35240_Z_COEFF(z_convert);

        data->axis_scale[0] = 1;
        data->axis_scale[1] = 1000;
        data->axis_scale[2] = 10000;

        return 0;
}

static int mmc35240_take_measurement(struct mmc35240_data *data)
{
        int ret, tries = 100;
        unsigned int reg_status;

        ret = regmap_write(data->regmap, MMC35240_REG_CTRL0,
                           MMC35240_CTRL0_TM_BIT);
        if (ret < 0)
                return ret;

        while (tries-- > 0) {
                ret = regmap_read(data->regmap, MMC35240_REG_STATUS,
                                  &reg_status);
                if (ret < 0)
                        return ret;
                if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT)
                        break;
                /* minimum wait time to complete measurement is 10 ms */
                usleep_range(10000, 11000);
        }

        if (tries < 0) {
                dev_err(&data->client->dev, "data not ready\n");
                return -EIO;
        }

        return 0;
}

static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3])
{
        int ret;

        ret = mmc35240_take_measurement(data);
        if (ret < 0)
                return ret;

        return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf,
                                3 * sizeof(__le16));
}

/**
 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply
                            compensation for output value.
 *
 * @data: device private data
 * @index: axis index for which we want the conversion
 * @buf: raw data to be converted, 2 bytes in little endian format
 * @val: compensated output reading (unit is milli gauss)
 *
 * Returns: 0 in case of success, -EINVAL when @index is not valid
 */
static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index,
                                  __le16 buf[], int *val)
{
        int raw[3];
        int sens[3];
        int nfo;

        raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]);
        raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]);
        raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]);

        sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X];
        sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y];
        sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z];

        nfo = mmc35240_props_table[data->res].nfo;

        switch (index) {
        case AXIS_X:
                *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X];
                break;
        case AXIS_Y:
                *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] -
                        (raw[AXIS_Z] - nfo)  * 1000 / sens[AXIS_Z];
                break;
        case AXIS_Z:
                *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] +
                        (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z];
                break;
        default:
                return -EINVAL;
        }
        /* apply OTP compensation */
        *val = (*val) * data->axis_coef[index] / data->axis_scale[index];

        return 0;
}

static int mmc35240_read_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan, int *val,
                             int *val2, long mask)
{
        struct mmc35240_data *data = iio_priv(indio_dev);
        int ret, i;
        unsigned int reg;
        __le16 buf[3];

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&data->mutex);
                ret = mmc35240_read_measurement(data, buf);
                mutex_unlock(&data->mutex);
                if (ret < 0)
                        return ret;
                ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val);
                if (ret < 0)
                        return ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = 1000;
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SAMP_FREQ:
                mutex_lock(&data->mutex);
                ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, &reg);
                mutex_unlock(&data->mutex);
                if (ret < 0)
                        return ret;

                i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT;
                if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq))
                        return -EINVAL;

                *val = mmc35240_samp_freq[i].val;
                *val2 = mmc35240_samp_freq[i].val2;
                return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
}

static int mmc35240_write_raw(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan, int val,
                              int val2, long mask)
{
        struct mmc35240_data *data = iio_priv(indio_dev);
        int i, ret;

        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
                i = mmc35240_get_samp_freq_index(data, val, val2);
                if (i < 0)
                        return -EINVAL;
                mutex_lock(&data->mutex);
                ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1,
                                         MMC35240_CTRL1_BW_MASK,
                                         i << MMC35240_CTRL1_BW_SHIFT);
                mutex_unlock(&data->mutex);
                return ret;
        default:
                return -EINVAL;
        }
}

static const struct iio_info mmc35240_info = {
        .read_raw       = mmc35240_read_raw,
        .write_raw      = mmc35240_write_raw,
        .attrs          = &mmc35240_attribute_group,
};

static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case MMC35240_REG_CTRL0:
        case MMC35240_REG_CTRL1:
                return true;
        default:
                return false;
        }
}

static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case MMC35240_REG_XOUT_L:
        case MMC35240_REG_XOUT_H:
        case MMC35240_REG_YOUT_L:
        case MMC35240_REG_YOUT_H:
        case MMC35240_REG_ZOUT_L:
        case MMC35240_REG_ZOUT_H:
        case MMC35240_REG_STATUS:
        case MMC35240_REG_ID:
                return true;
        default:
                return false;
        }
}

static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case MMC35240_REG_CTRL0:
        case MMC35240_REG_CTRL1:
                return false;
        default:
                return true;
        }
}

static struct reg_default mmc35240_reg_defaults[] = {
        { MMC35240_REG_CTRL0,  0x00 },
        { MMC35240_REG_CTRL1,  0x00 },
};

static const struct regmap_config mmc35240_regmap_config = {
        .name = MMC35240_REGMAP_NAME,

        .reg_bits = 8,
        .val_bits = 8,

        .max_register = MMC35240_REG_ID,
        .cache_type = REGCACHE_FLAT,

        .writeable_reg = mmc35240_is_writeable_reg,
        .readable_reg = mmc35240_is_readable_reg,
        .volatile_reg = mmc35240_is_volatile_reg,

        .reg_defaults = mmc35240_reg_defaults,
        .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults),
};

static int mmc35240_probe(struct i2c_client *client,
                          const struct i2c_device_id *id)
{
        struct mmc35240_data *data;
        struct iio_dev *indio_dev;
        struct regmap *regmap;
        int ret;

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

        regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(&client->dev, "regmap initialization failed\n");
                return PTR_ERR(regmap);
        }

        data = iio_priv(indio_dev);
        i2c_set_clientdata(client, indio_dev);
        data->client = client;
        data->regmap = regmap;
        data->res = MMC35240_16_BITS_SLOW;

        mutex_init(&data->mutex);

        indio_dev->dev.parent = &client->dev;
        indio_dev->info = &mmc35240_info;
        indio_dev->name = MMC35240_DRV_NAME;
        indio_dev->channels = mmc35240_channels;
        indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = mmc35240_init(data);
        if (ret < 0) {
                dev_err(&client->dev, "mmc35240 chip init failed\n");
                return ret;
        }
        return devm_iio_device_register(&client->dev, indio_dev);
}

#ifdef CONFIG_PM_SLEEP
static int mmc35240_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
        struct mmc35240_data *data = iio_priv(indio_dev);

        regcache_cache_only(data->regmap, true);

        return 0;
}

static int mmc35240_resume(struct device *dev)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
        struct mmc35240_data *data = iio_priv(indio_dev);
        int ret;

        regcache_mark_dirty(data->regmap);
        ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0,
                                   MMC35240_REG_CTRL1);
        if (ret < 0)
                dev_err(dev, "Failed to restore control registers\n");

        regcache_cache_only(data->regmap, false);

        return 0;
}
#endif

static const struct dev_pm_ops mmc35240_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume)
};

static const struct of_device_id mmc35240_of_match[] = {
        { .compatible = "memsic,mmc35240", },
        { }
};
MODULE_DEVICE_TABLE(of, mmc35240_of_match);

static const struct acpi_device_id mmc35240_acpi_match[] = {
        {"MMC35240", 0},
        { },
};
MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match);

static const struct i2c_device_id mmc35240_id[] = {
        {"mmc35240", 0},
        {}
};
MODULE_DEVICE_TABLE(i2c, mmc35240_id);

static struct i2c_driver mmc35240_driver = {
        .driver = {
                .name = MMC35240_DRV_NAME,
                .of_match_table = mmc35240_of_match,
                .pm = &mmc35240_pm_ops,
                .acpi_match_table = ACPI_PTR(mmc35240_acpi_match),
        },
        .probe          = mmc35240_probe,
        .id_table       = mmc35240_id,
};

module_i2c_driver(mmc35240_driver);

MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver");
MODULE_LICENSE("GPL v2");