// SPDX-License-Identifier: GPL-2.0-only
/*
 * MXC6255 - MEMSIC orientation sensing accelerometer
 *
 * Copyright (c) 2015, Intel Corporation.
 *
 * IIO driver for MXC6255 (7-bit I2C slave address 0x15).
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/iio/iio.h>
#include <linux/delay.h>
#include <linux/mod_devicetable.h>
#include <linux/regmap.h>
#include <linux/iio/sysfs.h>

#define MXC6255_DRV_NAME                "mxc6255"

#define MXC6255_REG_XOUT                0x00
#define MXC6255_REG_YOUT                0x01
#define MXC6255_REG_CHIP_ID             0x08

#define MXC6255_CHIP_ID                 0x05

/*
 * MXC6255 has only one measurement range: +/- 2G.
 * The acceleration output is an 8-bit value.
 *
 * Scale is calculated as follows:
 * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
 *
 * Scale value for +/- 2G measurement range
 */
#define MXC6255_SCALE                   153829

enum mxc6255_axis {
        AXIS_X,
        AXIS_Y,
};

struct mxc6255_data {
        struct i2c_client *client;
        struct regmap *regmap;
};

static int mxc6255_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        struct mxc6255_data *data = iio_priv(indio_dev);
        unsigned int reg;
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = regmap_read(data->regmap, chan->address, &reg);
                if (ret < 0) {
                        dev_err(&data->client->dev,
                                "Error reading reg %lu\n", chan->address);
                        return ret;
                }

                *val = sign_extend32(reg, 7);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = MXC6255_SCALE;
                return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
}

static const struct iio_info mxc6255_info = {
        .read_raw       = mxc6255_read_raw,
};

#define MXC6255_CHANNEL(_axis, reg) {                           \
        .type = IIO_ACCEL,                                      \
        .modified = 1,                                          \
        .channel2 = IIO_MOD_##_axis,                            \
        .address = reg,                                         \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
}

static const struct iio_chan_spec mxc6255_channels[] = {
        MXC6255_CHANNEL(X, MXC6255_REG_XOUT),
        MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
};

static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case MXC6255_REG_XOUT:
        case MXC6255_REG_YOUT:
        case MXC6255_REG_CHIP_ID:
                return true;
        default:
                return false;
        }
}

static const struct regmap_config mxc6255_regmap_config = {
        .name = "mxc6255_regmap",

        .reg_bits = 8,
        .val_bits = 8,

        .readable_reg = mxc6255_is_readable_reg,
};

static int mxc6255_probe(struct i2c_client *client)
{
        struct mxc6255_data *data;
        struct iio_dev *indio_dev;
        struct regmap *regmap;
        unsigned int chip_id;
        int ret;

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

        regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(&client->dev, "Error initializing regmap\n");
                return PTR_ERR(regmap);
        }

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

        indio_dev->name = MXC6255_DRV_NAME;
        indio_dev->channels = mxc6255_channels;
        indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &mxc6255_info;

        ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
        if (ret < 0) {
                dev_err(&client->dev, "Error reading chip id %d\n", ret);
                return ret;
        }

        if ((chip_id & 0x1f) != MXC6255_CHIP_ID) {
                dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
                return -ENODEV;
        }

        dev_dbg(&client->dev, "Chip id %x\n", chip_id);

        ret = devm_iio_device_register(&client->dev, indio_dev);
        if (ret < 0) {
                dev_err(&client->dev, "Could not register IIO device\n");
                return ret;
        }

        return 0;
}

static const struct acpi_device_id mxc6255_acpi_match[] = {
        {"MXC6225",     0},
        {"MXC6255",     0},
        { }
};
MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);

static const struct i2c_device_id mxc6255_id[] = {
        { "mxc6225" },
        { "mxc6255" },
        { }
};
MODULE_DEVICE_TABLE(i2c, mxc6255_id);

static struct i2c_driver mxc6255_driver = {
        .driver = {
                .name = MXC6255_DRV_NAME,
                .acpi_match_table = mxc6255_acpi_match,
        },
        .probe          = mxc6255_probe,
        .id_table       = mxc6255_id,
};

module_i2c_driver(mxc6255_driver);

MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
MODULE_LICENSE("GPL v2");