// SPDX-License-Identifier: GPL-2.0-only
/*
 * IIO driver for the 3-axis accelerometer Domintech DMARD09.
 *
 * Copyright (c) 2016, Jelle van der Waa <jelle@vdwaa.nl>
 */

#include <linux/unaligned.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>

#define DMARD09_DRV_NAME        "dmard09"

#define DMARD09_REG_CHIPID      0x18
#define DMARD09_REG_STAT        0x0A
#define DMARD09_REG_X           0x0C
#define DMARD09_REG_Y           0x0E
#define DMARD09_REG_Z           0x10
#define DMARD09_CHIPID          0x95

#define DMARD09_BUF_LEN 8
#define DMARD09_AXIS_X 0
#define DMARD09_AXIS_Y 1
#define DMARD09_AXIS_Z 2
#define DMARD09_AXIS_X_OFFSET ((DMARD09_AXIS_X + 1) * 2)
#define DMARD09_AXIS_Y_OFFSET ((DMARD09_AXIS_Y + 1) * 2)
#define DMARD09_AXIS_Z_OFFSET ((DMARD09_AXIS_Z + 1) * 2)

struct dmard09_data {
        struct i2c_client *client;
};

#define DMARD09_CHANNEL(_axis, offset) {                        \
        .type = IIO_ACCEL,                                      \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
        .modified = 1,                                          \
        .address = offset,                                      \
        .channel2 = IIO_MOD_##_axis,                            \
}

static const struct iio_chan_spec dmard09_channels[] = {
        DMARD09_CHANNEL(X, DMARD09_AXIS_X_OFFSET),
        DMARD09_CHANNEL(Y, DMARD09_AXIS_Y_OFFSET),
        DMARD09_CHANNEL(Z, DMARD09_AXIS_Z_OFFSET),
};

static int dmard09_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        struct dmard09_data *data = iio_priv(indio_dev);
        u8 buf[DMARD09_BUF_LEN];
        int ret;
        s16 accel;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                /*
                 * Read from the DMAR09_REG_STAT register, since the chip
                 * caches reads from the individual X, Y, Z registers.
                 */
                ret = i2c_smbus_read_i2c_block_data(data->client,
                                                    DMARD09_REG_STAT,
                                                    DMARD09_BUF_LEN, buf);
                if (ret < 0) {
                        dev_err(&data->client->dev, "Error reading reg %d\n",
                                DMARD09_REG_STAT);
                        return ret;
                }

                accel = get_unaligned_le16(&buf[chan->address]);

                /* Remove lower 3 bits and sign extend */
                accel <<= 4;
                accel >>= 7;

                *val = accel;

                return IIO_VAL_INT;
        default:
                return -EINVAL;
        }
}

static const struct iio_info dmard09_info = {
        .read_raw       = dmard09_read_raw,
};

static int dmard09_probe(struct i2c_client *client)
{
        int ret;
        struct iio_dev *indio_dev;
        struct dmard09_data *data;

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

        data = iio_priv(indio_dev);
        data->client = client;

        ret = i2c_smbus_read_byte_data(data->client, DMARD09_REG_CHIPID);
        if (ret < 0) {
                dev_err(&client->dev, "Error reading chip id %d\n", ret);
                return ret;
        }

        if (ret != DMARD09_CHIPID) {
                dev_err(&client->dev, "Invalid chip id %d\n", ret);
                return -ENODEV;
        }

        i2c_set_clientdata(client, indio_dev);
        indio_dev->name = DMARD09_DRV_NAME;
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->channels = dmard09_channels;
        indio_dev->num_channels = ARRAY_SIZE(dmard09_channels);
        indio_dev->info = &dmard09_info;

        return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id dmard09_id[] = {
        { "dmard09" },
        { }
};

MODULE_DEVICE_TABLE(i2c, dmard09_id);

static struct i2c_driver dmard09_driver = {
        .driver = {
                .name = DMARD09_DRV_NAME
        },
        .probe = dmard09_probe,
        .id_table = dmard09_id,
};

module_i2c_driver(dmard09_driver);

MODULE_AUTHOR("Jelle van der Waa <jelle@vdwaa.nl>");
MODULE_DESCRIPTION("DMARD09 3-axis accelerometer driver");
MODULE_LICENSE("GPL");