// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 Oleh Kravchenko <oleg@kaa.org.ua>
 *
 * SparkFun Qwiic Joystick
 * Product page:https://www.sparkfun.com/products/15168
 * Firmware and hardware sources:https://github.com/sparkfun/Qwiic_Joystick
 */

#include <linux/bits.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/module.h>

#define DRV_NAME "qwiic-joystick"

#define QWIIC_JSK_REG_VERS      1
#define QWIIC_JSK_REG_DATA      3

#define QWIIC_JSK_MAX_AXIS      GENMASK(9, 0)
#define QWIIC_JSK_FUZZ          2
#define QWIIC_JSK_FLAT          2
#define QWIIC_JSK_POLL_INTERVAL 16
#define QWIIC_JSK_POLL_MIN      8
#define QWIIC_JSK_POLL_MAX      32

struct qwiic_jsk {
        char phys[32];
        struct input_dev *dev;
        struct i2c_client *client;
};

struct qwiic_ver {
        u8 major;
        u8 minor;
};

struct qwiic_data {
        __be16 x;
        __be16 y;
        u8 thumb;
};

static void qwiic_poll(struct input_dev *input)
{
        struct qwiic_jsk *priv = input_get_drvdata(input);
        struct qwiic_data data;
        int err;

        err = i2c_smbus_read_i2c_block_data(priv->client, QWIIC_JSK_REG_DATA,
                                            sizeof(data), (u8 *)&data);
        if (err != sizeof(data))
                return;

        input_report_abs(input, ABS_X, be16_to_cpu(data.x) >> 6);
        input_report_abs(input, ABS_Y, be16_to_cpu(data.y) >> 6);
        input_report_key(input, BTN_THUMBL, !data.thumb);
        input_sync(input);
}

static int qwiic_probe(struct i2c_client *client)
{
        struct qwiic_jsk *priv;
        struct qwiic_ver vers;
        int err;

        err = i2c_smbus_read_i2c_block_data(client, QWIIC_JSK_REG_VERS,
                                            sizeof(vers), (u8 *)&vers);
        if (err < 0)
                return err;
        if (err != sizeof(vers))
                return -EIO;

        dev_dbg(&client->dev, "SparkFun Qwiic Joystick, FW: %u.%u\n",
                vers.major, vers.minor);

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

        priv->client = client;
        snprintf(priv->phys, sizeof(priv->phys),
                 "i2c/%s", dev_name(&client->dev));
        i2c_set_clientdata(client, priv);

        priv->dev = devm_input_allocate_device(&client->dev);
        if (!priv->dev)
                return -ENOMEM;

        priv->dev->id.bustype = BUS_I2C;
        priv->dev->name = "SparkFun Qwiic Joystick";
        priv->dev->phys = priv->phys;
        input_set_drvdata(priv->dev, priv);

        input_set_abs_params(priv->dev, ABS_X, 0, QWIIC_JSK_MAX_AXIS,
                             QWIIC_JSK_FUZZ, QWIIC_JSK_FLAT);
        input_set_abs_params(priv->dev, ABS_Y, 0, QWIIC_JSK_MAX_AXIS,
                             QWIIC_JSK_FUZZ, QWIIC_JSK_FLAT);
        input_set_capability(priv->dev, EV_KEY, BTN_THUMBL);

        err = input_setup_polling(priv->dev, qwiic_poll);
        if (err) {
                dev_err(&client->dev, "failed to set up polling: %d\n", err);
                return err;
        }
        input_set_poll_interval(priv->dev, QWIIC_JSK_POLL_INTERVAL);
        input_set_min_poll_interval(priv->dev, QWIIC_JSK_POLL_MIN);
        input_set_max_poll_interval(priv->dev, QWIIC_JSK_POLL_MAX);

        err = input_register_device(priv->dev);
        if (err) {
                dev_err(&client->dev, "failed to register joystick: %d\n", err);
                return err;
        }

        return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id of_qwiic_match[] = {
        { .compatible = "sparkfun,qwiic-joystick", },
        { },
};
MODULE_DEVICE_TABLE(of, of_qwiic_match);
#endif /* CONFIG_OF */

static const struct i2c_device_id qwiic_id_table[] = {
        { KBUILD_MODNAME },
        { }
};
MODULE_DEVICE_TABLE(i2c, qwiic_id_table);

static struct i2c_driver qwiic_driver = {
        .driver = {
                .name           = DRV_NAME,
                .of_match_table = of_match_ptr(of_qwiic_match),
        },
        .id_table       = qwiic_id_table,
        .probe          = qwiic_probe,
};
module_i2c_driver(qwiic_driver);

MODULE_AUTHOR("Oleh Kravchenko <oleg@kaa.org.ua>");
MODULE_DESCRIPTION("SparkFun Qwiic Joystick driver");
MODULE_LICENSE("GPL v2");