// SPDX-License-Identifier: GPL-2.0-only
/*
 * Microchip AR1020 and AR1021 driver for I2C
 *
 * Author: Christian Gmeiner <christian.gmeiner@gmail.com>
 */

#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/of.h>
#include <linux/i2c.h>
#include <linux/irq.h>
#include <linux/interrupt.h>

#define AR1021_TOUCH_PKG_SIZE   5

#define AR1021_MAX_X    4095
#define AR1021_MAX_Y    4095

#define AR1021_CMD      0x55

#define AR1021_CMD_ENABLE_TOUCH         0x12

struct ar1021_i2c {
        struct i2c_client *client;
        struct input_dev *input;
        u8 data[AR1021_TOUCH_PKG_SIZE];
};

static irqreturn_t ar1021_i2c_irq(int irq, void *dev_id)
{
        struct ar1021_i2c *ar1021 = dev_id;
        struct input_dev *input = ar1021->input;
        u8 *data = ar1021->data;
        unsigned int x, y, button;
        int retval;

        retval = i2c_master_recv(ar1021->client,
                                 ar1021->data, sizeof(ar1021->data));
        if (retval != sizeof(ar1021->data))
                goto out;

        /* sync bit set ? */
        if (!(data[0] & BIT(7)))
                goto out;

        button = data[0] & BIT(0);
        x = ((data[2] & 0x1f) << 7) | (data[1] & 0x7f);
        y = ((data[4] & 0x1f) << 7) | (data[3] & 0x7f);

        input_report_abs(input, ABS_X, x);
        input_report_abs(input, ABS_Y, y);
        input_report_key(input, BTN_TOUCH, button);
        input_sync(input);

out:
        return IRQ_HANDLED;
}

static int ar1021_i2c_open(struct input_dev *dev)
{
        static const u8 cmd_enable_touch[] = {
                AR1021_CMD,
                0x01, /* number of bytes after this */
                AR1021_CMD_ENABLE_TOUCH
        };
        struct ar1021_i2c *ar1021 = input_get_drvdata(dev);
        struct i2c_client *client = ar1021->client;
        int error;

        error = i2c_master_send(ar1021->client, cmd_enable_touch,
                                sizeof(cmd_enable_touch));
        if (error < 0)
                return error;

        enable_irq(client->irq);

        return 0;
}

static void ar1021_i2c_close(struct input_dev *dev)
{
        struct ar1021_i2c *ar1021 = input_get_drvdata(dev);
        struct i2c_client *client = ar1021->client;

        disable_irq(client->irq);
}

static int ar1021_i2c_probe(struct i2c_client *client)
{
        struct ar1021_i2c *ar1021;
        struct input_dev *input;
        int error;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                dev_err(&client->dev, "i2c_check_functionality error\n");
                return -ENXIO;
        }

        ar1021 = devm_kzalloc(&client->dev, sizeof(*ar1021), GFP_KERNEL);
        if (!ar1021)
                return -ENOMEM;

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

        ar1021->client = client;
        ar1021->input = input;

        input->name = "ar1021 I2C Touchscreen";
        input->id.bustype = BUS_I2C;
        input->dev.parent = &client->dev;
        input->open = ar1021_i2c_open;
        input->close = ar1021_i2c_close;

        __set_bit(INPUT_PROP_DIRECT, input->propbit);
        input_set_capability(input, EV_KEY, BTN_TOUCH);
        input_set_abs_params(input, ABS_X, 0, AR1021_MAX_X, 0, 0);
        input_set_abs_params(input, ABS_Y, 0, AR1021_MAX_Y, 0, 0);

        input_set_drvdata(input, ar1021);

        error = devm_request_threaded_irq(&client->dev, client->irq,
                                          NULL, ar1021_i2c_irq,
                                          IRQF_ONESHOT | IRQF_NO_AUTOEN,
                                          "ar1021_i2c", ar1021);
        if (error) {
                dev_err(&client->dev,
                        "Failed to enable IRQ, error: %d\n", error);
                return error;
        }

        error = input_register_device(ar1021->input);
        if (error) {
                dev_err(&client->dev,
                        "Failed to register input device, error: %d\n", error);
                return error;
        }

        return 0;
}

static int ar1021_i2c_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);

        disable_irq(client->irq);

        return 0;
}

static int ar1021_i2c_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);

        enable_irq(client->irq);

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(ar1021_i2c_pm,
                                ar1021_i2c_suspend, ar1021_i2c_resume);

static const struct i2c_device_id ar1021_i2c_id[] = {
        { "ar1021" },
        { }
};
MODULE_DEVICE_TABLE(i2c, ar1021_i2c_id);

static const struct of_device_id ar1021_i2c_of_match[] = {
        { .compatible = "microchip,ar1021-i2c", },
        { }
};
MODULE_DEVICE_TABLE(of, ar1021_i2c_of_match);

static struct i2c_driver ar1021_i2c_driver = {
        .driver = {
                .name   = "ar1021_i2c",
                .pm     = pm_sleep_ptr(&ar1021_i2c_pm),
                .of_match_table = ar1021_i2c_of_match,
        },

        .probe          = ar1021_i2c_probe,
        .id_table       = ar1021_i2c_id,
};
module_i2c_driver(ar1021_i2c_driver);

MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
MODULE_DESCRIPTION("Microchip AR1020 and AR1021 I2C Driver");
MODULE_LICENSE("GPL");