/*
 * Microchip AR1020 and AR1021 driver for I2C
 *
 * Author: Christian Gmeiner <christian.gmeiner@gmail.com>
 *
 * License: GPLv2 as published by the FSF.
 */

#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_TOCUH_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_TOCUH_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,
			    const struct i2c_device_id *id)
{
	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;

	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,
					  "ar1021_i2c", ar1021);
	if (error) {
		dev_err(&client->dev,
			"Failed to enable IRQ, error: %d\n", error);
		return error;
	}

	/* Disable the IRQ, we'll enable it in ar1021_i2c_open() */
	disable_irq(client->irq);

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

	disable_irq(client->irq);

	return 0;
}

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

	enable_irq(client->irq);

	return 0;
}

static SIMPLE_DEV_PM_OPS(ar1021_i2c_pm, ar1021_i2c_suspend, ar1021_i2c_resume);

static const struct i2c_device_id ar1021_i2c_id[] = {
	{ "ar1021", 0 },
	{ },
};
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	= &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");