// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for Novatek NT11205 i2c touchscreen controller as found
 * on the Acer Iconia One 7 B1-750 tablet.
 *
 * Copyright (c) 2023 Hans de Goede <hdegoede@redhat.com>
 */

#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/input/touchscreen.h>
#include <linux/module.h>

#include <asm/unaligned.h>

#define NVT_TS_TOUCH_START		0x00
#define NVT_TS_TOUCH_SIZE		6

#define NVT_TS_PARAMETERS_START		0x78
/* These are offsets from NVT_TS_PARAMETERS_START */
#define NVT_TS_PARAMS_WIDTH		0x04
#define NVT_TS_PARAMS_HEIGHT		0x06
#define NVT_TS_PARAMS_MAX_TOUCH		0x09
#define NVT_TS_PARAMS_MAX_BUTTONS	0x0a
#define NVT_TS_PARAMS_IRQ_TYPE		0x0b
#define NVT_TS_PARAMS_WAKE_TYPE		0x0c
#define NVT_TS_PARAMS_CHIP_ID		0x0e
#define NVT_TS_PARAMS_SIZE		0x0f

#define NVT_TS_SUPPORTED_WAKE_TYPE	0x05
#define NVT_TS_SUPPORTED_CHIP_ID	0x05

#define NVT_TS_MAX_TOUCHES		10
#define NVT_TS_MAX_SIZE			4096

#define NVT_TS_TOUCH_INVALID		0xff
#define NVT_TS_TOUCH_SLOT_SHIFT		3
#define NVT_TS_TOUCH_TYPE_MASK		GENMASK(2, 0)
#define NVT_TS_TOUCH_NEW		1
#define NVT_TS_TOUCH_UPDATE		2
#define NVT_TS_TOUCH_RELEASE		3

static const int nvt_ts_irq_type[4] = {
	IRQF_TRIGGER_RISING,
	IRQF_TRIGGER_FALLING,
	IRQF_TRIGGER_LOW,
	IRQF_TRIGGER_HIGH
};

struct nvt_ts_data {
	struct i2c_client *client;
	struct input_dev *input;
	struct gpio_desc *reset_gpio;
	struct touchscreen_properties prop;
	int max_touches;
	u8 buf[NVT_TS_TOUCH_SIZE * NVT_TS_MAX_TOUCHES];
};

static int nvt_ts_read_data(struct i2c_client *client, u8 reg, u8 *data, int count)
{
	struct i2c_msg msg[2] = {
		{
			.addr = client->addr,
			.len = 1,
			.buf = &reg,
		},
		{
			.addr = client->addr,
			.flags = I2C_M_RD,
			.len = count,
			.buf = data,
		}
	};
	int ret;

	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
	if (ret != ARRAY_SIZE(msg)) {
		dev_err(&client->dev, "Error reading from 0x%02x: %d\n", reg, ret);
		return (ret < 0) ? ret : -EIO;
	}

	return 0;
}

static irqreturn_t nvt_ts_irq(int irq, void *dev_id)
{
	struct nvt_ts_data *data = dev_id;
	struct device *dev = &data->client->dev;
	int i, error, slot, x, y;
	bool active;
	u8 *touch;

	error = nvt_ts_read_data(data->client, NVT_TS_TOUCH_START, data->buf,
				 data->max_touches * NVT_TS_TOUCH_SIZE);
	if (error)
		return IRQ_HANDLED;

	for (i = 0; i < data->max_touches; i++) {
		touch = &data->buf[i * NVT_TS_TOUCH_SIZE];

		if (touch[0] == NVT_TS_TOUCH_INVALID)
			continue;

		slot = touch[0] >> NVT_TS_TOUCH_SLOT_SHIFT;
		if (slot < 1 || slot > data->max_touches) {
			dev_warn(dev, "slot %d out of range, ignoring\n", slot);
			continue;
		}

		switch (touch[0] & NVT_TS_TOUCH_TYPE_MASK) {
		case NVT_TS_TOUCH_NEW:
		case NVT_TS_TOUCH_UPDATE:
			active = true;
			break;
		case NVT_TS_TOUCH_RELEASE:
			active = false;
			break;
		default:
			dev_warn(dev, "slot %d unknown state %d\n", slot, touch[0] & 7);
			continue;
		}

		slot--;
		x = (touch[1] << 4) | (touch[3] >> 4);
		y = (touch[2] << 4) | (touch[3] & 0x0f);

		input_mt_slot(data->input, slot);
		input_mt_report_slot_state(data->input, MT_TOOL_FINGER, active);
		touchscreen_report_pos(data->input, &data->prop, x, y, true);
	}

	input_mt_sync_frame(data->input);
	input_sync(data->input);

	return IRQ_HANDLED;
}

static int nvt_ts_start(struct input_dev *dev)
{
	struct nvt_ts_data *data = input_get_drvdata(dev);

	enable_irq(data->client->irq);
	gpiod_set_value_cansleep(data->reset_gpio, 0);

	return 0;
}

static void nvt_ts_stop(struct input_dev *dev)
{
	struct nvt_ts_data *data = input_get_drvdata(dev);

	disable_irq(data->client->irq);
	gpiod_set_value_cansleep(data->reset_gpio, 1);
}

static int nvt_ts_suspend(struct device *dev)
{
	struct nvt_ts_data *data = i2c_get_clientdata(to_i2c_client(dev));

	mutex_lock(&data->input->mutex);
	if (input_device_enabled(data->input))
		nvt_ts_stop(data->input);
	mutex_unlock(&data->input->mutex);

	return 0;
}

static int nvt_ts_resume(struct device *dev)
{
	struct nvt_ts_data *data = i2c_get_clientdata(to_i2c_client(dev));

	mutex_lock(&data->input->mutex);
	if (input_device_enabled(data->input))
		nvt_ts_start(data->input);
	mutex_unlock(&data->input->mutex);

	return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(nvt_ts_pm_ops, nvt_ts_suspend, nvt_ts_resume);

static int nvt_ts_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	int error, width, height, irq_type;
	struct nvt_ts_data *data;
	struct input_dev *input;

	if (!client->irq) {
		dev_err(dev, "Error no irq specified\n");
		return -EINVAL;
	}

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->client = client;
	i2c_set_clientdata(client, data);

	data->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
	error = PTR_ERR_OR_ZERO(data->reset_gpio);
	if (error) {
		dev_err(dev, "failed to request reset GPIO: %d\n", error);
		return error;
	}

	/* Wait for controller to come out of reset before params read */
	msleep(100);
	error = nvt_ts_read_data(data->client, NVT_TS_PARAMETERS_START,
				 data->buf, NVT_TS_PARAMS_SIZE);
	gpiod_set_value_cansleep(data->reset_gpio, 1); /* Put back in reset */
	if (error)
		return error;

	width  = get_unaligned_be16(&data->buf[NVT_TS_PARAMS_WIDTH]);
	height = get_unaligned_be16(&data->buf[NVT_TS_PARAMS_HEIGHT]);
	data->max_touches = data->buf[NVT_TS_PARAMS_MAX_TOUCH];
	irq_type = data->buf[NVT_TS_PARAMS_IRQ_TYPE];

	if (width > NVT_TS_MAX_SIZE || height >= NVT_TS_MAX_SIZE ||
	    data->max_touches > NVT_TS_MAX_TOUCHES ||
	    irq_type >= ARRAY_SIZE(nvt_ts_irq_type) ||
	    data->buf[NVT_TS_PARAMS_WAKE_TYPE] != NVT_TS_SUPPORTED_WAKE_TYPE ||
	    data->buf[NVT_TS_PARAMS_CHIP_ID] != NVT_TS_SUPPORTED_CHIP_ID) {
		dev_err(dev, "Unsupported touchscreen parameters: %*ph\n",
			NVT_TS_PARAMS_SIZE, data->buf);
		return -EIO;
	}

	dev_dbg(dev, "Detected %dx%d touchscreen with %d max touches\n",
		width, height, data->max_touches);

	if (data->buf[NVT_TS_PARAMS_MAX_BUTTONS])
		dev_warn(dev, "Touchscreen buttons are not supported\n");

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

	input->name = client->name;
	input->id.bustype = BUS_I2C;
	input->open = nvt_ts_start;
	input->close = nvt_ts_stop;

	input_set_abs_params(input, ABS_MT_POSITION_X, 0, width - 1, 0, 0);
	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, height - 1, 0, 0);
	touchscreen_parse_properties(input, true, &data->prop);

	error = input_mt_init_slots(input, data->max_touches,
				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
	if (error)
		return error;

	data->input = input;
	input_set_drvdata(input, data);

	error = devm_request_threaded_irq(dev, client->irq, NULL, nvt_ts_irq,
					  IRQF_ONESHOT | IRQF_NO_AUTOEN |
						nvt_ts_irq_type[irq_type],
					  client->name, data);
	if (error) {
		dev_err(dev, "failed to request irq: %d\n", error);
		return error;
	}

	error = input_register_device(input);
	if (error) {
		dev_err(dev, "failed to register input device: %d\n", error);
		return error;
	}

	return 0;
}

static const struct i2c_device_id nvt_ts_i2c_id[] = {
	{ "NVT-ts" },
	{ }
};
MODULE_DEVICE_TABLE(i2c, nvt_ts_i2c_id);

static struct i2c_driver nvt_ts_driver = {
	.driver = {
		.name	= "novatek-nvt-ts",
		.pm	= pm_sleep_ptr(&nvt_ts_pm_ops),
	},
	.probe = nvt_ts_probe,
	.id_table = nvt_ts_i2c_id,
};

module_i2c_driver(nvt_ts_driver);

MODULE_DESCRIPTION("Novatek NT11205 touchscreen driver");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL");