// 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 <linux/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_CHIP_ID           0x0e
#define NVT_TS_PARAMS_SIZE              0x0f

#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_i2c_chip_data {
        u8 chip_id;
};

struct nvt_ts_data {
        struct i2c_client *client;
        struct input_dev *input;
        struct gpio_desc *reset_gpio;
        struct regulator_bulk_data regulators[2];
        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);
        int error;

        error = regulator_bulk_enable(ARRAY_SIZE(data->regulators), data->regulators);
        if (error) {
                dev_err(&data->client->dev, "failed to enable regulators\n");
                return error;
        }

        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);
        regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
}

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;
        const struct nvt_ts_i2c_chip_data *chip;
        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;

        chip = device_get_match_data(&client->dev);
        if (!chip)
                return -EINVAL;

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

        /*
         * VCC is the analog voltage supply
         * IOVCC is the digital voltage supply
         */
        data->regulators[0].supply = "vcc";
        data->regulators[1].supply = "iovcc";
        error = devm_regulator_bulk_get(dev, ARRAY_SIZE(data->regulators), data->regulators);
        if (error) {
                dev_err(dev, "cannot get regulators: %d\n", error);
                return error;
        }

        error = regulator_bulk_enable(ARRAY_SIZE(data->regulators), data->regulators);
        if (error) {
                dev_err(dev, "failed to enable regulators: %d\n", error);
                return error;
        }

        data->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
        error = PTR_ERR_OR_ZERO(data->reset_gpio);
        if (error) {
                regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
                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 */
        regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
        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_CHIP_ID] != chip->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 nvt_ts_i2c_chip_data nvt_nt11205_ts_data = {
        .chip_id = 0x05,
};

static const struct nvt_ts_i2c_chip_data nvt_nt36672a_ts_data = {
        .chip_id = 0x08,
};

static const struct of_device_id nvt_ts_of_match[] = {
        { .compatible = "novatek,nt11205-ts", .data = &nvt_nt11205_ts_data },
        { .compatible = "novatek,nt36672a-ts", .data = &nvt_nt36672a_ts_data },
        { }
};
MODULE_DEVICE_TABLE(of, nvt_ts_of_match);

static const struct i2c_device_id nvt_ts_i2c_id[] = {
        { "nt11205-ts", (unsigned long) &nvt_nt11205_ts_data },
        { "nt36672a-ts", (unsigned long) &nvt_nt36672a_ts_data },
        { }
};
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),
                .of_match_table = nvt_ts_of_match,
        },
        .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");