// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for ChipOne icn8318 i2c touchscreen controller
 *
 * Copyright (c) 2015 Red Hat Inc.
 *
 * Red Hat authors:
 * Hans de Goede <hdegoede@redhat.com>
 */

#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/of.h>

#define ICN8318_REG_POWER               4
#define ICN8318_REG_TOUCHDATA           16

#define ICN8318_POWER_ACTIVE            0
#define ICN8318_POWER_MONITOR           1
#define ICN8318_POWER_HIBERNATE         2

#define ICN8318_MAX_TOUCHES             5

struct icn8318_touch {
        __u8 slot;
        __be16 x;
        __be16 y;
        __u8 pressure;  /* Seems more like finger width then pressure really */
        __u8 event;
/* The difference between 2 and 3 is unclear */
#define ICN8318_EVENT_NO_DATA   1 /* No finger seen yet since wakeup */
#define ICN8318_EVENT_UPDATE1   2 /* New or updated coordinates */
#define ICN8318_EVENT_UPDATE2   3 /* New or updated coordinates */
#define ICN8318_EVENT_END       4 /* Finger lifted */
} __packed;

struct icn8318_touch_data {
        __u8 softbutton;
        __u8 touch_count;
        struct icn8318_touch touches[ICN8318_MAX_TOUCHES];
} __packed;

struct icn8318_data {
        struct i2c_client *client;
        struct input_dev *input;
        struct gpio_desc *wake_gpio;
        struct touchscreen_properties prop;
};

static int icn8318_read_touch_data(struct i2c_client *client,
                                   struct icn8318_touch_data *touch_data)
{
        u8 reg = ICN8318_REG_TOUCHDATA;
        struct i2c_msg msg[2] = {
                {
                        .addr = client->addr,
                        .len = 1,
                        .buf = &reg
                },
                {
                        .addr = client->addr,
                        .flags = I2C_M_RD,
                        .len = sizeof(struct icn8318_touch_data),
                        .buf = (u8 *)touch_data
                }
        };

        return i2c_transfer(client->adapter, msg, 2);
}

static inline bool icn8318_touch_active(u8 event)
{
        return (event == ICN8318_EVENT_UPDATE1) ||
               (event == ICN8318_EVENT_UPDATE2);
}

static irqreturn_t icn8318_irq(int irq, void *dev_id)
{
        struct icn8318_data *data = dev_id;
        struct device *dev = &data->client->dev;
        struct icn8318_touch_data touch_data;
        int i, ret;

        ret = icn8318_read_touch_data(data->client, &touch_data);
        if (ret < 0) {
                dev_err(dev, "Error reading touch data: %d\n", ret);
                return IRQ_HANDLED;
        }

        if (touch_data.softbutton) {
                /*
                 * Other data is invalid when a softbutton is pressed.
                 * This needs some extra devicetree bindings to map the icn8318
                 * softbutton codes to evdev codes. Currently no known devices
                 * use this.
                 */
                return IRQ_HANDLED;
        }

        if (touch_data.touch_count > ICN8318_MAX_TOUCHES) {
                dev_warn(dev, "Too much touches %d > %d\n",
                         touch_data.touch_count, ICN8318_MAX_TOUCHES);
                touch_data.touch_count = ICN8318_MAX_TOUCHES;
        }

        for (i = 0; i < touch_data.touch_count; i++) {
                struct icn8318_touch *touch = &touch_data.touches[i];
                bool act = icn8318_touch_active(touch->event);

                input_mt_slot(data->input, touch->slot);
                input_mt_report_slot_state(data->input, MT_TOOL_FINGER, act);
                if (!act)
                        continue;

                touchscreen_report_pos(data->input, &data->prop,
                                       be16_to_cpu(touch->x),
                                       be16_to_cpu(touch->y), true);
        }

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

        return IRQ_HANDLED;
}

static int icn8318_start(struct input_dev *dev)
{
        struct icn8318_data *data = input_get_drvdata(dev);

        enable_irq(data->client->irq);
        gpiod_set_value_cansleep(data->wake_gpio, 1);

        return 0;
}

static void icn8318_stop(struct input_dev *dev)
{
        struct icn8318_data *data = input_get_drvdata(dev);

        disable_irq(data->client->irq);
        i2c_smbus_write_byte_data(data->client, ICN8318_REG_POWER,
                                  ICN8318_POWER_HIBERNATE);
        gpiod_set_value_cansleep(data->wake_gpio, 0);
}

static int icn8318_suspend(struct device *dev)
{
        struct icn8318_data *data = i2c_get_clientdata(to_i2c_client(dev));

        mutex_lock(&data->input->mutex);
        if (input_device_enabled(data->input))
                icn8318_stop(data->input);
        mutex_unlock(&data->input->mutex);

        return 0;
}

static int icn8318_resume(struct device *dev)
{
        struct icn8318_data *data = i2c_get_clientdata(to_i2c_client(dev));

        mutex_lock(&data->input->mutex);
        if (input_device_enabled(data->input))
                icn8318_start(data->input);
        mutex_unlock(&data->input->mutex);

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(icn8318_pm_ops, icn8318_suspend, icn8318_resume);

static int icn8318_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct icn8318_data *data;
        struct input_dev *input;
        int error;

        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->wake_gpio = devm_gpiod_get(dev, "wake", GPIOD_OUT_LOW);
        if (IS_ERR(data->wake_gpio))
                return dev_err_probe(dev, PTR_ERR(data->wake_gpio), "Error getting wake gpio\n");

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

        input->name = client->name;
        input->id.bustype = BUS_I2C;
        input->open = icn8318_start;
        input->close = icn8318_stop;
        input->dev.parent = dev;

        input_set_capability(input, EV_ABS, ABS_MT_POSITION_X);
        input_set_capability(input, EV_ABS, ABS_MT_POSITION_Y);

        touchscreen_parse_properties(input, true, &data->prop);
        if (!input_abs_get_max(input, ABS_MT_POSITION_X) ||
            !input_abs_get_max(input, ABS_MT_POSITION_Y)) {
                dev_err(dev, "Error touchscreen-size-x and/or -y missing\n");
                return -EINVAL;
        }

        error = input_mt_init_slots(input, ICN8318_MAX_TOUCHES,
                                    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
        if (error)
                return error;

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

        error = devm_request_threaded_irq(dev, client->irq, NULL, icn8318_irq,
                                          IRQF_ONESHOT, client->name, data);
        if (error) {
                dev_err(dev, "Error requesting irq: %d\n", error);
                return error;
        }

        /* Stop device till opened */
        icn8318_stop(data->input);

        error = input_register_device(input);
        if (error)
                return error;

        i2c_set_clientdata(client, data);

        return 0;
}

static const struct of_device_id icn8318_of_match[] = {
        { .compatible = "chipone,icn8318" },
        { }
};
MODULE_DEVICE_TABLE(of, icn8318_of_match);

/* This is useless for OF-enabled devices, but it is needed by I2C subsystem */
static const struct i2c_device_id icn8318_i2c_id[] = {
        { },
};
MODULE_DEVICE_TABLE(i2c, icn8318_i2c_id);

static struct i2c_driver icn8318_driver = {
        .driver = {
                .name   = "chipone_icn8318",
                .pm     = pm_sleep_ptr(&icn8318_pm_ops),
                .of_match_table = icn8318_of_match,
        },
        .probe = icn8318_probe,
        .id_table = icn8318_i2c_id,
};

module_i2c_driver(icn8318_driver);

MODULE_DESCRIPTION("ChipOne icn8318 I2C Touchscreen Driver");
MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
MODULE_LICENSE("GPL");