// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for MStar msg2638 touchscreens
 *
 * Copyright (c) 2021 Vincent Knecht <vincent.knecht@mailoo.org>
 *
 * Checksum and IRQ handler based on mstar_drv_common.c and
 * mstar_drv_mutual_fw_control.c
 * Copyright (c) 2006-2012 MStar Semiconductor, Inc.
 *
 * Driver structure based on zinitix.c by Michael Srba <Michael.Srba@seznam.cz>
 */

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

#define MODE_DATA_RAW                   0x5A

#define MSG2138_MAX_FINGERS             2
#define MSG2638_MAX_FINGERS             5

#define MAX_BUTTONS                     4

#define CHIP_ON_DELAY_MS                15
#define FIRMWARE_ON_DELAY_MS            50
#define RESET_DELAY_MIN_US              10000
#define RESET_DELAY_MAX_US              11000

struct msg_chip_data {
        irq_handler_t irq_handler;
        unsigned int max_fingers;
};

struct msg2138_packet {
        u8      xy_hi; /* higher bits of x and y coordinates */
        u8      x_low;
        u8      y_low;
};

struct msg2138_touch_event {
        u8      magic;
        struct  msg2138_packet pkt[MSG2138_MAX_FINGERS];
        u8      checksum;
};

struct msg2638_packet {
        u8      xy_hi; /* higher bits of x and y coordinates */
        u8      x_low;
        u8      y_low;
        u8      pressure;
};

struct msg2638_touch_event {
        u8      mode;
        struct  msg2638_packet pkt[MSG2638_MAX_FINGERS];
        u8      proximity;
        u8      checksum;
};

struct msg2638_ts_data {
        struct i2c_client *client;
        struct input_dev *input_dev;
        struct touchscreen_properties prop;
        struct regulator_bulk_data supplies[2];
        struct gpio_desc *reset_gpiod;
        int max_fingers;
        u32 keycodes[MAX_BUTTONS];
        int num_keycodes;
};

static u8 msg2638_checksum(u8 *data, u32 length)
{
        s32 sum = 0;
        u32 i;

        for (i = 0; i < length; i++)
                sum += data[i];

        return (u8)((-sum) & 0xFF);
}

static void msg2138_report_keys(struct msg2638_ts_data *msg2638, u8 keys)
{
        int i;

        /* keys can be 0x00 or 0xff when all keys have been released */
        if (keys == 0xff)
                keys = 0;

        for (i = 0; i < msg2638->num_keycodes; ++i)
                input_report_key(msg2638->input_dev, msg2638->keycodes[i],
                                 keys & BIT(i));
}

static irqreturn_t msg2138_ts_irq_handler(int irq, void *msg2638_handler)
{
        struct msg2638_ts_data *msg2638 = msg2638_handler;
        struct i2c_client *client = msg2638->client;
        struct input_dev *input = msg2638->input_dev;
        struct msg2138_touch_event touch_event;
        u32 len = sizeof(touch_event);
        struct i2c_msg msg[] = {
                {
                        .addr   = client->addr,
                        .flags  = I2C_M_RD,
                        .len    = sizeof(touch_event),
                        .buf    = (u8 *)&touch_event,
                },
        };
        struct msg2138_packet *p0, *p1;
        u16 x, y, delta_x, delta_y;
        int ret;

        ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
        if (ret != ARRAY_SIZE(msg)) {
                dev_err(&client->dev,
                        "Failed I2C transfer in irq handler: %d\n",
                        ret < 0 ? ret : -EIO);
                goto out;
        }

        if (msg2638_checksum((u8 *)&touch_event, len - 1) !=
                                                touch_event.checksum) {
                dev_err(&client->dev, "Failed checksum!\n");
                goto out;
        }

        p0 = &touch_event.pkt[0];
        p1 = &touch_event.pkt[1];

        /* Ignore non-pressed finger data, but check for key code */
        if (p0->xy_hi == 0xFF && p0->x_low == 0xFF && p0->y_low == 0xFF) {
                if (p1->xy_hi == 0xFF && p1->y_low == 0xFF)
                        msg2138_report_keys(msg2638, p1->x_low);
                goto report;
        }

        x = ((p0->xy_hi & 0xF0) << 4) | p0->x_low;
        y = ((p0->xy_hi & 0x0F) << 8) | p0->y_low;

        input_mt_slot(input, 0);
        input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
        touchscreen_report_pos(input, &msg2638->prop, x, y, true);

        /* Ignore non-pressed finger data */
        if (p1->xy_hi == 0xFF && p1->x_low == 0xFF && p1->y_low == 0xFF)
                goto report;

        /* Second finger is reported as a delta position */
        delta_x = ((p1->xy_hi & 0xF0) << 4) | p1->x_low;
        delta_y = ((p1->xy_hi & 0x0F) << 8) | p1->y_low;

        /* Ignore second finger if both deltas equal 0 */
        if (delta_x == 0 && delta_y == 0)
                goto report;

        x += delta_x;
        y += delta_y;

        input_mt_slot(input, 1);
        input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
        touchscreen_report_pos(input, &msg2638->prop, x, y, true);

report:
        input_mt_sync_frame(msg2638->input_dev);
        input_sync(msg2638->input_dev);

out:
        return IRQ_HANDLED;
}

static irqreturn_t msg2638_ts_irq_handler(int irq, void *msg2638_handler)
{
        struct msg2638_ts_data *msg2638 = msg2638_handler;
        struct i2c_client *client = msg2638->client;
        struct input_dev *input = msg2638->input_dev;
        struct msg2638_touch_event touch_event;
        u32 len = sizeof(touch_event);
        struct i2c_msg msg[] = {
                {
                        .addr   = client->addr,
                        .flags  = I2C_M_RD,
                        .len    = sizeof(touch_event),
                        .buf    = (u8 *)&touch_event,
                },
        };
        struct msg2638_packet *p;
        u16 x, y;
        int ret;
        int i;

        ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
        if (ret != ARRAY_SIZE(msg)) {
                dev_err(&client->dev,
                        "Failed I2C transfer in irq handler: %d\n",
                        ret < 0 ? ret : -EIO);
                goto out;
        }

        if (touch_event.mode != MODE_DATA_RAW)
                goto out;

        if (msg2638_checksum((u8 *)&touch_event, len - 1) !=
                                                touch_event.checksum) {
                dev_err(&client->dev, "Failed checksum!\n");
                goto out;
        }

        for (i = 0; i < msg2638->max_fingers; i++) {
                p = &touch_event.pkt[i];

                /* Ignore non-pressed finger data */
                if (p->xy_hi == 0xFF && p->x_low == 0xFF && p->y_low == 0xFF)
                        continue;

                x = (((p->xy_hi & 0xF0) << 4) | p->x_low);
                y = (((p->xy_hi & 0x0F) << 8) | p->y_low);

                input_mt_slot(input, i);
                input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
                touchscreen_report_pos(input, &msg2638->prop, x, y, true);
        }

        input_mt_sync_frame(msg2638->input_dev);
        input_sync(msg2638->input_dev);

out:
        return IRQ_HANDLED;
}

static void msg2638_reset(struct msg2638_ts_data *msg2638)
{
        gpiod_set_value_cansleep(msg2638->reset_gpiod, 1);
        usleep_range(RESET_DELAY_MIN_US, RESET_DELAY_MAX_US);
        gpiod_set_value_cansleep(msg2638->reset_gpiod, 0);
        msleep(FIRMWARE_ON_DELAY_MS);
}

static int msg2638_start(struct msg2638_ts_data *msg2638)
{
        int error;

        error = regulator_bulk_enable(ARRAY_SIZE(msg2638->supplies),
                                      msg2638->supplies);
        if (error) {
                dev_err(&msg2638->client->dev,
                        "Failed to enable regulators: %d\n", error);
                return error;
        }

        msleep(CHIP_ON_DELAY_MS);

        msg2638_reset(msg2638);

        enable_irq(msg2638->client->irq);

        return 0;
}

static int msg2638_stop(struct msg2638_ts_data *msg2638)
{
        int error;

        disable_irq(msg2638->client->irq);

        error = regulator_bulk_disable(ARRAY_SIZE(msg2638->supplies),
                                       msg2638->supplies);
        if (error) {
                dev_err(&msg2638->client->dev,
                        "Failed to disable regulators: %d\n", error);
                return error;
        }

        return 0;
}

static int msg2638_input_open(struct input_dev *dev)
{
        struct msg2638_ts_data *msg2638 = input_get_drvdata(dev);

        return msg2638_start(msg2638);
}

static void msg2638_input_close(struct input_dev *dev)
{
        struct msg2638_ts_data *msg2638 = input_get_drvdata(dev);

        msg2638_stop(msg2638);
}

static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
{
        struct device *dev = &msg2638->client->dev;
        struct input_dev *input_dev;
        int error;
        int i;

        input_dev = devm_input_allocate_device(dev);
        if (!input_dev) {
                dev_err(dev, "Failed to allocate input device.\n");
                return -ENOMEM;
        }

        input_set_drvdata(input_dev, msg2638);
        msg2638->input_dev = input_dev;

        input_dev->name = "MStar TouchScreen";
        input_dev->phys = "input/ts";
        input_dev->id.bustype = BUS_I2C;
        input_dev->open = msg2638_input_open;
        input_dev->close = msg2638_input_close;

        if (msg2638->num_keycodes) {
                input_dev->keycode = msg2638->keycodes;
                input_dev->keycodemax = msg2638->num_keycodes;
                input_dev->keycodesize = sizeof(msg2638->keycodes[0]);
                for (i = 0; i < msg2638->num_keycodes; i++)
                        input_set_capability(input_dev,
                                             EV_KEY, msg2638->keycodes[i]);
        }

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

        touchscreen_parse_properties(input_dev, true, &msg2638->prop);
        if (!msg2638->prop.max_x || !msg2638->prop.max_y) {
                dev_err(dev, "touchscreen-size-x and/or touchscreen-size-y not set in properties\n");
                return -EINVAL;
        }

        error = input_mt_init_slots(input_dev, msg2638->max_fingers,
                                    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
        if (error) {
                dev_err(dev, "Failed to initialize MT slots: %d\n", error);
                return error;
        }

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

        return 0;
}

static int msg2638_ts_probe(struct i2c_client *client)
{
        const struct msg_chip_data *chip_data;
        struct device *dev = &client->dev;
        struct msg2638_ts_data *msg2638;
        int error;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                dev_err(dev, "Failed to assert adapter's support for plain I2C.\n");
                return -ENXIO;
        }

        msg2638 = devm_kzalloc(dev, sizeof(*msg2638), GFP_KERNEL);
        if (!msg2638)
                return -ENOMEM;

        msg2638->client = client;
        i2c_set_clientdata(client, msg2638);

        chip_data = device_get_match_data(&client->dev);
        if (!chip_data || !chip_data->max_fingers) {
                dev_err(dev, "Invalid or missing chip data\n");
                return -EINVAL;
        }

        msg2638->max_fingers = chip_data->max_fingers;

        msg2638->supplies[0].supply = "vdd";
        msg2638->supplies[1].supply = "vddio";
        error = devm_regulator_bulk_get(dev, ARRAY_SIZE(msg2638->supplies),
                                        msg2638->supplies);
        if (error) {
                dev_err(dev, "Failed to get regulators: %d\n", error);
                return error;
        }

        msg2638->reset_gpiod = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
        if (IS_ERR(msg2638->reset_gpiod)) {
                error = PTR_ERR(msg2638->reset_gpiod);
                dev_err(dev, "Failed to request reset GPIO: %d\n", error);
                return error;
        }

        msg2638->num_keycodes = device_property_count_u32(dev,
                                                          "linux,keycodes");
        if (msg2638->num_keycodes == -EINVAL) {
                msg2638->num_keycodes = 0;
        } else if (msg2638->num_keycodes < 0) {
                dev_err(dev, "Unable to parse linux,keycodes property: %d\n",
                        msg2638->num_keycodes);
                return msg2638->num_keycodes;
        } else if (msg2638->num_keycodes > ARRAY_SIZE(msg2638->keycodes)) {
                dev_warn(dev, "Found %d linux,keycodes but max is %zd, ignoring the rest\n",
                         msg2638->num_keycodes, ARRAY_SIZE(msg2638->keycodes));
                msg2638->num_keycodes = ARRAY_SIZE(msg2638->keycodes);
        }

        if (msg2638->num_keycodes > 0) {
                error = device_property_read_u32_array(dev, "linux,keycodes",
                                                       msg2638->keycodes,
                                                       msg2638->num_keycodes);
                if (error) {
                        dev_err(dev, "Unable to read linux,keycodes values: %d\n",
                                error);
                        return error;
                }
        }

        error = devm_request_threaded_irq(dev, client->irq,
                                          NULL, chip_data->irq_handler,
                                          IRQF_ONESHOT | IRQF_NO_AUTOEN,
                                          client->name, msg2638);
        if (error) {
                dev_err(dev, "Failed to request IRQ: %d\n", error);
                return error;
        }

        error = msg2638_init_input_dev(msg2638);
        if (error) {
                dev_err(dev, "Failed to initialize input device: %d\n", error);
                return error;
        }

        return 0;
}

static int msg2638_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct msg2638_ts_data *msg2638 = i2c_get_clientdata(client);

        guard(mutex)(&msg2638->input_dev->mutex);

        if (input_device_enabled(msg2638->input_dev))
                msg2638_stop(msg2638);

        return 0;
}

static int msg2638_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct msg2638_ts_data *msg2638 = i2c_get_clientdata(client);
        int error;

        guard(mutex)(&msg2638->input_dev->mutex);

        if (input_device_enabled(msg2638->input_dev)) {
                error = msg2638_start(msg2638);
                if (error)
                        return error;
        }

        return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(msg2638_pm_ops, msg2638_suspend, msg2638_resume);

static const struct msg_chip_data msg2138_data = {
        .irq_handler = msg2138_ts_irq_handler,
        .max_fingers = MSG2138_MAX_FINGERS,
};

static const struct msg_chip_data msg2638_data = {
        .irq_handler = msg2638_ts_irq_handler,
        .max_fingers = MSG2638_MAX_FINGERS,
};

static const struct of_device_id msg2638_of_match[] = {
        { .compatible = "mstar,msg2138", .data = &msg2138_data },
        { .compatible = "mstar,msg2638", .data = &msg2638_data },
        { }
};
MODULE_DEVICE_TABLE(of, msg2638_of_match);

static struct i2c_driver msg2638_ts_driver = {
        .probe = msg2638_ts_probe,
        .driver = {
                .name = "MStar-TS",
                .pm = pm_sleep_ptr(&msg2638_pm_ops),
                .of_match_table = msg2638_of_match,
        },
};
module_i2c_driver(msg2638_ts_driver);

MODULE_AUTHOR("Vincent Knecht <vincent.knecht@mailoo.org>");
MODULE_DESCRIPTION("MStar MSG2638 touchscreen driver");
MODULE_LICENSE("GPL v2");