// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for I2C connected EETI EXC3000 multiple touch controller
 *
 * Copyright (C) 2017 Ahmet Inan <inan@distec.de>
 *
 * minimal implementation based on egalax_ts.c and egalax_i2c.c
 */

#include <linux/acpi.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/device.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/module.h>
#include <linux/of.h>
#include <linux/regulator/consumer.h>
#include <linux/sizes.h>
#include <linux/timer.h>
#include <linux/unaligned.h>

#define EXC3000_NUM_SLOTS               10
#define EXC3000_SLOTS_PER_FRAME         5
#define EXC3000_LEN_FRAME               66
#define EXC3000_LEN_VENDOR_REQUEST      68
#define EXC3000_LEN_POINT               10

#define EXC3000_LEN_MODEL_NAME          16
#define EXC3000_LEN_FW_VERSION          16

#define EXC3000_VENDOR_EVENT            0x03
#define EXC3000_MT1_EVENT               0x06
#define EXC3000_MT2_EVENT               0x18

#define EXC3000_TIMEOUT_MS              100

#define EXC3000_RESET_MS                10
#define EXC3000_READY_MS                100

static const struct i2c_device_id exc3000_id[];

struct eeti_dev_info {
        const char *name;
        int max_xy;
};

enum eeti_dev_id {
        EETI_EXC3000,
        EETI_EXC80H60,
        EETI_EXC80H84,
        EETI_EXC81W32,
};

static struct eeti_dev_info exc3000_info[] = {
        [EETI_EXC3000] = {
                .name = "EETI EXC3000 Touch Screen",
                .max_xy = SZ_4K - 1,
        },
        [EETI_EXC80H60] = {
                .name = "EETI EXC80H60 Touch Screen",
                .max_xy = SZ_16K - 1,
        },
        [EETI_EXC80H84] = {
                .name = "EETI EXC80H84 Touch Screen",
                .max_xy = SZ_16K - 1,
        },
        [EETI_EXC81W32] = {
                .name = "EETI EXC81W32 Touch Screen",
                .max_xy = SZ_16K - 1,
        },
};

struct exc3000_data {
        struct i2c_client *client;
        const struct eeti_dev_info *info;
        struct input_dev *input;
        struct touchscreen_properties prop;
        struct gpio_desc *reset;
        struct timer_list timer;
        u8 buf[2 * EXC3000_LEN_FRAME];
        struct completion wait_event;
        struct mutex query_lock;
};

static void exc3000_report_slots(struct input_dev *input,
                                 struct touchscreen_properties *prop,
                                 const u8 *buf, int num)
{
        for (; num--; buf += EXC3000_LEN_POINT) {
                if (buf[0] & BIT(0)) {
                        input_mt_slot(input, buf[1]);
                        input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
                        touchscreen_report_pos(input, prop,
                                               get_unaligned_le16(buf + 2),
                                               get_unaligned_le16(buf + 4),
                                               true);
                }
        }
}

static void exc3000_timer(struct timer_list *t)
{
        struct exc3000_data *data = timer_container_of(data, t, timer);

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

static inline void exc3000_schedule_timer(struct exc3000_data *data)
{
        mod_timer(&data->timer, jiffies + msecs_to_jiffies(EXC3000_TIMEOUT_MS));
}

static void exc3000_shutdown_timer(void *timer)
{
        timer_shutdown_sync(timer);
}

static int exc3000_read_frame(struct exc3000_data *data, u8 *buf)
{
        struct i2c_client *client = data->client;
        int ret;

        ret = i2c_master_send(client, "'", 2);
        if (ret < 0)
                return ret;

        if (ret != 2)
                return -EIO;

        ret = i2c_master_recv(client, buf, EXC3000_LEN_FRAME);
        if (ret < 0)
                return ret;

        if (ret != EXC3000_LEN_FRAME)
                return -EIO;

        if (get_unaligned_le16(buf) != EXC3000_LEN_FRAME)
                return -EINVAL;

        return 0;
}

static int exc3000_handle_mt_event(struct exc3000_data *data)
{
        struct input_dev *input = data->input;
        int ret, total_slots;
        u8 *buf = data->buf;

        total_slots = buf[3];
        if (!total_slots || total_slots > EXC3000_NUM_SLOTS) {
                ret = -EINVAL;
                goto out_fail;
        }

        if (total_slots > EXC3000_SLOTS_PER_FRAME) {
                /* Read 2nd frame to get the rest of the contacts. */
                ret = exc3000_read_frame(data, buf + EXC3000_LEN_FRAME);
                if (ret)
                        goto out_fail;

                /* 2nd chunk must have number of contacts set to 0. */
                if (buf[EXC3000_LEN_FRAME + 3] != 0) {
                        ret = -EINVAL;
                        goto out_fail;
                }
        }

        /*
         * We read full state successfully, no contacts will be "stuck".
         */
        timer_delete_sync(&data->timer);

        while (total_slots > 0) {
                int slots = min(total_slots, EXC3000_SLOTS_PER_FRAME);

                exc3000_report_slots(input, &data->prop, buf + 4, slots);
                total_slots -= slots;
                buf += EXC3000_LEN_FRAME;
        }

        input_mt_sync_frame(input);
        input_sync(input);

        return 0;

out_fail:
        /* Schedule a timer to release "stuck" contacts */
        exc3000_schedule_timer(data);

        return ret;
}

static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
{
        struct exc3000_data *data = dev_id;
        u8 *buf = data->buf;
        int ret;

        ret = exc3000_read_frame(data, buf);
        if (ret) {
                /* Schedule a timer to release "stuck" contacts */
                exc3000_schedule_timer(data);
                goto out;
        }

        switch (buf[2]) {
        case EXC3000_VENDOR_EVENT:
                complete(&data->wait_event);
                break;

        case EXC3000_MT1_EVENT:
        case EXC3000_MT2_EVENT:
                exc3000_handle_mt_event(data);
                break;

        default:
                break;
        }

out:
        return IRQ_HANDLED;
}

static int exc3000_vendor_data_request(struct exc3000_data *data, u8 *request,
                                       u8 request_len, u8 *response, int timeout)
{
        u8 buf[EXC3000_LEN_VENDOR_REQUEST] = { 0x67, 0x00, 0x42, 0x00, 0x03 };
        int ret;
        unsigned long time_left;

        guard(mutex)(&data->query_lock);

        reinit_completion(&data->wait_event);

        buf[5] = request_len;
        memcpy(&buf[6], request, request_len);

        ret = i2c_master_send(data->client, buf, EXC3000_LEN_VENDOR_REQUEST);
        if (ret < 0)
                return ret;

        time_left = wait_for_completion_timeout(&data->wait_event,
                                                timeout * HZ);
        if (time_left == 0)
                return -ETIMEDOUT;

        if (data->buf[3] >= EXC3000_LEN_FRAME)
                return -ENOSPC;

        memcpy(response, &data->buf[4], data->buf[3]);
        return data->buf[3];
}

static ssize_t fw_version_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct exc3000_data *data = i2c_get_clientdata(client);
        u8 response[EXC3000_LEN_FRAME];
        int ret;

        /* query bootloader info */
        ret = exc3000_vendor_data_request(data,
                                          (u8[]){0x39, 0x02}, 2, response, 1);
        if (ret < 0)
                return ret;

        /*
         * If the bootloader version is non-zero then the device is in
         * bootloader mode and won't answer a query for the application FW
         * version, so we just use the bootloader version info.
         */
        if (response[2] || response[3])
                return sprintf(buf, "%d.%d\n", response[2], response[3]);

        ret = exc3000_vendor_data_request(data, (u8[]){'D'}, 1, response, 1);
        if (ret < 0)
                return ret;

        return sprintf(buf, "%s\n", &response[1]);
}
static DEVICE_ATTR_RO(fw_version);

static ssize_t model_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct exc3000_data *data = i2c_get_clientdata(client);
        u8 response[EXC3000_LEN_FRAME];
        int ret;

        ret = exc3000_vendor_data_request(data, (u8[]){'E'}, 1, response, 1);
        if (ret < 0)
                return ret;

        return sprintf(buf, "%s\n", &response[1]);
}
static DEVICE_ATTR_RO(model);

static ssize_t type_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct exc3000_data *data = i2c_get_clientdata(client);
        u8 response[EXC3000_LEN_FRAME];
        int ret;

        ret = exc3000_vendor_data_request(data, (u8[]){'F'}, 1, response, 1);
        if (ret < 0)
                return ret;

        return sprintf(buf, "%s\n", &response[1]);
}
static DEVICE_ATTR_RO(type);

static struct attribute *exc3000_attrs[] = {
        &dev_attr_fw_version.attr,
        &dev_attr_model.attr,
        &dev_attr_type.attr,
        NULL
};
ATTRIBUTE_GROUPS(exc3000);

static int exc3000_probe(struct i2c_client *client)
{
        struct exc3000_data *data;
        struct input_dev *input;
        int error, max_xy, retry;

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

        data->client = client;
        data->info = device_get_match_data(&client->dev);
        if (!data->info) {
                enum eeti_dev_id eeti_dev_id =
                        i2c_match_id(exc3000_id, client)->driver_data;
                data->info = &exc3000_info[eeti_dev_id];
        }
        timer_setup(&data->timer, exc3000_timer, 0);
        init_completion(&data->wait_event);
        mutex_init(&data->query_lock);

        data->reset = devm_gpiod_get_optional(&client->dev, "reset",
                                              GPIOD_OUT_HIGH);
        if (IS_ERR(data->reset))
                return PTR_ERR(data->reset);

        /* For proper reset sequence, enable power while reset asserted */
        error = devm_regulator_get_enable(&client->dev, "vdd");
        if (error && error != -ENODEV)
                return dev_err_probe(&client->dev, error,
                                     "failed to request vdd regulator\n");

        if (data->reset) {
                msleep(EXC3000_RESET_MS);
                gpiod_set_value_cansleep(data->reset, 0);
                msleep(EXC3000_READY_MS);
        }

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

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

        input->name = data->info->name;
        input->id.bustype = BUS_I2C;

        max_xy = data->info->max_xy;
        input_set_abs_params(input, ABS_MT_POSITION_X, 0, max_xy, 0, 0);
        input_set_abs_params(input, ABS_MT_POSITION_Y, 0, max_xy, 0, 0);

        touchscreen_parse_properties(input, true, &data->prop);

        error = input_mt_init_slots(input, EXC3000_NUM_SLOTS,
                                    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
        if (error)
                return error;

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

        error = devm_add_action_or_reset(&client->dev, exc3000_shutdown_timer,
                                         &data->timer);
        if (error)
                return error;

        error = devm_request_threaded_irq(&client->dev, client->irq,
                                          NULL, exc3000_interrupt, IRQF_ONESHOT,
                                          client->name, data);
        if (error)
                return error;

        /*
         * I²C does not have built-in recovery, so retry on failure. This
         * ensures, that the device probe will not fail for temporary issues
         * on the bus.  This is not needed for the sysfs calls (userspace
         * will receive the error code and can start another query) and
         * cannot be done for touch events (but that only means loosing one
         * or two touch events anyways).
         */
        for (retry = 0; retry < 3; retry++) {
                u8 response[EXC3000_LEN_FRAME];

                error = exc3000_vendor_data_request(data, (u8[]){'E'}, 1,
                                                    response, 1);
                if (error > 0) {
                        dev_dbg(&client->dev, "TS Model: %s", &response[1]);
                        error = 0;
                        break;
                }
                dev_warn(&client->dev, "Retry %d get EETI EXC3000 model: %d\n",
                         retry + 1, error);
        }

        if (error)
                return error;

        i2c_set_clientdata(client, data);

        return 0;
}

static const struct i2c_device_id exc3000_id[] = {
        { .name = "exc3000", .driver_data = EETI_EXC3000 },
        { .name = "exc80h60", .driver_data = EETI_EXC80H60 },
        { .name = "exc80h84", .driver_data = EETI_EXC80H84 },
        { .name = "exc81w32", .driver_data = EETI_EXC81W32 },
        { }
};
MODULE_DEVICE_TABLE(i2c, exc3000_id);

#ifdef CONFIG_OF
static const struct of_device_id exc3000_of_match[] = {
        { .compatible = "eeti,exc3000", .data = &exc3000_info[EETI_EXC3000] },
        { .compatible = "eeti,exc80h60", .data = &exc3000_info[EETI_EXC80H60] },
        { .compatible = "eeti,exc80h84", .data = &exc3000_info[EETI_EXC80H84] },
        { .compatible = "eeti,exc81w32", .data = &exc3000_info[EETI_EXC81W32] },
        { }
};
MODULE_DEVICE_TABLE(of, exc3000_of_match);
#endif

#ifdef CONFIG_ACPI
static const struct acpi_device_id exc3000_acpi_match[] = {
        { "EGA00001", .driver_data = (kernel_ulong_t)&exc3000_info[EETI_EXC80H60] },
        { }
};
MODULE_DEVICE_TABLE(acpi, exc3000_acpi_match);
#endif

static struct i2c_driver exc3000_driver = {
        .driver = {
                .name   = "exc3000",
                .dev_groups = exc3000_groups,
                .of_match_table = of_match_ptr(exc3000_of_match),
                .acpi_match_table = ACPI_PTR(exc3000_acpi_match),
        },
        .id_table       = exc3000_id,
        .probe          = exc3000_probe,
};

module_i2c_driver(exc3000_driver);

MODULE_AUTHOR("Ahmet Inan <inan@distec.de>");
MODULE_DESCRIPTION("I2C connected EETI EXC3000 multiple touch controller driver");
MODULE_LICENSE("GPL v2");