// SPDX-License-Identifier: GPL-2.0
/*
 *  adv_swbutton.c - Software Button Interface Driver.
 *
 *  (C) Copyright 2020 Advantech Corporation, Inc
 *
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/acpi.h>
#include <linux/platform_device.h>

#define ACPI_BUTTON_HID_SWBTN               "AHC0310"

#define ACPI_BUTTON_NOTIFY_SWBTN_RELEASE    0x86
#define ACPI_BUTTON_NOTIFY_SWBTN_PRESSED    0x85

struct adv_swbutton {
        struct input_dev *input;
        char phys[32];
};

/*-------------------------------------------------------------------------
 *                               Driver Interface
 *--------------------------------------------------------------------------
 */
static void adv_swbutton_notify(acpi_handle handle, u32 event, void *context)
{
        struct platform_device *device = context;
        struct adv_swbutton *button = dev_get_drvdata(&device->dev);

        switch (event) {
        case ACPI_BUTTON_NOTIFY_SWBTN_RELEASE:
                input_report_key(button->input, KEY_PROG1, 0);
                input_sync(button->input);
                break;
        case ACPI_BUTTON_NOTIFY_SWBTN_PRESSED:
                input_report_key(button->input, KEY_PROG1, 1);
                input_sync(button->input);
                break;
        default:
                dev_dbg(&device->dev, "Unsupported event [0x%x]\n", event);
        }
}

static int adv_swbutton_probe(struct platform_device *device)
{
        struct adv_swbutton *button;
        struct input_dev *input;
        acpi_handle handle = ACPI_HANDLE(&device->dev);
        acpi_status status;
        int error;

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

        dev_set_drvdata(&device->dev, button);

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

        button->input = input;
        snprintf(button->phys, sizeof(button->phys), "%s/button/input0", ACPI_BUTTON_HID_SWBTN);

        input->name = "Advantech Software Button";
        input->phys = button->phys;
        input->id.bustype = BUS_HOST;
        input->dev.parent = &device->dev;
        set_bit(EV_REP, input->evbit);
        input_set_capability(input, EV_KEY, KEY_PROG1);

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

        device_init_wakeup(&device->dev, true);

        status = acpi_install_notify_handler(handle,
                                             ACPI_DEVICE_NOTIFY,
                                             adv_swbutton_notify,
                                             device);
        if (ACPI_FAILURE(status)) {
                dev_err(&device->dev, "Error installing notify handler\n");
                return -EIO;
        }

        return 0;
}

static void adv_swbutton_remove(struct platform_device *device)
{
        acpi_handle handle = ACPI_HANDLE(&device->dev);

        acpi_remove_notify_handler(handle, ACPI_DEVICE_NOTIFY,
                                   adv_swbutton_notify);
}

static const struct acpi_device_id button_device_ids[] = {
        {ACPI_BUTTON_HID_SWBTN, 0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, button_device_ids);

static struct platform_driver adv_swbutton_driver = {
        .driver = {
                .name = "adv_swbutton",
                .acpi_match_table = button_device_ids,
        },
        .probe = adv_swbutton_probe,
        .remove = adv_swbutton_remove,
};
module_platform_driver(adv_swbutton_driver);

MODULE_AUTHOR("Andrea Ho");
MODULE_DESCRIPTION("Advantech ACPI SW Button Driver");
MODULE_LICENSE("GPL v2");