// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  atlas_btns.c - Atlas Wallmount Touchscreen ACPI Extras
 *
 *  Copyright (C) 2006 Jaya Kumar
 *  Based on Toshiba ACPI by John Belmonte and ASUS ACPI
 *  This work was sponsored by CIS(M) Sdn Bhd.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/types.h>
#include <linux/acpi.h>
#include <linux/platform_device.h>

#define ACPI_ATLAS_NAME         "Atlas ACPI"

struct atlas_btns {
        struct input_dev *input_dev;
        unsigned short keymap[16];
};

/* button handling code */
static acpi_status acpi_atlas_button_setup(acpi_handle region_handle,
                                           u32 function, void *handler_context,
                                           void **return_context)
{
        *return_context =
                (function != ACPI_REGION_DEACTIVATE) ? handler_context : NULL;

        return AE_OK;
}

static acpi_status acpi_atlas_button_handler(u32 function,
                                             acpi_physical_address address,
                                             u32 bit_width, u64 *value,
                                             void *handler_context,
                                             void *region_context)
{
        struct atlas_btns *atlas = region_context;

        if (function == ACPI_WRITE) {
                int code = address & 0x0f;
                int key_down = !(address & 0x10);

                input_event(atlas->input_dev, EV_MSC, MSC_SCAN, code);
                input_report_key(atlas->input_dev, atlas->keymap[code],
                                 key_down);
                input_sync(atlas->input_dev);

                return AE_OK;
        }

        dev_warn(atlas->input_dev->dev.parent,
                 "unexpected function: function=%x,address=%lx,value=%x\n",
                 function, (unsigned long)address, (u32)*value);

        return AE_BAD_PARAMETER;
}

static int atlas_acpi_button_probe(struct platform_device *pdev)
{
        struct acpi_device *device;
        struct atlas_btns *atlas;
        struct input_dev *input_dev;
        acpi_status status;
        int i;
        int err;

        device = ACPI_COMPANION(&pdev->dev);
        if (!device)
                return -ENODEV;

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

        input_dev = devm_input_allocate_device(&pdev->dev);
        if (!input_dev)
                return -ENOMEM;

        atlas->input_dev = input_dev;

        input_dev->name = "Atlas ACPI button driver";
        input_dev->phys = "ASIM0000/atlas/input0";
        input_dev->id.bustype = BUS_HOST;
        input_dev->keycode = atlas->keymap;
        input_dev->keycodesize = sizeof(atlas->keymap[0]);
        input_dev->keycodemax = ARRAY_SIZE(atlas->keymap);

        input_set_capability(input_dev, EV_MSC, MSC_SCAN);
        for (i = 0; i < ARRAY_SIZE(atlas->keymap); i++) {
                if (i < 9) {
                        atlas->keymap[i] = KEY_F1 + i;
                        input_set_capability(input_dev, EV_KEY, KEY_F1 + i);
                } else {
                        atlas->keymap[i] = KEY_RESERVED;
                }
        }

        err = input_register_device(input_dev);
        if (err)
                return dev_err_probe(&pdev->dev, err,
                                     "couldn't register input device\n");

        /* hookup button handler */
        status = acpi_install_address_space_handler(device->handle,
                                                    0x81,
                                                    &acpi_atlas_button_handler,
                                                    &acpi_atlas_button_setup,
                                                    atlas);
        if (ACPI_FAILURE(status))
                return dev_err_probe(&pdev->dev, -EINVAL,
                                     "error installing addr spc handler\n");

        return 0;
}

static void atlas_acpi_button_remove(struct platform_device *pdev)
{
        struct acpi_device *device = ACPI_COMPANION(&pdev->dev);

        acpi_remove_address_space_handler(device->handle, 0x81,
                                          &acpi_atlas_button_handler);
}

static const struct acpi_device_id atlas_device_ids[] = {
        { "ASIM0000" },
        { "" }
};
MODULE_DEVICE_TABLE(acpi, atlas_device_ids);

static struct platform_driver atlas_acpi_driver = {
        .probe = atlas_acpi_button_probe,
        .remove = atlas_acpi_button_remove,
        .driver = {
                .name = ACPI_ATLAS_NAME,
                .acpi_match_table = atlas_device_ids,
        },
};
module_platform_driver(atlas_acpi_driver);

MODULE_AUTHOR("Jaya Kumar");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Atlas button driver");