// 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/uaccess.h>

#define ACPI_ATLAS_NAME         "Atlas ACPI"
#define ACPI_ATLAS_CLASS        "Atlas"

static unsigned short atlas_keymap[16];
static struct input_dev *input_dev;

/* 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)
{
        acpi_status status;

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

                input_event(input_dev, EV_MSC, MSC_SCAN, code);
                input_report_key(input_dev, atlas_keymap[code], key_down);
                input_sync(input_dev);

                status = AE_OK;
        } else {
                pr_warn("shrugged on unexpected function: function=%x,address=%lx,value=%x\n",
                        function, (unsigned long)address, (u32)*value);
                status = AE_BAD_PARAMETER;
        }

        return status;
}

static int atlas_acpi_button_add(struct acpi_device *device)
{
        acpi_status status;
        int i;
        int err;

        input_dev = input_allocate_device();
        if (!input_dev) {
                pr_err("unable to allocate input device\n");
                return -ENOMEM;
        }

        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(unsigned short);
        input_dev->keycodemax = ARRAY_SIZE(atlas_keymap);

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

        err = input_register_device(input_dev);
        if (err) {
                pr_err("couldn't register input device\n");
                input_free_device(input_dev);
                return err;
        }

        /* hookup button handler */
        status = acpi_install_address_space_handler(device->handle,
                                0x81, &acpi_atlas_button_handler,
                                &acpi_atlas_button_setup, device);
        if (ACPI_FAILURE(status)) {
                pr_err("error installing addr spc handler\n");
                input_unregister_device(input_dev);
                err = -EINVAL;
        }

        return err;
}

static void atlas_acpi_button_remove(struct acpi_device *device)
{
        acpi_status status;

        status = acpi_remove_address_space_handler(device->handle,
                                0x81, &acpi_atlas_button_handler);
        if (ACPI_FAILURE(status))
                pr_err("error removing addr spc handler\n");

        input_unregister_device(input_dev);
}

static const struct acpi_device_id atlas_device_ids[] = {
        {"ASIM0000", 0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, atlas_device_ids);

static struct acpi_driver atlas_acpi_driver = {
        .name   = ACPI_ATLAS_NAME,
        .class  = ACPI_ATLAS_CLASS,
        .ids    = atlas_device_ids,
        .ops    = {
                .add    = atlas_acpi_button_add,
                .remove = atlas_acpi_button_remove,
        },
};
module_acpi_driver(atlas_acpi_driver);

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