// 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");