1// SPDX-License-Identifier: GPL-2.0+
2/* fakekey.c
3 * Functions for simulating key presses.
4 *
5 * Copyright (C) 2010 the Speakup Team
6 */
7#include <linux/types.h>
8#include <linux/slab.h>
9#include <linux/preempt.h>
10#include <linux/percpu.h>
11#include <linux/input.h>
12
13#include "speakup.h"
14
15#define PRESSED 1
16#define RELEASED 0
17
18static DEFINE_PER_CPU(int, reporting_keystroke);
19
20static struct input_dev *virt_keyboard;
21
22int speakup_add_virtual_keyboard(void)
23{
24	int err;
25
26	virt_keyboard = input_allocate_device();
27
28	if (!virt_keyboard)
29		return -ENOMEM;
30
31	virt_keyboard->name = "Speakup";
32	virt_keyboard->id.bustype = BUS_VIRTUAL;
33	virt_keyboard->phys = "speakup/input0";
34	virt_keyboard->dev.parent = NULL;
35
36	__set_bit(EV_KEY, virt_keyboard->evbit);
37	__set_bit(KEY_DOWN, virt_keyboard->keybit);
38
39	err = input_register_device(virt_keyboard);
40	if (err) {
41		input_free_device(virt_keyboard);
42		virt_keyboard = NULL;
43	}
44
45	return err;
46}
47
48void speakup_remove_virtual_keyboard(void)
49{
50	if (virt_keyboard) {
51		input_unregister_device(virt_keyboard);
52		virt_keyboard = NULL;
53	}
54}
55
56/*
57 * Send a simulated down-arrow to the application.
58 */
59void speakup_fake_down_arrow(void)
60{
61	unsigned long flags;
62
63	/* disable keyboard interrupts */
64	local_irq_save(flags);
65	/* don't change CPU */
66	preempt_disable();
67
68	__this_cpu_write(reporting_keystroke, true);
69	input_report_key(virt_keyboard, KEY_DOWN, PRESSED);
70	input_report_key(virt_keyboard, KEY_DOWN, RELEASED);
71	input_sync(virt_keyboard);
72	__this_cpu_write(reporting_keystroke, false);
73
74	/* reenable preemption */
75	preempt_enable();
76	/* reenable keyboard interrupts */
77	local_irq_restore(flags);
78}
79
80/*
81 * Are we handling a simulated key press on the current CPU?
82 * Returns a boolean.
83 */
84bool speakup_fake_key_pressed(void)
85{
86	return this_cpu_read(reporting_keystroke);
87}
88