drivers/accessibility/speakup/fakekey.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /* fakekey.c
   3  * Functions for simulating keypresses.
   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
  18 static DEFINE_PER_CPU(int, reporting_keystroke);
  19
  20 static struct input_dev *virt_keyboard;
  21
  22 int 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
  48 void 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  */
  59 void 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 keypress on the current CPU?
  82  * Returns a boolean.
  83  */
  84 bool speakup_fake_key_pressed(void)
  85 {
  86         return this_cpu_read(reporting_keystroke);
  87 }