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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Minimalistic braille device kernel support.
*
* By default, shows console messages on the braille device.
* Pressing Insert switches to VC browsing.
*
* Copyright (C) Samuel Thibault <samuel.thibault@ens-lyon.org>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/console.h>
#include <linux/notifier.h>
#include <linux/selection.h>
#include <linux/vt_kern.h>
#include <linux/consolemap.h>
#include <linux/keyboard.h>
#include <linux/kbd_kern.h>
#include <linux/input.h>
MODULE_AUTHOR("samuel.thibault@ens-lyon.org");
MODULE_DESCRIPTION("braille device");
MODULE_LICENSE("GPL");
/*
* Braille device support part.
*/
/* Emit various sounds */
static bool sound;
module_param(sound, bool, 0);
MODULE_PARM_DESC(sound, "emit sounds");
static void beep(unsigned int freq)
{
if (sound)
kd_mksound(freq, HZ/10);
}
/* mini console */
#define WIDTH 40
#define BRAILLE_KEY KEY_INSERT
static u16 console_buf[WIDTH];
static int console_cursor;
/* mini view of VC */
static int vc_x, vc_y, lastvc_x, lastvc_y;
/* show console ? (or show VC) */
static int console_show = 1;
/* pending newline ? */
static int console_newline = 1;
static int lastVC = -1;
static struct console *braille_co;
/* Very VisioBraille-specific */
static void braille_write(u16 *buf)
{
static u16 lastwrite[WIDTH];
unsigned char data[1 + 1 + 2*WIDTH + 2 + 1], csum = 0, *c;
u16 out;
int i;
if (!braille_co)
return;
if (!memcmp(lastwrite, buf, WIDTH * sizeof(*buf)))
return;
memcpy(lastwrite, buf, WIDTH * sizeof(*buf));
#define SOH 1
#define STX 2
#define ETX 2
#define EOT 4
#define ENQ 5
data[0] = STX;
data[1] = '>';
csum ^= '>';
c = &data[2];
for (i = 0; i < WIDTH; i++) {
out = buf[i];
if (out >= 0x100)
out = '?';
else if (out == 0x00)
out = ' ';
csum ^= out;
if (out <= 0x05) {
*c++ = SOH;
out |= 0x40;
}
*c++ = out;
}
if (csum <= 0x05) {
*c++ = SOH;
csum |= 0x40;
}
*c++ = csum;
*c++ = ETX;
braille_co->write(braille_co, data, c - data);
}
/* Follow the VC cursor*/
static void vc_follow_cursor(struct vc_data *vc)
{
vc_x = vc->state.x - (vc->state.x % WIDTH);
vc_y = vc->state.y;
lastvc_x = vc->state.x;
lastvc_y = vc->state.y;
}
/* Maybe the VC cursor moved, if so follow it */
static void vc_maybe_cursor_moved(struct vc_data *vc)
{
if (vc->state.x != lastvc_x || vc->state.y != lastvc_y)
vc_follow_cursor(vc);
}
/* Show portion of VC at vc_x, vc_y */
static void vc_refresh(struct vc_data *vc)
{
u16 buf[WIDTH];
int i;
for (i = 0; i < WIDTH; i++) {
u16 glyph = screen_glyph(vc,
2 * (vc_x + i) + vc_y * vc->vc_size_row);
buf[i] = inverse_translate(vc, glyph, 1);
}
braille_write(buf);
}
/*
* Link to keyboard
*/
static int keyboard_notifier_call(struct notifier_block *blk,
unsigned long code, void *_param)
{
struct keyboard_notifier_param *param = _param;
struct vc_data *vc = param->vc;
int ret = NOTIFY_OK;
if (!param->down)
return ret;
switch (code) {
case KBD_KEYCODE:
if (console_show) {
if (param->value == BRAILLE_KEY) {
console_show = 0;
beep(880);
vc_maybe_cursor_moved(vc);
vc_refresh(vc);
ret = NOTIFY_STOP;
}
} else {
ret = NOTIFY_STOP;
switch (param->value) {
case KEY_INSERT:
beep(440);
console_show = 1;
lastVC = -1;
braille_write(console_buf);
break;
case KEY_LEFT:
if (vc_x > 0) {
vc_x -= WIDTH;
if (vc_x < 0)
vc_x = 0;
} else if (vc_y >= 1) {
beep(880);
vc_y--;
vc_x = vc->vc_cols-WIDTH;
} else
beep(220);
break;
case KEY_RIGHT:
if (vc_x + WIDTH < vc->vc_cols) {
vc_x += WIDTH;
} else if (vc_y + 1 < vc->vc_rows) {
beep(880);
vc_y++;
vc_x = 0;
} else
beep(220);
break;
case KEY_DOWN:
if (vc_y + 1 < vc->vc_rows)
vc_y++;
else
beep(220);
break;
case KEY_UP:
if (vc_y >= 1)
vc_y--;
else
beep(220);
break;
case KEY_HOME:
vc_follow_cursor(vc);
break;
case KEY_PAGEUP:
vc_x = 0;
vc_y = 0;
break;
case KEY_PAGEDOWN:
vc_x = 0;
vc_y = vc->vc_rows-1;
break;
default:
ret = NOTIFY_OK;
break;
}
if (ret == NOTIFY_STOP)
vc_refresh(vc);
}
break;
case KBD_POST_KEYSYM:
{
unsigned char type = KTYP(param->value) - 0xf0;
if (type == KT_SPEC) {
unsigned char val = KVAL(param->value);
int on_off = -1;
switch (val) {
case KVAL(K_CAPS):
on_off = vt_get_leds(fg_console, VC_CAPSLOCK);
break;
case KVAL(K_NUM):
on_off = vt_get_leds(fg_console, VC_NUMLOCK);
break;
case KVAL(K_HOLD):
on_off = vt_get_leds(fg_console, VC_SCROLLOCK);
break;
}
if (on_off == 1)
beep(880);
else if (on_off == 0)
beep(440);
}
}
case KBD_UNBOUND_KEYCODE:
case KBD_UNICODE:
case KBD_KEYSYM:
/* Unused */
break;
}
return ret;
}
static struct notifier_block keyboard_notifier_block = {
.notifier_call = keyboard_notifier_call,
};
static int vt_notifier_call(struct notifier_block *blk,
unsigned long code, void *_param)
{
struct vt_notifier_param *param = _param;
struct vc_data *vc = param->vc;
switch (code) {
case VT_ALLOCATE:
break;
case VT_DEALLOCATE:
break;
case VT_WRITE:
{
unsigned char c = param->c;
if (vc->vc_num != fg_console)
break;
switch (c) {
case '\b':
case 127:
if (console_cursor > 0) {
console_cursor--;
console_buf[console_cursor] = ' ';
}
break;
case '\n':
case '\v':
case '\f':
case '\r':
console_newline = 1;
break;
case '\t':
c = ' ';
fallthrough;
default:
if (c < 32)
/* Ignore other control sequences */
break;
if (console_newline) {
memset(console_buf, 0, sizeof(console_buf));
console_cursor = 0;
console_newline = 0;
}
if (console_cursor == WIDTH)
memmove(console_buf, &console_buf[1],
(WIDTH-1) * sizeof(*console_buf));
else
console_cursor++;
console_buf[console_cursor-1] = c;
break;
}
if (console_show)
braille_write(console_buf);
else {
vc_maybe_cursor_moved(vc);
vc_refresh(vc);
}
break;
}
case VT_UPDATE:
/* Maybe a VT switch, flush */
if (console_show) {
if (vc->vc_num != lastVC) {
lastVC = vc->vc_num;
memset(console_buf, 0, sizeof(console_buf));
console_cursor = 0;
braille_write(console_buf);
}
} else {
vc_maybe_cursor_moved(vc);
vc_refresh(vc);
}
break;
}
return NOTIFY_OK;
}
static struct notifier_block vt_notifier_block = {
.notifier_call = vt_notifier_call,
};
/*
* Called from printk.c when console=brl is given
*/
int braille_register_console(struct console *console, int index,
char *console_options, char *braille_options)
{
int ret;
if (!console_options)
/* Only support VisioBraille for now */
console_options = "57600o8";
if (braille_co)
return -ENODEV;
if (console->setup) {
ret = console->setup(console, console_options);
if (ret != 0)
return ret;
}
console->flags |= CON_ENABLED;
console->index = index;
braille_co = console;
register_keyboard_notifier(&keyboard_notifier_block);
register_vt_notifier(&vt_notifier_block);
return 1;
}
int braille_unregister_console(struct console *console)
{
if (braille_co != console)
return -EINVAL;
unregister_keyboard_notifier(&keyboard_notifier_block);
unregister_vt_notifier(&vt_notifier_block);
braille_co = NULL;
return 1;
}
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