1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Minimalistic braille device kernel support.
4 *
5 * By default, shows console messages on the braille device.
6 * Pressing Insert switches to VC browsing.
7 *
8 * Copyright (C) Samuel Thibault <samuel.thibault@ens-lyon.org>
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/moduleparam.h>
14 #include <linux/console.h>
15 #include <linux/notifier.h>
16
17 #include <linux/selection.h>
18 #include <linux/vt_kern.h>
19 #include <linux/consolemap.h>
20
21 #include <linux/keyboard.h>
22 #include <linux/kbd_kern.h>
23 #include <linux/input.h>
24
25 MODULE_AUTHOR("samuel.thibault@ens-lyon.org");
26 MODULE_DESCRIPTION("braille device");
27
28 /*
29 * Braille device support part.
30 */
31
32 /* Emit various sounds */
33 static bool sound;
34 module_param(sound, bool, 0);
35 MODULE_PARM_DESC(sound, "emit sounds");
36
beep(unsigned int freq)37 static void beep(unsigned int freq)
38 {
39 if (sound)
40 kd_mksound(freq, HZ/10);
41 }
42
43 /* mini console */
44 #define WIDTH 40
45 #define BRAILLE_KEY KEY_INSERT
46 static u16 console_buf[WIDTH];
47 static int console_cursor;
48
49 /* mini view of VC */
50 static int vc_x, vc_y, lastvc_x, lastvc_y;
51
52 /* show console ? (or show VC) */
53 static int console_show = 1;
54 /* pending newline ? */
55 static int console_newline = 1;
56 static int lastVC = -1;
57
58 static struct console *braille_co;
59
60 /* Very VisioBraille-specific */
braille_write(u16 * buf)61 static void braille_write(u16 *buf)
62 {
63 static u16 lastwrite[WIDTH];
64 unsigned char data[1 + 1 + 2*WIDTH + 2 + 1], csum = 0, *c;
65 u16 out;
66 int i;
67
68 if (!braille_co)
69 return;
70
71 if (!memcmp(lastwrite, buf, WIDTH * sizeof(*buf)))
72 return;
73 memcpy(lastwrite, buf, WIDTH * sizeof(*buf));
74
75 #define SOH 1
76 #define STX 2
77 #define ETX 2
78 #define EOT 4
79 #define ENQ 5
80 data[0] = STX;
81 data[1] = '>';
82 csum ^= '>';
83 c = &data[2];
84 for (i = 0; i < WIDTH; i++) {
85 out = buf[i];
86 if (out >= 0x100)
87 out = '?';
88 else if (out == 0x00)
89 out = ' ';
90 csum ^= out;
91 if (out <= 0x05) {
92 *c++ = SOH;
93 out |= 0x40;
94 }
95 *c++ = out;
96 }
97
98 if (csum <= 0x05) {
99 *c++ = SOH;
100 csum |= 0x40;
101 }
102 *c++ = csum;
103 *c++ = ETX;
104
105 braille_co->write(braille_co, data, c - data);
106 }
107
108 /* Follow the VC cursor*/
vc_follow_cursor(struct vc_data * vc)109 static void vc_follow_cursor(struct vc_data *vc)
110 {
111 vc_x = vc->state.x - (vc->state.x % WIDTH);
112 vc_y = vc->state.y;
113 lastvc_x = vc->state.x;
114 lastvc_y = vc->state.y;
115 }
116
117 /* Maybe the VC cursor moved, if so follow it */
vc_maybe_cursor_moved(struct vc_data * vc)118 static void vc_maybe_cursor_moved(struct vc_data *vc)
119 {
120 if (vc->state.x != lastvc_x || vc->state.y != lastvc_y)
121 vc_follow_cursor(vc);
122 }
123
124 /* Show portion of VC at vc_x, vc_y */
vc_refresh(struct vc_data * vc)125 static void vc_refresh(struct vc_data *vc)
126 {
127 u16 buf[WIDTH];
128 int i;
129
130 for (i = 0; i < WIDTH; i++) {
131 u16 glyph = screen_glyph(vc,
132 2 * (vc_x + i) + vc_y * vc->vc_size_row);
133 buf[i] = inverse_translate(vc, glyph, true);
134 }
135 braille_write(buf);
136 }
137
138 /*
139 * Link to keyboard
140 */
141
keyboard_notifier_call(struct notifier_block * blk,unsigned long code,void * _param)142 static int keyboard_notifier_call(struct notifier_block *blk,
143 unsigned long code, void *_param)
144 {
145 struct keyboard_notifier_param *param = _param;
146 struct vc_data *vc = param->vc;
147 int ret = NOTIFY_OK;
148
149 if (!param->down)
150 return ret;
151
152 switch (code) {
153 case KBD_KEYCODE:
154 if (console_show) {
155 if (param->value == BRAILLE_KEY) {
156 console_show = 0;
157 beep(880);
158 vc_maybe_cursor_moved(vc);
159 vc_refresh(vc);
160 ret = NOTIFY_STOP;
161 }
162 } else {
163 ret = NOTIFY_STOP;
164 switch (param->value) {
165 case KEY_INSERT:
166 beep(440);
167 console_show = 1;
168 lastVC = -1;
169 braille_write(console_buf);
170 break;
171 case KEY_LEFT:
172 if (vc_x > 0) {
173 vc_x -= WIDTH;
174 if (vc_x < 0)
175 vc_x = 0;
176 } else if (vc_y >= 1) {
177 beep(880);
178 vc_y--;
179 vc_x = vc->vc_cols-WIDTH;
180 } else
181 beep(220);
182 break;
183 case KEY_RIGHT:
184 if (vc_x + WIDTH < vc->vc_cols) {
185 vc_x += WIDTH;
186 } else if (vc_y + 1 < vc->vc_rows) {
187 beep(880);
188 vc_y++;
189 vc_x = 0;
190 } else
191 beep(220);
192 break;
193 case KEY_DOWN:
194 if (vc_y + 1 < vc->vc_rows)
195 vc_y++;
196 else
197 beep(220);
198 break;
199 case KEY_UP:
200 if (vc_y >= 1)
201 vc_y--;
202 else
203 beep(220);
204 break;
205 case KEY_HOME:
206 vc_follow_cursor(vc);
207 break;
208 case KEY_PAGEUP:
209 vc_x = 0;
210 vc_y = 0;
211 break;
212 case KEY_PAGEDOWN:
213 vc_x = 0;
214 vc_y = vc->vc_rows-1;
215 break;
216 default:
217 ret = NOTIFY_OK;
218 break;
219 }
220 if (ret == NOTIFY_STOP)
221 vc_refresh(vc);
222 }
223 break;
224 case KBD_POST_KEYSYM:
225 {
226 unsigned char type = KTYP(param->value) - 0xf0;
227
228 if (type == KT_SPEC) {
229 unsigned char val = KVAL(param->value);
230 int on_off = -1;
231
232 switch (val) {
233 case KVAL(K_CAPS):
234 on_off = vt_get_leds(fg_console, VC_CAPSLOCK);
235 break;
236 case KVAL(K_NUM):
237 on_off = vt_get_leds(fg_console, VC_NUMLOCK);
238 break;
239 case KVAL(K_HOLD):
240 on_off = vt_get_leds(fg_console, VC_SCROLLOCK);
241 break;
242 }
243 if (on_off == 1)
244 beep(880);
245 else if (on_off == 0)
246 beep(440);
247 }
248 }
249 break;
250 case KBD_UNBOUND_KEYCODE:
251 case KBD_UNICODE:
252 case KBD_KEYSYM:
253 /* Unused */
254 break;
255 }
256 return ret;
257 }
258
259 static struct notifier_block keyboard_notifier_block = {
260 .notifier_call = keyboard_notifier_call,
261 };
262
vt_notifier_call(struct notifier_block * blk,unsigned long code,void * _param)263 static int vt_notifier_call(struct notifier_block *blk,
264 unsigned long code, void *_param)
265 {
266 struct vt_notifier_param *param = _param;
267 struct vc_data *vc = param->vc;
268
269 switch (code) {
270 case VT_ALLOCATE:
271 break;
272 case VT_DEALLOCATE:
273 break;
274 case VT_WRITE:
275 {
276 unsigned char c = param->c;
277
278 if (vc->vc_num != fg_console)
279 break;
280 switch (c) {
281 case '\b':
282 case 127:
283 if (console_cursor > 0) {
284 console_cursor--;
285 console_buf[console_cursor] = ' ';
286 }
287 break;
288 case '\n':
289 case '\v':
290 case '\f':
291 case '\r':
292 console_newline = 1;
293 break;
294 case '\t':
295 c = ' ';
296 fallthrough;
297 default:
298 if (c < 32)
299 /* Ignore other control sequences */
300 break;
301 if (console_newline) {
302 memset(console_buf, 0, sizeof(console_buf));
303 console_cursor = 0;
304 console_newline = 0;
305 }
306 if (console_cursor == WIDTH)
307 memmove(console_buf, &console_buf[1],
308 (WIDTH-1) * sizeof(*console_buf));
309 else
310 console_cursor++;
311 console_buf[console_cursor-1] = c;
312 break;
313 }
314 if (console_show)
315 braille_write(console_buf);
316 else {
317 vc_maybe_cursor_moved(vc);
318 vc_refresh(vc);
319 }
320 break;
321 }
322 case VT_UPDATE:
323 /* Maybe a VT switch, flush */
324 if (console_show) {
325 if (vc->vc_num != lastVC) {
326 lastVC = vc->vc_num;
327 memset(console_buf, 0, sizeof(console_buf));
328 console_cursor = 0;
329 braille_write(console_buf);
330 }
331 } else {
332 vc_maybe_cursor_moved(vc);
333 vc_refresh(vc);
334 }
335 break;
336 }
337 return NOTIFY_OK;
338 }
339
340 static struct notifier_block vt_notifier_block = {
341 .notifier_call = vt_notifier_call,
342 };
343
344 /*
345 * Called from printk.c when console=brl is given
346 */
347
braille_register_console(struct console * console,int index,char * console_options,char * braille_options)348 int braille_register_console(struct console *console, int index,
349 char *console_options, char *braille_options)
350 {
351 int ret;
352
353 if (!console_options)
354 /* Only support VisioBraille for now */
355 console_options = "57600o8";
356 if (braille_co)
357 return -ENODEV;
358 if (console->setup) {
359 ret = console->setup(console, console_options);
360 if (ret != 0)
361 return ret;
362 }
363 console->flags |= CON_ENABLED;
364 console->index = index;
365 braille_co = console;
366 register_keyboard_notifier(&keyboard_notifier_block);
367 register_vt_notifier(&vt_notifier_block);
368 return 1;
369 }
370
braille_unregister_console(struct console * console)371 int braille_unregister_console(struct console *console)
372 {
373 if (braille_co != console)
374 return -EINVAL;
375 unregister_keyboard_notifier(&keyboard_notifier_block);
376 unregister_vt_notifier(&vt_notifier_block);
377 braille_co = NULL;
378 return 1;
379 }
380