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