1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * PS/2 driver library
4 *
5 * Copyright (c) 1999-2002 Vojtech Pavlik
6 * Copyright (c) 2004 Dmitry Torokhov
7 */
8
9
10 #include <linux/delay.h>
11 #include <linux/module.h>
12 #include <linux/sched.h>
13 #include <linux/interrupt.h>
14 #include <linux/input.h>
15 #include <linux/serio.h>
16 #include <linux/i8042.h>
17 #include <linux/libps2.h>
18
19 #define DRIVER_DESC "PS/2 driver library"
20
21 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
22 MODULE_DESCRIPTION("PS/2 driver library");
23 MODULE_LICENSE("GPL");
24
ps2_do_sendbyte(struct ps2dev * ps2dev,u8 byte,unsigned int timeout,unsigned int max_attempts)25 static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
26 unsigned int timeout, unsigned int max_attempts)
27 __releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
28 {
29 int attempt = 0;
30 int error;
31
32 lockdep_assert_held(&ps2dev->serio->lock);
33
34 do {
35 ps2dev->nak = 1;
36 ps2dev->flags |= PS2_FLAG_ACK;
37
38 serio_continue_rx(ps2dev->serio);
39
40 error = serio_write(ps2dev->serio, byte);
41 if (error)
42 dev_dbg(&ps2dev->serio->dev,
43 "failed to write %#02x: %d\n", byte, error);
44 else
45 wait_event_timeout(ps2dev->wait,
46 !(ps2dev->flags & PS2_FLAG_ACK),
47 msecs_to_jiffies(timeout));
48
49 serio_pause_rx(ps2dev->serio);
50 } while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);
51
52 ps2dev->flags &= ~PS2_FLAG_ACK;
53
54 if (!error) {
55 switch (ps2dev->nak) {
56 case 0:
57 break;
58 case PS2_RET_NAK:
59 error = -EAGAIN;
60 break;
61 case PS2_RET_ERR:
62 error = -EPROTO;
63 break;
64 default:
65 error = -EIO;
66 break;
67 }
68 }
69
70 if (error || attempt > 1)
71 dev_dbg(&ps2dev->serio->dev,
72 "%02x - %d (%x), attempt %d\n",
73 byte, error, ps2dev->nak, attempt);
74
75 return error;
76 }
77
78 /*
79 * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
80 * It doesn't handle retransmission, the caller is expected to handle
81 * it when needed.
82 *
83 * ps2_sendbyte() can only be called from a process context.
84 */
85
ps2_sendbyte(struct ps2dev * ps2dev,u8 byte,unsigned int timeout)86 int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
87 {
88 int retval;
89
90 serio_pause_rx(ps2dev->serio);
91
92 retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
93 dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
94
95 serio_continue_rx(ps2dev->serio);
96
97 return retval;
98 }
99 EXPORT_SYMBOL(ps2_sendbyte);
100
ps2_begin_command(struct ps2dev * ps2dev)101 void ps2_begin_command(struct ps2dev *ps2dev)
102 {
103 struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
104
105 mutex_lock(m);
106 }
107 EXPORT_SYMBOL(ps2_begin_command);
108
ps2_end_command(struct ps2dev * ps2dev)109 void ps2_end_command(struct ps2dev *ps2dev)
110 {
111 struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
112
113 mutex_unlock(m);
114 }
115 EXPORT_SYMBOL(ps2_end_command);
116
117 /*
118 * ps2_drain() waits for device to transmit requested number of bytes
119 * and discards them.
120 */
121
ps2_drain(struct ps2dev * ps2dev,size_t maxbytes,unsigned int timeout)122 void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
123 {
124 if (maxbytes > sizeof(ps2dev->cmdbuf)) {
125 WARN_ON(1);
126 maxbytes = sizeof(ps2dev->cmdbuf);
127 }
128
129 ps2_begin_command(ps2dev);
130
131 serio_pause_rx(ps2dev->serio);
132 ps2dev->flags = PS2_FLAG_CMD;
133 ps2dev->cmdcnt = maxbytes;
134 serio_continue_rx(ps2dev->serio);
135
136 wait_event_timeout(ps2dev->wait,
137 !(ps2dev->flags & PS2_FLAG_CMD),
138 msecs_to_jiffies(timeout));
139
140 ps2_end_command(ps2dev);
141 }
142 EXPORT_SYMBOL(ps2_drain);
143
144 /*
145 * ps2_is_keyboard_id() checks received ID byte against the list of
146 * known keyboard IDs.
147 */
148
ps2_is_keyboard_id(u8 id_byte)149 bool ps2_is_keyboard_id(u8 id_byte)
150 {
151 static const u8 keyboard_ids[] = {
152 0xab, /* Regular keyboards */
153 0xac, /* NCD Sun keyboard */
154 0x2b, /* Trust keyboard, translated */
155 0x5d, /* Trust keyboard */
156 0x60, /* NMB SGI keyboard, translated */
157 0x47, /* NMB SGI keyboard */
158 };
159
160 return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
161 }
162 EXPORT_SYMBOL(ps2_is_keyboard_id);
163
164 /*
165 * ps2_adjust_timeout() is called after receiving 1st byte of command
166 * response and tries to reduce remaining timeout to speed up command
167 * completion.
168 */
169
ps2_adjust_timeout(struct ps2dev * ps2dev,unsigned int command,unsigned int timeout)170 static int ps2_adjust_timeout(struct ps2dev *ps2dev,
171 unsigned int command, unsigned int timeout)
172 {
173 switch (command) {
174 case PS2_CMD_RESET_BAT:
175 /*
176 * Device has sent the first response byte after
177 * reset command, reset is thus done, so we can
178 * shorten the timeout.
179 * The next byte will come soon (keyboard) or not
180 * at all (mouse).
181 */
182 if (timeout > msecs_to_jiffies(100))
183 timeout = msecs_to_jiffies(100);
184 break;
185
186 case PS2_CMD_GETID:
187 /*
188 * Microsoft Natural Elite keyboard responds to
189 * the GET ID command as it were a mouse, with
190 * a single byte. Fail the command so atkbd will
191 * use alternative probe to detect it.
192 */
193 if (ps2dev->cmdbuf[1] == 0xaa) {
194 serio_pause_rx(ps2dev->serio);
195 ps2dev->flags = 0;
196 serio_continue_rx(ps2dev->serio);
197 timeout = 0;
198 }
199
200 /*
201 * If device behind the port is not a keyboard there
202 * won't be 2nd byte of ID response.
203 */
204 if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
205 serio_pause_rx(ps2dev->serio);
206 ps2dev->flags = ps2dev->cmdcnt = 0;
207 serio_continue_rx(ps2dev->serio);
208 timeout = 0;
209 }
210 break;
211
212 default:
213 break;
214 }
215
216 return timeout;
217 }
218
219 /*
220 * ps2_command() sends a command and its parameters to the mouse,
221 * then waits for the response and puts it in the param array.
222 *
223 * ps2_command() can only be called from a process context
224 */
225
__ps2_command(struct ps2dev * ps2dev,u8 * param,unsigned int command)226 int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
227 {
228 unsigned int timeout;
229 unsigned int send = (command >> 12) & 0xf;
230 unsigned int receive = (command >> 8) & 0xf;
231 int rc;
232 int i;
233 u8 send_param[16];
234
235 if (receive > sizeof(ps2dev->cmdbuf)) {
236 WARN_ON(1);
237 return -EINVAL;
238 }
239
240 if (send && !param) {
241 WARN_ON(1);
242 return -EINVAL;
243 }
244
245 memcpy(send_param, param, send);
246
247 serio_pause_rx(ps2dev->serio);
248
249 ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
250 ps2dev->cmdcnt = receive;
251 if (receive && param)
252 for (i = 0; i < receive; i++)
253 ps2dev->cmdbuf[(receive - 1) - i] = param[i];
254
255 /* Signal that we are sending the command byte */
256 ps2dev->flags |= PS2_FLAG_ACK_CMD;
257
258 /*
259 * Some devices (Synaptics) peform the reset before
260 * ACKing the reset command, and so it can take a long
261 * time before the ACK arrives.
262 */
263 timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
264
265 rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
266 if (rc)
267 goto out_reset_flags;
268
269 /* Now we are sending command parameters, if any */
270 ps2dev->flags &= ~PS2_FLAG_ACK_CMD;
271
272 for (i = 0; i < send; i++) {
273 rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
274 if (rc)
275 goto out_reset_flags;
276 }
277
278 serio_continue_rx(ps2dev->serio);
279
280 /*
281 * The reset command takes a long time to execute.
282 */
283 timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
284
285 timeout = wait_event_timeout(ps2dev->wait,
286 !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
287
288 if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
289
290 timeout = ps2_adjust_timeout(ps2dev, command, timeout);
291 wait_event_timeout(ps2dev->wait,
292 !(ps2dev->flags & PS2_FLAG_CMD), timeout);
293 }
294
295 serio_pause_rx(ps2dev->serio);
296
297 if (param)
298 for (i = 0; i < receive; i++)
299 param[i] = ps2dev->cmdbuf[(receive - 1) - i];
300
301 if (ps2dev->cmdcnt &&
302 (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
303 rc = -EPROTO;
304 goto out_reset_flags;
305 }
306
307 rc = 0;
308
309 out_reset_flags:
310 ps2dev->flags = 0;
311 serio_continue_rx(ps2dev->serio);
312
313 dev_dbg(&ps2dev->serio->dev,
314 "%02x [%*ph] - %x/%08lx [%*ph]\n",
315 command & 0xff, send, send_param,
316 ps2dev->nak, ps2dev->flags,
317 receive, param ?: send_param);
318
319 /*
320 * ps_command() handles resends itself, so do not leak -EAGAIN
321 * to the callers.
322 */
323 return rc != -EAGAIN ? rc : -EPROTO;
324 }
325 EXPORT_SYMBOL(__ps2_command);
326
ps2_command(struct ps2dev * ps2dev,u8 * param,unsigned int command)327 int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
328 {
329 int rc;
330
331 ps2_begin_command(ps2dev);
332 rc = __ps2_command(ps2dev, param, command);
333 ps2_end_command(ps2dev);
334
335 return rc;
336 }
337 EXPORT_SYMBOL(ps2_command);
338
339 /*
340 * ps2_sliced_command() sends an extended PS/2 command to the mouse
341 * using sliced syntax, understood by advanced devices, such as Logitech
342 * or Synaptics touchpads. The command is encoded as:
343 * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
344 * is the command.
345 */
346
ps2_sliced_command(struct ps2dev * ps2dev,u8 command)347 int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
348 {
349 int i;
350 int retval;
351
352 ps2_begin_command(ps2dev);
353
354 retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
355 if (retval)
356 goto out;
357
358 for (i = 6; i >= 0; i -= 2) {
359 u8 d = (command >> i) & 3;
360 retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
361 if (retval)
362 break;
363 }
364
365 out:
366 dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
367 ps2_end_command(ps2dev);
368 return retval;
369 }
370 EXPORT_SYMBOL(ps2_sliced_command);
371
372 /*
373 * ps2_init() initializes ps2dev structure
374 */
375
ps2_init(struct ps2dev * ps2dev,struct serio * serio)376 void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
377 {
378 mutex_init(&ps2dev->cmd_mutex);
379 lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
380 init_waitqueue_head(&ps2dev->wait);
381 ps2dev->serio = serio;
382 }
383 EXPORT_SYMBOL(ps2_init);
384
385 /*
386 * ps2_handle_ack() is supposed to be used in interrupt handler
387 * to properly process ACK/NAK of a command from a PS/2 device.
388 */
389
ps2_handle_ack(struct ps2dev * ps2dev,u8 data)390 bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
391 {
392 switch (data) {
393 case PS2_RET_ACK:
394 ps2dev->nak = 0;
395 break;
396
397 case PS2_RET_NAK:
398 ps2dev->flags |= PS2_FLAG_NAK;
399 ps2dev->nak = PS2_RET_NAK;
400 break;
401
402 case PS2_RET_ERR:
403 if (ps2dev->flags & PS2_FLAG_NAK) {
404 ps2dev->flags &= ~PS2_FLAG_NAK;
405 ps2dev->nak = PS2_RET_ERR;
406 break;
407 }
408 fallthrough;
409
410 /*
411 * Workaround for mice which don't ACK the Get ID command.
412 * These are valid mouse IDs that we recognize.
413 */
414 case 0x00:
415 case 0x03:
416 case 0x04:
417 if (ps2dev->flags & PS2_FLAG_WAITID) {
418 ps2dev->nak = 0;
419 break;
420 }
421 fallthrough;
422 default:
423 /*
424 * Do not signal errors if we get unexpected reply while
425 * waiting for an ACK to the initial (first) command byte:
426 * the device might not be quiesced yet and continue
427 * delivering data.
428 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
429 * for mice not acknowledging the Get ID command only triggers
430 * on the 1st byte; if device spews data we really want to see
431 * a real ACK from it.
432 */
433 dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
434 ps2dev->flags &= ~PS2_FLAG_WAITID;
435 return ps2dev->flags & PS2_FLAG_ACK_CMD;
436 }
437
438 if (!ps2dev->nak) {
439 ps2dev->flags &= ~PS2_FLAG_NAK;
440 if (ps2dev->cmdcnt)
441 ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
442 }
443
444 ps2dev->flags &= ~PS2_FLAG_ACK;
445 wake_up(&ps2dev->wait);
446
447 if (data != PS2_RET_ACK)
448 ps2_handle_response(ps2dev, data);
449
450 return true;
451 }
452 EXPORT_SYMBOL(ps2_handle_ack);
453
454 /*
455 * ps2_handle_response() is supposed to be used in interrupt handler
456 * to properly store device's response to a command and notify process
457 * waiting for completion of the command.
458 */
459
ps2_handle_response(struct ps2dev * ps2dev,u8 data)460 bool ps2_handle_response(struct ps2dev *ps2dev, u8 data)
461 {
462 if (ps2dev->cmdcnt)
463 ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
464
465 if (ps2dev->flags & PS2_FLAG_CMD1) {
466 ps2dev->flags &= ~PS2_FLAG_CMD1;
467 if (ps2dev->cmdcnt)
468 wake_up(&ps2dev->wait);
469 }
470
471 if (!ps2dev->cmdcnt) {
472 ps2dev->flags &= ~PS2_FLAG_CMD;
473 wake_up(&ps2dev->wait);
474 }
475
476 return true;
477 }
478 EXPORT_SYMBOL(ps2_handle_response);
479
ps2_cmd_aborted(struct ps2dev * ps2dev)480 void ps2_cmd_aborted(struct ps2dev *ps2dev)
481 {
482 if (ps2dev->flags & PS2_FLAG_ACK)
483 ps2dev->nak = 1;
484
485 if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
486 wake_up(&ps2dev->wait);
487
488 /* reset all flags except last nack */
489 ps2dev->flags &= PS2_FLAG_NAK;
490 }
491 EXPORT_SYMBOL(ps2_cmd_aborted);
492