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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/export.h>
12#include <linux/module.h>
13#include <linux/sched.h>
14#include <linux/interrupt.h>
15#include <linux/input.h>
16#include <linux/kmsan-checks.h>
17#include <linux/serio.h>
18#include <linux/i8042.h>
19#include <linux/libps2.h>
20
21#define DRIVER_DESC "PS/2 driver library"
22
23#define PS2_CMD_SETSCALE11 0x00e6
24#define PS2_CMD_SETRES 0x10e8
25#define PS2_CMD_EX_SETLEDS 0x20eb
26#define PS2_CMD_SETLEDS 0x10ed
27#define PS2_CMD_GETID 0x02f2
28#define PS2_CMD_SETREP 0x10f3 /* Set repeat rate/set report rate */
29#define PS2_CMD_RESET_BAT 0x02ff
30
31#define PS2_RET_BAT 0xaa
32#define PS2_RET_ID 0x00
33#define PS2_RET_ACK 0xfa
34#define PS2_RET_NAK 0xfe
35#define PS2_RET_ERR 0xfc
36
37#define PS2_FLAG_ACK BIT(0) /* Waiting for ACK/NAK */
38#define PS2_FLAG_CMD BIT(1) /* Waiting for a command to finish */
39#define PS2_FLAG_CMD1 BIT(2) /* Waiting for the first byte of command response */
40#define PS2_FLAG_WAITID BIT(3) /* Command executing is GET ID */
41#define PS2_FLAG_NAK BIT(4) /* Last transmission was NAKed */
42#define PS2_FLAG_PASS_NOACK BIT(5) /* Pass non-ACK byte to receive handler */
43
44static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
45 unsigned int timeout, unsigned int max_attempts)
46 __releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
47{
48 int attempt = 0;
49 int error;
50
51 lockdep_assert_held(&ps2dev->serio->lock);
52
53 do {
54 ps2dev->nak = 1;
55 ps2dev->flags |= PS2_FLAG_ACK;
56
57 serio_continue_rx(ps2dev->serio);
58
59 error = serio_write(ps2dev->serio, byte);
60 if (error)
61 dev_dbg(&ps2dev->serio->dev,
62 "failed to write %#02x: %d\n", byte, error);
63 else
64 wait_event_timeout(ps2dev->wait,
65 !(ps2dev->flags & PS2_FLAG_ACK),
66 msecs_to_jiffies(timeout));
67
68 serio_pause_rx(ps2dev->serio);
69 } while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);
70
71 ps2dev->flags &= ~PS2_FLAG_ACK;
72
73 if (!error) {
74 switch (ps2dev->nak) {
75 case 0:
76 break;
77 case PS2_RET_NAK:
78 error = -EAGAIN;
79 break;
80 case PS2_RET_ERR:
81 error = -EPROTO;
82 break;
83 default:
84 error = -EIO;
85 break;
86 }
87 }
88
89 if (error || attempt > 1)
90 dev_dbg(&ps2dev->serio->dev,
91 "%02x - %d (%x), attempt %d\n",
92 byte, error, ps2dev->nak, attempt);
93
94 return error;
95}
96
97/**
98 * ps2_sendbyte - sends a byte to the device and wait for acknowledgement
99 * @ps2dev: a PS/2 device to send the data to
100 * @byte: data to be sent to the device
101 * @timeout: timeout for sending the data and receiving an acknowledge
102 *
103 * The function doesn't handle retransmission, the caller is expected to handle
104 * it when needed.
105 *
106 * ps2_sendbyte() can only be called from a process context.
107 */
108int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
109{
110 int retval;
111
112 guard(serio_pause_rx)(ps2dev->serio);
113
114 retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
115 dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
116
117 return retval;
118}
119EXPORT_SYMBOL(ps2_sendbyte);
120
121/**
122 * ps2_begin_command - mark beginning of execution of a complex command
123 * @ps2dev: a PS/2 device executing the command
124 *
125 * Serializes a complex/compound command. Once command is finished
126 * ps2_end_command() should be called.
127 */
128void ps2_begin_command(struct ps2dev *ps2dev)
129{
130 struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
131
132 mutex_lock(m);
133}
134EXPORT_SYMBOL(ps2_begin_command);
135
136/**
137 * ps2_end_command - mark end of execution of a complex command
138 * @ps2dev: a PS/2 device executing the command
139 */
140void ps2_end_command(struct ps2dev *ps2dev)
141{
142 struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
143
144 mutex_unlock(m);
145}
146EXPORT_SYMBOL(ps2_end_command);
147
148/**
149 * ps2_drain - waits for device to transmit requested number of bytes
150 * and discards them
151 * @ps2dev: the PS/2 device that should be drained
152 * @maxbytes: maximum number of bytes to be drained
153 * @timeout: time to drain the device
154 */
155void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
156{
157 if (WARN_ON(maxbytes > sizeof(ps2dev->cmdbuf)))
158 maxbytes = sizeof(ps2dev->cmdbuf);
159
160 ps2_begin_command(ps2dev);
161
162 scoped_guard(serio_pause_rx, ps2dev->serio) {
163 ps2dev->flags = PS2_FLAG_CMD;
164 ps2dev->cmdcnt = maxbytes;
165 }
166
167 wait_event_timeout(ps2dev->wait,
168 !(ps2dev->flags & PS2_FLAG_CMD),
169 msecs_to_jiffies(timeout));
170
171 ps2_end_command(ps2dev);
172}
173EXPORT_SYMBOL(ps2_drain);
174
175/**
176 * ps2_is_keyboard_id - checks received ID byte against the list of
177 * known keyboard IDs
178 * @id_byte: data byte that should be checked
179 */
180bool ps2_is_keyboard_id(u8 id_byte)
181{
182 static const u8 keyboard_ids[] = {
183 0xab, /* Regular keyboards */
184 0xac, /* NCD Sun keyboard */
185 0x2b, /* Trust keyboard, translated */
186 0x5d, /* Trust keyboard */
187 0x60, /* NMB SGI keyboard, translated */
188 0x47, /* NMB SGI keyboard */
189 };
190
191 return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
192}
193EXPORT_SYMBOL(ps2_is_keyboard_id);
194
195/*
196 * ps2_adjust_timeout() is called after receiving 1st byte of command
197 * response and tries to reduce remaining timeout to speed up command
198 * completion.
199 */
200static int ps2_adjust_timeout(struct ps2dev *ps2dev,
201 unsigned int command, unsigned int timeout)
202{
203 switch (command) {
204 case PS2_CMD_RESET_BAT:
205 /*
206 * Device has sent the first response byte after
207 * reset command, reset is thus done, so we can
208 * shorten the timeout.
209 * The next byte will come soon (keyboard) or not
210 * at all (mouse).
211 */
212 if (timeout > msecs_to_jiffies(100))
213 timeout = msecs_to_jiffies(100);
214 break;
215
216 case PS2_CMD_GETID:
217 /*
218 * Microsoft Natural Elite keyboard responds to
219 * the GET ID command as it were a mouse, with
220 * a single byte. Fail the command so atkbd will
221 * use alternative probe to detect it.
222 */
223 if (ps2dev->cmdbuf[1] == 0xaa) {
224 scoped_guard(serio_pause_rx, ps2dev->serio)
225 ps2dev->flags = 0;
226
227 timeout = 0;
228 }
229
230 /*
231 * If device behind the port is not a keyboard there
232 * won't be 2nd byte of ID response.
233 */
234 if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
235 scoped_guard(serio_pause_rx, ps2dev->serio)
236 ps2dev->flags = ps2dev->cmdcnt = 0;
237
238 timeout = 0;
239 }
240 break;
241
242 default:
243 break;
244 }
245
246 return timeout;
247}
248
249/**
250 * __ps2_command - send a command to PS/2 device
251 * @ps2dev: the PS/2 device that should execute the command
252 * @param: a buffer containing parameters to be sent along with the command,
253 * or place where the results of the command execution will be deposited,
254 * or both
255 * @command: command word that encodes the command itself, as well as number of
256 * additional parameter bytes that should be sent to the device and expected
257 * length of the command response
258 *
259 * Not serialized. Callers should use ps2_begin_command() and ps2_end_command()
260 * to ensure proper serialization for complex commands.
261 */
262int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
263{
264 unsigned int timeout;
265 unsigned int send = (command >> 12) & 0xf;
266 unsigned int receive = (command >> 8) & 0xf;
267 int rc;
268 int i;
269 u8 send_param[16];
270
271 if (WARN_ON(receive > sizeof(ps2dev->cmdbuf)))
272 return -EINVAL;
273
274 if (WARN_ON(send && !param))
275 return -EINVAL;
276
277 memcpy(send_param, param, send);
278
279 /*
280 * Not using guard notation because we need to break critical
281 * section below while waiting for the response.
282 */
283 serio_pause_rx(ps2dev->serio);
284
285 ps2dev->cmdcnt = receive;
286
287 switch (command) {
288 case PS2_CMD_GETID:
289 /*
290 * Some mice do not ACK the "get ID" command, prepare to
291 * handle this.
292 */
293 ps2dev->flags = PS2_FLAG_WAITID;
294 break;
295
296 case PS2_CMD_SETLEDS:
297 case PS2_CMD_EX_SETLEDS:
298 case PS2_CMD_SETREP:
299 ps2dev->flags = PS2_FLAG_PASS_NOACK;
300 break;
301
302 default:
303 ps2dev->flags = 0;
304 break;
305 }
306
307 if (receive) {
308 /* Indicate that we expect response to the command. */
309 ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
310 if (param)
311 for (i = 0; i < receive; i++)
312 ps2dev->cmdbuf[(receive - 1) - i] = param[i];
313 }
314
315 /*
316 * Some devices (Synaptics) perform the reset before
317 * ACKing the reset command, and so it can take a long
318 * time before the ACK arrives.
319 */
320 timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
321
322 rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
323 if (rc)
324 goto out_reset_flags;
325
326 /* Send command parameters, if any. */
327 for (i = 0; i < send; i++) {
328 rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
329 if (rc)
330 goto out_reset_flags;
331 }
332
333 serio_continue_rx(ps2dev->serio);
334
335 /*
336 * The reset command takes a long time to execute.
337 */
338 timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
339
340 timeout = wait_event_timeout(ps2dev->wait,
341 !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
342
343 if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
344
345 timeout = ps2_adjust_timeout(ps2dev, command, timeout);
346 wait_event_timeout(ps2dev->wait,
347 !(ps2dev->flags & PS2_FLAG_CMD), timeout);
348 }
349
350 serio_pause_rx(ps2dev->serio);
351
352 if (param) {
353 for (i = 0; i < receive; i++)
354 param[i] = ps2dev->cmdbuf[(receive - 1) - i];
355 kmsan_unpoison_memory(param, receive);
356 }
357
358 if (ps2dev->cmdcnt &&
359 (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
360 rc = -EPROTO;
361 goto out_reset_flags;
362 }
363
364 rc = 0;
365
366 out_reset_flags:
367 ps2dev->flags = 0;
368 serio_continue_rx(ps2dev->serio);
369
370 dev_dbg(&ps2dev->serio->dev,
371 "%02x [%*ph] - %x/%08lx [%*ph]\n",
372 command & 0xff, send, send_param,
373 ps2dev->nak, ps2dev->flags,
374 receive, param ?: send_param);
375
376 /*
377 * ps_command() handles resends itself, so do not leak -EAGAIN
378 * to the callers.
379 */
380 return rc != -EAGAIN ? rc : -EPROTO;
381}
382EXPORT_SYMBOL(__ps2_command);
383
384/**
385 * ps2_command - send a command to PS/2 device
386 * @ps2dev: the PS/2 device that should execute the command
387 * @param: a buffer containing parameters to be sent along with the command,
388 * or place where the results of the command execution will be deposited,
389 * or both
390 * @command: command word that encodes the command itself, as well as number of
391 * additional parameter bytes that should be sent to the device and expected
392 * length of the command response
393 *
394 * Note: ps2_command() serializes the command execution so that only one
395 * command can be executed at a time for either individual port or the entire
396 * 8042 controller.
397 */
398int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
399{
400 int rc;
401
402 ps2_begin_command(ps2dev);
403 rc = __ps2_command(ps2dev, param, command);
404 ps2_end_command(ps2dev);
405
406 return rc;
407}
408EXPORT_SYMBOL(ps2_command);
409
410/**
411 * ps2_sliced_command - sends an extended PS/2 command to a mouse
412 * @ps2dev: the PS/2 device that should execute the command
413 * @command: command byte
414 *
415 * The command is sent using "sliced" syntax understood by advanced devices,
416 * such as Logitech or Synaptics touchpads. The command is encoded as:
417 * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
418 * is the command.
419 */
420int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
421{
422 int i;
423 int retval;
424
425 ps2_begin_command(ps2dev);
426
427 retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
428 if (retval)
429 goto out;
430
431 for (i = 6; i >= 0; i -= 2) {
432 u8 d = (command >> i) & 3;
433 retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
434 if (retval)
435 break;
436 }
437
438out:
439 dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
440 ps2_end_command(ps2dev);
441 return retval;
442}
443EXPORT_SYMBOL(ps2_sliced_command);
444
445/**
446 * ps2_init - initializes ps2dev structure
447 * @ps2dev: structure to be initialized
448 * @serio: serio port associated with the PS/2 device
449 * @pre_receive_handler: validation handler to check basic communication state
450 * @receive_handler: main protocol handler
451 *
452 * Prepares ps2dev structure for use in drivers for PS/2 devices.
453 */
454void ps2_init(struct ps2dev *ps2dev, struct serio *serio,
455 ps2_pre_receive_handler_t pre_receive_handler,
456 ps2_receive_handler_t receive_handler)
457{
458 ps2dev->pre_receive_handler = pre_receive_handler;
459 ps2dev->receive_handler = receive_handler;
460
461 mutex_init(&ps2dev->cmd_mutex);
462 lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
463 init_waitqueue_head(&ps2dev->wait);
464 ps2dev->serio = serio;
465 serio_set_drvdata(serio, ps2dev);
466}
467EXPORT_SYMBOL(ps2_init);
468
469/*
470 * ps2_handle_response() stores device's response to a command and notifies
471 * the process waiting for completion of the command. Note that there is a
472 * distinction between waiting for the first byte of the response, and
473 * waiting for subsequent bytes. It is done so that callers could shorten
474 * timeouts once first byte of response is received.
475 */
476static void ps2_handle_response(struct ps2dev *ps2dev, u8 data)
477{
478 if (ps2dev->cmdcnt)
479 ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
480
481 if (ps2dev->flags & PS2_FLAG_CMD1) {
482 ps2dev->flags &= ~PS2_FLAG_CMD1;
483 if (ps2dev->cmdcnt)
484 wake_up(&ps2dev->wait);
485 }
486
487 if (!ps2dev->cmdcnt) {
488 ps2dev->flags &= ~PS2_FLAG_CMD;
489 wake_up(&ps2dev->wait);
490 }
491}
492
493/*
494 * ps2_handle_ack() processes ACK/NAK of a command from a PS/2 device,
495 * possibly applying workarounds for mice not acknowledging the "get ID"
496 * command.
497 */
498static void ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
499{
500 switch (data) {
501 case PS2_RET_ACK:
502 ps2dev->nak = 0;
503 break;
504
505 case PS2_RET_NAK:
506 ps2dev->flags |= PS2_FLAG_NAK;
507 ps2dev->nak = PS2_RET_NAK;
508 break;
509
510 case PS2_RET_ERR:
511 if (ps2dev->flags & PS2_FLAG_NAK) {
512 ps2dev->flags &= ~PS2_FLAG_NAK;
513 ps2dev->nak = PS2_RET_ERR;
514 break;
515 }
516 fallthrough;
517
518 /*
519 * Workaround for mice which don't ACK the Get ID command.
520 * These are valid mouse IDs that we recognize.
521 */
522 case 0x00:
523 case 0x03:
524 case 0x04:
525 if (ps2dev->flags & PS2_FLAG_WAITID) {
526 ps2dev->nak = 0;
527 break;
528 }
529 fallthrough;
530 default:
531 /*
532 * Do not signal errors if we get unexpected reply while
533 * waiting for an ACK to the initial (first) command byte:
534 * the device might not be quiesced yet and continue
535 * delivering data. For certain commands (such as set leds and
536 * set repeat rate) that can be used during normal device
537 * operation, we even pass this data byte to the normal receive
538 * handler.
539 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
540 * for mice not acknowledging the Get ID command only triggers
541 * on the 1st byte; if device spews data we really want to see
542 * a real ACK from it.
543 */
544 dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
545 if (ps2dev->flags & PS2_FLAG_PASS_NOACK)
546 ps2dev->receive_handler(ps2dev, data);
547 ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK);
548 return;
549 }
550
551 if (!ps2dev->nak)
552 ps2dev->flags &= ~PS2_FLAG_NAK;
553
554 ps2dev->flags &= ~PS2_FLAG_ACK;
555
556 if (!ps2dev->nak && data != PS2_RET_ACK)
557 ps2_handle_response(ps2dev, data);
558 else
559 wake_up(&ps2dev->wait);
560}
561
562/*
563 * Clears state of PS/2 device after communication error by resetting majority
564 * of flags and waking up waiters, if any.
565 */
566static void ps2_cleanup(struct ps2dev *ps2dev)
567{
568 unsigned long old_flags = ps2dev->flags;
569
570 /* reset all flags except last nak */
571 ps2dev->flags &= PS2_FLAG_NAK;
572
573 if (old_flags & PS2_FLAG_ACK)
574 ps2dev->nak = 1;
575
576 if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
577 wake_up(&ps2dev->wait);
578}
579
580/**
581 * ps2_interrupt - common interrupt handler for PS/2 devices
582 * @serio: serio port for the device
583 * @data: a data byte received from the device
584 * @flags: flags such as %SERIO_PARITY or %SERIO_TIMEOUT indicating state of
585 * the data transfer
586 *
587 * ps2_interrupt() invokes pre-receive handler, optionally handles command
588 * acknowledgement and response from the device, and finally passes the data
589 * to the main protocol handler for future processing.
590 */
591irqreturn_t ps2_interrupt(struct serio *serio, u8 data, unsigned int flags) {
592 struct ps2dev *ps2dev = serio_get_drvdata(serio);
593 enum ps2_disposition rc;
594
595 rc = ps2dev->pre_receive_handler(ps2dev, data, flags);
596 switch (rc) {
597 case PS2_ERROR:
598 ps2_cleanup(ps2dev);
599 break;
600
601 case PS2_IGNORE:
602 break;
603
604 case PS2_PROCESS:
605 if (ps2dev->flags & PS2_FLAG_ACK)
606 ps2_handle_ack(ps2dev, data);
607 else if (ps2dev->flags & PS2_FLAG_CMD)
608 ps2_handle_response(ps2dev, data);
609 else
610 ps2dev->receive_handler(ps2dev, data);
611 break;
612 }
613
614 return IRQ_HANDLED;
615}
616EXPORT_SYMBOL(ps2_interrupt);
617
618MODULE_AUTHOR("Dmitry Torokhov <[email protected]>");
619MODULE_DESCRIPTION("PS/2 driver library");
620MODULE_LICENSE("GPL");