xref: /openbmc/linux/drivers/input/serio/libps2.c (revision 85250a24) 
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/kmsan-checks.h>
16 #include <linux/serio.h>
17 #include <linux/i8042.h>
18 #include <linux/libps2.h>
19 
20 #define DRIVER_DESC	"PS/2 driver library"
21 
22 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
23 MODULE_DESCRIPTION("PS/2 driver library");
24 MODULE_LICENSE("GPL");
25 
26 static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte,
27 			   unsigned int timeout, unsigned int max_attempts)
28 	__releases(&ps2dev->serio->lock) __acquires(&ps2dev->serio->lock)
29 {
30 	int attempt = 0;
31 	int error;
32 
33 	lockdep_assert_held(&ps2dev->serio->lock);
34 
35 	do {
36 		ps2dev->nak = 1;
37 		ps2dev->flags |= PS2_FLAG_ACK;
38 
39 		serio_continue_rx(ps2dev->serio);
40 
41 		error = serio_write(ps2dev->serio, byte);
42 		if (error)
43 			dev_dbg(&ps2dev->serio->dev,
44 				"failed to write %#02x: %d\n", byte, error);
45 		else
46 			wait_event_timeout(ps2dev->wait,
47 					   !(ps2dev->flags & PS2_FLAG_ACK),
48 					   msecs_to_jiffies(timeout));
49 
50 		serio_pause_rx(ps2dev->serio);
51 	} while (ps2dev->nak == PS2_RET_NAK && ++attempt < max_attempts);
52 
53 	ps2dev->flags &= ~PS2_FLAG_ACK;
54 
55 	if (!error) {
56 		switch (ps2dev->nak) {
57 		case 0:
58 			break;
59 		case PS2_RET_NAK:
60 			error = -EAGAIN;
61 			break;
62 		case PS2_RET_ERR:
63 			error = -EPROTO;
64 			break;
65 		default:
66 			error = -EIO;
67 			break;
68 		}
69 	}
70 
71 	if (error || attempt > 1)
72 		dev_dbg(&ps2dev->serio->dev,
73 			"%02x - %d (%x), attempt %d\n",
74 			byte, error, ps2dev->nak, attempt);
75 
76 	return error;
77 }
78 
79 /*
80  * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
81  * It doesn't handle retransmission, the caller is expected to handle
82  * it when needed.
83  *
84  * ps2_sendbyte() can only be called from a process context.
85  */
86 
87 int ps2_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout)
88 {
89 	int retval;
90 
91 	serio_pause_rx(ps2dev->serio);
92 
93 	retval = ps2_do_sendbyte(ps2dev, byte, timeout, 1);
94 	dev_dbg(&ps2dev->serio->dev, "%02x - %x\n", byte, ps2dev->nak);
95 
96 	serio_continue_rx(ps2dev->serio);
97 
98 	return retval;
99 }
100 EXPORT_SYMBOL(ps2_sendbyte);
101 
102 void ps2_begin_command(struct ps2dev *ps2dev)
103 {
104 	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
105 
106 	mutex_lock(m);
107 }
108 EXPORT_SYMBOL(ps2_begin_command);
109 
110 void ps2_end_command(struct ps2dev *ps2dev)
111 {
112 	struct mutex *m = ps2dev->serio->ps2_cmd_mutex ?: &ps2dev->cmd_mutex;
113 
114 	mutex_unlock(m);
115 }
116 EXPORT_SYMBOL(ps2_end_command);
117 
118 /*
119  * ps2_drain() waits for device to transmit requested number of bytes
120  * and discards them.
121  */
122 
123 void ps2_drain(struct ps2dev *ps2dev, size_t maxbytes, unsigned int timeout)
124 {
125 	if (maxbytes > sizeof(ps2dev->cmdbuf)) {
126 		WARN_ON(1);
127 		maxbytes = sizeof(ps2dev->cmdbuf);
128 	}
129 
130 	ps2_begin_command(ps2dev);
131 
132 	serio_pause_rx(ps2dev->serio);
133 	ps2dev->flags = PS2_FLAG_CMD;
134 	ps2dev->cmdcnt = maxbytes;
135 	serio_continue_rx(ps2dev->serio);
136 
137 	wait_event_timeout(ps2dev->wait,
138 			   !(ps2dev->flags & PS2_FLAG_CMD),
139 			   msecs_to_jiffies(timeout));
140 
141 	ps2_end_command(ps2dev);
142 }
143 EXPORT_SYMBOL(ps2_drain);
144 
145 /*
146  * ps2_is_keyboard_id() checks received ID byte against the list of
147  * known keyboard IDs.
148  */
149 
150 bool ps2_is_keyboard_id(u8 id_byte)
151 {
152 	static const u8 keyboard_ids[] = {
153 		0xab,	/* Regular keyboards		*/
154 		0xac,	/* NCD Sun keyboard		*/
155 		0x2b,	/* Trust keyboard, translated	*/
156 		0x5d,	/* Trust keyboard		*/
157 		0x60,	/* NMB SGI keyboard, translated */
158 		0x47,	/* NMB SGI keyboard		*/
159 	};
160 
161 	return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
162 }
163 EXPORT_SYMBOL(ps2_is_keyboard_id);
164 
165 /*
166  * ps2_adjust_timeout() is called after receiving 1st byte of command
167  * response and tries to reduce remaining timeout to speed up command
168  * completion.
169  */
170 
171 static int ps2_adjust_timeout(struct ps2dev *ps2dev,
172 			      unsigned int command, unsigned int timeout)
173 {
174 	switch (command) {
175 	case PS2_CMD_RESET_BAT:
176 		/*
177 		 * Device has sent the first response byte after
178 		 * reset command, reset is thus done, so we can
179 		 * shorten the timeout.
180 		 * The next byte will come soon (keyboard) or not
181 		 * at all (mouse).
182 		 */
183 		if (timeout > msecs_to_jiffies(100))
184 			timeout = msecs_to_jiffies(100);
185 		break;
186 
187 	case PS2_CMD_GETID:
188 		/*
189 		 * Microsoft Natural Elite keyboard responds to
190 		 * the GET ID command as it were a mouse, with
191 		 * a single byte. Fail the command so atkbd will
192 		 * use alternative probe to detect it.
193 		 */
194 		if (ps2dev->cmdbuf[1] == 0xaa) {
195 			serio_pause_rx(ps2dev->serio);
196 			ps2dev->flags = 0;
197 			serio_continue_rx(ps2dev->serio);
198 			timeout = 0;
199 		}
200 
201 		/*
202 		 * If device behind the port is not a keyboard there
203 		 * won't be 2nd byte of ID response.
204 		 */
205 		if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
206 			serio_pause_rx(ps2dev->serio);
207 			ps2dev->flags = ps2dev->cmdcnt = 0;
208 			serio_continue_rx(ps2dev->serio);
209 			timeout = 0;
210 		}
211 		break;
212 
213 	default:
214 		break;
215 	}
216 
217 	return timeout;
218 }
219 
220 /*
221  * ps2_command() sends a command and its parameters to the mouse,
222  * then waits for the response and puts it in the param array.
223  *
224  * ps2_command() can only be called from a process context
225  */
226 
227 int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
228 {
229 	unsigned int timeout;
230 	unsigned int send = (command >> 12) & 0xf;
231 	unsigned int receive = (command >> 8) & 0xf;
232 	int rc;
233 	int i;
234 	u8 send_param[16];
235 
236 	if (receive > sizeof(ps2dev->cmdbuf)) {
237 		WARN_ON(1);
238 		return -EINVAL;
239 	}
240 
241 	if (send && !param) {
242 		WARN_ON(1);
243 		return -EINVAL;
244 	}
245 
246 	memcpy(send_param, param, send);
247 
248 	serio_pause_rx(ps2dev->serio);
249 
250 	ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
251 	ps2dev->cmdcnt = receive;
252 	if (receive && param)
253 		for (i = 0; i < receive; i++)
254 			ps2dev->cmdbuf[(receive - 1) - i] = param[i];
255 
256 	/* Signal that we are sending the command byte */
257 	ps2dev->flags |= PS2_FLAG_ACK_CMD;
258 
259 	/*
260 	 * Some devices (Synaptics) peform the reset before
261 	 * ACKing the reset command, and so it can take a long
262 	 * time before the ACK arrives.
263 	 */
264 	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
265 
266 	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
267 	if (rc)
268 		goto out_reset_flags;
269 
270 	/* Now we are sending command parameters, if any */
271 	ps2dev->flags &= ~PS2_FLAG_ACK_CMD;
272 
273 	for (i = 0; i < send; i++) {
274 		rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
275 		if (rc)
276 			goto out_reset_flags;
277 	}
278 
279 	serio_continue_rx(ps2dev->serio);
280 
281 	/*
282 	 * The reset command takes a long time to execute.
283 	 */
284 	timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
285 
286 	timeout = wait_event_timeout(ps2dev->wait,
287 				     !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
288 
289 	if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
290 
291 		timeout = ps2_adjust_timeout(ps2dev, command, timeout);
292 		wait_event_timeout(ps2dev->wait,
293 				   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
294 	}
295 
296 	serio_pause_rx(ps2dev->serio);
297 
298 	if (param) {
299 		for (i = 0; i < receive; i++)
300 			param[i] = ps2dev->cmdbuf[(receive - 1) - i];
301 		kmsan_unpoison_memory(param, receive);
302 	}
303 
304 	if (ps2dev->cmdcnt &&
305 	    (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
306 		rc = -EPROTO;
307 		goto out_reset_flags;
308 	}
309 
310 	rc = 0;
311 
312  out_reset_flags:
313 	ps2dev->flags = 0;
314 	serio_continue_rx(ps2dev->serio);
315 
316 	dev_dbg(&ps2dev->serio->dev,
317 		"%02x [%*ph] - %x/%08lx [%*ph]\n",
318 		command & 0xff, send, send_param,
319 		ps2dev->nak, ps2dev->flags,
320 		receive, param ?: send_param);
321 
322 	/*
323 	 * ps_command() handles resends itself, so do not leak -EAGAIN
324 	 * to the callers.
325 	 */
326 	return rc != -EAGAIN ? rc : -EPROTO;
327 }
328 EXPORT_SYMBOL(__ps2_command);
329 
330 int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
331 {
332 	int rc;
333 
334 	ps2_begin_command(ps2dev);
335 	rc = __ps2_command(ps2dev, param, command);
336 	ps2_end_command(ps2dev);
337 
338 	return rc;
339 }
340 EXPORT_SYMBOL(ps2_command);
341 
342 /*
343  * ps2_sliced_command() sends an extended PS/2 command to the mouse
344  * using sliced syntax, understood by advanced devices, such as Logitech
345  * or Synaptics touchpads. The command is encoded as:
346  * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
347  * is the command.
348  */
349 
350 int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
351 {
352 	int i;
353 	int retval;
354 
355 	ps2_begin_command(ps2dev);
356 
357 	retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
358 	if (retval)
359 		goto out;
360 
361 	for (i = 6; i >= 0; i -= 2) {
362 		u8 d = (command >> i) & 3;
363 		retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
364 		if (retval)
365 			break;
366 	}
367 
368 out:
369 	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
370 	ps2_end_command(ps2dev);
371 	return retval;
372 }
373 EXPORT_SYMBOL(ps2_sliced_command);
374 
375 /*
376  * ps2_init() initializes ps2dev structure
377  */
378 
379 void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
380 {
381 	mutex_init(&ps2dev->cmd_mutex);
382 	lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
383 	init_waitqueue_head(&ps2dev->wait);
384 	ps2dev->serio = serio;
385 }
386 EXPORT_SYMBOL(ps2_init);
387 
388 /*
389  * ps2_handle_ack() is supposed to be used in interrupt handler
390  * to properly process ACK/NAK of a command from a PS/2 device.
391  */
392 
393 bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
394 {
395 	switch (data) {
396 	case PS2_RET_ACK:
397 		ps2dev->nak = 0;
398 		break;
399 
400 	case PS2_RET_NAK:
401 		ps2dev->flags |= PS2_FLAG_NAK;
402 		ps2dev->nak = PS2_RET_NAK;
403 		break;
404 
405 	case PS2_RET_ERR:
406 		if (ps2dev->flags & PS2_FLAG_NAK) {
407 			ps2dev->flags &= ~PS2_FLAG_NAK;
408 			ps2dev->nak = PS2_RET_ERR;
409 			break;
410 		}
411 		fallthrough;
412 
413 	/*
414 	 * Workaround for mice which don't ACK the Get ID command.
415 	 * These are valid mouse IDs that we recognize.
416 	 */
417 	case 0x00:
418 	case 0x03:
419 	case 0x04:
420 		if (ps2dev->flags & PS2_FLAG_WAITID) {
421 			ps2dev->nak = 0;
422 			break;
423 		}
424 		fallthrough;
425 	default:
426 		/*
427 		 * Do not signal errors if we get unexpected reply while
428 		 * waiting for an ACK to the initial (first) command byte:
429 		 * the device might not be quiesced yet and continue
430 		 * delivering data.
431 		 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
432 		 * for mice not acknowledging the Get ID command only triggers
433 		 * on the 1st byte; if device spews data we really want to see
434 		 * a real ACK from it.
435 		 */
436 		dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
437 		ps2dev->flags &= ~PS2_FLAG_WAITID;
438 		return ps2dev->flags & PS2_FLAG_ACK_CMD;
439 	}
440 
441 	if (!ps2dev->nak) {
442 		ps2dev->flags &= ~PS2_FLAG_NAK;
443 		if (ps2dev->cmdcnt)
444 			ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
445 	}
446 
447 	ps2dev->flags &= ~PS2_FLAG_ACK;
448 	wake_up(&ps2dev->wait);
449 
450 	if (data != PS2_RET_ACK)
451 		ps2_handle_response(ps2dev, data);
452 
453 	return true;
454 }
455 EXPORT_SYMBOL(ps2_handle_ack);
456 
457 /*
458  * ps2_handle_response() is supposed to be used in interrupt handler
459  * to properly store device's response to a command and notify process
460  * waiting for completion of the command.
461  */
462 
463 bool ps2_handle_response(struct ps2dev *ps2dev, u8 data)
464 {
465 	if (ps2dev->cmdcnt)
466 		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
467 
468 	if (ps2dev->flags & PS2_FLAG_CMD1) {
469 		ps2dev->flags &= ~PS2_FLAG_CMD1;
470 		if (ps2dev->cmdcnt)
471 			wake_up(&ps2dev->wait);
472 	}
473 
474 	if (!ps2dev->cmdcnt) {
475 		ps2dev->flags &= ~PS2_FLAG_CMD;
476 		wake_up(&ps2dev->wait);
477 	}
478 
479 	return true;
480 }
481 EXPORT_SYMBOL(ps2_handle_response);
482 
483 void ps2_cmd_aborted(struct ps2dev *ps2dev)
484 {
485 	if (ps2dev->flags & PS2_FLAG_ACK)
486 		ps2dev->nak = 1;
487 
488 	if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
489 		wake_up(&ps2dev->wait);
490 
491 	/* reset all flags except last nack */
492 	ps2dev->flags &= PS2_FLAG_NAK;
493 }
494 EXPORT_SYMBOL(ps2_cmd_aborted);
495