xref: /linux/drivers/input/serio/libps2.c (revision 6a143a7cf94730f57544ea14a987dc025364dbb8) 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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