libps2.c

  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 (maxbytes > sizeof(ps2dev->cmdbuf)) {
158		WARN_ON(1);
159		maxbytes = sizeof(ps2dev->cmdbuf);
160	}
161
162	ps2_begin_command(ps2dev);
163
164	scoped_guard(serio_pause_rx, ps2dev->serio) {
165		ps2dev->flags = PS2_FLAG_CMD;
166		ps2dev->cmdcnt = maxbytes;
167	}
168
169	wait_event_timeout(ps2dev->wait,
170			   !(ps2dev->flags & PS2_FLAG_CMD),
171			   msecs_to_jiffies(timeout));
172
173	ps2_end_command(ps2dev);
174}
175EXPORT_SYMBOL(ps2_drain);
176
177/**
178 * ps2_is_keyboard_id - checks received ID byte against the list of
179 *   known keyboard IDs
180 * @id_byte: data byte that should be checked
181 */
182bool ps2_is_keyboard_id(u8 id_byte)
183{
184	static const u8 keyboard_ids[] = {
185		0xab,	/* Regular keyboards		*/
186		0xac,	/* NCD Sun keyboard		*/
187		0x2b,	/* Trust keyboard, translated	*/
188		0x5d,	/* Trust keyboard		*/
189		0x60,	/* NMB SGI keyboard, translated */
190		0x47,	/* NMB SGI keyboard		*/
191	};
192
193	return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
194}
195EXPORT_SYMBOL(ps2_is_keyboard_id);
196
197/*
198 * ps2_adjust_timeout() is called after receiving 1st byte of command
199 * response and tries to reduce remaining timeout to speed up command
200 * completion.
201 */
202static int ps2_adjust_timeout(struct ps2dev *ps2dev,
203			      unsigned int command, unsigned int timeout)
204{
205	switch (command) {
206	case PS2_CMD_RESET_BAT:
207		/*
208		 * Device has sent the first response byte after
209		 * reset command, reset is thus done, so we can
210		 * shorten the timeout.
211		 * The next byte will come soon (keyboard) or not
212		 * at all (mouse).
213		 */
214		if (timeout > msecs_to_jiffies(100))
215			timeout = msecs_to_jiffies(100);
216		break;
217
218	case PS2_CMD_GETID:
219		/*
220		 * Microsoft Natural Elite keyboard responds to
221		 * the GET ID command as it were a mouse, with
222		 * a single byte. Fail the command so atkbd will
223		 * use alternative probe to detect it.
224		 */
225		if (ps2dev->cmdbuf[1] == 0xaa) {
226			scoped_guard(serio_pause_rx, ps2dev->serio)
227				ps2dev->flags = 0;
228
229			timeout = 0;
230		}
231
232		/*
233		 * If device behind the port is not a keyboard there
234		 * won't be 2nd byte of ID response.
235		 */
236		if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
237			scoped_guard(serio_pause_rx, ps2dev->serio)
238				ps2dev->flags = ps2dev->cmdcnt = 0;
239
240			timeout = 0;
241		}
242		break;
243
244	default:
245		break;
246	}
247
248	return timeout;
249}
250
251/**
252 * __ps2_command - send a command to PS/2 device
253 * @ps2dev: the PS/2 device that should execute the command
254 * @param: a buffer containing parameters to be sent along with the command,
255 *   or place where the results of the command execution will be deposited,
256 *   or both
257 * @command: command word that encodes the command itself, as well as number of
258 *   additional parameter bytes that should be sent to the device and expected
259 *   length of the command response
260 *
261 * Not serialized. Callers should use ps2_begin_command() and ps2_end_command()
262 * to ensure proper serialization for complex commands.
263 */
264int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
265{
266	unsigned int timeout;
267	unsigned int send = (command >> 12) & 0xf;
268	unsigned int receive = (command >> 8) & 0xf;
269	int rc;
270	int i;
271	u8 send_param[16];
272
273	if (receive > sizeof(ps2dev->cmdbuf)) {
274		WARN_ON(1);
275		return -EINVAL;
276	}
277
278	if (send && !param) {
279		WARN_ON(1);
280		return -EINVAL;
281	}
282
283	memcpy(send_param, param, send);
284
285	/*
286	 * Not using guard notation because we need to break critical
287	 * section below while waiting for the response.
288	 */
289	serio_pause_rx(ps2dev->serio);
290
291	ps2dev->cmdcnt = receive;
292
293	switch (command) {
294	case PS2_CMD_GETID:
295		/*
296		 * Some mice do not ACK the "get ID" command, prepare to
297		 * handle this.
298		 */
299		ps2dev->flags = PS2_FLAG_WAITID;
300		break;
301
302	case PS2_CMD_SETLEDS:
303	case PS2_CMD_EX_SETLEDS:
304	case PS2_CMD_SETREP:
305		ps2dev->flags = PS2_FLAG_PASS_NOACK;
306		break;
307
308	default:
309		ps2dev->flags = 0;
310		break;
311	}
312
313	if (receive) {
314		/* Indicate that we expect response to the command. */
315		ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
316		if (param)
317			for (i = 0; i < receive; i++)
318				ps2dev->cmdbuf[(receive - 1) - i] = param[i];
319	}
320
321	/*
322	 * Some devices (Synaptics) perform the reset before
323	 * ACKing the reset command, and so it can take a long
324	 * time before the ACK arrives.
325	 */
326	timeout = command == PS2_CMD_RESET_BAT ? 1000 : 200;
327
328	rc = ps2_do_sendbyte(ps2dev, command & 0xff, timeout, 2);
329	if (rc)
330		goto out_reset_flags;
331
332	/* Send command parameters, if any. */
333	for (i = 0; i < send; i++) {
334		rc = ps2_do_sendbyte(ps2dev, param[i], 200, 2);
335		if (rc)
336			goto out_reset_flags;
337	}
338
339	serio_continue_rx(ps2dev->serio);
340
341	/*
342	 * The reset command takes a long time to execute.
343	 */
344	timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
345
346	timeout = wait_event_timeout(ps2dev->wait,
347				     !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
348
349	if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
350
351		timeout = ps2_adjust_timeout(ps2dev, command, timeout);
352		wait_event_timeout(ps2dev->wait,
353				   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
354	}
355
356	serio_pause_rx(ps2dev->serio);
357
358	if (param) {
359		for (i = 0; i < receive; i++)
360			param[i] = ps2dev->cmdbuf[(receive - 1) - i];
361		kmsan_unpoison_memory(param, receive);
362	}
363
364	if (ps2dev->cmdcnt &&
365	    (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1)) {
366		rc = -EPROTO;
367		goto out_reset_flags;
368	}
369
370	rc = 0;
371
372 out_reset_flags:
373	ps2dev->flags = 0;
374	serio_continue_rx(ps2dev->serio);
375
376	dev_dbg(&ps2dev->serio->dev,
377		"%02x [%*ph] - %x/%08lx [%*ph]\n",
378		command & 0xff, send, send_param,
379		ps2dev->nak, ps2dev->flags,
380		receive, param ?: send_param);
381
382	/*
383	 * ps_command() handles resends itself, so do not leak -EAGAIN
384	 * to the callers.
385	 */
386	return rc != -EAGAIN ? rc : -EPROTO;
387}
388EXPORT_SYMBOL(__ps2_command);
389
390/**
391 * ps2_command - send a command to PS/2 device
392 * @ps2dev: the PS/2 device that should execute the command
393 * @param: a buffer containing parameters to be sent along with the command,
394 *   or place where the results of the command execution will be deposited,
395 *   or both
396 * @command: command word that encodes the command itself, as well as number of
397 *   additional parameter bytes that should be sent to the device and expected
398 *   length of the command response
399 *
400 * Note: ps2_command() serializes the command execution so that only one
401 * command can be executed at a time for either individual port or the entire
402 * 8042 controller.
403 */
404int ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
405{
406	int rc;
407
408	ps2_begin_command(ps2dev);
409	rc = __ps2_command(ps2dev, param, command);
410	ps2_end_command(ps2dev);
411
412	return rc;
413}
414EXPORT_SYMBOL(ps2_command);
415
416/**
417 * ps2_sliced_command - sends an extended PS/2 command to a mouse
418 * @ps2dev: the PS/2 device that should execute the command
419 * @command: command byte
420 *
421 * The command is sent using "sliced" syntax understood by advanced devices,
422 * such as Logitech or Synaptics touchpads. The command is encoded as:
423 * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
424 * is the command.
425 */
426int ps2_sliced_command(struct ps2dev *ps2dev, u8 command)
427{
428	int i;
429	int retval;
430
431	ps2_begin_command(ps2dev);
432
433	retval = __ps2_command(ps2dev, NULL, PS2_CMD_SETSCALE11);
434	if (retval)
435		goto out;
436
437	for (i = 6; i >= 0; i -= 2) {
438		u8 d = (command >> i) & 3;
439		retval = __ps2_command(ps2dev, &d, PS2_CMD_SETRES);
440		if (retval)
441			break;
442	}
443
444out:
445	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
446	ps2_end_command(ps2dev);
447	return retval;
448}
449EXPORT_SYMBOL(ps2_sliced_command);
450
451/**
452 * ps2_init - initializes ps2dev structure
453 * @ps2dev: structure to be initialized
454 * @serio: serio port associated with the PS/2 device
455 * @pre_receive_handler: validation handler to check basic communication state
456 * @receive_handler: main protocol handler
457 *
458 * Prepares ps2dev structure for use in drivers for PS/2 devices.
459 */
460void ps2_init(struct ps2dev *ps2dev, struct serio *serio,
461	      ps2_pre_receive_handler_t pre_receive_handler,
462	      ps2_receive_handler_t receive_handler)
463{
464	ps2dev->pre_receive_handler = pre_receive_handler;
465	ps2dev->receive_handler = receive_handler;
466
467	mutex_init(&ps2dev->cmd_mutex);
468	lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
469	init_waitqueue_head(&ps2dev->wait);
470	ps2dev->serio = serio;
471	serio_set_drvdata(serio, ps2dev);
472}
473EXPORT_SYMBOL(ps2_init);
474
475/*
476 * ps2_handle_response() stores device's response to a command and notifies
477 * the process waiting for completion of the command. Note that there is a
478 * distinction between waiting for the first byte of the response, and
479 * waiting for subsequent bytes. It is done so that callers could shorten
480 * timeouts once first byte of response is received.
481 */
482static void ps2_handle_response(struct ps2dev *ps2dev, u8 data)
483{
484	if (ps2dev->cmdcnt)
485		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
486
487	if (ps2dev->flags & PS2_FLAG_CMD1) {
488		ps2dev->flags &= ~PS2_FLAG_CMD1;
489		if (ps2dev->cmdcnt)
490			wake_up(&ps2dev->wait);
491	}
492
493	if (!ps2dev->cmdcnt) {
494		ps2dev->flags &= ~PS2_FLAG_CMD;
495		wake_up(&ps2dev->wait);
496	}
497}
498
499/*
500 * ps2_handle_ack() processes ACK/NAK of a command from a PS/2 device,
501 * possibly applying workarounds for mice not acknowledging the "get ID"
502 * command.
503 */
504static void ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
505{
506	switch (data) {
507	case PS2_RET_ACK:
508		ps2dev->nak = 0;
509		break;
510
511	case PS2_RET_NAK:
512		ps2dev->flags |= PS2_FLAG_NAK;
513		ps2dev->nak = PS2_RET_NAK;
514		break;
515
516	case PS2_RET_ERR:
517		if (ps2dev->flags & PS2_FLAG_NAK) {
518			ps2dev->flags &= ~PS2_FLAG_NAK;
519			ps2dev->nak = PS2_RET_ERR;
520			break;
521		}
522		fallthrough;
523
524	/*
525	 * Workaround for mice which don't ACK the Get ID command.
526	 * These are valid mouse IDs that we recognize.
527	 */
528	case 0x00:
529	case 0x03:
530	case 0x04:
531		if (ps2dev->flags & PS2_FLAG_WAITID) {
532			ps2dev->nak = 0;
533			break;
534		}
535		fallthrough;
536	default:
537		/*
538		 * Do not signal errors if we get unexpected reply while
539		 * waiting for an ACK to the initial (first) command byte:
540		 * the device might not be quiesced yet and continue
541		 * delivering data. For certain commands (such as set leds and
542		 * set repeat rate) that can be used during normal device
543		 * operation, we even pass this data byte to the normal receive
544		 * handler.
545		 * Note that we reset PS2_FLAG_WAITID flag, so the workaround
546		 * for mice not acknowledging the Get ID command only triggers
547		 * on the 1st byte; if device spews data we really want to see
548		 * a real ACK from it.
549		 */
550		dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data);
551		if (ps2dev->flags & PS2_FLAG_PASS_NOACK)
552			ps2dev->receive_handler(ps2dev, data);
553		ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK);
554		return;
555	}
556
557	if (!ps2dev->nak)
558		ps2dev->flags &= ~PS2_FLAG_NAK;
559
560	ps2dev->flags &= ~PS2_FLAG_ACK;
561
562	if (!ps2dev->nak && data != PS2_RET_ACK)
563		ps2_handle_response(ps2dev, data);
564	else
565		wake_up(&ps2dev->wait);
566}
567
568/*
569 * Clears state of PS/2 device after communication error by resetting majority
570 * of flags and waking up waiters, if any.
571 */
572static void ps2_cleanup(struct ps2dev *ps2dev)
573{
574	unsigned long old_flags = ps2dev->flags;
575
576	/* reset all flags except last nak */
577	ps2dev->flags &= PS2_FLAG_NAK;
578
579	if (old_flags & PS2_FLAG_ACK)
580		ps2dev->nak = 1;
581
582	if (old_flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
583		wake_up(&ps2dev->wait);
584}
585
586/**
587 * ps2_interrupt - common interrupt handler for PS/2 devices
588 * @serio: serio port for the device
589 * @data: a data byte received from the device
590 * @flags: flags such as %SERIO_PARITY or %SERIO_TIMEOUT indicating state of
591 *   the data transfer
592 *
593 * ps2_interrupt() invokes pre-receive handler, optionally handles command
594 * acknowledgement and response from the device, and finally passes the data
595 * to the main protocol handler for future processing.
596 */
597irqreturn_t ps2_interrupt(struct serio *serio, u8 data, unsigned int flags) {
598	struct ps2dev *ps2dev = serio_get_drvdata(serio);
599	enum ps2_disposition rc;
600
601	rc = ps2dev->pre_receive_handler(ps2dev, data, flags);
602	switch (rc) {
603	case PS2_ERROR:
604		ps2_cleanup(ps2dev);
605		break;
606
607	case PS2_IGNORE:
608		break;
609
610	case PS2_PROCESS:
611		if (ps2dev->flags & PS2_FLAG_ACK)
612			ps2_handle_ack(ps2dev, data);
613		else if (ps2dev->flags & PS2_FLAG_CMD)
614			ps2_handle_response(ps2dev, data);
615		else
616			ps2dev->receive_handler(ps2dev, data);
617		break;
618	}
619
620	return IRQ_HANDLED;
621}
622EXPORT_SYMBOL(ps2_interrupt);
623
624MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
625MODULE_DESCRIPTION("PS/2 driver library");
626MODULE_LICENSE("GPL");