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
21MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
22MODULE_DESCRIPTION("PS/2 driver library");
23MODULE_LICENSE("GPL");
24
25static 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
86int 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}
99EXPORT_SYMBOL(ps2_sendbyte);
100
101void 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}
107EXPORT_SYMBOL(ps2_begin_command);
108
109void 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}
115EXPORT_SYMBOL(ps2_end_command);
116
117/*
118 * ps2_drain() waits for device to transmit requested number of bytes
119 * and discards them.
120 */
121
122void 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}
142EXPORT_SYMBOL(ps2_drain);
143
144/*
145 * ps2_is_keyboard_id() checks received ID byte against the list of
146 * known keyboard IDs.
147 */
148
149bool 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}
162EXPORT_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
170static 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
226int __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}
325EXPORT_SYMBOL(__ps2_command);
326
327int 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}
337EXPORT_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
347int 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
365out:
366	dev_dbg(&ps2dev->serio->dev, "%02x - %d\n", command, retval);
367	ps2_end_command(ps2dev);
368	return retval;
369}
370EXPORT_SYMBOL(ps2_sliced_command);
371
372/*
373 * ps2_init() initializes ps2dev structure
374 */
375
376void 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}
383EXPORT_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
390bool 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		/* Fall through */
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}
452EXPORT_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
460bool 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}
478EXPORT_SYMBOL(ps2_handle_response);
479
480void 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}
491EXPORT_SYMBOL(ps2_cmd_aborted);
492