xref: /openbmc/linux/drivers/input/serio/libps2.c (revision fd589a8f) 
1 /*
2  * PS/2 driver library
3  *
4  * Copyright (c) 1999-2002 Vojtech Pavlik
5  * Copyright (c) 2004 Dmitry Torokhov
6  */
7 
8 /*
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License version 2 as published by
11  * the Free Software Foundation.
12  */
13 
14 #include <linux/delay.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/interrupt.h>
18 #include <linux/input.h>
19 #include <linux/serio.h>
20 #include <linux/init.h>
21 #include <linux/libps2.h>
22 
23 #define DRIVER_DESC	"PS/2 driver library"
24 
25 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
26 MODULE_DESCRIPTION("PS/2 driver library");
27 MODULE_LICENSE("GPL");
28 
29 /*
30  * ps2_sendbyte() sends a byte to the device and waits for acknowledge.
31  * It doesn't handle retransmission, though it could - because if there
32  * is a need for retransmissions device has to be replaced anyway.
33  *
34  * ps2_sendbyte() can only be called from a process context.
35  */
36 
37 int ps2_sendbyte(struct ps2dev *ps2dev, unsigned char byte, int timeout)
38 {
39 	serio_pause_rx(ps2dev->serio);
40 	ps2dev->nak = 1;
41 	ps2dev->flags |= PS2_FLAG_ACK;
42 	serio_continue_rx(ps2dev->serio);
43 
44 	if (serio_write(ps2dev->serio, byte) == 0)
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 	ps2dev->flags &= ~PS2_FLAG_ACK;
51 	serio_continue_rx(ps2dev->serio);
52 
53 	return -ps2dev->nak;
54 }
55 EXPORT_SYMBOL(ps2_sendbyte);
56 
57 /*
58  * ps2_drain() waits for device to transmit requested number of bytes
59  * and discards them.
60  */
61 
62 void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
63 {
64 	if (maxbytes > sizeof(ps2dev->cmdbuf)) {
65 		WARN_ON(1);
66 		maxbytes = sizeof(ps2dev->cmdbuf);
67 	}
68 
69 	mutex_lock(&ps2dev->cmd_mutex);
70 
71 	serio_pause_rx(ps2dev->serio);
72 	ps2dev->flags = PS2_FLAG_CMD;
73 	ps2dev->cmdcnt = maxbytes;
74 	serio_continue_rx(ps2dev->serio);
75 
76 	wait_event_timeout(ps2dev->wait,
77 			   !(ps2dev->flags & PS2_FLAG_CMD),
78 			   msecs_to_jiffies(timeout));
79 	mutex_unlock(&ps2dev->cmd_mutex);
80 }
81 EXPORT_SYMBOL(ps2_drain);
82 
83 /*
84  * ps2_is_keyboard_id() checks received ID byte against the list of
85  * known keyboard IDs.
86  */
87 
88 int ps2_is_keyboard_id(char id_byte)
89 {
90 	static const char keyboard_ids[] = {
91 		0xab,	/* Regular keyboards		*/
92 		0xac,	/* NCD Sun keyboard		*/
93 		0x2b,	/* Trust keyboard, translated	*/
94 		0x5d,	/* Trust keyboard		*/
95 		0x60,	/* NMB SGI keyboard, translated */
96 		0x47,	/* NMB SGI keyboard		*/
97 	};
98 
99 	return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
100 }
101 EXPORT_SYMBOL(ps2_is_keyboard_id);
102 
103 /*
104  * ps2_adjust_timeout() is called after receiving 1st byte of command
105  * response and tries to reduce remaining timeout to speed up command
106  * completion.
107  */
108 
109 static int ps2_adjust_timeout(struct ps2dev *ps2dev, int command, int timeout)
110 {
111 	switch (command) {
112 		case PS2_CMD_RESET_BAT:
113 			/*
114 			 * Device has sent the first response byte after
115 			 * reset command, reset is thus done, so we can
116 			 * shorten the timeout.
117 			 * The next byte will come soon (keyboard) or not
118 			 * at all (mouse).
119 			 */
120 			if (timeout > msecs_to_jiffies(100))
121 				timeout = msecs_to_jiffies(100);
122 			break;
123 
124 		case PS2_CMD_GETID:
125 			/*
126 			 * Microsoft Natural Elite keyboard responds to
127 			 * the GET ID command as it were a mouse, with
128 			 * a single byte. Fail the command so atkbd will
129 			 * use alternative probe to detect it.
130 			 */
131 			if (ps2dev->cmdbuf[1] == 0xaa) {
132 				serio_pause_rx(ps2dev->serio);
133 				ps2dev->flags = 0;
134 				serio_continue_rx(ps2dev->serio);
135 				timeout = 0;
136 			}
137 
138 			/*
139 			 * If device behind the port is not a keyboard there
140 			 * won't be 2nd byte of ID response.
141 			 */
142 			if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
143 				serio_pause_rx(ps2dev->serio);
144 				ps2dev->flags = ps2dev->cmdcnt = 0;
145 				serio_continue_rx(ps2dev->serio);
146 				timeout = 0;
147 			}
148 			break;
149 
150 		default:
151 			break;
152 	}
153 
154 	return timeout;
155 }
156 
157 /*
158  * ps2_command() sends a command and its parameters to the mouse,
159  * then waits for the response and puts it in the param array.
160  *
161  * ps2_command() can only be called from a process context
162  */
163 
164 int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
165 {
166 	int timeout;
167 	int send = (command >> 12) & 0xf;
168 	int receive = (command >> 8) & 0xf;
169 	int rc = -1;
170 	int i;
171 
172 	if (receive > sizeof(ps2dev->cmdbuf)) {
173 		WARN_ON(1);
174 		return -1;
175 	}
176 
177 	if (send && !param) {
178 		WARN_ON(1);
179 		return -1;
180 	}
181 
182 	serio_pause_rx(ps2dev->serio);
183 	ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
184 	ps2dev->cmdcnt = receive;
185 	if (receive && param)
186 		for (i = 0; i < receive; i++)
187 			ps2dev->cmdbuf[(receive - 1) - i] = param[i];
188 	serio_continue_rx(ps2dev->serio);
189 
190 	/*
191 	 * Some devices (Synaptics) peform the reset before
192 	 * ACKing the reset command, and so it can take a long
193 	 * time before the ACK arrrives.
194 	 */
195 	if (ps2_sendbyte(ps2dev, command & 0xff,
196 			 command == PS2_CMD_RESET_BAT ? 1000 : 200))
197 		goto out;
198 
199 	for (i = 0; i < send; i++)
200 		if (ps2_sendbyte(ps2dev, param[i], 200))
201 			goto out;
202 
203 	/*
204 	 * The reset command takes a long time to execute.
205 	 */
206 	timeout = msecs_to_jiffies(command == PS2_CMD_RESET_BAT ? 4000 : 500);
207 
208 	timeout = wait_event_timeout(ps2dev->wait,
209 				     !(ps2dev->flags & PS2_FLAG_CMD1), timeout);
210 
211 	if (ps2dev->cmdcnt && !(ps2dev->flags & PS2_FLAG_CMD1)) {
212 
213 		timeout = ps2_adjust_timeout(ps2dev, command, timeout);
214 		wait_event_timeout(ps2dev->wait,
215 				   !(ps2dev->flags & PS2_FLAG_CMD), timeout);
216 	}
217 
218 	if (param)
219 		for (i = 0; i < receive; i++)
220 			param[i] = ps2dev->cmdbuf[(receive - 1) - i];
221 
222 	if (ps2dev->cmdcnt && (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1))
223 		goto out;
224 
225 	rc = 0;
226 
227  out:
228 	serio_pause_rx(ps2dev->serio);
229 	ps2dev->flags = 0;
230 	serio_continue_rx(ps2dev->serio);
231 
232 	return rc;
233 }
234 EXPORT_SYMBOL(__ps2_command);
235 
236 int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
237 {
238 	int rc;
239 
240 	mutex_lock(&ps2dev->cmd_mutex);
241 	rc = __ps2_command(ps2dev, param, command);
242 	mutex_unlock(&ps2dev->cmd_mutex);
243 
244 	return rc;
245 }
246 EXPORT_SYMBOL(ps2_command);
247 
248 /*
249  * ps2_init() initializes ps2dev structure
250  */
251 
252 void ps2_init(struct ps2dev *ps2dev, struct serio *serio)
253 {
254 	mutex_init(&ps2dev->cmd_mutex);
255 	lockdep_set_subclass(&ps2dev->cmd_mutex, serio->depth);
256 	init_waitqueue_head(&ps2dev->wait);
257 	ps2dev->serio = serio;
258 }
259 EXPORT_SYMBOL(ps2_init);
260 
261 /*
262  * ps2_handle_ack() is supposed to be used in interrupt handler
263  * to properly process ACK/NAK of a command from a PS/2 device.
264  */
265 
266 int ps2_handle_ack(struct ps2dev *ps2dev, unsigned char data)
267 {
268 	switch (data) {
269 		case PS2_RET_ACK:
270 			ps2dev->nak = 0;
271 			break;
272 
273 		case PS2_RET_NAK:
274 			ps2dev->flags |= PS2_FLAG_NAK;
275 			ps2dev->nak = PS2_RET_NAK;
276 			break;
277 
278 		case PS2_RET_ERR:
279 			if (ps2dev->flags & PS2_FLAG_NAK) {
280 				ps2dev->flags &= ~PS2_FLAG_NAK;
281 				ps2dev->nak = PS2_RET_ERR;
282 				break;
283 			}
284 
285 		/*
286 		 * Workaround for mice which don't ACK the Get ID command.
287 		 * These are valid mouse IDs that we recognize.
288 		 */
289 		case 0x00:
290 		case 0x03:
291 		case 0x04:
292 			if (ps2dev->flags & PS2_FLAG_WAITID) {
293 				ps2dev->nak = 0;
294 				break;
295 			}
296 			/* Fall through */
297 		default:
298 			return 0;
299 	}
300 
301 
302 	if (!ps2dev->nak) {
303 		ps2dev->flags &= ~PS2_FLAG_NAK;
304 		if (ps2dev->cmdcnt)
305 			ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
306 	}
307 
308 	ps2dev->flags &= ~PS2_FLAG_ACK;
309 	wake_up(&ps2dev->wait);
310 
311 	if (data != PS2_RET_ACK)
312 		ps2_handle_response(ps2dev, data);
313 
314 	return 1;
315 }
316 EXPORT_SYMBOL(ps2_handle_ack);
317 
318 /*
319  * ps2_handle_response() is supposed to be used in interrupt handler
320  * to properly store device's response to a command and notify process
321  * waiting for completion of the command.
322  */
323 
324 int ps2_handle_response(struct ps2dev *ps2dev, unsigned char data)
325 {
326 	if (ps2dev->cmdcnt)
327 		ps2dev->cmdbuf[--ps2dev->cmdcnt] = data;
328 
329 	if (ps2dev->flags & PS2_FLAG_CMD1) {
330 		ps2dev->flags &= ~PS2_FLAG_CMD1;
331 		if (ps2dev->cmdcnt)
332 			wake_up(&ps2dev->wait);
333 	}
334 
335 	if (!ps2dev->cmdcnt) {
336 		ps2dev->flags &= ~PS2_FLAG_CMD;
337 		wake_up(&ps2dev->wait);
338 	}
339 
340 	return 1;
341 }
342 EXPORT_SYMBOL(ps2_handle_response);
343 
344 void ps2_cmd_aborted(struct ps2dev *ps2dev)
345 {
346 	if (ps2dev->flags & PS2_FLAG_ACK)
347 		ps2dev->nak = 1;
348 
349 	if (ps2dev->flags & (PS2_FLAG_ACK | PS2_FLAG_CMD))
350 		wake_up(&ps2dev->wait);
351 
352 	/* reset all flags except last nack */
353 	ps2dev->flags &= PS2_FLAG_NAK;
354 }
355 EXPORT_SYMBOL(ps2_cmd_aborted);
356