1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * TQC PS/2 Multiplexer driver
4 *
5 * Copyright (C) 2010 Dmitry Eremin-Solenikov
6 */
7
8
9 #include <linux/kernel.h>
10 #include <linux/slab.h>
11 #include <linux/module.h>
12 #include <linux/serio.h>
13
14 MODULE_AUTHOR("Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>");
15 MODULE_DESCRIPTION("TQC PS/2 Multiplexer driver");
16 MODULE_LICENSE("GPL");
17
18 #define PS2MULT_KB_SELECTOR 0xA0
19 #define PS2MULT_MS_SELECTOR 0xA1
20 #define PS2MULT_ESCAPE 0x7D
21 #define PS2MULT_BSYNC 0x7E
22 #define PS2MULT_SESSION_START 0x55
23 #define PS2MULT_SESSION_END 0x56
24
25 struct ps2mult_port {
26 struct serio *serio;
27 unsigned char sel;
28 bool registered;
29 };
30
31 #define PS2MULT_NUM_PORTS 2
32 #define PS2MULT_KBD_PORT 0
33 #define PS2MULT_MOUSE_PORT 1
34
35 struct ps2mult {
36 struct serio *mx_serio;
37 struct ps2mult_port ports[PS2MULT_NUM_PORTS];
38
39 spinlock_t lock;
40 struct ps2mult_port *in_port;
41 struct ps2mult_port *out_port;
42 bool escape;
43 };
44
45 /* First MUST come PS2MULT_NUM_PORTS selectors */
46 static const unsigned char ps2mult_controls[] = {
47 PS2MULT_KB_SELECTOR, PS2MULT_MS_SELECTOR,
48 PS2MULT_ESCAPE, PS2MULT_BSYNC,
49 PS2MULT_SESSION_START, PS2MULT_SESSION_END,
50 };
51
52 static const struct serio_device_id ps2mult_serio_ids[] = {
53 {
54 .type = SERIO_RS232,
55 .proto = SERIO_PS2MULT,
56 .id = SERIO_ANY,
57 .extra = SERIO_ANY,
58 },
59 { 0 }
60 };
61
62 MODULE_DEVICE_TABLE(serio, ps2mult_serio_ids);
63
ps2mult_select_port(struct ps2mult * psm,struct ps2mult_port * port)64 static void ps2mult_select_port(struct ps2mult *psm, struct ps2mult_port *port)
65 {
66 struct serio *mx_serio = psm->mx_serio;
67
68 serio_write(mx_serio, port->sel);
69 psm->out_port = port;
70 dev_dbg(&mx_serio->dev, "switched to sel %02x\n", port->sel);
71 }
72
ps2mult_serio_write(struct serio * serio,unsigned char data)73 static int ps2mult_serio_write(struct serio *serio, unsigned char data)
74 {
75 struct serio *mx_port = serio->parent;
76 struct ps2mult *psm = serio_get_drvdata(mx_port);
77 struct ps2mult_port *port = serio->port_data;
78 bool need_escape;
79
80 guard(spinlock_irqsave)(&psm->lock);
81
82 if (psm->out_port != port)
83 ps2mult_select_port(psm, port);
84
85 need_escape = memchr(ps2mult_controls, data, sizeof(ps2mult_controls));
86
87 dev_dbg(&serio->dev,
88 "write: %s%02x\n", need_escape ? "ESC " : "", data);
89
90 if (need_escape)
91 serio_write(mx_port, PS2MULT_ESCAPE);
92
93 serio_write(mx_port, data);
94
95 return 0;
96 }
97
ps2mult_serio_start(struct serio * serio)98 static int ps2mult_serio_start(struct serio *serio)
99 {
100 struct ps2mult *psm = serio_get_drvdata(serio->parent);
101 struct ps2mult_port *port = serio->port_data;
102
103 guard(spinlock_irqsave)(&psm->lock);
104
105 port->registered = true;
106
107 return 0;
108 }
109
ps2mult_serio_stop(struct serio * serio)110 static void ps2mult_serio_stop(struct serio *serio)
111 {
112 struct ps2mult *psm = serio_get_drvdata(serio->parent);
113 struct ps2mult_port *port = serio->port_data;
114
115 guard(spinlock_irqsave)(&psm->lock);
116
117 port->registered = false;
118 }
119
ps2mult_create_port(struct ps2mult * psm,int i)120 static int ps2mult_create_port(struct ps2mult *psm, int i)
121 {
122 struct serio *mx_serio = psm->mx_serio;
123 struct serio *serio;
124
125 serio = kzalloc(sizeof(*serio), GFP_KERNEL);
126 if (!serio)
127 return -ENOMEM;
128
129 strscpy(serio->name, "TQC PS/2 Multiplexer", sizeof(serio->name));
130 snprintf(serio->phys, sizeof(serio->phys),
131 "%s/port%d", mx_serio->phys, i);
132 serio->id.type = SERIO_8042;
133 serio->write = ps2mult_serio_write;
134 serio->start = ps2mult_serio_start;
135 serio->stop = ps2mult_serio_stop;
136 serio->parent = psm->mx_serio;
137 serio->port_data = &psm->ports[i];
138
139 psm->ports[i].serio = serio;
140
141 return 0;
142 }
143
ps2mult_reset(struct ps2mult * psm)144 static void ps2mult_reset(struct ps2mult *psm)
145 {
146 guard(spinlock_irqsave)(&psm->lock);
147
148 serio_write(psm->mx_serio, PS2MULT_SESSION_END);
149 serio_write(psm->mx_serio, PS2MULT_SESSION_START);
150
151 ps2mult_select_port(psm, &psm->ports[PS2MULT_KBD_PORT]);
152 }
153
ps2mult_connect(struct serio * serio,struct serio_driver * drv)154 static int ps2mult_connect(struct serio *serio, struct serio_driver *drv)
155 {
156 struct ps2mult *psm;
157 int i;
158 int error;
159
160 if (!serio->write)
161 return -EINVAL;
162
163 psm = kzalloc(sizeof(*psm), GFP_KERNEL);
164 if (!psm)
165 return -ENOMEM;
166
167 spin_lock_init(&psm->lock);
168 psm->mx_serio = serio;
169
170 for (i = 0; i < PS2MULT_NUM_PORTS; i++) {
171 psm->ports[i].sel = ps2mult_controls[i];
172 error = ps2mult_create_port(psm, i);
173 if (error)
174 goto err_out;
175 }
176
177 psm->in_port = psm->out_port = &psm->ports[PS2MULT_KBD_PORT];
178
179 serio_set_drvdata(serio, psm);
180 error = serio_open(serio, drv);
181 if (error)
182 goto err_out;
183
184 ps2mult_reset(psm);
185
186 for (i = 0; i < PS2MULT_NUM_PORTS; i++) {
187 struct serio *s = psm->ports[i].serio;
188
189 dev_info(&serio->dev, "%s port at %s\n", s->name, serio->phys);
190 serio_register_port(s);
191 }
192
193 return 0;
194
195 err_out:
196 while (--i >= 0)
197 kfree(psm->ports[i].serio);
198 kfree(psm);
199 return error;
200 }
201
ps2mult_disconnect(struct serio * serio)202 static void ps2mult_disconnect(struct serio *serio)
203 {
204 struct ps2mult *psm = serio_get_drvdata(serio);
205
206 /* Note that serio core already take care of children ports */
207 serio_write(serio, PS2MULT_SESSION_END);
208 serio_close(serio);
209 kfree(psm);
210
211 serio_set_drvdata(serio, NULL);
212 }
213
ps2mult_reconnect(struct serio * serio)214 static int ps2mult_reconnect(struct serio *serio)
215 {
216 struct ps2mult *psm = serio_get_drvdata(serio);
217
218 ps2mult_reset(psm);
219
220 return 0;
221 }
222
ps2mult_interrupt(struct serio * serio,unsigned char data,unsigned int dfl)223 static irqreturn_t ps2mult_interrupt(struct serio *serio,
224 unsigned char data, unsigned int dfl)
225 {
226 struct ps2mult *psm = serio_get_drvdata(serio);
227 struct ps2mult_port *in_port;
228
229 dev_dbg(&serio->dev, "Received %02x flags %02x\n", data, dfl);
230
231 guard(spinlock_irqsave)(&psm->lock);
232
233 if (psm->escape) {
234 psm->escape = false;
235 in_port = psm->in_port;
236 if (in_port->registered)
237 serio_interrupt(in_port->serio, data, dfl);
238 goto out;
239 }
240
241 switch (data) {
242 case PS2MULT_ESCAPE:
243 dev_dbg(&serio->dev, "ESCAPE\n");
244 psm->escape = true;
245 break;
246
247 case PS2MULT_BSYNC:
248 dev_dbg(&serio->dev, "BSYNC\n");
249 psm->in_port = psm->out_port;
250 break;
251
252 case PS2MULT_SESSION_START:
253 dev_dbg(&serio->dev, "SS\n");
254 break;
255
256 case PS2MULT_SESSION_END:
257 dev_dbg(&serio->dev, "SE\n");
258 break;
259
260 case PS2MULT_KB_SELECTOR:
261 dev_dbg(&serio->dev, "KB\n");
262 psm->in_port = &psm->ports[PS2MULT_KBD_PORT];
263 break;
264
265 case PS2MULT_MS_SELECTOR:
266 dev_dbg(&serio->dev, "MS\n");
267 psm->in_port = &psm->ports[PS2MULT_MOUSE_PORT];
268 break;
269
270 default:
271 in_port = psm->in_port;
272 if (in_port->registered)
273 serio_interrupt(in_port->serio, data, dfl);
274 break;
275 }
276
277 out:
278 return IRQ_HANDLED;
279 }
280
281 static struct serio_driver ps2mult_drv = {
282 .driver = {
283 .name = "ps2mult",
284 },
285 .description = "TQC PS/2 Multiplexer driver",
286 .id_table = ps2mult_serio_ids,
287 .interrupt = ps2mult_interrupt,
288 .connect = ps2mult_connect,
289 .disconnect = ps2mult_disconnect,
290 .reconnect = ps2mult_reconnect,
291 };
292
293 module_serio_driver(ps2mult_drv);
294