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1/*
2 * Parallel port to Keyboard port adapter driver for Linux
3 *
4 * Copyright (c) 1999-2004 Vojtech Pavlik
5 */
6
7/*
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published by
10 * the Free Software Foundation.
11 */
12
13/*
14 * To connect an AT or XT keyboard to the parallel port, a fairly simple adapter
15 * can be made:
16 *
17 * Parallel port Keyboard port
18 *
19 * +5V --------------------- +5V (4)
20 *
21 * ______
22 * +5V -------|______|--.
23 * |
24 * ACK (10) ------------|
25 * |--- KBD CLOCK (5)
26 * STROBE (1) ---|<|----'
27 *
28 * ______
29 * +5V -------|______|--.
30 * |
31 * BUSY (11) -----------|
32 * |--- KBD DATA (1)
33 * AUTOFD (14) --|<|----'
34 *
35 * GND (18-25) ------------- GND (3)
36 *
37 * The diodes can be fairly any type, and the resistors should be somewhere
38 * around 5 kOhm, but the adapter will likely work without the resistors,
39 * too.
40 *
41 * The +5V source can be taken either from USB, from mouse or keyboard ports,
42 * or from a joystick port. Unfortunately, the parallel port of a PC doesn't
43 * have a +5V pin, and feeding the keyboard from signal pins is out of question
44 * with 300 mA power reqirement of a typical AT keyboard.
45 */
46
47#include <linux/module.h>
48#include <linux/parport.h>
49#include <linux/slab.h>
50#include <linux/init.h>
51#include <linux/serio.h>
52
53MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
54MODULE_DESCRIPTION("Parallel port to Keyboard port adapter driver");
55MODULE_LICENSE("GPL");
56
57static unsigned int parkbd_pp_no;
58module_param_named(port, parkbd_pp_no, int, 0);
59MODULE_PARM_DESC(port, "Parallel port the adapter is connected to (default is 0)");
60
61static unsigned int parkbd_mode = SERIO_8042;
62module_param_named(mode, parkbd_mode, uint, 0);
63MODULE_PARM_DESC(mode, "Mode of operation: XT = 0/AT = 1 (default)");
64
65#define PARKBD_CLOCK 0x01 /* Strobe & Ack */
66#define PARKBD_DATA 0x02 /* AutoFd & Busy */
67
68static int parkbd_buffer;
69static int parkbd_counter;
70static unsigned long parkbd_last;
71static int parkbd_writing;
72static unsigned long parkbd_start;
73
74static struct pardevice *parkbd_dev;
75static struct serio *parkbd_port;
76
77static int parkbd_readlines(void)
78{
79 return (parport_read_status(parkbd_dev->port) >> 6) ^ 2;
80}
81
82static void parkbd_writelines(int data)
83{
84 parport_write_control(parkbd_dev->port, (~data & 3) | 0x10);
85}
86
87static int parkbd_write(struct serio *port, unsigned char c)
88{
89 unsigned char p;
90
91 if (!parkbd_mode) return -1;
92
93 p = c ^ (c >> 4);
94 p = p ^ (p >> 2);
95 p = p ^ (p >> 1);
96
97 parkbd_counter = 0;
98 parkbd_writing = 1;
99 parkbd_buffer = c | (((int) (~p & 1)) << 8) | 0x600;
100
101 parkbd_writelines(2);
102
103 return 0;
104}
105
106static void parkbd_interrupt(void *dev_id)
107{
108
109 if (parkbd_writing) {
110
111 if (parkbd_counter && ((parkbd_counter == 11) || time_after(jiffies, parkbd_last + HZ/100))) {
112 parkbd_counter = 0;
113 parkbd_buffer = 0;
114 parkbd_writing = 0;
115 parkbd_writelines(3);
116 return;
117 }
118
119 parkbd_writelines(((parkbd_buffer >> parkbd_counter++) & 1) | 2);
120
121 if (parkbd_counter == 11) {
122 parkbd_counter = 0;
123 parkbd_buffer = 0;
124 parkbd_writing = 0;
125 parkbd_writelines(3);
126 }
127
128 } else {
129
130 if ((parkbd_counter == parkbd_mode + 10) || time_after(jiffies, parkbd_last + HZ/100)) {
131 parkbd_counter = 0;
132 parkbd_buffer = 0;
133 }
134
135 parkbd_buffer |= (parkbd_readlines() >> 1) << parkbd_counter++;
136
137 if (parkbd_counter == parkbd_mode + 10)
138 serio_interrupt(parkbd_port, (parkbd_buffer >> (2 - parkbd_mode)) & 0xff, 0);
139 }
140
141 parkbd_last = jiffies;
142}
143
144static int parkbd_getport(void)
145{
146 struct parport *pp;
147
148 pp = parport_find_number(parkbd_pp_no);
149
150 if (pp == NULL) {
151 printk(KERN_ERR "parkbd: no such parport\n");
152 return -ENODEV;
153 }
154
155 parkbd_dev = parport_register_device(pp, "parkbd", NULL, NULL, parkbd_interrupt, PARPORT_DEV_EXCL, NULL);
156 parport_put_port(pp);
157
158 if (!parkbd_dev)
159 return -ENODEV;
160
161 if (parport_claim(parkbd_dev)) {
162 parport_unregister_device(parkbd_dev);
163 return -EBUSY;
164 }
165
166 parkbd_start = jiffies;
167
168 return 0;
169}
170
171static struct serio * __init parkbd_allocate_serio(void)
172{
173 struct serio *serio;
174
175 serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
176 if (serio) {
177 serio->id.type = parkbd_mode;
178 serio->write = parkbd_write,
179 strlcpy(serio->name, "PARKBD AT/XT keyboard adapter", sizeof(serio->name));
180 snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", parkbd_dev->port->name);
181 }
182
183 return serio;
184}
185
186static int __init parkbd_init(void)
187{
188 int err;
189
190 err = parkbd_getport();
191 if (err)
192 return err;
193
194 parkbd_port = parkbd_allocate_serio();
195 if (!parkbd_port) {
196 parport_release(parkbd_dev);
197 return -ENOMEM;
198 }
199
200 parkbd_writelines(3);
201
202 serio_register_port(parkbd_port);
203
204 printk(KERN_INFO "serio: PARKBD %s adapter on %s\n",
205 parkbd_mode ? "AT" : "XT", parkbd_dev->port->name);
206
207 return 0;
208}
209
210static void __exit parkbd_exit(void)
211{
212 parport_release(parkbd_dev);
213 serio_unregister_port(parkbd_port);
214 parport_unregister_device(parkbd_dev);
215}
216
217module_init(parkbd_init);
218module_exit(parkbd_exit);