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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/init.h>
50#include <linux/serio.h>
51
52MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
53MODULE_DESCRIPTION("Parallel port to Keyboard port adapter driver");
54MODULE_LICENSE("GPL");
55
56static unsigned int parkbd_pp_no;
57module_param_named(port, parkbd_pp_no, int, 0);
58MODULE_PARM_DESC(port, "Parallel port the adapter is connected to (default is 0)");
59
60static unsigned int parkbd_mode = SERIO_8042;
61module_param_named(mode, parkbd_mode, uint, 0);
62MODULE_PARM_DESC(mode, "Mode of operation: XT = 0/AT = 1 (default)");
63
64#define PARKBD_CLOCK 0x01 /* Strobe & Ack */
65#define PARKBD_DATA 0x02 /* AutoFd & Busy */
66
67static int parkbd_buffer;
68static int parkbd_counter;
69static unsigned long parkbd_last;
70static int parkbd_writing;
71static unsigned long parkbd_start;
72
73static struct pardevice *parkbd_dev;
74static struct serio *parkbd_port;
75
76static int parkbd_readlines(void)
77{
78 return (parport_read_status(parkbd_dev->port) >> 6) ^ 2;
79}
80
81static void parkbd_writelines(int data)
82{
83 parport_write_control(parkbd_dev->port, (~data & 3) | 0x10);
84}
85
86static int parkbd_write(struct serio *port, unsigned char c)
87{
88 unsigned char p;
89
90 if (!parkbd_mode) return -1;
91
92 p = c ^ (c >> 4);
93 p = p ^ (p >> 2);
94 p = p ^ (p >> 1);
95
96 parkbd_counter = 0;
97 parkbd_writing = 1;
98 parkbd_buffer = c | (((int) (~p & 1)) << 8) | 0x600;
99
100 parkbd_writelines(2);
101
102 return 0;
103}
104
105static void parkbd_interrupt(int irq, void *dev_id, struct pt_regs *regs)
106{
107
108 if (parkbd_writing) {
109
110 if (parkbd_counter && ((parkbd_counter == 11) || time_after(jiffies, parkbd_last + HZ/100))) {
111 parkbd_counter = 0;
112 parkbd_buffer = 0;
113 parkbd_writing = 0;
114 parkbd_writelines(3);
115 return;
116 }
117
118 parkbd_writelines(((parkbd_buffer >> parkbd_counter++) & 1) | 2);
119
120 if (parkbd_counter == 11) {
121 parkbd_counter = 0;
122 parkbd_buffer = 0;
123 parkbd_writing = 0;
124 parkbd_writelines(3);
125 }
126
127 } else {
128
129 if ((parkbd_counter == parkbd_mode + 10) || time_after(jiffies, parkbd_last + HZ/100)) {
130 parkbd_counter = 0;
131 parkbd_buffer = 0;
132 }
133
134 parkbd_buffer |= (parkbd_readlines() >> 1) << parkbd_counter++;
135
136 if (parkbd_counter == parkbd_mode + 10)
137 serio_interrupt(parkbd_port, (parkbd_buffer >> (2 - parkbd_mode)) & 0xff, 0, regs);
138 }
139
140 parkbd_last = jiffies;
141}
142
143static int parkbd_getport(void)
144{
145 struct parport *pp;
146
147 pp = parport_find_number(parkbd_pp_no);
148
149 if (pp == NULL) {
150 printk(KERN_ERR "parkbd: no such parport\n");
151 return -ENODEV;
152 }
153
154 parkbd_dev = parport_register_device(pp, "parkbd", NULL, NULL, parkbd_interrupt, PARPORT_DEV_EXCL, NULL);
155 parport_put_port(pp);
156
157 if (!parkbd_dev)
158 return -ENODEV;
159
160 if (parport_claim(parkbd_dev)) {
161 parport_unregister_device(parkbd_dev);
162 return -EBUSY;
163 }
164
165 parkbd_start = jiffies;
166
167 return 0;
168}
169
170static struct serio * __init parkbd_allocate_serio(void)
171{
172 struct serio *serio;
173
174 serio = kmalloc(sizeof(struct serio), GFP_KERNEL);
175 if (serio) {
176 memset(serio, 0, sizeof(struct 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);