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/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)
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);
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 = kzalloc(sizeof(struct serio), GFP_KERNEL);
175	if (serio) {
176		serio->id.type = parkbd_mode;
177		serio->write = parkbd_write,
178		strlcpy(serio->name, "PARKBD AT/XT keyboard adapter", sizeof(serio->name));
179		snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", parkbd_dev->port->name);
180	}
181
182	return serio;
183}
184
185static int __init parkbd_init(void)
186{
187	int err;
188
189	err = parkbd_getport();
190	if (err)
191		return err;
192
193	parkbd_port = parkbd_allocate_serio();
194	if (!parkbd_port) {
195		parport_release(parkbd_dev);
196		return -ENOMEM;
197	}
198
199	parkbd_writelines(3);
200
201	serio_register_port(parkbd_port);
202
203	printk(KERN_INFO "serio: PARKBD %s adapter on %s\n",
204                        parkbd_mode ? "AT" : "XT", parkbd_dev->port->name);
205
206	return 0;
207}
208
209static void __exit parkbd_exit(void)
210{
211	parport_release(parkbd_dev);
212	serio_unregister_port(parkbd_port);
213	parport_unregister_device(parkbd_dev);
214}
215
216module_init(parkbd_init);
217module_exit(parkbd_exit);
218