2 * Parallel port to Keyboard port adapter driver for Linux
4 * Copyright (c) 1999-2004 Vojtech Pavlik
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.
14 * To connect an AT or XT keyboard to the parallel port, a fairly simple adapter
17 * Parallel port Keyboard port
19 * +5V --------------------- +5V (4)
22 * +5V -------|______|--.
24 * ACK (10) ------------|
26 * STROBE (1) ---|<|----'
29 * +5V -------|______|--.
31 * BUSY (11) -----------|
33 * AUTOFD (14) --|<|----'
35 * GND (18-25) ------------- GND (3)
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,
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.
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>
53 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
54 MODULE_DESCRIPTION("Parallel port to Keyboard port adapter driver");
55 MODULE_LICENSE("GPL");
57 static unsigned int parkbd_pp_no;
58 module_param_named(port, parkbd_pp_no, int, 0);
59 MODULE_PARM_DESC(port, "Parallel port the adapter is connected to (default is 0)");
61 static unsigned int parkbd_mode = SERIO_8042;
62 module_param_named(mode, parkbd_mode, uint, 0);
63 MODULE_PARM_DESC(mode, "Mode of operation: XT = 0/AT = 1 (default)");
65 #define PARKBD_CLOCK 0x01 /* Strobe & Ack */
66 #define PARKBD_DATA 0x02 /* AutoFd & Busy */
68 static int parkbd_buffer;
69 static int parkbd_counter;
70 static unsigned long parkbd_last;
71 static int parkbd_writing;
72 static unsigned long parkbd_start;
74 static struct pardevice *parkbd_dev;
75 static struct serio *parkbd_port;
77 static int parkbd_readlines(void)
79 return (parport_read_status(parkbd_dev->port) >> 6) ^ 2;
82 static void parkbd_writelines(int data)
84 parport_write_control(parkbd_dev->port, (~data & 3) | 0x10);
87 static int parkbd_write(struct serio *port, unsigned char c)
91 if (!parkbd_mode) return -1;
99 parkbd_buffer = c | (((int) (~p & 1)) << 8) | 0x600;
101 parkbd_writelines(2);
106 static void parkbd_interrupt(void *dev_id)
109 if (parkbd_writing) {
111 if (parkbd_counter && ((parkbd_counter == 11) || time_after(jiffies, parkbd_last + HZ/100))) {
115 parkbd_writelines(3);
119 parkbd_writelines(((parkbd_buffer >> parkbd_counter++) & 1) | 2);
121 if (parkbd_counter == 11) {
125 parkbd_writelines(3);
130 if ((parkbd_counter == parkbd_mode + 10) || time_after(jiffies, parkbd_last + HZ/100)) {
135 parkbd_buffer |= (parkbd_readlines() >> 1) << parkbd_counter++;
137 if (parkbd_counter == parkbd_mode + 10)
138 serio_interrupt(parkbd_port, (parkbd_buffer >> (2 - parkbd_mode)) & 0xff, 0);
141 parkbd_last = jiffies;
144 static int parkbd_getport(struct parport *pp)
146 struct pardev_cb parkbd_parport_cb;
148 parkbd_parport_cb.irq_func = parkbd_interrupt;
149 parkbd_parport_cb.flags = PARPORT_FLAG_EXCL;
151 parkbd_dev = parport_register_dev_model(pp, "parkbd",
152 &parkbd_parport_cb, 0);
157 if (parport_claim(parkbd_dev)) {
158 parport_unregister_device(parkbd_dev);
162 parkbd_start = jiffies;
167 static struct serio * __init parkbd_allocate_serio(void)
171 serio = kzalloc(sizeof(struct serio), GFP_KERNEL);
173 serio->id.type = parkbd_mode;
174 serio->write = parkbd_write,
175 strlcpy(serio->name, "PARKBD AT/XT keyboard adapter", sizeof(serio->name));
176 snprintf(serio->phys, sizeof(serio->phys), "%s/serio0", parkbd_dev->port->name);
182 static void parkbd_attach(struct parport *pp)
184 if (pp->number != parkbd_pp_no) {
185 pr_debug("Not using parport%d.\n", pp->number);
189 if (parkbd_getport(pp))
192 parkbd_port = parkbd_allocate_serio();
194 parport_release(parkbd_dev);
195 parport_unregister_device(parkbd_dev);
199 parkbd_writelines(3);
201 serio_register_port(parkbd_port);
203 printk(KERN_INFO "serio: PARKBD %s adapter on %s\n",
204 parkbd_mode ? "AT" : "XT", parkbd_dev->port->name);
209 static void parkbd_detach(struct parport *port)
211 if (!parkbd_port || port->number != parkbd_pp_no)
214 parport_release(parkbd_dev);
215 serio_unregister_port(parkbd_port);
216 parport_unregister_device(parkbd_dev);
220 static struct parport_driver parkbd_parport_driver = {
222 .match_port = parkbd_attach,
223 .detach = parkbd_detach,
227 static int __init parkbd_init(void)
229 return parport_register_driver(&parkbd_parport_driver);
232 static void __exit parkbd_exit(void)
234 parport_unregister_driver(&parkbd_parport_driver);
237 module_init(parkbd_init);
238 module_exit(parkbd_exit);