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 52 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>"); 53 MODULE_DESCRIPTION("Parallel port to Keyboard port adapter driver"); 54 MODULE_LICENSE("GPL"); 55 56 static unsigned int parkbd_pp_no; 57 module_param_named(port, parkbd_pp_no, int, 0); 58 MODULE_PARM_DESC(port, "Parallel port the adapter is connected to (default is 0)"); 59 60 static unsigned int parkbd_mode = SERIO_8042; 61 module_param_named(mode, parkbd_mode, uint, 0); 62 MODULE_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 67 static int parkbd_buffer; 68 static int parkbd_counter; 69 static unsigned long parkbd_last; 70 static int parkbd_writing; 71 static unsigned long parkbd_start; 72 73 static struct pardevice *parkbd_dev; 74 static struct serio *parkbd_port; 75 76 static int parkbd_readlines(void) 77 { 78 return (parport_read_status(parkbd_dev->port) >> 6) ^ 2; 79 } 80 81 static void parkbd_writelines(int data) 82 { 83 parport_write_control(parkbd_dev->port, (~data & 3) | 0x10); 84 } 85 86 static 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 } 104 105 static void parkbd_interrupt(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 } 142 143 static 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 } 169 170 static 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 } 184 185 static 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 } 208 209 static void __exit parkbd_exit(void) 210 { 211 parport_release(parkbd_dev); 212 serio_unregister_port(parkbd_port); 213 parport_unregister_device(parkbd_dev); 214 } 215 216 module_init(parkbd_init); 217 module_exit(parkbd_exit); 218