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 53 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>"); 54 MODULE_DESCRIPTION("Parallel port to Keyboard port adapter driver"); 55 MODULE_LICENSE("GPL"); 56 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)"); 60 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)"); 64 65 #define PARKBD_CLOCK 0x01 /* Strobe & Ack */ 66 #define PARKBD_DATA 0x02 /* AutoFd & Busy */ 67 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; 73 74 static struct pardevice *parkbd_dev; 75 static struct serio *parkbd_port; 76 77 static int parkbd_readlines(void) 78 { 79 return (parport_read_status(parkbd_dev->port) >> 6) ^ 2; 80 } 81 82 static void parkbd_writelines(int data) 83 { 84 parport_write_control(parkbd_dev->port, (~data & 3) | 0x10); 85 } 86 87 static 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 } 105 106 static 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 } 143 144 static 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 } 170 171 static 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 } 185 186 static 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 } 209 210 static void __exit parkbd_exit(void) 211 { 212 parport_release(parkbd_dev); 213 serio_unregister_port(parkbd_port); 214 parport_unregister_device(parkbd_dev); 215 } 216 217 module_init(parkbd_init); 218 module_exit(parkbd_exit); 219