drivers/input/serio/parkbd.c

   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);