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/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(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
 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);