linux/drivers/input/serio/parkbd.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Parallel port to Keyboard port adapter driver for Linux
 *
 *  Copyright (c) 1999-2004 Vojtech Pavlik
 */


/*
 * To connect an AT or XT keyboard to the parallel port, a fairly simple adapter
 * can be made:
 * 
 *  Parallel port            Keyboard port
 *
 *     +5V --------------------- +5V (4)
 *  
 *                 ______
 *     +5V -------|______|--.
 *                          |
 *     ACK (10) ------------|
 *                          |--- KBD CLOCK (5)
 *     STROBE (1) ---|<|----'
 *     
 *                 ______
 *     +5V -------|______|--.
 *                          |
 *     BUSY (11) -----------|
 *                          |--- KBD DATA (1)
 *     AUTOFD (14) --|<|----'
 *
 *     GND (18-25) ------------- GND (3)
 *     
 * The diodes can be fairly any type, and the resistors should be somewhere
 * around 5 kOhm, but the adapter will likely work without the resistors,
 * too.
 *
 * The +5V source can be taken either from USB, from mouse or keyboard ports,
 * or from a joystick port. Unfortunately, the parallel port of a PC doesn't
 * have a +5V pin, and feeding the keyboard from signal pins is out of question
 * with 300 mA power reqirement of a typical AT keyboard.
 */

#include <linux/module.h>
#include <linux/parport.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/serio.h>

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;

static unsigned int parkbd_pp_no;
module_param_named(port, parkbd_pp_no, int, 0);
MODULE_PARM_DESC(…) …;

static unsigned int parkbd_mode = …;
module_param_named(mode, parkbd_mode, uint, 0);
MODULE_PARM_DESC(…) …;

#define PARKBD_CLOCK …
#define PARKBD_DATA …

static int parkbd_buffer;
static int parkbd_counter;
static unsigned long parkbd_last;
static int parkbd_writing;
static unsigned long parkbd_start;

static struct pardevice *parkbd_dev;
static struct serio *parkbd_port;

static int parkbd_readlines(void)
{ … }

static void parkbd_writelines(int data)
{ … }

static int parkbd_write(struct serio *port, unsigned char c)
{ … }

static void parkbd_interrupt(void *dev_id)
{ … }

static int parkbd_getport(struct parport *pp)
{ … }

static struct serio *parkbd_allocate_serio(void)
{ … }

static void parkbd_attach(struct parport *pp)
{ … }

static void parkbd_detach(struct parport *port)
{ … }

static struct parport_driver parkbd_parport_driver = …;
module_parport_driver(…) …;