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/*
* Written by Oron Peled <oron@actcom.co.il>
* Copyright (C) 2007, Xorcom
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <linux/version.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,0)
# warning "This module is tested only with 2.6 kernels"
#endif
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/parport.h>
#include "parport_debug.h"
static struct parport *debug_sync_parport = NULL;
static int parport_toggles[8]; /* 8 bit flip-flop */
void flip_parport_bit(unsigned char bitnum)
{
static unsigned char last_value;
spinlock_t lock = SPIN_LOCK_UNLOCKED;
unsigned long flags;
unsigned char mask;
unsigned char value;
if(!debug_sync_parport) {
if(printk_ratelimit()) {
printk(KERN_NOTICE "%s: no debug parallel port\n",
THIS_MODULE->name);
}
return;
}
BUG_ON(bitnum > 7);
mask = 1 << bitnum;
spin_lock_irqsave(&lock, flags);
value = last_value & ~mask;
if(parport_toggles[bitnum] % 2) /* square wave */
value |= mask;
last_value = value;
parport_toggles[bitnum]++;
spin_unlock_irqrestore(&lock, flags);
parport_write_data(debug_sync_parport, value);
}
EXPORT_SYMBOL(flip_parport_bit);
static void parport_attach(struct parport *port)
{
printk(KERN_INFO "%s: Using %s for debugging\n", THIS_MODULE->name, port->name);
if(debug_sync_parport) {
printk(KERN_ERR "%s: Using %s, ignore new attachment %s\n",
THIS_MODULE->name, debug_sync_parport->name, port->name);
return;
}
parport_get_port(port);
debug_sync_parport = port;
}
static void parport_detach(struct parport *port)
{
printk(KERN_INFO "%s: Releasing %s\n", THIS_MODULE->name, port->name);
if(debug_sync_parport != port) {
printk(KERN_ERR "%s: Using %s, ignore new detachment %s\n",
THIS_MODULE->name, debug_sync_parport->name, port->name);
return;
}
parport_put_port(debug_sync_parport);
debug_sync_parport = NULL;
}
static struct parport_driver debug_parport_driver = {
.name = "parport_debug",
.attach = parport_attach,
.detach = parport_detach,
};
int __init parallel_dbg_init(void)
{
int ret;
ret = parport_register_driver(&debug_parport_driver);
return ret;
}
void __exit parallel_dbg_cleanup(void)
{
parport_unregister_driver(&debug_parport_driver);
}
MODULE_DESCRIPTION("Use parallel port to debug drivers");
MODULE_AUTHOR("Oron Peled <oron@actcom.co.il>");
MODULE_LICENSE("GPL");
MODULE_VERSION("$Id:");
module_init(parallel_dbg_init);
module_exit(parallel_dbg_cleanup);
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