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