1 files changed, 113 insertions, 0 deletions
diff --git a/xpp/parport_debug.c b/xpp/parport_debug.c
new file mode 100644
index 0000000..93049ef
--- /dev/null
+++ b/xpp/parport_debug.c
@@ -0,0 +1,113 @@
+/*
+ * 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);