firewire: debug interrupt events

This adds debug printks for asynchronous transmission and reception and
for self ID reception.  They can be enabled at module load time, and at
runtime via /sys/module/firewire_ohci/parameters/debug.

Signed-off-by: Jarod Wilson <jwilson@redhat.com>

Also added:  Logging of interrupt event codes and of cancelled AT
packets.

The code now depends on a Kconfig variable.  This makes it easier to
build firewire-ohci without the feature or to make it an option in the
future.  The variable is currently hidden and always on.

This feature inflates firewire-ohci.ko by 7 kB = 27% on x86-64 and by
4 kB = 23% on i686.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/Kconfig b/drivers/firewire/Kconfig
index 25bdc2d..fb4d391 100644
--- a/drivers/firewire/Kconfig
+++ b/drivers/firewire/Kconfig
@@ -54,6 +54,11 @@
 	  directive, use "install modulename /bin/true" for the modules to be
 	  blacklisted.
 
+config FIREWIRE_OHCI_DEBUG
+	bool
+	depends on FIREWIRE_OHCI
+	default y
+
 config FIREWIRE_SBP2
 	tristate "Support for storage devices (SBP-2 protocol driver)"
 	depends on FIREWIRE && SCSI