Andrew, Paul,

This is an hvc_console patch which provides driver and ppc64
architecture fixes to enable the hvc_console driver to register itself
as a vio device with the vio bus, provide hotplug add/remove for vty
adapters, and act as an interrupt driven driver on Power-5 hardware or
remain as a polling driver on Power-4 hardware. 

Paul MacKerras should probably approve this patch since it includes
arch/ppc64/ changes.

Ben Herrenschmidt wrote the original patch for the Ameslab tree, which
provided the int-driven or poll driven console that this patch is
extends upon.  He had me add his 'signed-off-by' line.

Changelog:

arch/ppc64/kernel/hvconsole.c
-----------------------------------------------------------------------
-Changed hvc_get_chars() and hvc_put_chars() api to take vtermno rather
than index number.

-Added hvc_find_vtys() function which walks the bus looking for
vterm/vty devices to callback to the hvc_console driver.  This provides
console output functionality prior to early console init (pre mem init
and pre device probe).

include/asm-ppc64/hvconsole.h
-----------------------------------------------------------------------

-Changed hvc_get_chars() and hvc_put_chars() api to take vtermno rather
than index number.

-Added hvc_find_vtys() function.

-Added hvc_instantiate() function which is implemented by a console
driver wanting to receive a callback of and early console init.

drivers/char/hvc_console.c
-----------------------------------------------------------------------

-Switch khvcd from kernel_threads to kthreads which got rid of
deprecated daemonize().

-Added module exit clause to be thorough (not terribly necessary with a
console driver of course)

-Added early discovery of vterm/vty adapters by doing a bus walk on
early console init which results in hvc_instantiate() callback and
addition of the vtermno into a static array of vtermnos supported as
console adapters (meaning the console api's work against these vtermnos
prior to full console initialization).

-This driver is now registered as a vio driver which means that vty
adapters are now managed via probe/remove.  This means hvc_console
supports hotplug vty adapters.

-Driver now requests more device nodes than what was found on the
initial bus walk when registered as a tty driver to make room for
hotplug vty adapters.  These secondary vty adapters provide a tty tunnel
between partitions.

-Removed static hvc_struct array and replaced with a linux list that has
elements (hvc_struct instances) added/removed on probe/remove AFTER
early console init.  This is important because kmalloc can't be done at
early console init.

-Driver now either runs in interrupt driven mode or in polling mode on
older hardware.  The khvcd is smart enough to not 'schedule()' when
there are no interrupts.

-kobjects are now used for ref counting on the hvc_struct instances.

This patch was tested on both Power-4 and Power-5 hardware.
Thanks,

Ryan S. Arnold
IBM Linux Technology Center