powerpc: udbg-based backend for hvc_console

This adds a new backend for the hvc console based on the low-level
udbg callbacks.  This effectively implements a working runtime console
in terms of the simple udbg primitives.  This is kind of a hack -
since udbg isn't something you really want to be using routinely - but
it's really useful during bringup.

This can be used to quickly implement a userspace-usable console while
you're working on a proper driver for whatever console I/O device the
hardware has.  Or, it can be used to avoid writing a full blown
tty/console driver entirely for quick-and-dirty I/O hardware that will
later be replaced by something else.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 43b35d0..19e255c 100644 (file)
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -631,6 +631,12 @@ config HVC_XEN
        help
          Xen virtual console device driver
 
+config HVC_UDBG
+       bool "udbg based fake hypervisor console"
+       depends on PPC && EXPERIMENTAL
+       select HVC_DRIVER
+       default n
+
 config VIRTIO_CONSOLE
        tristate "Virtio console"
        depends on VIRTIO

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 438f713..52e1552 100644 (file)
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_HVC_BEAT)                += hvc_beat.o
 obj-$(CONFIG_HVC_DRIVER)       += hvc_console.o
 obj-$(CONFIG_HVC_IRQ)          += hvc_irq.o
 obj-$(CONFIG_HVC_XEN)          += hvc_xen.o
+obj-$(CONFIG_HVC_UDBG)         += hvc_udbg.o
 obj-$(CONFIG_VIRTIO_CONSOLE)   += virtio_console.o
 obj-$(CONFIG_RAW_DRIVER)       += raw.o
 obj-$(CONFIG_SGI_SNSC)         += snsc.o snsc_event.o

diff --cc drivers/char/hvc_udbg.c
Simple merge