powerpc/powernv: Support for OPAL console

This adds a udbg and an hvc console backend for supporting a console
using the OPAL console interfaces.

On OPAL v1 we have hvc0 mapped to whatever console the system was
configured for (network or hvsi serial port) via the service
processor.

On OPAL v2 we have hvcN mapped to the Nth console provided by OPAL
which generally corresponds to:

	hvc0 : network console (raw protocol)
	hvc1 : serial port S1 (hvsi)
	hvc2 : serial port S2 (hvsi)

Note: At this point, early debug console only works with OPAL v1
and shouldn't be enabled in a normal kernel.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig
index e371753ba921..4222035acfb7 100644
--- a/drivers/tty/hvc/Kconfig
+++ b/drivers/tty/hvc/Kconfig
@@ -34,6 +34,15 @@ config HVC_ISERIES
         help
           iSeries machines support a hypervisor virtual console.
 
+config HVC_OPAL
+        bool "OPAL Console support"
+        depends on PPC_POWERNV
+        select HVC_DRIVER
+        select HVC_IRQ
+        default y
+        help
+          PowerNV machines running under OPAL need that driver to get a console
+
 config HVC_RTAS
         bool "IBM RTAS Console support"
         depends on PPC_RTAS