tty/powerpc: introduce the ePAPR embedded hypervisor byte channel driver

The ePAPR embedded hypervisor specification provides an API for "byte
channels", which are serial-like virtual devices for sending and receiving
streams of bytes.  This driver provides Linux kernel support for byte
channels via three distinct interfaces:

1) An early-console (udbg) driver.  This provides early console output
through a byte channel.  The byte channel handle must be specified in a
Kconfig option.

2) A normal console driver.  Output is sent to the byte channel designated
for stdout in the device tree.  The console driver is for handling kernel
printk calls.

3) A tty driver, which is used to handle user-space input and output.  The
byte channel used for the console is designated as the default tty.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c
index faa82c1f3f68..b4607a91d1f4 100644
--- a/arch/powerpc/kernel/udbg.c
+++ b/arch/powerpc/kernel/udbg.c
@@ -67,6 +67,8 @@ void __init udbg_early_init(void)
         udbg_init_usbgecko();
 #elif defined(CONFIG_PPC_EARLY_DEBUG_WSP)
         udbg_init_wsp();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_EHV_BC)
+        udbg_init_ehv_bc();
 #endif
 
 #ifdef CONFIG_PPC_EARLY_DEBUG