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authorTimur Tabi <timur@freescale.com>2011-07-08 19:06:12 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2011-08-23 10:32:56 -0700
commitdcd83aaff1c8cbd5b48c152b559e0af3ea1a7b65 (patch)
tree536ce3416fd908f0506899b371d86fb21171078c /drivers/tty/Kconfig
parentfcb8ce5cfe30ca9ca5c9a79cdfe26d1993e65e0c (diff)
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>
Diffstat (limited to 'drivers/tty/Kconfig')
-rw-r--r--drivers/tty/Kconfig34
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
index bd7cc0527999..f1ea59b09444 100644
--- a/drivers/tty/Kconfig
+++ b/drivers/tty/Kconfig
@@ -350,3 +350,37 @@ config TRACE_SINK
If you select this option, you need to select
"Trace data router for MIPI P1149.7 cJTAG standard".
+
+config PPC_EPAPR_HV_BYTECHAN
+ tristate "ePAPR hypervisor byte channel driver"
+ depends on PPC
+ help
+ This driver creates /dev entries for each ePAPR hypervisor byte
+ channel, thereby allowing applications to communicate with byte
+ channels as if they were serial ports.
+
+config PPC_EARLY_DEBUG_EHV_BC
+ bool "Early console (udbg) support for ePAPR hypervisors"
+ depends on PPC_EPAPR_HV_BYTECHAN
+ help
+ Select this option to enable early console (a.k.a. "udbg") support
+ via an ePAPR byte channel. You also need to choose the byte channel
+ handle below.
+
+config PPC_EARLY_DEBUG_EHV_BC_HANDLE
+ int "Byte channel handle for early console (udbg)"
+ depends on PPC_EARLY_DEBUG_EHV_BC
+ default 0
+ help
+ If you want early console (udbg) output through a byte channel,
+ specify the handle of the byte channel to use.
+
+ For this to work, the byte channel driver must be compiled
+ in-kernel, not as a module.
+
+ Note that only one early console driver can be enabled, so don't
+ enable any others if you enable this one.
+
+ If the number you specify is not a valid byte channel handle, then
+ there simply will be no early console output. This is true also
+ if you don't boot under a hypervisor at all.