powerpc: Add driver for Barrier Synchronization Register

Adds a character driver for BSR support on IBM POWER systems including
Power5 and Power6.  The BSR is an optional processor facility not currently
implemented by any other processors.  It's primary purpose is fast large SMP
synchronization.  More details on the BSR are in comments to the code which
follows.  This patch adds BSR driver to pseries_defconfig.

Signed-off-by: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
Signed-off-by: Joel Schopp <jschopp@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 2d854bb9373e..650e6b44ce65 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -649,6 +649,14 @@ config HVCS
           which will also be compiled when this driver is built as a
           module.
 
+config IBM_BSR
+        tristate "IBM POWER Barrier Synchronization Register support"
+        depends on PPC_PSERIES
+        help
+          This devices exposes a hardware mechanism for fast synchronization
+          of threads across a large system which avoids bouncing a cacheline
+          between several cores on a system
+
 source "drivers/char/ipmi/Kconfig"
 
 config DS1620