DCA: Add Direct Cache Access driver

Direct Cache Access (DCA) is a method for warming the CPU cache before data
is used, with the intent of lessening the impact of cache misses.  This
patch adds a manager and interface for matching up client requests for DCA
services with devices that offer DCA services.

In order to use DCA, a module must do bus writes with the appropriate tag
bits set to trigger a cache read for a specific CPU.  However, different
CPUs and chipsets can require different sets of tag bits, and the methods
for determining the correct bits may be simple hardcoding or may be a
hardware specific magic incantation.  This interface is a way for DCA
clients to find the correct tag bits for the targeted CPU without needing
to know the specifics.

    [Dave Miller] use DEFINE_SPINLOCK()

Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/dca/Kconfig b/drivers/dca/Kconfig
new file mode 100644
index 000000000000..e2f7436da051
--- /dev/null
+++ b/drivers/dca/Kconfig
@@ -0,0 +1,11 @@
+#
+# DCA server configuration
+#
+
+config DCA
+	tristate "DCA support for clients and providers"
+	default m
+	help
+	  This is a server to help modules that want to use Direct Cache
+	  Access to find DCA providers that will supply correct CPU tags.
+