cxl: Add documentation for userspace APIs

This documentation gives an overview of the hardware architecture, userspace
APIs via /dev/cxl/afuM.N and the syfs files. It also adds a MAINTAINERS file
entry for cxl.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/MAINTAINERS b/MAINTAINERS
index 809ecd6..facc219 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2711,6 +2711,18 @@
 S:	Supported
 F:	drivers/net/ethernet/chelsio/cxgb4vf/
 
+CXL (IBM Coherent Accelerator Processor Interface CAPI) DRIVER
+M:	Ian Munsie <imunsie@au1.ibm.com>
+M:	Michael Neuling <mikey@neuling.org>
+L:	linuxppc-dev@lists.ozlabs.org
+S:	Supported
+F:	drivers/misc/cxl/
+F:	include/misc/cxl.h
+F:	include/uapi/misc/cxl.h
+F:	Documentation/powerpc/cxl.txt
+F:	Documentation/powerpc/cxl.txt
+F:	Documentation/ABI/testing/sysfs-class-cxl
+
 STMMAC ETHERNET DRIVER
 M:	Giuseppe Cavallaro <peppe.cavallaro@st.com>
 L:	netdev@vger.kernel.org