docs: split up the driver book

We don't need to keep it as a single large file anymore; split it up so
that it is easier to manage and the individual sections can be read
directly as plain files.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst
new file mode 100644
index 0000000..b50c410
--- /dev/null
+++ b/Documentation/driver-api/index.rst
@@ -0,0 +1,24 @@
+========================================
+The Linux driver implementer's API guide
+========================================
+
+The kernel offers a wide variety of interfaces to support the development
+of device drivers.  This document is an only somewhat organized collection
+of some of those interfaces — it will hopefully get better over time!  The
+available subsections can be seen below.
+
+.. class:: toc-title
+
+	   Table of contents
+
+.. toctree::
+   :maxdepth: 2
+
+   basics
+   infrastructure
+   message-based
+   sound
+   frame-buffer
+   input
+   serial-interfaces
+   miscellaneous