Documentation/cxl: add library API documentation

Add library API documentation for libcxl(3) using the existing
asciidoc(tor) build system. Add a section 3 man page for 'libcxl' that
provides an overview of the library and its usage, and a man page for
the 'cxl_new()' API.

Cc: Ben Widawsky <ben.widawsky@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

6 files changed, 162 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 6a97b92c..6468c7a9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,12 +14,15 @@ Makefile.in
 /libtool
 /stamp-h1
 *.1
+*.3
 Documentation/daxctl/asciidoc.conf
 Documentation/ndctl/asciidoc.conf
 Documentation/cxl/asciidoc.conf
+Documentation/cxl/lib/asciidoc.conf
 Documentation/daxctl/asciidoctor-extensions.rb
 Documentation/ndctl/asciidoctor-extensions.rb
 Documentation/cxl/asciidoctor-extensions.rb
+Documentation/cxl/lib/asciidoctor-extensions.rb
 Documentation/ndctl/attrs.adoc
 .dirstamp
 daxctl/config.h
diff --git a/Documentation/cxl/lib/Makefile.am b/Documentation/cxl/lib/Makefile.am
new file mode 100644
index 00000000..41e3a5fc
--- /dev/null
+++ b/Documentation/cxl/lib/Makefile.am
@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020-2021 Intel Corporation. All rights reserved.
+
+if USE_ASCIIDOCTOR
+
+do_subst = sed -e 's,@Utility@,Libcxl,g' -e's,@utility@,libcxl,g'
+CONFFILE = asciidoctor-extensions.rb
+asciidoctor-extensions.rb: ../../asciidoctor-extensions.rb.in
+	$(AM_V_GEN) $(do_subst) < $< > $@
+
+else
+
+do_subst = sed -e 's,UTILITY,libcxl,g'
+CONFFILE = asciidoc.conf
+asciidoc.conf: ../../asciidoc.conf.in
+	$(AM_V_GEN) $(do_subst) < $< > $@
+
+endif
+
+man3_MANS = \
+	libcxl.3 \
+	cxl_new.3
+
+EXTRA_DIST = $(man3_MANS)
+
+CLEANFILES = $(man3_MANS)
+
+XML_DEPS = \
+	../../../version.m4 \
+	../../copyright.txt \
+	Makefile \
+	$(CONFFILE)
+
+RM ?= rm -f
+
+if USE_ASCIIDOCTOR
+
+%.3: %.txt $(XML_DEPS)
+	$(AM_V_GEN)$(RM) $@+ $@ && \
+		$(ASCIIDOC) -b manpage -d manpage -acompat-mode \
+		-I. -rasciidoctor-extensions \
+		-amansource=libcxl -amanmanual="libcxl Manual" \
+		-andctl_version=$(VERSION) -o $@+ $< && \
+		mv $@+ $@
+
+else
+
+%.xml: %.txt $(XML_DEPS)
+	$(AM_V_GEN)$(RM) $@+ $@ && \
+		$(ASCIIDOC) -b docbook -d manpage -f asciidoc.conf \
+		--unsafe -alibcxl_version=$(VERSION) -o $@+ $< && \
+		mv $@+ $@
+
+%.3: %.xml $(XML_DEPS)
+	$(AM_V_GEN)$(RM) $@ && \
+		$(XMLTO) -o . -m ../../manpage-normal.xsl man $<
+
+endif
diff --git a/Documentation/cxl/lib/cxl_new.txt b/Documentation/cxl/lib/cxl_new.txt
new file mode 100644
index 00000000..147d4e04
--- /dev/null
+++ b/Documentation/cxl/lib/cxl_new.txt
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: LGPL-2.0
+
+cxl_new(3)
+==========
+
+NAME
+----
+cxl_new - Create a new library context object that acts as a handle for all
+library operations
+
+SYNOPSIS
+--------
+[verse]
+----
+#include <cxl/libcxl.h>
+
+int cxl_new(struct cxl_ctx **ctx);
+----
+
+DESCRIPTION
+-----------
+Instantiates a new library context, and stores an opaque pointer in ctx. The
+context is freed by linklibcxl:cxl_unref[3], i.e. cxl_new(3) implies an
+internal linklibcxl:cxl_ref[3].
+
+
+RETURN VALUE
+------------
+Returns 0 on success, and a negative errno on failure.
+Possible error codes are:
+
+ * -ENOMEM
+ * -ENXIO
+
+EXAMPLE
+-------
+See example usage in test/libcxl.c
+
+include::../../copyright.txt[]
+
+SEE ALSO
+--------
+linklibcxl:cxl_ref[3], linklibcxl:cxl_unref[3]
diff --git a/Documentation/cxl/lib/libcxl.txt b/Documentation/cxl/lib/libcxl.txt
new file mode 100644
index 00000000..2539369e
--- /dev/null
+++ b/Documentation/cxl/lib/libcxl.txt
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: LGPL-2.0
+
+libcxl(3)
+=========
+
+NAME
+----
+libcxl - A library to interact with CXL devices through sysfs(5)
+and ioctl(2) interfaces
+
+SYNOPSIS
+--------
+[verse]
+#include <cxl/libcxl.h>
+cc ... -lcxl
+
+DESCRIPTION
+-----------
+libcxl provides interfaces to interact with CXL devices in Linux, using sysfs
+interfaces for most kernel interactions, and the ioctl() interface for command
+submission.
+
+The starting point for all library interfaces is a 'cxl_ctx' object, returned
+by linklibcxl:cxl_new[3]. CXL 'Type 3' memory devices are children of the
+cxl_ctx object, and can be iterated through using an iterator API.
+
+Library level interfaces that are agnostic to any device, or a specific
+subclass of operations have the prefix 'cxl_'
+
+The object representing a CXL Type 3 device is 'cxl_memdev'. Library interfaces
+related to these devices have the prefix 'cxl_memdev_'. These interfaces are
+mostly associated with sysfs interactions (unless otherwise noted in their
+respective documentation pages). They are typically used to retrieve data
+published by the kernel, or to send data or trigger kernel operations for a
+given device.
+
+A 'cxl_cmd' is a reference counted object which is used to perform 'Mailbox'
+commands as described in the CXL Specification. A 'cxl_cmd' object is tied to a
+'cxl_memdev'. Associated library interfaces have the prefix 'cxl_cmd_'. Within
+this sub-class of interfaces, there are:
+
+ * 'cxl_cmd_new_*' interfaces that allocate a new cxl_cmd object for a given
+   command type.
+
+ * 'cxl_cmd_submit' which submits the command via ioctl()
+
+ * 'cxl_cmd_<name>_get_<field>' interfaces that get specific fields out of the
+   command response
+
+ * 'cxl_cmd_get_*' interfaces to get general command related information.
+
+include::../../copyright.txt[]
+
+SEE ALSO
+--------
+linklibcxl:cxl[1]
diff --git a/Makefile.am b/Makefile.am
index 4904ee78..e2f6befb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -4,6 +4,7 @@ ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
 SUBDIRS = . cxl/lib daxctl/lib ndctl/lib cxl ndctl daxctl
 if ENABLE_DOCS
 SUBDIRS += Documentation/ndctl Documentation/daxctl Documentation/cxl
+SUBDIRS += Documentation/cxl/lib
 endif
 SUBDIRS += test
 
diff --git a/configure.ac b/configure.ac
index dadae0a6..00497aeb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -231,6 +231,7 @@ AC_CONFIG_FILES([
         Documentation/ndctl/Makefile
         Documentation/daxctl/Makefile
         Documentation/cxl/Makefile
+        Documentation/cxl/lib/Makefile
 ])
 
 AC_OUTPUT