[PATCH V2 4/4] rust: Integrate building of rust bindings with make

[Viresh Kumar <viresh.kumar@xxxxxxxxxx>]

Let make build rust bindings as well.

Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
 README                    |  8 +++++---
 TODO                      |  8 --------
 bindings/Makefile.am      |  6 ++++++
 bindings/rust/Makefile.am | 29 +++++++++++++++++++++++++++++
 configure.ac              | 16 ++++++++++++++++
 5 files changed, 56 insertions(+), 11 deletions(-)
 create mode 100644 bindings/rust/Makefile.am

diff --git a/README b/README
index 814a0f161fd2..68b5d69f9b66 100644
--- a/README
+++ b/README
@@ -119,9 +119,9 @@ TOOLS
 BINDINGS
 --------
 
-High-level, object-oriented bindings for C++ and python3 are provided. They
-can be enabled by passing --enable-bindings-cxx and --enable-bindings-python
-arguments respectively to configure.
+High-level, object-oriented bindings for C++, python3 and Rust are provided.
+They can be enabled by passing --enable-bindings-cxx, --enable-bindings-python
+and --enable-bindings-rust arguments respectively to configure.
 
 C++ bindings require C++11 support and autoconf-archive collection if building
 from git.
@@ -132,6 +132,8 @@ the PYTHON_CPPFLAGS and PYTHON_LIBS variables in order to point the build
 system to the correct locations. During native builds, the configure script
 can auto-detect the location of the development files.
 
+Rust bindings require cargo support.
+
 TESTING
 -------
 
diff --git a/TODO b/TODO
index 8bb4d8f3ad56..cf4fd7b4a962 100644
--- a/TODO
+++ b/TODO
@@ -28,14 +28,6 @@ and is partially functional.
 
 ----------
 
-* implement rust bindings
-
-With Rust gaining popularity as a low-level system's language and the
-possibility of it making its way into the linux kernel, it's probably time to
-provide Rust bindings to libgpiod as part of the project.
-
-----------
-
 * implement a simple daemon for controlling GPIOs in C together with a client
   program
 
diff --git a/bindings/Makefile.am b/bindings/Makefile.am
index 8f8c762f254f..004ae23dbc58 100644
--- a/bindings/Makefile.am
+++ b/bindings/Makefile.am
@@ -14,3 +14,9 @@ if WITH_BINDINGS_PYTHON
 SUBDIRS += python
 
 endif
+
+if WITH_BINDINGS_RUST
+
+SUBDIRS += rust
+
+endif
diff --git a/bindings/rust/Makefile.am b/bindings/rust/Makefile.am
new file mode 100644
index 000000000000..ac05692b966d
--- /dev/null
+++ b/bindings/rust/Makefile.am
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# SPDX-FileCopyrightText: 2021 Viresh Kumar <viresh.kumar@xxxxxxxxxx>
+
+LIBGPIOD_SRC =					\
+	Cargo.toml				\
+	build.rs				\
+	src/bindings.rs				\
+	src/chip.rs				\
+	src/edge_event.rs			\
+	src/event_buffer.rs			\
+	src/info_event.rs			\
+	src/lib.rs				\
+	src/line_config.rs			\
+	src/line_info.rs			\
+	src/line_request.rs			\
+	src/request_config.rs			\
+	examples/gpiodetect.rs			\
+	examples/gpiofind.rs			\
+	examples/gpioget.rs			\
+	examples/gpioinfo.rs			\
+	examples/gpiomon.rs			\
+	examples/gpioset.rs
+
+
+all: $(LIBGPIOD_SRC)
+	cargo build --lib --examples
+
+clean:
+	cargo clean
diff --git a/configure.ac b/configure.ac
index ce6de99c1edd..e83eca2a5e14 100644
--- a/configure.ac
+++ b/configure.ac
@@ -199,6 +199,21 @@ then
 		[AC_SUBST(PYTHON_LIBS, [`$PYTHON-config --libs`])])
 fi
 
+AC_ARG_ENABLE([bindings-rust],
+	[AS_HELP_STRING([--enable-bindings-rust],[enable rust bindings [default=no]])],
+	[if test "x$enableval" = xyes; then with_bindings_rust=true; fi],
+	[with_bindings_rust=false])
+AM_CONDITIONAL([WITH_BINDINGS_RUST], [test "x$with_bindings_rust" = xtrue])
+
+if test "x$with_bindings_rust" = xtrue
+then
+	AC_CHECK_PROG([has_cargo], [cargo], [true], [false])
+	if test "x$has_cargo" = xfalse
+	then
+		AC_MSG_ERROR([cargo not found - needed for rust bindings])
+	fi
+fi
+
 AC_CHECK_PROG([has_doxygen], [doxygen], [true], [false])
 AM_CONDITIONAL([HAS_DOXYGEN], [test "x$has_doxygen" = xtrue])
 if test "x$has_doxygen" = xfalse
@@ -232,6 +247,7 @@ AC_CONFIG_FILES([Makefile
 		 bindings/python/Makefile
 		 bindings/python/examples/Makefile
 		 bindings/python/tests/Makefile
+		 bindings/rust/Makefile
 		 man/Makefile])
 
 AC_OUTPUT
-- 
2.31.1.272.g89b43f80a514