gnu: Add ddcutil.

* gnu/packages/hardware.scm: New file.
(ddcutil): New public variable.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add the new file.

gnu/local.mk

@@ -213,6 +213,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/packages/guile-wm.scm			\
   %D%/packages/gv.scm				\
   %D%/packages/gxmessage.scm			\
+  %D%/packages/hardware.scm			\
   %D%/packages/haskell.scm			\
   %D%/packages/haskell-check.scm		\
   %D%/packages/haskell-crypto.scm		\

gnu/packages/hardware.scm

@@ -0,0 +1,75 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Tobias Geerinckx-Rice <me@tobias.gr>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu packages hardware)
+  #:use-module (gnu packages compression)
+  #:use-module (gnu packages glib)
+  #:use-module (gnu packages libusb)
+  #:use-module (gnu packages linux)
+  #:use-module (gnu packages pkg-config)
+  #:use-module (gnu packages xdisorg)
+  #:use-module (gnu packages xorg)
+  #:use-module (guix build-system gnu)
+  #:use-module (guix download)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:use-module (guix packages))
+
+;; This is a module for packages related to physical hardware that don't (yet)
+;; have a more specific home like gps.scm, security-token.scm, &c.
+
+(define-public ddcutil
+  (package
+    (name "ddcutil")
+    (version "0.9.1")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append "https://www.ddcutil.com/tarballs/"
+                           name "-" version ".tar.gz"))
+       (sha256
+        (base32 "1b4bm3zhk5vnad6fxf0mn8nrlj3fngifl7nzxgxw0n56hlv7ccv0"))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("pkg-config" ,pkg-config)))
+    (inputs
+     `(("eudev" ,eudev)
+       ("glib" ,glib)
+       ("libdrm" ,libdrm)               ; enhanced diagnostics
+       ("libusb" ,libusb)               ; support USB monitors
+       ("libx11" ,libx11)               ; enhanced diagnostics
+       ("libxrandr" ,libxrandr)
+       ("zlib" ,zlib)))
+    (home-page "https://www.ddcutil.com/")
+    (synopsis "Control external monitor settings")
+    (description
+     "ddcutil can query and modify most external monitors' settings, such as
+brightness, colour levels, and input sources.  Generally speaking, any setting
+that can be changed by pressing buttons on the monitor can be modified by
+ddcutil.
+
+ddcutil communicates directly with monitors implementing the Monitor Control
+Command Set (@dfn{MCCS}).  It usually does so through the the Display Data
+Channel Command Interface (@dfn{DDC/CI}) protocol on the I2C bus, but can also
+communicate over USB as per the USB Monitor Control Class Specification.
+
+One particular use case is in colour profile management.  Monitor calibration
+is relative to the monitor colour settings currently in effect, e.g. red gain.
+ddcutil allows colour-related settings to be saved at the time a monitor is
+calibrated, and restored when the calibration is applied.")
+    (license (list license:bsd-3        ; FindDDCUtil.cmake
+                   license:gpl2+))))    ; everything else