From 032e57b4e9a90dc11352f1d6640ee246e3f32fb7 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Wed, 14 Aug 2013 01:57:02 +0200

Subject: [PATCH] backlight: add minimal tool to save/restore screen brightness

 across reboots

As many laptops don't save/restore screen brightness across reboots,

let's do this in systemd with a minimal tool, that restores the

brightness as early as possible, and saves it as late as possible. This

will cover consoles and graphical logins, but graphical desktops should

do their own per-user stuff probably.

This only touches firmware brightness controls for now.

---

 .gitignore                          |   1 +

 Makefile.am                         |  20 ++++++

 configure.ac                        |   9 +++

 rules/99-systemd.rules.in           |   4 ++

 rules/Makefile                      |   1 +

 src/backlight/Makefile              |   1 +

 src/backlight/backlight.c           | 126 ++++++++++++++++++++++++++++++++++++

 units/.gitignore                    |   1 +

 units/systemd-backlight@.service.in |  21 ++++++

 9 files changed, 184 insertions(+)

 create mode 120000 rules/Makefile

 create mode 120000 src/backlight/Makefile

 create mode 100644 src/backlight/backlight.c

 create mode 100644 units/systemd-backlight@.service.in

diff --git a/.gitignore b/.gitignore

index bdf9d4a..379a3c1 100644

--- a/.gitignore

+++ b/.gitignore

@@ -29,6 +29,7 @@

 /systemd-ac-power

 /systemd-analyze

 /systemd-ask-password

+/systemd-backlight

 /systemd-binfmt

 /systemd-bootchart

 /systemd-cat

diff --git a/Makefile.am b/Makefile.am

index 7933de6..0059b1d 100644

--- a/Makefile.am

+++ b/Makefile.am

@@ -3267,6 +3267,26 @@ EXTRA_DIST += \

 	units/systemd-random-seed.service.in

 # ------------------------------------------------------------------------------

+if ENABLE_BACKLIGHT

+rootlibexec_PROGRAMS += \

+	systemd-backlight

+

+nodist_systemunit_DATA += \

+	units/systemd-backlight@.service

+

+systemd_backlight_SOURCES = \

+	src/backlight/backlight.c

+

+systemd_backlight_LDADD = \

+	libsystemd-label.la \

+	libsystemd-shared.la \

+	libudev-private.la

+endif

+

+EXTRA_DIST += \

+	units/systemd-backlight@.service.in

+

+# ------------------------------------------------------------------------------

 if HAVE_LIBCRYPTSETUP

 rootlibexec_PROGRAMS += \

 	systemd-cryptsetup

diff --git a/configure.ac b/configure.ac

index 759073a..f7237bd 100644

--- a/configure.ac

+++ b/configure.ac

@@ -667,6 +667,14 @@ fi

 AM_CONDITIONAL(ENABLE_RANDOMSEED, [test "$have_randomseed" = "yes"])

 # ------------------------------------------------------------------------------

+have_backlight=no

+AC_ARG_ENABLE(backlight, AS_HELP_STRING([--disable-backlight], [disable backlight tools]))

+if test "x$enable_backlight" != "xno"; then

+        have_backlight=yes

+fi

+AM_CONDITIONAL(ENABLE_BACKLIGHT, [test "$have_backlight" = "yes"])

+

+# ------------------------------------------------------------------------------

 have_logind=no

 AC_ARG_ENABLE(logind, AS_HELP_STRING([--disable-logind], [disable login daemon]))

 if test "x$enable_logind" != "xno"; then

@@ -992,6 +1000,7 @@ AC_MSG_RESULT([

         quotacheck:              ${have_quotacheck}

         tmpfiles:                ${have_tmpfiles}

         randomseed:              ${have_randomseed}

+        backlight:               ${have_backlight}

         logind:                  ${have_logind}

         machined:                ${have_machined}

         hostnamed:               ${have_hostnamed}

diff --git a/rules/99-systemd.rules.in b/rules/99-systemd.rules.in

index e9b2da7..ac4bc86 100644

--- a/rules/99-systemd.rules.in

+++ b/rules/99-systemd.rules.in

@@ -51,6 +51,10 @@ SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ENV{ID_USB_INTERFACES}=="*:0701??:

 ACTION=="add", SUBSYSTEM=="net", KERNEL!="lo", RUN+="@rootlibexecdir@/systemd-sysctl --prefix=/proc/sys/net/ipv4/conf/$name --prefix=/proc/sys/net/ipv4/neigh/$name --prefix=/proc/sys/net/ipv6/conf/$name --prefix=/proc/sys/net/ipv6/neigh/$name"

+# Pull in backlight save/restore for all firmware backlight devices

+

+ACTION=="add", SUBSYSTEM=="backlight", ATTR{type}=="firmware", TAG+="systemd", ENV{SYSTEMD_WANTS}+="systemd-backlight@sys%p.service"

+

 # Asynchronously mount file systems implemented by these modules as

 # soon as they are loaded.

diff --git a/rules/Makefile b/rules/Makefile

new file mode 120000

index 0000000..bd10475

--- /dev/null

+++ b/rules/Makefile

@@ -0,0 +1 @@

+../src/Makefile

\ No newline at end of file

diff --git a/src/backlight/Makefile b/src/backlight/Makefile

new file mode 120000

index 0000000..d0b0e8e

--- /dev/null

+++ b/src/backlight/Makefile

@@ -0,0 +1 @@

+../Makefile

\ No newline at end of file

diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c

new file mode 100644

index 0000000..3378907

--- /dev/null

+++ b/src/backlight/backlight.c

@@ -0,0 +1,126 @@

+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

+

+/***

+  This file is part of systemd.

+

+  Copyright 2013 Lennart Poettering

+

+  systemd is free software; you can redistribute it and/or modify it

+  under the terms of the GNU Lesser General Public License as published by

+  the Free Software Foundation; either version 2.1 of the License, or

+  (at your option) any later version.

+

+  systemd 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

+  Lesser General Public License for more details.

+

+  You should have received a copy of the GNU Lesser General Public License

+  along with systemd; If not, see <http://www.gnu.org/licenses/>.

+***/

+

+#include <libudev.h>

+

+#include "util.h"

+#include "mkdir.h"

+#include "fileio.h"

+

+int main(int argc, char *argv[]) {

+        struct udev *udev = NULL;

+        struct udev_device *device = NULL;

+        _cleanup_free_ char *saved = NULL;

+        int r;

+

+        if (argc != 3) {

+                log_error("This program requires two arguments.");

+                return EXIT_FAILURE;

+        }

+

+        log_set_target(LOG_TARGET_AUTO);

+        log_parse_environment();

+        log_open();

+

+        umask(0022);

+

+        r = mkdir_p("/var/lib/backlight", 0755);

+        if (r < 0) {

+                log_error("Failed to create backlight directory: %s", strerror(-r));

+                goto finish;

+        }

+

+        udev = udev_new();

+        if (!udev) {

+                r = log_oom();

+                goto finish;

+        }

+

+        device = udev_device_new_from_syspath(udev, argv[2]);

+        if (!device) {

+                r = log_oom();

+                goto finish;

+        }

+

+        if (!streq_ptr(udev_device_get_subsystem(device), "backlight")) {

+                log_error("Not a backlight device: %s", argv[2]);

+                r = -ENODEV;

+                goto finish;

+        }

+

+        saved = strappend("/var/lib/backlight/", udev_device_get_sysname(device));

+        if (!saved) {

+                r = log_oom();

+                goto finish;

+        }

+

+        if (streq(argv[1], "load")) {

+                _cleanup_free_ char *value = NULL;

+

+                r = read_one_line_file(saved, &value);

+                if (r < 0) {

+

+                        if (r == -ENOENT) {

+                                r = 0;

+                                goto finish;

+                        }

+

+                        log_error("Failed to read %s: %s", saved, strerror(-r));

+                        goto finish;

+                }

+

+                r = udev_device_set_sysattr_value(device, "brightness", value);

+                if (r < 0) {

+                        log_error("Failed to write system attribute: %s", strerror(-r));

+                        goto finish;

+                }

+

+        } else if (streq(argv[1], "save")) {

+                const char *value;

+

+                value = udev_device_get_sysattr_value(device, "brightness");

+                if (!value) {

+                        log_error("Failed to read system attribute: %s", strerror(-r));

+                        goto finish;

+                }

+

+                r = write_string_file(saved, value);

+                if (r < 0) {

+                        log_error("Failed to write %s: %s", saved, strerror(-r));

+                        goto finish;

+                }

+

+        } else {

+                log_error("Unknown verb %s.", argv[1]);

+                r = -EINVAL;

+                goto finish;

+        }

+

+finish:

+        if (device)

+                udev_device_unref(device);

+

+        if (udev)

+                udev_unref(udev);

+

+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;

+

+}

diff --git a/units/.gitignore b/units/.gitignore

index 9aee00f..9c65075 100644

--- a/units/.gitignore

+++ b/units/.gitignore

@@ -1,3 +1,4 @@

+/systemd-backlight@.service

 /halt-local.service

 /rc-local.service

 /systemd-hybrid-sleep.service

diff --git a/units/systemd-backlight@.service.in b/units/systemd-backlight@.service.in

new file mode 100644

index 0000000..14b1219

--- /dev/null

+++ b/units/systemd-backlight@.service.in

@@ -0,0 +1,21 @@

+#  This file is part of systemd.

+#

+#  systemd is free software; you can redistribute it and/or modify it

+#  under the terms of the GNU Lesser General Public License as published by

+#  the Free Software Foundation; either version 2.1 of the License, or

+#  (at your option) any later version.

+

+[Unit]

+Description=Load/Save Screen Backlight Brightness of %f

+Documentation=man:systemd-backlight@.service(8)

+DefaultDependencies=no

+RequiresMountsFor=/var/lib/backlight

+Conflicts=shutdown.target

+After=systemd-readahead-collect.service systemd-readahead-replay.service systemd-remount-fs.service

+Before=sysinit.target shutdown.target

+

+[Service]

+Type=oneshot

+RemainAfterExit=yes

+ExecStart=@rootlibexecdir@/systemd-backlight load %f

+ExecStop=@rootlibexecdir@/systemd-backlight save %f