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Diffstat (limited to 'src/grp-initprogs/systemd-backlight/backlight.c')
-rw-r--r--src/grp-initprogs/systemd-backlight/backlight.c434
1 files changed, 434 insertions, 0 deletions
diff --git a/src/grp-initprogs/systemd-backlight/backlight.c b/src/grp-initprogs/systemd-backlight/backlight.c
new file mode 100644
index 0000000000..f5b80c395e
--- /dev/null
+++ b/src/grp-initprogs/systemd-backlight/backlight.c
@@ -0,0 +1,434 @@
+/***
+ 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 "systemd-basic/alloc-util.h"
+#include "systemd-basic/def.h"
+#include "systemd-basic/escape.h"
+#include "systemd-basic/fileio.h"
+#include "systemd-basic/mkdir.h"
+#include "systemd-basic/parse-util.h"
+#include "systemd-basic/proc-cmdline.h"
+#include "systemd-basic/string-util.h"
+#include "systemd-basic/util.h"
+#include "systemd-shared/udev-util.h"
+
+static struct udev_device *find_pci_or_platform_parent(struct udev_device *device) {
+ struct udev_device *parent;
+ const char *subsystem, *sysname;
+
+ assert(device);
+
+ parent = udev_device_get_parent(device);
+ if (!parent)
+ return NULL;
+
+ subsystem = udev_device_get_subsystem(parent);
+ if (!subsystem)
+ return NULL;
+
+ sysname = udev_device_get_sysname(parent);
+ if (!sysname)
+ return NULL;
+
+ if (streq(subsystem, "drm")) {
+ const char *c;
+
+ c = startswith(sysname, "card");
+ if (!c)
+ return NULL;
+
+ c += strspn(c, DIGITS);
+ if (*c == '-') {
+ /* A connector DRM device, let's ignore all but LVDS and eDP! */
+
+ if (!startswith(c, "-LVDS-") &&
+ !startswith(c, "-Embedded DisplayPort-"))
+ return NULL;
+ }
+
+ } else if (streq(subsystem, "pci")) {
+ const char *value;
+
+ value = udev_device_get_sysattr_value(parent, "class");
+ if (value) {
+ unsigned long class = 0;
+
+ if (safe_atolu(value, &class) < 0) {
+ log_warning("Cannot parse PCI class %s of device %s:%s.",
+ value, subsystem, sysname);
+ return NULL;
+ }
+
+ /* Graphics card */
+ if (class == 0x30000)
+ return parent;
+ }
+
+ } else if (streq(subsystem, "platform"))
+ return parent;
+
+ return find_pci_or_platform_parent(parent);
+}
+
+static bool same_device(struct udev_device *a, struct udev_device *b) {
+ assert(a);
+ assert(b);
+
+ if (!streq_ptr(udev_device_get_subsystem(a), udev_device_get_subsystem(b)))
+ return false;
+
+ if (!streq_ptr(udev_device_get_sysname(a), udev_device_get_sysname(b)))
+ return false;
+
+ return true;
+}
+
+static bool validate_device(struct udev *udev, struct udev_device *device) {
+ _cleanup_udev_enumerate_unref_ struct udev_enumerate *enumerate = NULL;
+ struct udev_list_entry *item = NULL, *first = NULL;
+ struct udev_device *parent;
+ const char *v, *subsystem;
+ int r;
+
+ assert(udev);
+ assert(device);
+
+ /* Verify whether we should actually care for a specific
+ * backlight device. For backlight devices there might be
+ * multiple ways to access the same control: "firmware"
+ * (i.e. ACPI), "platform" (i.e. via the machine's EC) and
+ * "raw" (via the graphics card). In general we should prefer
+ * "firmware" (i.e. ACPI) or "platform" access over "raw"
+ * access, in order not to confuse the BIOS/EC, and
+ * compatibility with possible low-level hotkey handling of
+ * screen brightness. The kernel will already make sure to
+ * expose only one of "firmware" and "platform" for the same
+ * device to userspace. However, we still need to make sure
+ * that we use "raw" only if no "firmware" or "platform"
+ * device for the same device exists. */
+
+ subsystem = udev_device_get_subsystem(device);
+ if (!streq_ptr(subsystem, "backlight"))
+ return true;
+
+ v = udev_device_get_sysattr_value(device, "type");
+ if (!streq_ptr(v, "raw"))
+ return true;
+
+ parent = find_pci_or_platform_parent(device);
+ if (!parent)
+ return true;
+
+ subsystem = udev_device_get_subsystem(parent);
+ if (!subsystem)
+ return true;
+
+ enumerate = udev_enumerate_new(udev);
+ if (!enumerate)
+ return true;
+
+ r = udev_enumerate_add_match_subsystem(enumerate, "backlight");
+ if (r < 0)
+ return true;
+
+ r = udev_enumerate_scan_devices(enumerate);
+ if (r < 0)
+ return true;
+
+ first = udev_enumerate_get_list_entry(enumerate);
+ udev_list_entry_foreach(item, first) {
+ _cleanup_udev_device_unref_ struct udev_device *other;
+ struct udev_device *other_parent;
+ const char *other_subsystem;
+
+ other = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
+ if (!other)
+ return true;
+
+ if (same_device(device, other))
+ continue;
+
+ v = udev_device_get_sysattr_value(other, "type");
+ if (!STRPTR_IN_SET(v, "platform", "firmware"))
+ continue;
+
+ /* OK, so there's another backlight device, and it's a
+ * platform or firmware device, so, let's see if we
+ * can verify it belongs to the same device as
+ * ours. */
+ other_parent = find_pci_or_platform_parent(other);
+ if (!other_parent)
+ continue;
+
+ if (same_device(parent, other_parent)) {
+ /* Both have the same PCI parent, that means
+ * we are out. */
+ log_debug("Skipping backlight device %s, since device %s is on same PCI device and takes precedence.",
+ udev_device_get_sysname(device),
+ udev_device_get_sysname(other));
+ return false;
+ }
+
+ other_subsystem = udev_device_get_subsystem(other_parent);
+ if (streq_ptr(other_subsystem, "platform") && streq_ptr(subsystem, "pci")) {
+ /* The other is connected to the platform bus
+ * and we are a PCI device, that also means we
+ * are out. */
+ log_debug("Skipping backlight device %s, since device %s is a platform device and takes precedence.",
+ udev_device_get_sysname(device),
+ udev_device_get_sysname(other));
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static unsigned get_max_brightness(struct udev_device *device) {
+ int r;
+ const char *max_brightness_str;
+ unsigned max_brightness;
+
+ max_brightness_str = udev_device_get_sysattr_value(device, "max_brightness");
+ if (!max_brightness_str) {
+ log_warning("Failed to read 'max_brightness' attribute.");
+ return 0;
+ }
+
+ r = safe_atou(max_brightness_str, &max_brightness);
+ if (r < 0) {
+ log_warning_errno(r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str);
+ return 0;
+ }
+
+ if (max_brightness <= 0) {
+ log_warning("Maximum brightness is 0, ignoring device.");
+ return 0;
+ }
+
+ return max_brightness;
+}
+
+/* Some systems turn the backlight all the way off at the lowest levels.
+ * clamp_brightness clamps the saved brightness to at least 1 or 5% of
+ * max_brightness in case of 'backlight' subsystem. This avoids preserving
+ * an unreadably dim screen, which would otherwise force the user to
+ * disable state restoration. */
+static void clamp_brightness(struct udev_device *device, char **value, unsigned max_brightness) {
+ int r;
+ unsigned brightness, new_brightness, min_brightness;
+ const char *subsystem;
+
+ r = safe_atou(*value, &brightness);
+ if (r < 0) {
+ log_warning_errno(r, "Failed to parse brightness \"%s\": %m", *value);
+ return;
+ }
+
+ subsystem = udev_device_get_subsystem(device);
+ if (streq_ptr(subsystem, "backlight"))
+ min_brightness = MAX(1U, max_brightness/20);
+ else
+ min_brightness = 0;
+
+ new_brightness = CLAMP(brightness, min_brightness, max_brightness);
+ if (new_brightness != brightness) {
+ char *old_value = *value;
+
+ r = asprintf(value, "%u", new_brightness);
+ if (r < 0) {
+ log_oom();
+ return;
+ }
+
+ log_info("Saved brightness %s %s to %s.", old_value,
+ new_brightness > brightness ?
+ "too low; increasing" : "too high; decreasing",
+ *value);
+
+ free(old_value);
+ }
+}
+
+int main(int argc, char *argv[]) {
+ _cleanup_udev_unref_ struct udev *udev = NULL;
+ _cleanup_udev_device_unref_ struct udev_device *device = NULL;
+ _cleanup_free_ char *saved = NULL, *ss = NULL, *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL;
+ const char *sysname, *path_id;
+ unsigned max_brightness;
+ 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/systemd/backlight", 0755);
+ if (r < 0) {
+ log_error_errno(r, "Failed to create backlight directory /var/lib/systemd/backlight: %m");
+ return EXIT_FAILURE;
+ }
+
+ udev = udev_new();
+ if (!udev) {
+ log_oom();
+ return EXIT_FAILURE;
+ }
+
+ sysname = strchr(argv[2], ':');
+ if (!sysname) {
+ log_error("Requires a subsystem and sysname pair specifying a backlight device.");
+ return EXIT_FAILURE;
+ }
+
+ ss = strndup(argv[2], sysname - argv[2]);
+ if (!ss) {
+ log_oom();
+ return EXIT_FAILURE;
+ }
+
+ sysname++;
+
+ if (!streq(ss, "backlight") && !streq(ss, "leds")) {
+ log_error("Not a backlight or LED device: '%s:%s'", ss, sysname);
+ return EXIT_FAILURE;
+ }
+
+ errno = 0;
+ device = udev_device_new_from_subsystem_sysname(udev, ss, sysname);
+ if (!device) {
+ if (errno > 0)
+ log_error_errno(errno, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname);
+ else
+ log_oom();
+
+ return EXIT_FAILURE;
+ }
+
+ /* If max_brightness is 0, then there is no actual backlight
+ * device. This happens on desktops with Asus mainboards
+ * that load the eeepc-wmi module.
+ */
+ max_brightness = get_max_brightness(device);
+ if (max_brightness == 0)
+ return EXIT_SUCCESS;
+
+ escaped_ss = cescape(ss);
+ if (!escaped_ss) {
+ log_oom();
+ return EXIT_FAILURE;
+ }
+
+ escaped_sysname = cescape(sysname);
+ if (!escaped_sysname) {
+ log_oom();
+ return EXIT_FAILURE;
+ }
+
+ path_id = udev_device_get_property_value(device, "ID_PATH");
+ if (path_id) {
+ escaped_path_id = cescape(path_id);
+ if (!escaped_path_id) {
+ log_oom();
+ return EXIT_FAILURE;
+ }
+
+ saved = strjoin("/var/lib/systemd/backlight/", escaped_path_id, ":", escaped_ss, ":", escaped_sysname, NULL);
+ } else
+ saved = strjoin("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname, NULL);
+
+ if (!saved) {
+ log_oom();
+ return EXIT_FAILURE;
+ }
+
+ /* If there are multiple conflicting backlight devices, then
+ * their probing at boot-time might happen in any order. This
+ * means the validity checking of the device then is not
+ * reliable, since it might not see other devices conflicting
+ * with a specific backlight. To deal with this, we will
+ * actively delete backlight state files at shutdown (where
+ * device probing should be complete), so that the validity
+ * check at boot time doesn't have to be reliable. */
+
+ if (streq(argv[1], "load")) {
+ _cleanup_free_ char *value = NULL;
+ const char *clamp;
+
+ if (shall_restore_state() == 0)
+ return EXIT_SUCCESS;
+
+ if (!validate_device(udev, device))
+ return EXIT_SUCCESS;
+
+ r = read_one_line_file(saved, &value);
+ if (r < 0) {
+
+ if (r == -ENOENT)
+ return EXIT_SUCCESS;
+
+ log_error_errno(r, "Failed to read %s: %m", saved);
+ return EXIT_FAILURE;
+ }
+
+ clamp = udev_device_get_property_value(device, "ID_BACKLIGHT_CLAMP");
+ if (!clamp || parse_boolean(clamp) != 0) /* default to clamping */
+ clamp_brightness(device, &value, max_brightness);
+
+ r = udev_device_set_sysattr_value(device, "brightness", value);
+ if (r < 0) {
+ log_error_errno(r, "Failed to write system 'brightness' attribute: %m");
+ return EXIT_FAILURE;
+ }
+
+ } else if (streq(argv[1], "save")) {
+ const char *value;
+
+ if (!validate_device(udev, device)) {
+ unlink(saved);
+ return EXIT_SUCCESS;
+ }
+
+ value = udev_device_get_sysattr_value(device, "brightness");
+ if (!value) {
+ log_error("Failed to read system 'brightness' attribute");
+ return EXIT_FAILURE;
+ }
+
+ r = write_string_file(saved, value, WRITE_STRING_FILE_CREATE);
+ if (r < 0) {
+ log_error_errno(r, "Failed to write %s: %m", saved);
+ return EXIT_FAILURE;
+ }
+
+ } else {
+ log_error("Unknown verb %s.", argv[1]);
+ return EXIT_FAILURE;
+ }
+
+ return EXIT_SUCCESS;
+}
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