435 lines
15 KiB
C
435 lines
15 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2013 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "libudev.h"
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#include "def.h"
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#include "escape.h"
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#include "fileio.h"
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#include "mkdir.h"
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#include "string-util.h"
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#include "udev-util.h"
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#include "util.h"
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#include "parse-util.h"
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static struct udev_device *find_pci_or_platform_parent(struct udev_device *device) {
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struct udev_device *parent;
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const char *subsystem, *sysname;
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assert(device);
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parent = udev_device_get_parent(device);
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if (!parent)
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return NULL;
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subsystem = udev_device_get_subsystem(parent);
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if (!subsystem)
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return NULL;
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sysname = udev_device_get_sysname(parent);
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if (!sysname)
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return NULL;
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if (streq(subsystem, "drm")) {
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const char *c;
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c = startswith(sysname, "card");
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if (!c)
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return NULL;
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c += strspn(c, DIGITS);
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if (*c == '-') {
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/* A connector DRM device, let's ignore all but LVDS and eDP! */
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if (!startswith(c, "-LVDS-") &&
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!startswith(c, "-Embedded DisplayPort-"))
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return NULL;
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}
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} else if (streq(subsystem, "pci")) {
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const char *value;
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value = udev_device_get_sysattr_value(parent, "class");
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if (value) {
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unsigned long class = 0;
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if (safe_atolu(value, &class) < 0) {
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log_warning("Cannot parse PCI class %s of device %s:%s.",
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value, subsystem, sysname);
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return NULL;
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}
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/* Graphics card */
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if (class == 0x30000)
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return parent;
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}
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} else if (streq(subsystem, "platform"))
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return parent;
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return find_pci_or_platform_parent(parent);
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}
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static bool same_device(struct udev_device *a, struct udev_device *b) {
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assert(a);
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assert(b);
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if (!streq_ptr(udev_device_get_subsystem(a), udev_device_get_subsystem(b)))
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return false;
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if (!streq_ptr(udev_device_get_sysname(a), udev_device_get_sysname(b)))
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return false;
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return true;
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}
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static bool validate_device(struct udev *udev, struct udev_device *device) {
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_cleanup_udev_enumerate_unref_ struct udev_enumerate *enumerate = NULL;
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struct udev_list_entry *item = NULL, *first = NULL;
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struct udev_device *parent;
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const char *v, *subsystem;
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int r;
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assert(udev);
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assert(device);
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/* Verify whether we should actually care for a specific
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* backlight device. For backlight devices there might be
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* multiple ways to access the same control: "firmware"
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* (i.e. ACPI), "platform" (i.e. via the machine's EC) and
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* "raw" (via the graphics card). In general we should prefer
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* "firmware" (i.e. ACPI) or "platform" access over "raw"
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* access, in order not to confuse the BIOS/EC, and
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* compatibility with possible low-level hotkey handling of
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* screen brightness. The kernel will already make sure to
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* expose only one of "firmware" and "platform" for the same
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* device to userspace. However, we still need to make sure
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* that we use "raw" only if no "firmware" or "platform"
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* device for the same device exists. */
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subsystem = udev_device_get_subsystem(device);
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if (!streq_ptr(subsystem, "backlight"))
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return true;
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v = udev_device_get_sysattr_value(device, "type");
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if (!streq_ptr(v, "raw"))
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return true;
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parent = find_pci_or_platform_parent(device);
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if (!parent)
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return true;
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subsystem = udev_device_get_subsystem(parent);
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if (!subsystem)
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return true;
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enumerate = udev_enumerate_new(udev);
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if (!enumerate)
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return true;
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r = udev_enumerate_add_match_subsystem(enumerate, "backlight");
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if (r < 0)
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return true;
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r = udev_enumerate_scan_devices(enumerate);
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if (r < 0)
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return true;
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first = udev_enumerate_get_list_entry(enumerate);
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udev_list_entry_foreach(item, first) {
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_cleanup_udev_device_unref_ struct udev_device *other;
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struct udev_device *other_parent;
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const char *other_subsystem;
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other = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
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if (!other)
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return true;
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if (same_device(device, other))
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continue;
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v = udev_device_get_sysattr_value(other, "type");
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if (!streq_ptr(v, "platform") && !streq_ptr(v, "firmware"))
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continue;
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/* OK, so there's another backlight device, and it's a
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* platform or firmware device, so, let's see if we
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* can verify it belongs to the same device as
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* ours. */
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other_parent = find_pci_or_platform_parent(other);
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if (!other_parent)
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continue;
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if (same_device(parent, other_parent)) {
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/* Both have the same PCI parent, that means
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* we are out. */
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log_debug("Skipping backlight device %s, since device %s is on same PCI device and takes precedence.",
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udev_device_get_sysname(device),
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udev_device_get_sysname(other));
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return false;
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}
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other_subsystem = udev_device_get_subsystem(other_parent);
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if (streq_ptr(other_subsystem, "platform") && streq_ptr(subsystem, "pci")) {
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/* The other is connected to the platform bus
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* and we are a PCI device, that also means we
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* are out. */
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log_debug("Skipping backlight device %s, since device %s is a platform device and takes precedence.",
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udev_device_get_sysname(device),
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udev_device_get_sysname(other));
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return false;
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}
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}
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return true;
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}
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static unsigned get_max_brightness(struct udev_device *device) {
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int r;
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const char *max_brightness_str;
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unsigned max_brightness;
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max_brightness_str = udev_device_get_sysattr_value(device, "max_brightness");
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if (!max_brightness_str) {
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log_warning("Failed to read 'max_brightness' attribute.");
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return 0;
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}
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r = safe_atou(max_brightness_str, &max_brightness);
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if (r < 0) {
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log_warning_errno(r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str);
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return 0;
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}
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if (max_brightness <= 0) {
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log_warning("Maximum brightness is 0, ignoring device.");
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return 0;
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}
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return max_brightness;
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}
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/* Some systems turn the backlight all the way off at the lowest levels.
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* clamp_brightness clamps the saved brightness to at least 1 or 5% of
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* max_brightness in case of 'backlight' subsystem. This avoids preserving
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* an unreadably dim screen, which would otherwise force the user to
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* disable state restoration. */
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static void clamp_brightness(struct udev_device *device, char **value, unsigned max_brightness) {
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int r;
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unsigned brightness, new_brightness, min_brightness;
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const char *subsystem;
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r = safe_atou(*value, &brightness);
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if (r < 0) {
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log_warning_errno(r, "Failed to parse brightness \"%s\": %m", *value);
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return;
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}
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subsystem = udev_device_get_subsystem(device);
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if (streq_ptr(subsystem, "backlight"))
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min_brightness = MAX(1U, max_brightness/20);
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else
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min_brightness = 0;
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new_brightness = CLAMP(brightness, min_brightness, max_brightness);
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if (new_brightness != brightness) {
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char *old_value = *value;
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r = asprintf(value, "%u", new_brightness);
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if (r < 0) {
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log_oom();
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return;
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}
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log_info("Saved brightness %s %s to %s.", old_value,
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new_brightness > brightness ?
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"too low; increasing" : "too high; decreasing",
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*value);
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free(old_value);
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}
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}
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int main(int argc, char *argv[]) {
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_cleanup_udev_unref_ struct udev *udev = NULL;
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_cleanup_udev_device_unref_ struct udev_device *device = NULL;
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_cleanup_free_ char *saved = NULL, *ss = NULL, *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL;
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const char *sysname, *path_id;
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unsigned max_brightness;
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int r;
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if (argc != 3) {
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log_error("This program requires two arguments.");
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return EXIT_FAILURE;
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}
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log_set_target(LOG_TARGET_AUTO);
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log_parse_environment();
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log_open();
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umask(0022);
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r = mkdir_p("/var/lib/systemd/backlight", 0755);
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if (r < 0) {
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log_error_errno(r, "Failed to create backlight directory /var/lib/systemd/backlight: %m");
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return EXIT_FAILURE;
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}
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udev = udev_new();
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if (!udev) {
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log_oom();
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return EXIT_FAILURE;
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}
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sysname = strchr(argv[2], ':');
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if (!sysname) {
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log_error("Requires a subsystem and sysname pair specifying a backlight device.");
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return EXIT_FAILURE;
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}
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ss = strndup(argv[2], sysname - argv[2]);
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if (!ss) {
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log_oom();
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return EXIT_FAILURE;
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}
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sysname++;
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if (!streq(ss, "backlight") && !streq(ss, "leds")) {
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log_error("Not a backlight or LED device: '%s:%s'", ss, sysname);
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return EXIT_FAILURE;
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}
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errno = 0;
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device = udev_device_new_from_subsystem_sysname(udev, ss, sysname);
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if (!device) {
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if (errno != 0)
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log_error_errno(errno, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname);
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else
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log_oom();
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return EXIT_FAILURE;
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}
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/* If max_brightness is 0, then there is no actual backlight
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* device. This happens on desktops with Asus mainboards
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* that load the eeepc-wmi module.
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*/
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max_brightness = get_max_brightness(device);
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if (max_brightness == 0)
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return EXIT_SUCCESS;
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escaped_ss = cescape(ss);
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if (!escaped_ss) {
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log_oom();
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return EXIT_FAILURE;
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}
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escaped_sysname = cescape(sysname);
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if (!escaped_sysname) {
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log_oom();
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return EXIT_FAILURE;
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}
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path_id = udev_device_get_property_value(device, "ID_PATH");
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if (path_id) {
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escaped_path_id = cescape(path_id);
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if (!escaped_path_id) {
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log_oom();
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return EXIT_FAILURE;
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}
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saved = strjoin("/var/lib/systemd/backlight/", escaped_path_id, ":", escaped_ss, ":", escaped_sysname, NULL);
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} else
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saved = strjoin("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname, NULL);
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if (!saved) {
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log_oom();
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return EXIT_FAILURE;
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}
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/* If there are multiple conflicting backlight devices, then
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* their probing at boot-time might happen in any order. This
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* means the validity checking of the device then is not
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* reliable, since it might not see other devices conflicting
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* with a specific backlight. To deal with this, we will
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* actively delete backlight state files at shutdown (where
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* device probing should be complete), so that the validity
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* check at boot time doesn't have to be reliable. */
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if (streq(argv[1], "load")) {
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_cleanup_free_ char *value = NULL;
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const char *clamp;
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if (!shall_restore_state())
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return EXIT_SUCCESS;
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if (!validate_device(udev, device))
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return EXIT_SUCCESS;
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r = read_one_line_file(saved, &value);
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if (r < 0) {
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if (r == -ENOENT)
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return EXIT_SUCCESS;
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log_error_errno(r, "Failed to read %s: %m", saved);
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return EXIT_FAILURE;
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}
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clamp = udev_device_get_property_value(device, "ID_BACKLIGHT_CLAMP");
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if (!clamp || parse_boolean(clamp) != 0) /* default to clamping */
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clamp_brightness(device, &value, max_brightness);
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r = udev_device_set_sysattr_value(device, "brightness", value);
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if (r < 0) {
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log_error_errno(r, "Failed to write system 'brightness' attribute: %m");
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return EXIT_FAILURE;
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}
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} else if (streq(argv[1], "save")) {
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const char *value;
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if (!validate_device(udev, device)) {
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unlink(saved);
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return EXIT_SUCCESS;
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}
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value = udev_device_get_sysattr_value(device, "brightness");
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if (!value) {
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log_error("Failed to read system 'brightness' attribute");
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return EXIT_FAILURE;
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}
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r = write_string_file(saved, value, WRITE_STRING_FILE_CREATE);
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if (r < 0) {
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log_error_errno(r, "Failed to write %s: %m", saved);
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return EXIT_FAILURE;
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}
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} else {
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log_error("Unknown verb %s.", argv[1]);
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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