| /* SPDX-License-Identifier: LGPL-2.1+ */ |
| /*** |
| 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 "alloc-util.h" |
| #include "def.h" |
| #include "escape.h" |
| #include "fileio.h" |
| #include "mkdir.h" |
| #include "parse-util.h" |
| #include "proc-cmdline.h" |
| #include "string-util.h" |
| #include "udev-util.h" |
| #include "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); |
| } else |
| saved = strjoin("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname); |
| |
| 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; |
| } |