/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include "sd-device.h" #include "alloc-util.h" #include "device-util.h" #include "escape.h" #include "fileio.h" #include "main-func.h" #include "mkdir.h" #include "parse-util.h" #include "pretty-print.h" #include "process-util.h" #include "reboot-util.h" #include "string-util.h" #include "strv.h" #include "terminal-util.h" #include "util.h" static int help(void) { _cleanup_free_ char *link = NULL; int r; r = terminal_urlify_man("systemd-backlight", "8", &link); if (r < 0) return log_oom(); printf("%s save [backlight|leds]:DEVICE\n" "%s load [backlight|leds]:DEVICE\n" "\n%sSave and restore backlight brightness at shutdown and boot.%s\n\n" " save Save current brightness\n" " load Set brightness to be the previously saved value\n" "\nSee the %s for details.\n", program_invocation_short_name, program_invocation_short_name, ansi_highlight(), ansi_normal(), link); return 0; } static int find_pci_or_platform_parent(sd_device *device, sd_device **ret) { const char *subsystem, *sysname, *value; sd_device *parent; int r; assert(device); assert(ret); r = sd_device_get_parent(device, &parent); if (r < 0) return r; r = sd_device_get_subsystem(parent, &subsystem); if (r < 0) return r; r = sd_device_get_sysname(parent, &sysname); if (r < 0) return r; if (streq(subsystem, "drm")) { const char *c; c = startswith(sysname, "card"); if (!c) return -ENODATA; c += strspn(c, DIGITS); if (*c == '-' && !STARTSWITH_SET(c, "-LVDS-", "-Embedded DisplayPort-")) /* A connector DRM device, let's ignore all but LVDS and eDP! */ return -EOPNOTSUPP; } else if (streq(subsystem, "pci") && sd_device_get_sysattr_value(parent, "class", &value) >= 0) { unsigned long class; r = safe_atolu(value, &class); if (r < 0) return log_warning_errno(r, "Cannot parse PCI class '%s' of device %s:%s: %m", value, subsystem, sysname); /* Graphics card */ if (class == 0x30000) { *ret = parent; return 0; } } else if (streq(subsystem, "platform")) { *ret = parent; return 0; } return find_pci_or_platform_parent(parent, ret); } static int same_device(sd_device *a, sd_device *b) { const char *a_val, *b_val; int r; assert(a); assert(b); r = sd_device_get_subsystem(a, &a_val); if (r < 0) return r; r = sd_device_get_subsystem(b, &b_val); if (r < 0) return r; if (!streq(a_val, b_val)) return false; r = sd_device_get_sysname(a, &a_val); if (r < 0) return r; r = sd_device_get_sysname(b, &b_val); if (r < 0) return r; return streq(a_val, b_val); } static int validate_device(sd_device *device) { _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *enumerate = NULL; const char *v, *subsystem; sd_device *parent, *other; int r; 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. */ r = sd_device_get_subsystem(device, &subsystem); if (r < 0) return r; if (!streq(subsystem, "backlight")) return true; r = sd_device_get_sysattr_value(device, "type", &v); if (r < 0) return r; if (!streq(v, "raw")) return true; r = find_pci_or_platform_parent(device, &parent); if (r < 0) return r; r = sd_device_get_subsystem(parent, &subsystem); if (r < 0) return r; r = sd_device_enumerator_new(&enumerate); if (r < 0) return r; r = sd_device_enumerator_allow_uninitialized(enumerate); if (r < 0) return r; r = sd_device_enumerator_add_match_subsystem(enumerate, "backlight", true); if (r < 0) return r; FOREACH_DEVICE(enumerate, other) { const char *other_subsystem; sd_device *other_parent; if (same_device(device, other) > 0) continue; if (sd_device_get_sysattr_value(other, "type", &v) < 0 || !STR_IN_SET(v, "platform", "firmware")) continue; /* OK, so there's another backlight device, and it's a platform or firmware device. * Let's see if we can verify it belongs to the same device as ours. */ if (find_pci_or_platform_parent(other, &other_parent) < 0) continue; if (same_device(parent, other_parent) > 0) { const char *device_sysname = NULL, *other_sysname = NULL; /* Both have the same PCI parent, that means we are out. */ (void) sd_device_get_sysname(device, &device_sysname); (void) sd_device_get_sysname(other, &other_sysname); log_debug("Skipping backlight device %s, since device %s is on same PCI device and takes precedence.", device_sysname, other_sysname); return false; } if (sd_device_get_subsystem(other_parent, &other_subsystem) < 0) continue; if (streq(other_subsystem, "platform") && streq(subsystem, "pci")) { const char *device_sysname = NULL, *other_sysname = NULL; /* The other is connected to the platform bus and we are a PCI device, that also means we are out. */ (void) sd_device_get_sysname(device, &device_sysname); (void) sd_device_get_sysname(other, &other_sysname); log_debug("Skipping backlight device %s, since device %s is a platform device and takes precedence.", device_sysname, other_sysname); return false; } } return true; } static int get_max_brightness(sd_device *device, unsigned *ret) { const char *s; int r; assert(device); assert(ret); r = sd_device_get_sysattr_value(device, "max_brightness", &s); if (r < 0) return log_device_warning_errno(device, r, "Failed to read 'max_brightness' attribute: %m"); r = safe_atou(s, ret); if (r < 0) return log_device_warning_errno(device, r, "Failed to parse 'max_brightness' \"%s\": %m", s); return 0; } static int clamp_brightness(sd_device *device, bool saved, unsigned max_brightness, unsigned *brightness) { unsigned new_brightness, min_brightness; const char *subsystem; int r; assert(device); assert(brightness); /* Some systems turn the backlight all the way off at the lowest levels. This 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. */ r = sd_device_get_subsystem(device, &subsystem); if (r < 0) return log_device_warning_errno(device, r, "Failed to get device subsystem: %m"); if (streq(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) log_device_info(device, "%s brightness %u is %s to %u.", saved ? "Saved" : "Current", *brightness, new_brightness > *brightness ? "too low; increasing" : "too high; decreasing", new_brightness); *brightness = new_brightness; return 0; } static bool shall_clamp(sd_device *d) { const char *s; int r; assert(d); r = sd_device_get_property_value(d, "ID_BACKLIGHT_CLAMP", &s); if (r < 0) { if (r != -ENOENT) log_device_debug_errno(d, r, "Failed to get ID_BACKLIGHT_CLAMP property, ignoring: %m"); return true; } r = parse_boolean(s); if (r < 0) { log_device_debug_errno(d, r, "Failed to parse ID_BACKLIGHT_CLAMP property, ignoring: %m"); return true; } return r; } static int read_brightness(sd_device *device, unsigned max_brightness, unsigned *ret_brightness) { const char *subsystem, *value; unsigned brightness; int r; assert(device); assert(ret_brightness); r = sd_device_get_subsystem(device, &subsystem); if (r < 0) return log_device_debug_errno(device, r, "Failed to get subsystem: %m"); if (streq(subsystem, "backlight")) { r = sd_device_get_sysattr_value(device, "actual_brightness", &value); if (r == -ENOENT) { log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute, " "fall back to use 'brightness' attribute: %m"); goto use_brightness; } if (r < 0) return log_device_debug_errno(device, r, "Failed to read 'actual_brightness' attribute: %m"); r = safe_atou(value, &brightness); if (r < 0) { log_device_debug_errno(device, r, "Failed to parse 'actual_brightness' attribute, " "fall back to use 'brightness' attribute: %s", value); goto use_brightness; } if (brightness > max_brightness) { log_device_debug(device, "actual_brightness=%u is larger than max_brightness=%u, " "fall back to use 'brightness' attribute", brightness, max_brightness); goto use_brightness; } log_device_debug(device, "Current actual_brightness is %u", brightness); *ret_brightness = brightness; return 0; } use_brightness: r = sd_device_get_sysattr_value(device, "brightness", &value); if (r < 0) return log_device_debug_errno(device, r, "Failed to read 'brightness' attribute: %m"); r = safe_atou(value, &brightness); if (r < 0) return log_device_debug_errno(device, r, "Failed to parse 'brightness' attribute: %s", value); if (brightness > max_brightness) return log_device_debug_errno(device, SYNTHETIC_ERRNO(EINVAL), "brightness=%u is larger than max_brightness=%u", brightness, max_brightness); log_device_debug(device, "Current brightness is %u", brightness); *ret_brightness = brightness; return 0; } static int run(int argc, char *argv[]) { _cleanup_(sd_device_unrefp) sd_device *device = NULL; _cleanup_free_ char *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL; const char *sysname, *path_id, *ss, *saved; unsigned max_brightness, brightness; int r; log_setup(); if (argv_looks_like_help(argc, argv)) return help(); if (argc != 3) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program requires two arguments."); if (!STR_IN_SET(argv[1], "load", "save")) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Unknown verb %s.", argv[1]); umask(0022); r = mkdir_p("/var/lib/systemd/backlight", 0755); if (r < 0) return log_error_errno(r, "Failed to create backlight directory /var/lib/systemd/backlight: %m"); sysname = strchr(argv[2], ':'); if (!sysname) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Requires a subsystem and sysname pair specifying a backlight device."); ss = strndupa_safe(argv[2], sysname - argv[2]); sysname++; if (!STR_IN_SET(ss, "backlight", "leds")) return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Not a backlight or LED device: '%s:%s'", ss, sysname); r = sd_device_new_from_subsystem_sysname(&device, ss, sysname); if (r < 0) { bool ignore = r == -ENODEV; /* Some drivers, e.g. for AMD GPU, removes acpi backlight device soon after it is added. * See issue #21997. */ log_full_errno(ignore ? LOG_DEBUG : LOG_ERR, r, "Failed to get backlight or LED device '%s:%s'%s: %m", ss, sysname, ignore ? ", ignoring" : ""); return ignore ? 0 : r; } /* 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. */ if (get_max_brightness(device, &max_brightness) < 0) return 0; if (max_brightness == 0) { log_device_warning(device, "Maximum brightness is 0, ignoring device."); return 0; } log_device_debug(device, "Maximum brightness is %u", max_brightness); escaped_ss = cescape(ss); if (!escaped_ss) return log_oom(); escaped_sysname = cescape(sysname); if (!escaped_sysname) return log_oom(); if (sd_device_get_property_value(device, "ID_PATH", &path_id) >= 0) { escaped_path_id = cescape(path_id); if (!escaped_path_id) return log_oom(); saved = strjoina("/var/lib/systemd/backlight/", escaped_path_id, ":", escaped_ss, ":", escaped_sysname); } else saved = strjoina("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname); /* 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; bool clamp; if (shall_restore_state() == 0) return 0; if (validate_device(device) == 0) return 0; clamp = shall_clamp(device); r = read_one_line_file(saved, &value); if (r < 0 && r != -ENOENT) return log_error_errno(r, "Failed to read %s: %m", saved); if (r > 0) { r = safe_atou(value, &brightness); if (r < 0) { log_warning_errno(r, "Failed to parse saved brightness '%s', removing %s.", value, saved); (void) unlink(saved); } else { log_debug("Using saved brightness %u.", brightness); if (clamp) (void) clamp_brightness(device, true, max_brightness, &brightness); /* Do not fall back to read current brightness below. */ r = 1; } } if (r <= 0) { /* Fallback to clamping current brightness or exit early if clamping is not * supported/enabled. */ if (!clamp) return 0; r = read_brightness(device, max_brightness, &brightness); if (r < 0) return log_device_error_errno(device, r, "Failed to read current brightness: %m"); (void) clamp_brightness(device, false, max_brightness, &brightness); } r = sd_device_set_sysattr_valuef(device, "brightness", "%u", brightness); if (r < 0) return log_device_error_errno(device, r, "Failed to write system 'brightness' attribute: %m"); } else if (streq(argv[1], "save")) { if (validate_device(device) == 0) { (void) unlink(saved); return 0; } r = read_brightness(device, max_brightness, &brightness); if (r < 0) return log_device_error_errno(device, r, "Failed to read current brightness: %m"); r = write_string_filef(saved, WRITE_STRING_FILE_CREATE, "%u", brightness); if (r < 0) return log_device_error_errno(device, r, "Failed to write %s: %m", saved); } else assert_not_reached(); return 0; } DEFINE_MAIN_FUNCTION(run);