/* SPDX-License-Identifier: LGPL-2.1+ */ #include "sd-device.h" #include "alloc-util.h" #include "def.h" #include "device-util.h" #include "escape.h" #include "fileio.h" #include "mkdir.h" #include "parse-util.h" #include "proc-cmdline.h" #include "string-util.h" #include "strv.h" #include "util.h" 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 == '-') { /* A connector DRM device, let's ignore all but LVDS and eDP! */ if (!startswith(c, "-LVDS-") && !startswith(c, "-Embedded DisplayPort-")) return -EOPNOTSUPP; } } else if (streq(subsystem, "pci") && sd_device_get_sysattr_value(parent, "class", &value) >= 0) { unsigned long class = 0; 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, so, 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)) { 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 *max_brightness_str; unsigned max_brightness; int r; assert(device); assert(ret); r = sd_device_get_sysattr_value(device, "max_brightness", &max_brightness_str); if (r < 0) return log_warning_errno(r, "Failed to read 'max_brightness' attribute: %m"); r = safe_atou(max_brightness_str, &max_brightness); if (r < 0) return log_warning_errno(r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str); if (max_brightness <= 0) { log_warning("Maximum brightness is 0, ignoring device."); return -EINVAL; } *ret = max_brightness; return 0; } /* 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 int clamp_brightness(sd_device *device, char **value, unsigned max_brightness) { unsigned brightness, new_brightness, min_brightness; const char *subsystem; int r; assert(value); assert(*value); r = safe_atou(*value, &brightness); if (r < 0) return log_warning_errno(r, "Failed to parse brightness \"%s\": %m", *value); r = sd_device_get_subsystem(device, &subsystem); if (r < 0) return log_warning_errno(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) { char *new_value; r = asprintf(&new_value, "%u", new_brightness); if (r < 0) return log_oom(); log_info("Saved brightness %s %s to %s.", *value, new_brightness > brightness ? "too low; increasing" : "too high; decreasing", new_value); free_and_replace(*value, new_value); } 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) return true; r = parse_boolean(s); if (r < 0) { log_debug_errno(r, "Failed to parse ID_BACKLIGHT_CLAMP property, ignoring: %m"); return true; } return r; } int main(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; 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; } sysname = strchr(argv[2], ':'); if (!sysname) { log_error("Requires a subsystem and sysname pair specifying a backlight device."); return EXIT_FAILURE; } ss = strndupa(argv[2], sysname - argv[2]); sysname++; if (!STR_IN_SET(ss, "backlight", "leds")) { log_error("Not a backlight or LED device: '%s:%s'", ss, sysname); return EXIT_FAILURE; } r = sd_device_new_from_subsystem_sysname(&device, ss, sysname); if (r < 0) { log_error_errno(r, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname); 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. */ r = get_max_brightness(device, &max_brightness); if (r < 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; } if (sd_device_get_property_value(device, "ID_PATH", &path_id) >= 0) { escaped_path_id = cescape(path_id); if (!escaped_path_id) { log_oom(); return EXIT_FAILURE; } 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 EXIT_SUCCESS; if (validate_device(device) == 0) return EXIT_SUCCESS; clamp = shall_clamp(device); r = read_one_line_file(saved, &value); if (r == -ENOENT) { const char *curval; /* Fallback to clamping current brightness or exit early if * clamping is not supported/enabled. */ if (!clamp) return EXIT_SUCCESS; r = sd_device_get_sysattr_value(device, "brightness", &curval); if (r < 0) { log_warning_errno(r, "Failed to read 'brightness' attribute: %m"); return EXIT_FAILURE; } value = strdup(curval); if (!value) { log_oom(); return EXIT_FAILURE; } } else if (r < 0) { log_error_errno(r, "Failed to read %s: %m", saved); return EXIT_FAILURE; } if (clamp) (void) clamp_brightness(device, &value, max_brightness); r = sd_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(device) == 0) { unlink(saved); return EXIT_SUCCESS; } r = sd_device_get_sysattr_value(device, "brightness", &value); if (r < 0) { log_error_errno(r, "Failed to read system 'brightness' attribute: %m"); 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; }