diff options
Diffstat (limited to 'src/grp-helperunits/systemd-backlight/backlight.c')
| -rw-r--r-- | src/grp-helperunits/systemd-backlight/backlight.c | 434 |
1 files changed, 434 insertions, 0 deletions
diff --git a/src/grp-helperunits/systemd-backlight/backlight.c b/src/grp-helperunits/systemd-backlight/backlight.c new file mode 100644 index 0000000000..45be135a23 --- /dev/null +++ b/src/grp-helperunits/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 "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 (!streq_ptr(v, "platform") && !streq_ptr(v, "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; +} |