diff options
Diffstat (limited to 'src/backlight')
| -rw-r--r-- | src/backlight/backlight.c | 511 |
1 files changed, 511 insertions, 0 deletions
diff --git a/src/backlight/backlight.c b/src/backlight/backlight.c new file mode 100644 index 0000000..d1b6a81 --- /dev/null +++ b/src/backlight/backlight.c @@ -0,0 +1,511 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <sys/stat.h> +#include <sys/types.h> +#include <unistd.h> + +#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 "terminal-util.h" +#include "reboot-util.h" +#include "string-util.h" +#include "strv.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 == '-') { + /* A connector DRM device, let's ignore all but LVDS and eDP! */ + if (!STARTSWITH_SET(c, "-LVDS-", "-Embedded DisplayPort-")) + 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, 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_device_warning_errno(device, r, "Failed to read 'max_brightness' attribute: %m"); + + r = safe_atou(max_brightness_str, &max_brightness); + if (r < 0) + return log_device_warning_errno(device, r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str); + + if (max_brightness <= 0) + return log_device_warning_errno(device, SYNTHETIC_ERRNO(EINVAL), "Maximum brightness is 0, ignoring device."); + + log_device_debug(device, "Maximum brightness is %u", max_brightness); + *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, bool saved, unsigned max_brightness, unsigned *brightness) { + unsigned new_brightness, min_brightness; + const char *subsystem; + int r; + + assert(device); + assert(brightness); + + 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_service(); + + if (strv_contains(strv_skip(argv, 1), "--help")) + return help(); + + if (argc != 3) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program requires two arguments."); + + 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(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) + return log_error_errno(r, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname); + + /* 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; + + 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 + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Unknown verb %s.", argv[1]); + + return 0; +} + +DEFINE_MAIN_FUNCTION(run); |