432 lines
15 KiB
C
432 lines
15 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include "sd-device.h"
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#include "alloc-util.h"
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#include "device-util.h"
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#include "escape.h"
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#include "fileio.h"
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#include "main-func.h"
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#include "mkdir.h"
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#include "parse-util.h"
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#include "proc-cmdline.h"
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#include "string-util.h"
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#include "strv.h"
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#include "util.h"
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static int find_pci_or_platform_parent(sd_device *device, sd_device **ret) {
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const char *subsystem, *sysname, *value;
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sd_device *parent;
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int r;
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assert(device);
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assert(ret);
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r = sd_device_get_parent(device, &parent);
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if (r < 0)
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return r;
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r = sd_device_get_subsystem(parent, &subsystem);
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if (r < 0)
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return r;
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r = sd_device_get_sysname(parent, &sysname);
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if (r < 0)
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return r;
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if (streq(subsystem, "drm")) {
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const char *c;
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c = startswith(sysname, "card");
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if (!c)
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return -ENODATA;
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c += strspn(c, DIGITS);
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if (*c == '-') {
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/* A connector DRM device, let's ignore all but LVDS and eDP! */
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if (!STARTSWITH_SET(c, "-LVDS-", "-Embedded DisplayPort-"))
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return -EOPNOTSUPP;
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}
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} else if (streq(subsystem, "pci") &&
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sd_device_get_sysattr_value(parent, "class", &value) >= 0) {
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unsigned long class = 0;
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r = safe_atolu(value, &class);
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if (r < 0)
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return log_warning_errno(r, "Cannot parse PCI class '%s' of device %s:%s: %m",
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value, subsystem, sysname);
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/* Graphics card */
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if (class == 0x30000) {
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*ret = parent;
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return 0;
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}
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} else if (streq(subsystem, "platform")) {
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*ret = parent;
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return 0;
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}
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return find_pci_or_platform_parent(parent, ret);
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}
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static int same_device(sd_device *a, sd_device *b) {
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const char *a_val, *b_val;
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int r;
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assert(a);
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assert(b);
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r = sd_device_get_subsystem(a, &a_val);
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if (r < 0)
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return r;
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r = sd_device_get_subsystem(b, &b_val);
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if (r < 0)
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return r;
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if (!streq(a_val, b_val))
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return false;
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r = sd_device_get_sysname(a, &a_val);
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if (r < 0)
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return r;
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r = sd_device_get_sysname(b, &b_val);
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if (r < 0)
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return r;
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return streq(a_val, b_val);
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}
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static int validate_device(sd_device *device) {
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_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *enumerate = NULL;
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const char *v, *subsystem;
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sd_device *parent, *other;
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int r;
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assert(device);
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/* Verify whether we should actually care for a specific
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* backlight device. For backlight devices there might be
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* multiple ways to access the same control: "firmware"
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* (i.e. ACPI), "platform" (i.e. via the machine's EC) and
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* "raw" (via the graphics card). In general we should prefer
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* "firmware" (i.e. ACPI) or "platform" access over "raw"
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* access, in order not to confuse the BIOS/EC, and
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* compatibility with possible low-level hotkey handling of
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* screen brightness. The kernel will already make sure to
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* expose only one of "firmware" and "platform" for the same
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* device to userspace. However, we still need to make sure
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* that we use "raw" only if no "firmware" or "platform"
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* device for the same device exists. */
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r = sd_device_get_subsystem(device, &subsystem);
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if (r < 0)
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return r;
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if (!streq(subsystem, "backlight"))
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return true;
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r = sd_device_get_sysattr_value(device, "type", &v);
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if (r < 0)
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return r;
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if (!streq(v, "raw"))
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return true;
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r = find_pci_or_platform_parent(device, &parent);
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if (r < 0)
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return r;
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r = sd_device_get_subsystem(parent, &subsystem);
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if (r < 0)
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return r;
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r = sd_device_enumerator_new(&enumerate);
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if (r < 0)
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return r;
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r = sd_device_enumerator_allow_uninitialized(enumerate);
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if (r < 0)
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return r;
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r = sd_device_enumerator_add_match_subsystem(enumerate, "backlight", true);
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if (r < 0)
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return r;
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FOREACH_DEVICE(enumerate, other) {
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const char *other_subsystem;
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sd_device *other_parent;
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if (same_device(device, other) > 0)
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continue;
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if (sd_device_get_sysattr_value(other, "type", &v) < 0 ||
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!STR_IN_SET(v, "platform", "firmware"))
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continue;
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/* OK, so there's another backlight device, and it's a
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* platform or firmware device, so, let's see if we
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* can verify it belongs to the same device as ours. */
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if (find_pci_or_platform_parent(other, &other_parent) < 0)
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continue;
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if (same_device(parent, other_parent)) {
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const char *device_sysname = NULL, *other_sysname = NULL;
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/* Both have the same PCI parent, that means we are out. */
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(void) sd_device_get_sysname(device, &device_sysname);
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(void) sd_device_get_sysname(other, &other_sysname);
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log_debug("Skipping backlight device %s, since device %s is on same PCI device and takes precedence.",
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device_sysname, other_sysname);
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return false;
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}
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if (sd_device_get_subsystem(other_parent, &other_subsystem) < 0)
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continue;
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if (streq(other_subsystem, "platform") && streq(subsystem, "pci")) {
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const char *device_sysname = NULL, *other_sysname = NULL;
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/* The other is connected to the platform bus and we are a PCI device, that also means we are out. */
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(void) sd_device_get_sysname(device, &device_sysname);
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(void) sd_device_get_sysname(other, &other_sysname);
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log_debug("Skipping backlight device %s, since device %s is a platform device and takes precedence.",
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device_sysname, other_sysname);
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return false;
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}
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}
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return true;
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}
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static int get_max_brightness(sd_device *device, unsigned *ret) {
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const char *max_brightness_str;
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unsigned max_brightness;
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int r;
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assert(device);
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assert(ret);
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r = sd_device_get_sysattr_value(device, "max_brightness", &max_brightness_str);
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if (r < 0)
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return log_device_warning_errno(device, r, "Failed to read 'max_brightness' attribute: %m");
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r = safe_atou(max_brightness_str, &max_brightness);
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if (r < 0)
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return log_device_warning_errno(device, r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str);
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if (max_brightness <= 0) {
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log_device_warning(device, "Maximum brightness is 0, ignoring device.");
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return -EINVAL;
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}
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*ret = max_brightness;
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return 0;
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}
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/* Some systems turn the backlight all the way off at the lowest levels.
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* clamp_brightness clamps the saved brightness to at least 1 or 5% of
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* max_brightness in case of 'backlight' subsystem. This avoids preserving
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* an unreadably dim screen, which would otherwise force the user to
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* disable state restoration. */
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static int clamp_brightness(sd_device *device, char **value, unsigned max_brightness) {
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unsigned brightness, new_brightness, min_brightness;
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const char *subsystem;
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int r;
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assert(value);
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assert(*value);
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r = safe_atou(*value, &brightness);
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if (r < 0)
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return log_device_warning_errno(device, r, "Failed to parse brightness \"%s\": %m", *value);
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r = sd_device_get_subsystem(device, &subsystem);
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if (r < 0)
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return log_device_warning_errno(device, r, "Failed to get device subsystem: %m");
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if (streq(subsystem, "backlight"))
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min_brightness = MAX(1U, max_brightness/20);
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else
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min_brightness = 0;
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new_brightness = CLAMP(brightness, min_brightness, max_brightness);
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if (new_brightness != brightness) {
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char *new_value;
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r = asprintf(&new_value, "%u", new_brightness);
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if (r < 0)
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return log_oom();
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log_device_info(device, "Saved brightness %s %s to %s.", *value,
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new_brightness > brightness ?
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"too low; increasing" : "too high; decreasing",
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new_value);
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free_and_replace(*value, new_value);
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}
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return 0;
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}
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static bool shall_clamp(sd_device *d) {
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const char *s;
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int r;
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assert(d);
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r = sd_device_get_property_value(d, "ID_BACKLIGHT_CLAMP", &s);
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if (r < 0) {
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log_device_debug_errno(d, r, "Failed to get ID_BACKLIGHT_CLAMP property, ignoring: %m");
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return true;
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}
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r = parse_boolean(s);
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if (r < 0) {
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log_device_debug_errno(d, r, "Failed to parse ID_BACKLIGHT_CLAMP property, ignoring: %m");
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return true;
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}
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return r;
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}
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static int run(int argc, char *argv[]) {
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_cleanup_(sd_device_unrefp) sd_device *device = NULL;
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_cleanup_free_ char *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL;
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const char *sysname, *path_id, *ss, *saved;
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unsigned max_brightness;
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int r;
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if (argc != 3) {
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log_error("This program requires two arguments.");
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return -EINVAL;
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}
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log_setup_service();
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umask(0022);
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r = mkdir_p("/var/lib/systemd/backlight", 0755);
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if (r < 0)
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return log_error_errno(r, "Failed to create backlight directory /var/lib/systemd/backlight: %m");
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sysname = strchr(argv[2], ':');
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if (!sysname) {
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log_error("Requires a subsystem and sysname pair specifying a backlight device.");
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return -EINVAL;
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}
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ss = strndupa(argv[2], sysname - argv[2]);
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sysname++;
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if (!STR_IN_SET(ss, "backlight", "leds")) {
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log_error("Not a backlight or LED device: '%s:%s'", ss, sysname);
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return -EINVAL;
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}
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r = sd_device_new_from_subsystem_sysname(&device, ss, sysname);
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if (r < 0)
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return log_error_errno(r, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname);
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/* If max_brightness is 0, then there is no actual backlight
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* device. This happens on desktops with Asus mainboards
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* that load the eeepc-wmi module. */
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if (get_max_brightness(device, &max_brightness) < 0)
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return 0;
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escaped_ss = cescape(ss);
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if (!escaped_ss)
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return log_oom();
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escaped_sysname = cescape(sysname);
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if (!escaped_sysname)
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return log_oom();
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if (sd_device_get_property_value(device, "ID_PATH", &path_id) >= 0) {
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escaped_path_id = cescape(path_id);
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if (!escaped_path_id)
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return log_oom();
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saved = strjoina("/var/lib/systemd/backlight/", escaped_path_id, ":", escaped_ss, ":", escaped_sysname);
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} else
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saved = strjoina("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname);
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/* If there are multiple conflicting backlight devices, then
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* their probing at boot-time might happen in any order. This
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* means the validity checking of the device then is not
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* reliable, since it might not see other devices conflicting
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* with a specific backlight. To deal with this, we will
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* actively delete backlight state files at shutdown (where
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* device probing should be complete), so that the validity
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* check at boot time doesn't have to be reliable. */
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if (streq(argv[1], "load")) {
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_cleanup_free_ char *value = NULL;
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bool clamp;
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if (shall_restore_state() == 0)
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return 0;
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if (validate_device(device) == 0)
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return 0;
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clamp = shall_clamp(device);
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r = read_one_line_file(saved, &value);
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if (r == -ENOENT) {
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const char *curval;
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/* Fallback to clamping current brightness or exit early if
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* clamping is not supported/enabled. */
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if (!clamp)
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return 0;
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r = sd_device_get_sysattr_value(device, "brightness", &curval);
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if (r < 0)
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return log_device_warning_errno(device, r, "Failed to read 'brightness' attribute: %m");
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value = strdup(curval);
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if (!value)
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return log_oom();
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} else if (r < 0)
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return log_error_errno(r, "Failed to read %s: %m", saved);
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if (clamp)
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(void) clamp_brightness(device, &value, max_brightness);
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r = sd_device_set_sysattr_value(device, "brightness", value);
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if (r < 0)
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return log_device_error_errno(device, r, "Failed to write system 'brightness' attribute: %m");
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} else if (streq(argv[1], "save")) {
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const char *value;
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if (validate_device(device) == 0) {
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unlink(saved);
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return 0;
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}
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r = sd_device_get_sysattr_value(device, "brightness", &value);
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if (r < 0)
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return log_device_error_errno(device, r, "Failed to read system 'brightness' attribute: %m");
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r = write_string_file(saved, value, WRITE_STRING_FILE_CREATE);
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if (r < 0)
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return log_device_error_errno(device, r, "Failed to write %s: %m", saved);
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} else {
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log_error("Unknown verb %s.", argv[1]);
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return -EINVAL;
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}
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return 0;
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}
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DEFINE_MAIN_FUNCTION(run);
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