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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
3731acf1 | 2 | |
b4bbcaa9 TA |
3 | #include "libudev.h" |
4 | ||
b5efdb8a | 5 | #include "alloc-util.h" |
4f5dd394 LP |
6 | #include "def.h" |
7 | #include "escape.h" | |
3731acf1 | 8 | #include "fileio.h" |
4f5dd394 | 9 | #include "mkdir.h" |
4e731273 LP |
10 | #include "parse-util.h" |
11 | #include "proc-cmdline.h" | |
07630cea | 12 | #include "string-util.h" |
1ca208fb | 13 | #include "udev-util.h" |
4f5dd394 | 14 | #include "util.h" |
3731acf1 | 15 | |
0f4ba83c LP |
16 | static struct udev_device *find_pci_or_platform_parent(struct udev_device *device) { |
17 | struct udev_device *parent; | |
18 | const char *subsystem, *sysname; | |
19 | ||
20 | assert(device); | |
21 | ||
22 | parent = udev_device_get_parent(device); | |
23 | if (!parent) | |
24 | return NULL; | |
25 | ||
26 | subsystem = udev_device_get_subsystem(parent); | |
27 | if (!subsystem) | |
28 | return NULL; | |
29 | ||
30 | sysname = udev_device_get_sysname(parent); | |
31 | if (!sysname) | |
32 | return NULL; | |
33 | ||
34 | if (streq(subsystem, "drm")) { | |
35 | const char *c; | |
36 | ||
37 | c = startswith(sysname, "card"); | |
38 | if (!c) | |
39 | return NULL; | |
40 | ||
938d2699 | 41 | c += strspn(c, DIGITS); |
0f4ba83c LP |
42 | if (*c == '-') { |
43 | /* A connector DRM device, let's ignore all but LVDS and eDP! */ | |
44 | ||
45 | if (!startswith(c, "-LVDS-") && | |
46 | !startswith(c, "-Embedded DisplayPort-")) | |
47 | return NULL; | |
48 | } | |
49 | ||
50 | } else if (streq(subsystem, "pci")) { | |
51 | const char *value; | |
52 | ||
53 | value = udev_device_get_sysattr_value(parent, "class"); | |
54 | if (value) { | |
39883f62 | 55 | unsigned long class = 0; |
0f4ba83c LP |
56 | |
57 | if (safe_atolu(value, &class) < 0) { | |
938d2699 ZJS |
58 | log_warning("Cannot parse PCI class %s of device %s:%s.", |
59 | value, subsystem, sysname); | |
0f4ba83c LP |
60 | return NULL; |
61 | } | |
62 | ||
63 | /* Graphics card */ | |
64 | if (class == 0x30000) | |
65 | return parent; | |
66 | } | |
67 | ||
68 | } else if (streq(subsystem, "platform")) | |
69 | return parent; | |
70 | ||
71 | return find_pci_or_platform_parent(parent); | |
72 | } | |
73 | ||
74 | static bool same_device(struct udev_device *a, struct udev_device *b) { | |
75 | assert(a); | |
76 | assert(b); | |
77 | ||
78 | if (!streq_ptr(udev_device_get_subsystem(a), udev_device_get_subsystem(b))) | |
79 | return false; | |
80 | ||
81 | if (!streq_ptr(udev_device_get_sysname(a), udev_device_get_sysname(b))) | |
82 | return false; | |
83 | ||
84 | return true; | |
85 | } | |
86 | ||
87 | static bool validate_device(struct udev *udev, struct udev_device *device) { | |
8e766630 | 88 | _cleanup_(udev_enumerate_unrefp) struct udev_enumerate *enumerate = NULL; |
0f4ba83c LP |
89 | struct udev_list_entry *item = NULL, *first = NULL; |
90 | struct udev_device *parent; | |
91 | const char *v, *subsystem; | |
92 | int r; | |
93 | ||
94 | assert(udev); | |
95 | assert(device); | |
96 | ||
97 | /* Verify whether we should actually care for a specific | |
98 | * backlight device. For backlight devices there might be | |
99 | * multiple ways to access the same control: "firmware" | |
100 | * (i.e. ACPI), "platform" (i.e. via the machine's EC) and | |
101 | * "raw" (via the graphics card). In general we should prefer | |
102 | * "firmware" (i.e. ACPI) or "platform" access over "raw" | |
103 | * access, in order not to confuse the BIOS/EC, and | |
104 | * compatibility with possible low-level hotkey handling of | |
105 | * screen brightness. The kernel will already make sure to | |
106 | * expose only one of "firmware" and "platform" for the same | |
107 | * device to userspace. However, we still need to make sure | |
108 | * that we use "raw" only if no "firmware" or "platform" | |
109 | * device for the same device exists. */ | |
110 | ||
111 | subsystem = udev_device_get_subsystem(device); | |
112 | if (!streq_ptr(subsystem, "backlight")) | |
113 | return true; | |
114 | ||
115 | v = udev_device_get_sysattr_value(device, "type"); | |
116 | if (!streq_ptr(v, "raw")) | |
117 | return true; | |
118 | ||
119 | parent = find_pci_or_platform_parent(device); | |
120 | if (!parent) | |
121 | return true; | |
122 | ||
123 | subsystem = udev_device_get_subsystem(parent); | |
124 | if (!subsystem) | |
125 | return true; | |
126 | ||
127 | enumerate = udev_enumerate_new(udev); | |
128 | if (!enumerate) | |
129 | return true; | |
130 | ||
131 | r = udev_enumerate_add_match_subsystem(enumerate, "backlight"); | |
132 | if (r < 0) | |
133 | return true; | |
134 | ||
135 | r = udev_enumerate_scan_devices(enumerate); | |
136 | if (r < 0) | |
137 | return true; | |
138 | ||
139 | first = udev_enumerate_get_list_entry(enumerate); | |
140 | udev_list_entry_foreach(item, first) { | |
8e766630 | 141 | _cleanup_(udev_device_unrefp) struct udev_device *other; |
0f4ba83c LP |
142 | struct udev_device *other_parent; |
143 | const char *other_subsystem; | |
144 | ||
145 | other = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)); | |
146 | if (!other) | |
147 | return true; | |
148 | ||
149 | if (same_device(device, other)) | |
150 | continue; | |
151 | ||
152 | v = udev_device_get_sysattr_value(other, "type"); | |
1cf03a4f | 153 | if (!STRPTR_IN_SET(v, "platform", "firmware")) |
0f4ba83c LP |
154 | continue; |
155 | ||
156 | /* OK, so there's another backlight device, and it's a | |
157 | * platform or firmware device, so, let's see if we | |
158 | * can verify it belongs to the same device as | |
159 | * ours. */ | |
160 | other_parent = find_pci_or_platform_parent(other); | |
161 | if (!other_parent) | |
162 | continue; | |
163 | ||
164 | if (same_device(parent, other_parent)) { | |
165 | /* Both have the same PCI parent, that means | |
166 | * we are out. */ | |
938d2699 ZJS |
167 | log_debug("Skipping backlight device %s, since device %s is on same PCI device and takes precedence.", |
168 | udev_device_get_sysname(device), | |
169 | udev_device_get_sysname(other)); | |
0f4ba83c LP |
170 | return false; |
171 | } | |
172 | ||
173 | other_subsystem = udev_device_get_subsystem(other_parent); | |
174 | if (streq_ptr(other_subsystem, "platform") && streq_ptr(subsystem, "pci")) { | |
175 | /* The other is connected to the platform bus | |
176 | * and we are a PCI device, that also means we | |
177 | * are out. */ | |
938d2699 ZJS |
178 | log_debug("Skipping backlight device %s, since device %s is a platform device and takes precedence.", |
179 | udev_device_get_sysname(device), | |
180 | udev_device_get_sysname(other)); | |
0f4ba83c LP |
181 | return false; |
182 | } | |
183 | } | |
184 | ||
185 | return true; | |
186 | } | |
187 | ||
3cadce7d | 188 | static unsigned get_max_brightness(struct udev_device *device) { |
7b909d74 JT |
189 | int r; |
190 | const char *max_brightness_str; | |
3cadce7d | 191 | unsigned max_brightness; |
7b909d74 JT |
192 | |
193 | max_brightness_str = udev_device_get_sysattr_value(device, "max_brightness"); | |
194 | if (!max_brightness_str) { | |
c7fdf44d | 195 | log_warning("Failed to read 'max_brightness' attribute."); |
3cadce7d | 196 | return 0; |
7b909d74 JT |
197 | } |
198 | ||
3cadce7d | 199 | r = safe_atou(max_brightness_str, &max_brightness); |
7b909d74 | 200 | if (r < 0) { |
da927ba9 | 201 | log_warning_errno(r, "Failed to parse 'max_brightness' \"%s\": %m", max_brightness_str); |
c7fdf44d LP |
202 | return 0; |
203 | } | |
204 | ||
205 | if (max_brightness <= 0) { | |
206 | log_warning("Maximum brightness is 0, ignoring device."); | |
3cadce7d | 207 | return 0; |
7b909d74 JT |
208 | } |
209 | ||
3cadce7d TB |
210 | return max_brightness; |
211 | } | |
212 | ||
213 | /* Some systems turn the backlight all the way off at the lowest levels. | |
214 | * clamp_brightness clamps the saved brightness to at least 1 or 5% of | |
4cd2b2cf DT |
215 | * max_brightness in case of 'backlight' subsystem. This avoids preserving |
216 | * an unreadably dim screen, which would otherwise force the user to | |
217 | * disable state restoration. */ | |
3cadce7d | 218 | static void clamp_brightness(struct udev_device *device, char **value, unsigned max_brightness) { |
0c9d8f1d | 219 | unsigned brightness, new_brightness, min_brightness; |
4cd2b2cf | 220 | const char *subsystem; |
3e44d24d | 221 | int r; |
3cadce7d TB |
222 | |
223 | r = safe_atou(*value, &brightness); | |
7b909d74 | 224 | if (r < 0) { |
da927ba9 | 225 | log_warning_errno(r, "Failed to parse brightness \"%s\": %m", *value); |
7b909d74 JT |
226 | return; |
227 | } | |
228 | ||
4cd2b2cf DT |
229 | subsystem = udev_device_get_subsystem(device); |
230 | if (streq_ptr(subsystem, "backlight")) | |
231 | min_brightness = MAX(1U, max_brightness/20); | |
232 | else | |
233 | min_brightness = 0; | |
234 | ||
0c9d8f1d | 235 | new_brightness = CLAMP(brightness, min_brightness, max_brightness); |
7b909d74 JT |
236 | if (new_brightness != brightness) { |
237 | char *old_value = *value; | |
238 | ||
239 | r = asprintf(value, "%u", new_brightness); | |
240 | if (r < 0) { | |
241 | log_oom(); | |
242 | return; | |
243 | } | |
244 | ||
0c9d8f1d JN |
245 | log_info("Saved brightness %s %s to %s.", old_value, |
246 | new_brightness > brightness ? | |
247 | "too low; increasing" : "too high; decreasing", | |
248 | *value); | |
249 | ||
7b909d74 JT |
250 | free(old_value); |
251 | } | |
252 | } | |
253 | ||
4432b941 SR |
254 | static bool shall_clamp(struct udev_device *d) { |
255 | const char *s; | |
256 | int r; | |
257 | ||
258 | assert(d); | |
259 | ||
260 | s = udev_device_get_property_value(d, "ID_BACKLIGHT_CLAMP"); | |
261 | if (!s) | |
262 | return true; | |
263 | ||
264 | r = parse_boolean(s); | |
265 | if (r < 0) { | |
266 | log_debug_errno(r, "Failed to parse ID_BACKLIGHT_CLAMP property, ignoring: %m"); | |
267 | return true; | |
268 | } | |
269 | ||
270 | return r; | |
271 | } | |
272 | ||
3731acf1 | 273 | int main(int argc, char *argv[]) { |
8e766630 LP |
274 | _cleanup_(udev_unrefp) struct udev *udev = NULL; |
275 | _cleanup_(udev_device_unrefp) struct udev_device *device = NULL; | |
3e44d24d LP |
276 | _cleanup_free_ char *escaped_ss = NULL, *escaped_sysname = NULL, *escaped_path_id = NULL; |
277 | const char *sysname, *path_id, *ss, *saved; | |
3cadce7d | 278 | unsigned max_brightness; |
3731acf1 LP |
279 | int r; |
280 | ||
281 | if (argc != 3) { | |
282 | log_error("This program requires two arguments."); | |
283 | return EXIT_FAILURE; | |
284 | } | |
285 | ||
286 | log_set_target(LOG_TARGET_AUTO); | |
287 | log_parse_environment(); | |
288 | log_open(); | |
289 | ||
290 | umask(0022); | |
291 | ||
ef5bfcf6 | 292 | r = mkdir_p("/var/lib/systemd/backlight", 0755); |
3731acf1 | 293 | if (r < 0) { |
c33b3297 | 294 | log_error_errno(r, "Failed to create backlight directory /var/lib/systemd/backlight: %m"); |
1ca208fb | 295 | return EXIT_FAILURE; |
3731acf1 LP |
296 | } |
297 | ||
298 | udev = udev_new(); | |
299 | if (!udev) { | |
1ca208fb ZJS |
300 | log_oom(); |
301 | return EXIT_FAILURE; | |
3731acf1 LP |
302 | } |
303 | ||
0f4ba83c LP |
304 | sysname = strchr(argv[2], ':'); |
305 | if (!sysname) { | |
938d2699 | 306 | log_error("Requires a subsystem and sysname pair specifying a backlight device."); |
0f4ba83c LP |
307 | return EXIT_FAILURE; |
308 | } | |
309 | ||
3e44d24d | 310 | ss = strndupa(argv[2], sysname - argv[2]); |
0f4ba83c LP |
311 | |
312 | sysname++; | |
313 | ||
3e44d24d | 314 | if (!STR_IN_SET(ss, "backlight", "leds")) { |
0f4ba83c LP |
315 | log_error("Not a backlight or LED device: '%s:%s'", ss, sysname); |
316 | return EXIT_FAILURE; | |
317 | } | |
318 | ||
875c6e1b | 319 | errno = 0; |
0f4ba83c | 320 | device = udev_device_new_from_subsystem_sysname(udev, ss, sysname); |
3731acf1 | 321 | if (!device) { |
b3267152 | 322 | if (errno > 0) |
56f64d95 | 323 | log_error_errno(errno, "Failed to get backlight or LED device '%s:%s': %m", ss, sysname); |
1ca208fb | 324 | else |
0f4ba83c | 325 | log_oom(); |
3731acf1 | 326 | |
1ca208fb | 327 | return EXIT_FAILURE; |
3731acf1 LP |
328 | } |
329 | ||
3cadce7d TB |
330 | /* If max_brightness is 0, then there is no actual backlight |
331 | * device. This happens on desktops with Asus mainboards | |
332 | * that load the eeepc-wmi module. | |
333 | */ | |
334 | max_brightness = get_max_brightness(device); | |
335 | if (max_brightness == 0) | |
336 | return EXIT_SUCCESS; | |
337 | ||
be3f52f4 LP |
338 | escaped_ss = cescape(ss); |
339 | if (!escaped_ss) { | |
340 | log_oom(); | |
341 | return EXIT_FAILURE; | |
342 | } | |
343 | ||
344 | escaped_sysname = cescape(sysname); | |
345 | if (!escaped_sysname) { | |
346 | log_oom(); | |
347 | return EXIT_FAILURE; | |
348 | } | |
349 | ||
350 | path_id = udev_device_get_property_value(device, "ID_PATH"); | |
351 | if (path_id) { | |
352 | escaped_path_id = cescape(path_id); | |
353 | if (!escaped_path_id) { | |
354 | log_oom(); | |
355 | return EXIT_FAILURE; | |
356 | } | |
357 | ||
3e44d24d | 358 | saved = strjoina("/var/lib/systemd/backlight/", escaped_path_id, ":", escaped_ss, ":", escaped_sysname); |
be3f52f4 | 359 | } else |
3e44d24d | 360 | saved = strjoina("/var/lib/systemd/backlight/", escaped_ss, ":", escaped_sysname); |
3731acf1 | 361 | |
0f4ba83c LP |
362 | /* If there are multiple conflicting backlight devices, then |
363 | * their probing at boot-time might happen in any order. This | |
364 | * means the validity checking of the device then is not | |
365 | * reliable, since it might not see other devices conflicting | |
73e231ab | 366 | * with a specific backlight. To deal with this, we will |
0f4ba83c LP |
367 | * actively delete backlight state files at shutdown (where |
368 | * device probing should be complete), so that the validity | |
369 | * check at boot time doesn't have to be reliable. */ | |
370 | ||
b76388e1 | 371 | if (streq(argv[1], "load")) { |
3731acf1 | 372 | _cleanup_free_ char *value = NULL; |
4432b941 | 373 | bool clamp; |
3731acf1 | 374 | |
934ae16b | 375 | if (shall_restore_state() == 0) |
b76388e1 MB |
376 | return EXIT_SUCCESS; |
377 | ||
0f4ba83c LP |
378 | if (!validate_device(udev, device)) |
379 | return EXIT_SUCCESS; | |
380 | ||
4432b941 SR |
381 | clamp = shall_clamp(device); |
382 | ||
3731acf1 | 383 | r = read_one_line_file(saved, &value); |
4432b941 SR |
384 | if (r == -ENOENT) { |
385 | const char *curval; | |
3731acf1 | 386 | |
4432b941 SR |
387 | /* Fallback to clamping current brightness or exit early if |
388 | * clamping is not supported/enabled. */ | |
389 | if (!clamp) | |
1ca208fb | 390 | return EXIT_SUCCESS; |
3731acf1 | 391 | |
4432b941 SR |
392 | curval = udev_device_get_sysattr_value(device, "brightness"); |
393 | if (!curval) { | |
394 | log_warning("Failed to read 'brightness' attribute."); | |
395 | return EXIT_FAILURE; | |
396 | } | |
397 | ||
398 | value = strdup(curval); | |
399 | if (!value) { | |
400 | log_oom(); | |
401 | return EXIT_FAILURE; | |
402 | } | |
403 | } else if (r < 0) { | |
da927ba9 | 404 | log_error_errno(r, "Failed to read %s: %m", saved); |
1ca208fb | 405 | return EXIT_FAILURE; |
3731acf1 LP |
406 | } |
407 | ||
4432b941 | 408 | if (clamp) |
bca81be7 | 409 | clamp_brightness(device, &value, max_brightness); |
7b909d74 | 410 | |
3731acf1 LP |
411 | r = udev_device_set_sysattr_value(device, "brightness", value); |
412 | if (r < 0) { | |
c33b3297 | 413 | log_error_errno(r, "Failed to write system 'brightness' attribute: %m"); |
1ca208fb | 414 | return EXIT_FAILURE; |
3731acf1 LP |
415 | } |
416 | ||
417 | } else if (streq(argv[1], "save")) { | |
418 | const char *value; | |
419 | ||
0f4ba83c LP |
420 | if (!validate_device(udev, device)) { |
421 | unlink(saved); | |
422 | return EXIT_SUCCESS; | |
423 | } | |
424 | ||
3731acf1 LP |
425 | value = udev_device_get_sysattr_value(device, "brightness"); |
426 | if (!value) { | |
938d2699 | 427 | log_error("Failed to read system 'brightness' attribute"); |
1ca208fb | 428 | return EXIT_FAILURE; |
3731acf1 LP |
429 | } |
430 | ||
4c1fc3e4 | 431 | r = write_string_file(saved, value, WRITE_STRING_FILE_CREATE); |
3731acf1 | 432 | if (r < 0) { |
da927ba9 | 433 | log_error_errno(r, "Failed to write %s: %m", saved); |
1ca208fb | 434 | return EXIT_FAILURE; |
3731acf1 LP |
435 | } |
436 | ||
437 | } else { | |
438 | log_error("Unknown verb %s.", argv[1]); | |
1ca208fb | 439 | return EXIT_FAILURE; |
3731acf1 LP |
440 | } |
441 | ||
1ca208fb | 442 | return EXIT_SUCCESS; |
3731acf1 | 443 | } |