xref: /freebsd-src/sys/compat/linuxkpi/common/src/linux_cmdline.c (revision c89d94ad5d95fd15e891b2723caae8a6104ee153)
1*c89d94adSVladimir Kondratyev /*-
2*c89d94adSVladimir Kondratyev  * Copyright (c) 2022 Beckhoff Automation GmbH & Co. KG
3*c89d94adSVladimir Kondratyev  *
4*c89d94adSVladimir Kondratyev  * Redistribution and use in source and binary forms, with or without
5*c89d94adSVladimir Kondratyev  * modification, are permitted provided that the following conditions
6*c89d94adSVladimir Kondratyev  * are met:
7*c89d94adSVladimir Kondratyev  * 1. Redistributions of source code must retain the above copyright
8*c89d94adSVladimir Kondratyev  *    notice, this list of conditions and the following disclaimer.
9*c89d94adSVladimir Kondratyev  * 2. Redistributions in binary form must reproduce the above copyright
10*c89d94adSVladimir Kondratyev  *    notice, this list of conditions and the following disclaimer in the
11*c89d94adSVladimir Kondratyev  *    documentation and/or other materials provided with the distribution.
12*c89d94adSVladimir Kondratyev  *
13*c89d94adSVladimir Kondratyev  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14*c89d94adSVladimir Kondratyev  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15*c89d94adSVladimir Kondratyev  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16*c89d94adSVladimir Kondratyev  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17*c89d94adSVladimir Kondratyev  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18*c89d94adSVladimir Kondratyev  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19*c89d94adSVladimir Kondratyev  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20*c89d94adSVladimir Kondratyev  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21*c89d94adSVladimir Kondratyev  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22*c89d94adSVladimir Kondratyev  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23*c89d94adSVladimir Kondratyev  * SUCH DAMAGE.
24*c89d94adSVladimir Kondratyev  *
25*c89d94adSVladimir Kondratyev  */
26*c89d94adSVladimir Kondratyev 
27*c89d94adSVladimir Kondratyev #include <sys/param.h>
28*c89d94adSVladimir Kondratyev #include <sys/systm.h>
29*c89d94adSVladimir Kondratyev 
30*c89d94adSVladimir Kondratyev #include <video/cmdline.h>
31*c89d94adSVladimir Kondratyev 
32*c89d94adSVladimir Kondratyev const char *
33*c89d94adSVladimir Kondratyev video_get_options(const char *connector_name)
34*c89d94adSVladimir Kondratyev {
35*c89d94adSVladimir Kondratyev 	char tunable[64];
36*c89d94adSVladimir Kondratyev 	const char *options;
37*c89d94adSVladimir Kondratyev 
38*c89d94adSVladimir Kondratyev 	/*
39*c89d94adSVladimir Kondratyev 	 * A user may use loader tunables to set a specific mode for the
40*c89d94adSVladimir Kondratyev 	 * console. Tunables are read in the following order:
41*c89d94adSVladimir Kondratyev 	 *     1. kern.vt.fb.modes.$connector_name
42*c89d94adSVladimir Kondratyev 	 *     2. kern.vt.fb.default_mode
43*c89d94adSVladimir Kondratyev 	 *
44*c89d94adSVladimir Kondratyev 	 * Example of a mode specific to the LVDS connector:
45*c89d94adSVladimir Kondratyev 	 *     kern.vt.fb.modes.LVDS="1024x768"
46*c89d94adSVladimir Kondratyev 	 *
47*c89d94adSVladimir Kondratyev 	 * Example of a mode applied to all connectors not having a
48*c89d94adSVladimir Kondratyev 	 * connector-specific mode:
49*c89d94adSVladimir Kondratyev 	 *     kern.vt.fb.default_mode="640x480"
50*c89d94adSVladimir Kondratyev 	 */
51*c89d94adSVladimir Kondratyev 	snprintf(tunable, sizeof(tunable), "kern.vt.fb.modes.%s",
52*c89d94adSVladimir Kondratyev 	    connector_name);
53*c89d94adSVladimir Kondratyev 	if (bootverbose) {
54*c89d94adSVladimir Kondratyev 		printf("[drm] Connector %s: get mode from tunables:\n", connector_name);
55*c89d94adSVladimir Kondratyev 		printf("[drm]  - %s\n", tunable);
56*c89d94adSVladimir Kondratyev 		printf("[drm]  - kern.vt.fb.default_mode\n");
57*c89d94adSVladimir Kondratyev 	}
58*c89d94adSVladimir Kondratyev 	options = kern_getenv(tunable);
59*c89d94adSVladimir Kondratyev 	if (options == NULL)
60*c89d94adSVladimir Kondratyev 		options = kern_getenv("kern.vt.fb.default_mode");
61*c89d94adSVladimir Kondratyev 
62*c89d94adSVladimir Kondratyev 	return (options);
63*c89d94adSVladimir Kondratyev }
64