via_aux_edid.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Copyright 2011 Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
 4 */
 5/*
 6 * generic EDID driver
 7 */
 8
 9#include <linux/slab.h>
10#include <linux/fb.h>
11#include "via_aux.h"
12#include "../edid.h"
13
14
15static const char *name = "EDID";
16
17
18static void query_edid(struct via_aux_drv *drv)
19{
20	struct fb_monspecs *spec = drv->data;
21	unsigned char edid[EDID_LENGTH];
22	bool valid = false;
23
24	if (spec) {
25		fb_destroy_modedb(spec->modedb);
26	} else {
27		spec = kmalloc(sizeof(*spec), GFP_KERNEL);
28		if (!spec)
29			return;
30	}
31
32	spec->version = spec->revision = 0;
33	if (via_aux_read(drv, 0x00, edid, EDID_LENGTH)) {
34		fb_edid_to_monspecs(edid, spec);
35		valid = spec->version || spec->revision;
36	}
37
38	if (!valid) {
39		kfree(spec);
40		spec = NULL;
41	} else
42		printk(KERN_DEBUG "EDID: %s %s\n", spec->manufacturer, spec->monitor);
43
44	drv->data = spec;
45}
46
47static const struct fb_videomode *get_preferred_mode(struct via_aux_drv *drv)
48{
49	struct fb_monspecs *spec = drv->data;
50	int i;
51
52	if (!spec || !spec->modedb || !(spec->misc & FB_MISC_1ST_DETAIL))
53		return NULL;
54
55	for (i = 0; i < spec->modedb_len; i++) {
56		if (spec->modedb[i].flag & FB_MODE_IS_FIRST &&
57			spec->modedb[i].flag & FB_MODE_IS_DETAILED)
58			return &spec->modedb[i];
59	}
60
61	return NULL;
62}
63
64static void cleanup(struct via_aux_drv *drv)
65{
66	struct fb_monspecs *spec = drv->data;
67
68	if (spec)
69		fb_destroy_modedb(spec->modedb);
70}
71
72void via_aux_edid_probe(struct via_aux_bus *bus)
73{
74	struct via_aux_drv drv = {
75		.bus	=	bus,
76		.addr	=	0x50,
77		.name	=	name,
78		.cleanup	=	cleanup,
79		.get_preferred_mode	=	get_preferred_mode};
80
81	query_edid(&drv);
82
83	/* as EDID devices can be connected/disconnected just add the driver */
84	via_aux_add(&drv);
85}