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 
15 static const char *name = "EDID";
16 
17 
18 static 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 
47 static 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 
64 static 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 
72 void 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 }
86