1 /*
2 * Generic System Framebuffers on x86
3 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the Free
7 * Software Foundation; either version 2 of the License, or (at your option)
8 * any later version.
9 */
10
11 /*
12 * simple-framebuffer probing
13 * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
14 * If the mode is incompatible, we return "false" and let the caller create
15 * legacy nodes instead.
16 */
17
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/mm.h>
22 #include <linux/platform_data/simplefb.h>
23 #include <linux/platform_device.h>
24 #include <linux/screen_info.h>
25 #include <asm/sysfb.h>
26
27 static const char simplefb_resname[] = "BOOTFB";
28 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
29
30 /* try parsing x86 screen_info into a simple-framebuffer mode struct */
parse_mode(const struct screen_info * si,struct simplefb_platform_data * mode)31 __init bool parse_mode(const struct screen_info *si,
32 struct simplefb_platform_data *mode)
33 {
34 const struct simplefb_format *f;
35 __u8 type;
36 unsigned int i;
37
38 type = si->orig_video_isVGA;
39 if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
40 return false;
41
42 for (i = 0; i < ARRAY_SIZE(formats); ++i) {
43 f = &formats[i];
44 if (si->lfb_depth == f->bits_per_pixel &&
45 si->red_size == f->red.length &&
46 si->red_pos == f->red.offset &&
47 si->green_size == f->green.length &&
48 si->green_pos == f->green.offset &&
49 si->blue_size == f->blue.length &&
50 si->blue_pos == f->blue.offset &&
51 si->rsvd_size == f->transp.length &&
52 si->rsvd_pos == f->transp.offset) {
53 mode->format = f->name;
54 mode->width = si->lfb_width;
55 mode->height = si->lfb_height;
56 mode->stride = si->lfb_linelength;
57 return true;
58 }
59 }
60
61 return false;
62 }
63
create_simplefb(const struct screen_info * si,const struct simplefb_platform_data * mode)64 __init int create_simplefb(const struct screen_info *si,
65 const struct simplefb_platform_data *mode)
66 {
67 struct platform_device *pd;
68 struct resource res;
69 u64 base, size;
70 u32 length;
71
72 /*
73 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
74 * upper half of the base address. Assemble the address, then make sure
75 * it is valid and we can actually access it.
76 */
77 base = si->lfb_base;
78 if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
79 base |= (u64)si->ext_lfb_base << 32;
80 if (!base || (u64)(resource_size_t)base != base) {
81 printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
82 return -EINVAL;
83 }
84
85 /*
86 * Don't use lfb_size as IORESOURCE size, since it may contain the
87 * entire VMEM, and thus require huge mappings. Use just the part we
88 * need, that is, the part where the framebuffer is located. But verify
89 * that it does not exceed the advertised VMEM.
90 * Note that in case of VBE, the lfb_size is shifted by 16 bits for
91 * historical reasons.
92 */
93 size = si->lfb_size;
94 if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
95 size <<= 16;
96 length = mode->height * mode->stride;
97 length = PAGE_ALIGN(length);
98 if (length > size) {
99 printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
100 return -EINVAL;
101 }
102
103 /* setup IORESOURCE_MEM as framebuffer memory */
104 memset(&res, 0, sizeof(res));
105 res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
106 res.name = simplefb_resname;
107 res.start = base;
108 res.end = res.start + length - 1;
109 if (res.end <= res.start)
110 return -EINVAL;
111
112 pd = platform_device_register_resndata(NULL, "simple-framebuffer", 0,
113 &res, 1, mode, sizeof(*mode));
114 return PTR_ERR_OR_ZERO(pd);
115 }
116