1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Generic System Framebuffers on x86
4 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
5 */
6
7 /*
8 * simple-framebuffer probing
9 * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
10 * If the mode is incompatible, we return "false" and let the caller create
11 * legacy nodes instead.
12 */
13
14 #include <linux/err.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/mm.h>
18 #include <linux/platform_data/simplefb.h>
19 #include <linux/platform_device.h>
20 #include <linux/screen_info.h>
21 #include <asm/sysfb.h>
22
23 static const char simplefb_resname[] = "BOOTFB";
24 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
25
26 /* try parsing x86 screen_info into a simple-framebuffer mode struct */
parse_mode(const struct screen_info * si,struct simplefb_platform_data * mode)27 __init bool parse_mode(const struct screen_info *si,
28 struct simplefb_platform_data *mode)
29 {
30 const struct simplefb_format *f;
31 __u8 type;
32 unsigned int i;
33
34 type = si->orig_video_isVGA;
35 if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
36 return false;
37
38 for (i = 0; i < ARRAY_SIZE(formats); ++i) {
39 f = &formats[i];
40 if (si->lfb_depth == f->bits_per_pixel &&
41 si->red_size == f->red.length &&
42 si->red_pos == f->red.offset &&
43 si->green_size == f->green.length &&
44 si->green_pos == f->green.offset &&
45 si->blue_size == f->blue.length &&
46 si->blue_pos == f->blue.offset &&
47 si->rsvd_size == f->transp.length &&
48 si->rsvd_pos == f->transp.offset) {
49 mode->format = f->name;
50 mode->width = si->lfb_width;
51 mode->height = si->lfb_height;
52 mode->stride = si->lfb_linelength;
53 return true;
54 }
55 }
56
57 return false;
58 }
59
create_simplefb(const struct screen_info * si,const struct simplefb_platform_data * mode)60 __init int create_simplefb(const struct screen_info *si,
61 const struct simplefb_platform_data *mode)
62 {
63 struct platform_device *pd;
64 struct resource res;
65 u64 base, size;
66 u32 length;
67
68 /*
69 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
70 * upper half of the base address. Assemble the address, then make sure
71 * it is valid and we can actually access it.
72 */
73 base = si->lfb_base;
74 if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
75 base |= (u64)si->ext_lfb_base << 32;
76 if (!base || (u64)(resource_size_t)base != base) {
77 printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
78 return -EINVAL;
79 }
80
81 /*
82 * Don't use lfb_size as IORESOURCE size, since it may contain the
83 * entire VMEM, and thus require huge mappings. Use just the part we
84 * need, that is, the part where the framebuffer is located. But verify
85 * that it does not exceed the advertised VMEM.
86 * Note that in case of VBE, the lfb_size is shifted by 16 bits for
87 * historical reasons.
88 */
89 size = si->lfb_size;
90 if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
91 size <<= 16;
92 length = mode->height * mode->stride;
93 if (length > size) {
94 printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
95 return -EINVAL;
96 }
97 length = PAGE_ALIGN(length);
98
99 /* setup IORESOURCE_MEM as framebuffer memory */
100 memset(&res, 0, sizeof(res));
101 res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
102 res.name = simplefb_resname;
103 res.start = base;
104 res.end = res.start + length - 1;
105 if (res.end <= res.start)
106 return -EINVAL;
107
108 pd = platform_device_register_resndata(NULL, "simple-framebuffer", 0,
109 &res, 1, mode, sizeof(*mode));
110 return PTR_ERR_OR_ZERO(pd);
111 }
112
