1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Generic System Framebuffers
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 <linux/sysfb.h>
22 
23 static const char simplefb_resname[] = "BOOTFB";
24 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
25 
26 /* try parsing screen_info into a simple-framebuffer mode struct */
27 __init bool sysfb_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 
60 __init int sysfb_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 	int ret;
68 
69 	/*
70 	 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
71 	 * upper half of the base address. Assemble the address, then make sure
72 	 * it is valid and we can actually access it.
73 	 */
74 	base = si->lfb_base;
75 	if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
76 		base |= (u64)si->ext_lfb_base << 32;
77 	if (!base || (u64)(resource_size_t)base != base) {
78 		printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
79 		return -EINVAL;
80 	}
81 
82 	/*
83 	 * Don't use lfb_size as IORESOURCE size, since it may contain the
84 	 * entire VMEM, and thus require huge mappings. Use just the part we
85 	 * need, that is, the part where the framebuffer is located. But verify
86 	 * that it does not exceed the advertised VMEM.
87 	 * Note that in case of VBE, the lfb_size is shifted by 16 bits for
88 	 * historical reasons.
89 	 */
90 	size = si->lfb_size;
91 	if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
92 		size <<= 16;
93 	length = mode->height * mode->stride;
94 	if (length > size) {
95 		printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
96 		return -EINVAL;
97 	}
98 	length = PAGE_ALIGN(length);
99 
100 	/* setup IORESOURCE_MEM as framebuffer memory */
101 	memset(&res, 0, sizeof(res));
102 	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
103 	res.name = simplefb_resname;
104 	res.start = base;
105 	res.end = res.start + length - 1;
106 	if (res.end <= res.start)
107 		return -EINVAL;
108 
109 	pd = platform_device_alloc("simple-framebuffer", 0);
110 	if (!pd)
111 		return -ENOMEM;
112 
113 	sysfb_apply_efi_quirks(pd);
114 
115 	ret = platform_device_add_resources(pd, &res, 1);
116 	if (ret)
117 		return ret;
118 
119 	ret = platform_device_add_data(pd, mode, sizeof(*mode));
120 	if (ret)
121 		return ret;
122 
123 	return platform_device_add(pd);
124 }
125