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 | __u8 type; |
31 | u32 bits_per_pixel; |
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 | /* |
39 | * The meaning of depth and bpp for direct-color formats is |
40 | * inconsistent: |
41 | * |
42 | * - DRM format info specifies depth as the number of color |
43 | * bits; including alpha, but not including filler bits. |
44 | * - Linux' EFI platform code computes lfb_depth from the |
45 | * individual color channels, including the reserved bits. |
46 | * - VBE 1.1 defines lfb_depth for XRGB1555 as 16, but later |
47 | * versions use 15. |
48 | * - On the kernel command line, 'bpp' of 32 is usually |
49 | * XRGB8888 including the filler bits, but 15 is XRGB1555 |
50 | * not including the filler bit. |
51 | * |
52 | * It's not easily possible to fix this in struct screen_info, |
53 | * as this could break UAPI. The best solution is to compute |
54 | * bits_per_pixel from the color bits, reserved bits and |
55 | * reported lfb_depth, whichever is highest. In the loop below, |
56 | * ignore simplefb formats with alpha bits, as EFI and VESA |
57 | * don't specify alpha channels. |
58 | */ |
59 | if (si->lfb_depth > 8) { |
60 | bits_per_pixel = max(max3(si->red_size + si->red_pos, |
61 | si->green_size + si->green_pos, |
62 | si->blue_size + si->blue_pos), |
63 | si->rsvd_size + si->rsvd_pos); |
64 | bits_per_pixel = max_t(u32, bits_per_pixel, si->lfb_depth); |
65 | } else { |
66 | bits_per_pixel = si->lfb_depth; |
67 | } |
68 | |
69 | for (i = 0; i < ARRAY_SIZE(formats); ++i) { |
70 | const struct simplefb_format *f = &formats[i]; |
71 | |
72 | if (f->transp.length) |
73 | continue; /* transparent formats are unsupported by VESA/EFI */ |
74 | |
75 | if (bits_per_pixel == f->bits_per_pixel && |
76 | si->red_size == f->red.length && |
77 | si->red_pos == f->red.offset && |
78 | si->green_size == f->green.length && |
79 | si->green_pos == f->green.offset && |
80 | si->blue_size == f->blue.length && |
81 | si->blue_pos == f->blue.offset) { |
82 | mode->format = f->name; |
83 | mode->width = si->lfb_width; |
84 | mode->height = si->lfb_height; |
85 | mode->stride = si->lfb_linelength; |
86 | return true; |
87 | } |
88 | } |
89 | |
90 | return false; |
91 | } |
92 | |
93 | __init struct platform_device *sysfb_create_simplefb(const struct screen_info *si, |
94 | const struct simplefb_platform_data *mode, |
95 | struct device *parent) |
96 | { |
97 | struct platform_device *pd; |
98 | struct resource res; |
99 | u64 base, size; |
100 | u32 length; |
101 | int ret; |
102 | |
103 | /* |
104 | * If the 64BIT_BASE capability is set, ext_lfb_base will contain the |
105 | * upper half of the base address. Assemble the address, then make sure |
106 | * it is valid and we can actually access it. |
107 | */ |
108 | base = si->lfb_base; |
109 | if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE) |
110 | base |= (u64)si->ext_lfb_base << 32; |
111 | if (!base || (u64)(resource_size_t)base != base) { |
112 | printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n" ); |
113 | return ERR_PTR(error: -EINVAL); |
114 | } |
115 | |
116 | /* |
117 | * Don't use lfb_size as IORESOURCE size, since it may contain the |
118 | * entire VMEM, and thus require huge mappings. Use just the part we |
119 | * need, that is, the part where the framebuffer is located. But verify |
120 | * that it does not exceed the advertised VMEM. |
121 | * Note that in case of VBE, the lfb_size is shifted by 16 bits for |
122 | * historical reasons. |
123 | */ |
124 | size = si->lfb_size; |
125 | if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) |
126 | size <<= 16; |
127 | length = mode->height * mode->stride; |
128 | if (length > size) { |
129 | printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n" ); |
130 | return ERR_PTR(error: -EINVAL); |
131 | } |
132 | length = PAGE_ALIGN(length); |
133 | |
134 | /* setup IORESOURCE_MEM as framebuffer memory */ |
135 | memset(&res, 0, sizeof(res)); |
136 | res.flags = IORESOURCE_MEM; |
137 | res.name = simplefb_resname; |
138 | res.start = base; |
139 | res.end = res.start + length - 1; |
140 | if (res.end <= res.start) |
141 | return ERR_PTR(error: -EINVAL); |
142 | |
143 | pd = platform_device_alloc(name: "simple-framebuffer" , id: 0); |
144 | if (!pd) |
145 | return ERR_PTR(error: -ENOMEM); |
146 | |
147 | pd->dev.parent = parent; |
148 | |
149 | sysfb_set_efifb_fwnode(pd); |
150 | |
151 | ret = platform_device_add_resources(pdev: pd, res: &res, num: 1); |
152 | if (ret) |
153 | goto err_put_device; |
154 | |
155 | ret = platform_device_add_data(pdev: pd, data: mode, size: sizeof(*mode)); |
156 | if (ret) |
157 | goto err_put_device; |
158 | |
159 | ret = platform_device_add(pdev: pd); |
160 | if (ret) |
161 | goto err_put_device; |
162 | |
163 | return pd; |
164 | |
165 | err_put_device: |
166 | platform_device_put(pdev: pd); |
167 | |
168 | return ERR_PTR(error: ret); |
169 | } |
170 | |