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 here and ignore lfb_depth. In the loop below, 55 * ignore simplefb formats with alpha bits, as EFI and VESA 56 * don't specify alpha channels. 57 */ 58 if (si->lfb_depth > 8) { 59 bits_per_pixel = max(max3(si->red_size + si->red_pos, 60 si->green_size + si->green_pos, 61 si->blue_size + si->blue_pos), 62 si->rsvd_size + si->rsvd_pos); 63 } else { 64 bits_per_pixel = si->lfb_depth; 65 } 66 67 for (i = 0; i < ARRAY_SIZE(formats); ++i) { 68 const struct simplefb_format *f = &formats[i]; 69 70 if (f->transp.length) 71 continue; /* transparent formats are unsupported by VESA/EFI */ 72 73 if (bits_per_pixel == f->bits_per_pixel && 74 si->red_size == f->red.length && 75 si->red_pos == f->red.offset && 76 si->green_size == f->green.length && 77 si->green_pos == f->green.offset && 78 si->blue_size == f->blue.length && 79 si->blue_pos == f->blue.offset) { 80 mode->format = f->name; 81 mode->width = si->lfb_width; 82 mode->height = si->lfb_height; 83 mode->stride = si->lfb_linelength; 84 return true; 85 } 86 } 87 88 return false; 89 } 90 91 __init struct platform_device *sysfb_create_simplefb(const struct screen_info *si, 92 const struct simplefb_platform_data *mode) 93 { 94 struct platform_device *pd; 95 struct resource res; 96 u64 base, size; 97 u32 length; 98 int ret; 99 100 /* 101 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the 102 * upper half of the base address. Assemble the address, then make sure 103 * it is valid and we can actually access it. 104 */ 105 base = si->lfb_base; 106 if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE) 107 base |= (u64)si->ext_lfb_base << 32; 108 if (!base || (u64)(resource_size_t)base != base) { 109 printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n"); 110 return ERR_PTR(-EINVAL); 111 } 112 113 /* 114 * Don't use lfb_size as IORESOURCE size, since it may contain the 115 * entire VMEM, and thus require huge mappings. Use just the part we 116 * need, that is, the part where the framebuffer is located. But verify 117 * that it does not exceed the advertised VMEM. 118 * Note that in case of VBE, the lfb_size is shifted by 16 bits for 119 * historical reasons. 120 */ 121 size = si->lfb_size; 122 if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) 123 size <<= 16; 124 length = mode->height * mode->stride; 125 if (length > size) { 126 printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n"); 127 return ERR_PTR(-EINVAL); 128 } 129 length = PAGE_ALIGN(length); 130 131 /* setup IORESOURCE_MEM as framebuffer memory */ 132 memset(&res, 0, sizeof(res)); 133 res.flags = IORESOURCE_MEM; 134 res.name = simplefb_resname; 135 res.start = base; 136 res.end = res.start + length - 1; 137 if (res.end <= res.start) 138 return ERR_PTR(-EINVAL); 139 140 pd = platform_device_alloc("simple-framebuffer", 0); 141 if (!pd) 142 return ERR_PTR(-ENOMEM); 143 144 sysfb_apply_efi_quirks(pd); 145 146 ret = platform_device_add_resources(pd, &res, 1); 147 if (ret) 148 goto err_put_device; 149 150 ret = platform_device_add_data(pd, mode, sizeof(*mode)); 151 if (ret) 152 goto err_put_device; 153 154 ret = platform_device_add(pd); 155 if (ret) 156 goto err_put_device; 157 158 return pd; 159 160 err_put_device: 161 platform_device_put(pd); 162 163 return ERR_PTR(ret); 164 } 165