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 { 96 struct platform_device *pd; 97 struct resource res; 98 u64 base, size; 99 u32 length; 100 int ret; 101 102 /* 103 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the 104 * upper half of the base address. Assemble the address, then make sure 105 * it is valid and we can actually access it. 106 */ 107 base = si->lfb_base; 108 if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE) 109 base |= (u64)si->ext_lfb_base << 32; 110 if (!base || (u64)(resource_size_t)base != base) { 111 printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n"); 112 return ERR_PTR(-EINVAL); 113 } 114 115 /* 116 * Don't use lfb_size as IORESOURCE size, since it may contain the 117 * entire VMEM, and thus require huge mappings. Use just the part we 118 * need, that is, the part where the framebuffer is located. But verify 119 * that it does not exceed the advertised VMEM. 120 * Note that in case of VBE, the lfb_size is shifted by 16 bits for 121 * historical reasons. 122 */ 123 size = si->lfb_size; 124 if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) 125 size <<= 16; 126 length = mode->height * mode->stride; 127 if (length > size) { 128 printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n"); 129 return ERR_PTR(-EINVAL); 130 } 131 length = PAGE_ALIGN(length); 132 133 /* setup IORESOURCE_MEM as framebuffer memory */ 134 memset(&res, 0, sizeof(res)); 135 res.flags = IORESOURCE_MEM; 136 res.name = simplefb_resname; 137 res.start = base; 138 res.end = res.start + length - 1; 139 if (res.end <= res.start) 140 return ERR_PTR(-EINVAL); 141 142 pd = platform_device_alloc("simple-framebuffer", 0); 143 if (!pd) 144 return ERR_PTR(-ENOMEM); 145 146 sysfb_set_efifb_fwnode(pd); 147 148 ret = platform_device_add_resources(pd, &res, 1); 149 if (ret) 150 goto err_put_device; 151 152 ret = platform_device_add_data(pd, mode, sizeof(*mode)); 153 if (ret) 154 goto err_put_device; 155 156 ret = platform_device_add(pd); 157 if (ret) 158 goto err_put_device; 159 160 return pd; 161 162 err_put_device: 163 platform_device_put(pd); 164 165 return ERR_PTR(ret); 166 } 167