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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Generic System Framebuffers4 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>5 */6 7/*8 * simple-framebuffer probing9 * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.10 * If the mode is incompatible, we return "false" and let the caller create11 * 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 23static const char simplefb_resname[] = "BOOTFB";24static 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 is40 * inconsistent:41 *42 * - DRM format info specifies depth as the number of color43 * bits; including alpha, but not including filler bits.44 * - Linux' EFI platform code computes lfb_depth from the45 * individual color channels, including the reserved bits.46 * - VBE 1.1 defines lfb_depth for XRGB1555 as 16, but later47 * versions use 15.48 * - On the kernel command line, 'bpp' of 32 is usually49 * XRGB8888 including the filler bits, but 15 is XRGB155550 * 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 compute54 * bits_per_pixel from the color bits, reserved bits and55 * reported lfb_depth, whichever is highest. In the loop below,56 * ignore simplefb formats with alpha bits, as EFI and VESA57 * 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 the105 * upper half of the base address. Assemble the address, then make sure106 * 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(-EINVAL);114 }115 116 /*117 * Don't use lfb_size as IORESOURCE size, since it may contain the118 * entire VMEM, and thus require huge mappings. Use just the part we119 * need, that is, the part where the framebuffer is located. But verify120 * that it does not exceed the advertised VMEM.121 * Note that in case of VBE, the lfb_size is shifted by 16 bits for122 * 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(-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(-EINVAL);142 143 pd = platform_device_alloc("simple-framebuffer", 0);144 if (!pd)145 return ERR_PTR(-ENOMEM);146 147 pd->dev.parent = parent;148 149 sysfb_set_efifb_fwnode(pd);150 151 ret = platform_device_add_resources(pd, &res, 1);152 if (ret)153 goto err_put_device;154 155 ret = platform_device_add_data(pd, mode, sizeof(*mode));156 if (ret)157 goto err_put_device;158 159 ret = platform_device_add(pd);160 if (ret)161 goto err_put_device;162 163 return pd;164 165err_put_device:166 platform_device_put(pd);167 168 return ERR_PTR(ret);169}170