LXR linux/arch/x86/kernel/sysfb

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Generic System Framebuffers on x86
   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 <asm/sysfb.h>
  22
  23static const char simplefb_resname[] = "BOOTFB";
  24static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
  25
  26/* try parsing x86 screen_info into a simple-framebuffer mode struct */
  27__init bool 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 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
  68        /*
  69         * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
  70         * upper half of the base address. Assemble the address, then make sure
  71         * it is valid and we can actually access it.
  72         */
  73        base = si->lfb_base;
  74        if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
  75                base |= (u64)si->ext_lfb_base << 32;
  76        if (!base || (u64)(resource_size_t)base != base) {
  77                printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
  78                return -EINVAL;
  79        }
  80
  81        /*
  82         * Don't use lfb_size as IORESOURCE size, since it may contain the
  83         * entire VMEM, and thus require huge mappings. Use just the part we
  84         * need, that is, the part where the framebuffer is located. But verify
  85         * that it does not exceed the advertised VMEM.
  86         * Note that in case of VBE, the lfb_size is shifted by 16 bits for
  87         * historical reasons.
  88         */
  89        size = si->lfb_size;
  90        if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
  91                size <<= 16;
  92        length = mode->height * mode->stride;
  93        length = PAGE_ALIGN(length);
  94        if (length > size) {
  95                printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
  96                return -EINVAL;
  97        }
  98
  99        /* setup IORESOURCE_MEM as framebuffer memory */
 100        memset(&res, 0, sizeof(res));
 101        res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 102        res.name = simplefb_resname;
 103        res.start = base;
 104        res.end = res.start + length - 1;
 105        if (res.end <= res.start)
 106                return -EINVAL;
 107
 108        pd = platform_device_register_resndata(NULL, "simple-framebuffer", 0,
 109                                               &res, 1, mode, sizeof(*mode));
 110        return PTR_ERR_OR_ZERO(pd);
 111}
 112