arch/x86/kernel/sysfb_simplefb.c

   1 /*
   2  * Generic System Framebuffers on x86
   3  * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the Free
   7  * Software Foundation; either version 2 of the License, or (at your option)
   8  * any later version.
   9  */
  10
  11 /*
  12  * simple-framebuffer probing
  13  * Try to convert "screen_info" into a "simple-framebuffer" compatible mode.
  14  * If the mode is incompatible, we return "false" and let the caller create
  15  * legacy nodes instead.
  16  */
  17
  18 #include <linux/err.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/mm.h>
  22 #include <linux/platform_data/simplefb.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/screen_info.h>
  25 #include <asm/sysfb.h>
  26
  27 static const char simplefb_resname[] = "BOOTFB";
  28 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
  29
  30 /* try parsing x86 screen_info into a simple-framebuffer mode struct */
  31 __init bool parse_mode(const struct screen_info *si,
  32                        struct simplefb_platform_data *mode)
  33 {
  34         const struct simplefb_format *f;
  35         __u8 type;
  36         unsigned int i;
  37
  38         type = si->orig_video_isVGA;
  39         if (type != VIDEO_TYPE_VLFB && type != VIDEO_TYPE_EFI)
  40                 return false;
  41
  42         for (i = 0; i < ARRAY_SIZE(formats); ++i) {
  43                 f = &formats[i];
  44                 if (si->lfb_depth == f->bits_per_pixel &&
  45                     si->red_size == f->red.length &&
  46                     si->red_pos == f->red.offset &&
  47                     si->green_size == f->green.length &&
  48                     si->green_pos == f->green.offset &&
  49                     si->blue_size == f->blue.length &&
  50                     si->blue_pos == f->blue.offset &&
  51                     si->rsvd_size == f->transp.length &&
  52                     si->rsvd_pos == f->transp.offset) {
  53                         mode->format = f->name;
  54                         mode->width = si->lfb_width;
  55                         mode->height = si->lfb_height;
  56                         mode->stride = si->lfb_linelength;
  57                         return true;
  58                 }
  59         }
  60
  61         return false;
  62 }
  63
  64 __init int create_simplefb(const struct screen_info *si,
  65                            const struct simplefb_platform_data *mode)
  66 {
  67         struct platform_device *pd;
  68         struct resource res;
  69         u64 base, size;
  70         u32 length;
  71
  72         /*
  73          * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
  74          * upper half of the base address. Assemble the address, then make sure
  75          * it is valid and we can actually access it.
  76          */
  77         base = si->lfb_base;
  78         if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
  79                 base |= (u64)si->ext_lfb_base << 32;
  80         if (!base || (u64)(resource_size_t)base != base) {
  81                 printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");
  82                 return -EINVAL;
  83         }
  84
  85         /*
  86          * Don't use lfb_size as IORESOURCE size, since it may contain the
  87          * entire VMEM, and thus require huge mappings. Use just the part we
  88          * need, that is, the part where the framebuffer is located. But verify
  89          * that it does not exceed the advertised VMEM.
  90          * Note that in case of VBE, the lfb_size is shifted by 16 bits for
  91          * historical reasons.
  92          */
  93         size = si->lfb_size;
  94         if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
  95                 size <<= 16;
  96         length = mode->height * mode->stride;
  97         length = PAGE_ALIGN(length);
  98         if (length > size) {
  99                 printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
 100                 return -EINVAL;
 101         }
 102
 103         /* setup IORESOURCE_MEM as framebuffer memory */
 104         memset(&res, 0, sizeof(res));
 105         res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 106         res.name = simplefb_resname;
 107         res.start = base;
 108         res.end = res.start + length - 1;
 109         if (res.end <= res.start)
 110                 return -EINVAL;
 111
 112         pd = platform_device_register_resndata(NULL, "simple-framebuffer", 0,
 113                                                &res, 1, mode, sizeof(*mode));
 114         return PTR_ERR_OR_ZERO(pd);
 115 }