arch/x86/kernel/sysfb.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 support for x86 systems
  13  * Create a platform-device for any available boot framebuffer. The
  14  * simple-framebuffer platform device is already available on DT systems, so
  15  * this module parses the global "screen_info" object and creates a suitable
  16  * platform device compatible with the "simple-framebuffer" DT object. If
  17  * the framebuffer is incompatible, we instead create a legacy
  18  * "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and
  19  * pass the screen_info as platform_data. This allows legacy drivers
  20  * to pick these devices up without messing with simple-framebuffer drivers.
  21  * The global "screen_info" is still valid at all times.
  22  *
  23  * If CONFIG_X86_SYSFB is not selected, we never register "simple-framebuffer"
  24  * platform devices, but only use legacy framebuffer devices for
  25  * backwards compatibility.
  26  *
  27  * TODO: We set the dev_id field of all platform-devices to 0. This allows
  28  * other x86 OF/DT parsers to create such devices, too. However, they must
  29  * start at offset 1 for this to work.
  30  */
  31
  32 #include <linux/err.h>
  33 #include <linux/init.h>
  34 #include <linux/kernel.h>
  35 #include <linux/mm.h>
  36 #include <linux/platform_data/simplefb.h>
  37 #include <linux/platform_device.h>
  38 #include <linux/screen_info.h>
  39 #include <asm/sysfb.h>
  40
  41 static __init int sysfb_init(void)
  42 {
  43         struct screen_info *si = &screen_info;
  44         struct simplefb_platform_data mode;
  45         struct platform_device *pd;
  46         const char *name;
  47         bool compatible;
  48         int ret;
  49
  50         sysfb_apply_efi_quirks();
  51
  52         /* try to create a simple-framebuffer device */
  53         compatible = parse_mode(si, &mode);
  54         if (compatible) {
  55                 ret = create_simplefb(si, &mode);
  56                 if (!ret)
  57                         return 0;
  58         }
  59
  60         /* if the FB is incompatible, create a legacy framebuffer device */
  61         if (si->orig_video_isVGA == VIDEO_TYPE_EFI)
  62                 name = "efi-framebuffer";
  63         else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
  64                 name = "vesa-framebuffer";
  65         else
  66                 name = "platform-framebuffer";
  67
  68         pd = platform_device_register_resndata(NULL, name, 0,
  69                                                NULL, 0, si, sizeof(*si));
  70         return PTR_ERR_OR_ZERO(pd);
  71 }
  72
  73 /* must execute after PCI subsystem for EFI quirks */
  74 device_initcall(sysfb_init);