arch/ia64/pci/fixup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Exceptions for specific devices. Usually work-arounds for fatal design flaws.
   4  * Derived from fixup.c of i386 tree.
   5  */
   6
   7 #include <linux/pci.h>
   8 #include <linux/init.h>
   9 #include <linux/vgaarb.h>
  10 #include <linux/screen_info.h>
  11 #include <asm/uv/uv.h>
  12
  13 /*
  14  * Fixup to mark boot BIOS video selected by BIOS before it changes
  15  *
  16  * From information provided by "Jon Smirl" <jonsmirl@gmail.com>
  17  *
  18  * The standard boot ROM sequence for an x86 machine uses the BIOS
  19  * to select an initial video card for boot display. This boot video
  20  * card will have its BIOS copied to 0xC0000 in system RAM.
  21  * IORESOURCE_ROM_SHADOW is used to associate the boot video
  22  * card with this copy. On laptops this copy has to be used since
  23  * the main ROM may be compressed or combined with another image.
  24  * See pci_map_rom() for use of this flag. Before marking the device
  25  * with IORESOURCE_ROM_SHADOW check if a vga_default_device is already set
  26  * by either arch code or vga-arbitration; if so only apply the fixup to this
  27  * already-determined primary video card.
  28  */
  29
  30 static void pci_fixup_video(struct pci_dev *pdev)
  31 {
  32         struct pci_dev *bridge;
  33         struct pci_bus *bus;
  34         u16 config;
  35         struct resource *res;
  36
  37         if (is_uv_system())
  38                 return;
  39         /* Maybe, this machine supports legacy memory map. */
  40
  41         /* Is VGA routed to us? */
  42         bus = pdev->bus;
  43         while (bus) {
  44                 bridge = bus->self;
  45
  46                 /*
  47                  * From information provided by
  48                  * "David Miller" <davem@davemloft.net>
  49                  * The bridge control register is valid for PCI header
  50                  * type BRIDGE, or CARDBUS. Host to PCI controllers use
  51                  * PCI header type NORMAL.
  52                  */
  53                 if (bridge && (pci_is_bridge(bridge))) {
  54                         pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
  55                                                 &config);
  56                         if (!(config & PCI_BRIDGE_CTL_VGA))
  57                                 return;
  58                 }
  59                 bus = bus->parent;
  60         }
  61         if (!vga_default_device() || pdev == vga_default_device()) {
  62                 pci_read_config_word(pdev, PCI_COMMAND, &config);
  63                 if (config & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
  64                         res = &pdev->resource[PCI_ROM_RESOURCE];
  65
  66                         pci_disable_rom(pdev);
  67                         if (res->parent)
  68                                 release_resource(res);
  69
  70                         res->start = 0xC0000;
  71                         res->end = res->start + 0x20000 - 1;
  72                         res->flags = IORESOURCE_MEM | IORESOURCE_ROM_SHADOW |
  73                                      IORESOURCE_PCI_FIXED;
  74                         dev_info(&pdev->dev, "Video device with shadowed ROM at %pR\n",
  75                                  res);
  76                 }
  77         }
  78 }
  79 DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID,
  80                                 PCI_CLASS_DISPLAY_VGA, 8, pci_fixup_video);