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 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
30static 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}
79DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID,
80				PCI_CLASS_DISPLAY_VGA, 8, pci_fixup_video);