1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/pci.h>
4#include <linux/printk.h>
5#include <linux/screen_info.h>
6#include <linux/string.h>
7
8static struct pci_dev *screen_info_lfb_pdev;
9static size_t screen_info_lfb_bar;
10static resource_size_t screen_info_lfb_offset;
11static struct resource screen_info_lfb_res = DEFINE_RES_MEM(0, 0);
12
13static bool __screen_info_relocation_is_valid(const struct screen_info *si, struct resource *pr)
14{
15	u64 size = __screen_info_lfb_size(si, screen_info_video_type(si));
16
17	if (screen_info_lfb_offset > resource_size(pr))
18		return false;
19	if (size > resource_size(pr))
20		return false;
21	if (resource_size(pr) - size < screen_info_lfb_offset)
22		return false;
23
24	return true;
25}
26
27void screen_info_apply_fixups(void)
28{
29	struct screen_info *si = &screen_info;
30
31	if (screen_info_lfb_pdev) {
32		struct resource *pr = &screen_info_lfb_pdev->resource[screen_info_lfb_bar];
33
34		if (pr->start != screen_info_lfb_res.start) {
35			if (__screen_info_relocation_is_valid(si, pr)) {
36				/*
37				 * Only update base if we have an actual
38				 * relocation to a valid I/O range.
39				 */
40				__screen_info_set_lfb_base(si, pr->start + screen_info_lfb_offset);
41				pr_info("Relocating firmware framebuffer to offset %pa[d] within %pr\n",
42					&screen_info_lfb_offset, pr);
43			} else {
44				pr_warn("Invalid relocating, disabling firmware framebuffer\n");
45			}
46		}
47	}
48}
49
50static void screen_info_fixup_lfb(struct pci_dev *pdev)
51{
52	unsigned int type;
53	struct resource res[SCREEN_INFO_MAX_RESOURCES];
54	size_t i, numres;
55	int ret;
56	const struct screen_info *si = &screen_info;
57
58	if (screen_info_lfb_pdev)
59		return; // already found
60
61	type = screen_info_video_type(si);
62	if (type != VIDEO_TYPE_EFI)
63		return; // only applies to EFI
64
65	ret = screen_info_resources(si, res, ARRAY_SIZE(res));
66	if (ret < 0)
67		return;
68	numres = ret;
69
70	for (i = 0; i < numres; ++i) {
71		struct resource *r = &res[i];
72		const struct resource *pr;
73
74		if (!(r->flags & IORESOURCE_MEM))
75			continue;
76		pr = pci_find_resource(pdev, r);
77		if (!pr)
78			continue;
79
80		/*
81		 * We've found a PCI device with the framebuffer
82		 * resource. Store away the parameters to track
83		 * relocation of the framebuffer aperture.
84		 */
85		screen_info_lfb_pdev = pdev;
86		screen_info_lfb_bar = pr - pdev->resource;
87		screen_info_lfb_offset = r->start - pr->start;
88		memcpy(&screen_info_lfb_res, r, sizeof(screen_info_lfb_res));
89	}
90}
91DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY, 16,
92			       screen_info_fixup_lfb);
93
94static struct pci_dev *__screen_info_pci_dev(struct resource *res)
95{
96	struct pci_dev *pdev = NULL;
97	const struct resource *r = NULL;
98
99	if (!(res->flags & IORESOURCE_MEM))
100		return NULL;
101
102	while (!r && (pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev))) {
103		r = pci_find_resource(pdev, res);
104	}
105
106	return pdev;
107}
108
109/**
110 * screen_info_pci_dev() - Return PCI parent device that contains screen_info's framebuffer
111 * @si: the screen_info
112 *
113 * Returns:
114 * The screen_info's parent device or NULL on success, or a pointer-encoded
115 * errno value otherwise. The value NULL is not an error. It signals that no
116 * PCI device has been found.
117 */
118struct pci_dev *screen_info_pci_dev(const struct screen_info *si)
119{
120	struct resource res[SCREEN_INFO_MAX_RESOURCES];
121	ssize_t i, numres;
122
123	numres = screen_info_resources(si, res, ARRAY_SIZE(res));
124	if (numres < 0)
125		return ERR_PTR(numres);
126
127	for (i = 0; i < numres; ++i) {
128		struct pci_dev *pdev = __screen_info_pci_dev(&res[i]);
129
130		if (pdev)
131			return pdev;
132	}
133
134	return NULL;
135}
136EXPORT_SYMBOL(screen_info_pci_dev);
137