1// SPDX-License-Identifier: GPL-2.0-only
2
3#define pr_fmt(fmt) "efi: " fmt
4
5#include <linux/module.h>
6#include <linux/init.h>
7#include <linux/efi.h>
8#include <linux/libfdt.h>
9#include <linux/of_fdt.h>
10
11#include <asm/unaligned.h>
12
13enum {
14	SYSTAB,
15	MMBASE,
16	MMSIZE,
17	DCSIZE,
18	DCVERS,
19
20	PARAMCOUNT
21};
22
23static __initconst const char name[][22] = {
24	[SYSTAB] = "System Table         ",
25	[MMBASE] = "MemMap Address       ",
26	[MMSIZE] = "MemMap Size          ",
27	[DCSIZE] = "MemMap Desc. Size    ",
28	[DCVERS] = "MemMap Desc. Version ",
29};
30
31static __initconst const struct {
32	const char	path[17];
33	const char	params[PARAMCOUNT][26];
34} dt_params[] = {
35	{
36#ifdef CONFIG_XEN    //  <-------17------>
37		.path = "/hypervisor/uefi",
38		.params = {
39			[SYSTAB] = "xen,uefi-system-table",
40			[MMBASE] = "xen,uefi-mmap-start",
41			[MMSIZE] = "xen,uefi-mmap-size",
42			[DCSIZE] = "xen,uefi-mmap-desc-size",
43			[DCVERS] = "xen,uefi-mmap-desc-ver",
44		}
45	}, {
46#endif
47		.path = "/chosen",
48		.params = {	//  <-----------26----------->
49			[SYSTAB] = "linux,uefi-system-table",
50			[MMBASE] = "linux,uefi-mmap-start",
51			[MMSIZE] = "linux,uefi-mmap-size",
52			[DCSIZE] = "linux,uefi-mmap-desc-size",
53			[DCVERS] = "linux,uefi-mmap-desc-ver",
54		}
55	}
56};
57
58static int __init efi_get_fdt_prop(const void *fdt, int node, const char *pname,
59				   const char *rname, void *var, int size)
60{
61	const void *prop;
62	int len;
63	u64 val;
64
65	prop = fdt_getprop(fdt, node, pname, &len);
66	if (!prop)
67		return 1;
68
69	val = (len == 4) ? (u64)be32_to_cpup(prop) : get_unaligned_be64(prop);
70
71	if (size == 8)
72		*(u64 *)var = val;
73	else
74		*(u32 *)var = (val < U32_MAX) ? val : U32_MAX; // saturate
75
76	if (efi_enabled(EFI_DBG))
77		pr_info("  %s: 0x%0*llx\n", rname, size * 2, val);
78
79	return 0;
80}
81
82u64 __init efi_get_fdt_params(struct efi_memory_map_data *mm)
83{
84	const void *fdt = initial_boot_params;
85	unsigned long systab;
86	int i, j, node;
87	struct {
88		void	*var;
89		int	size;
90	} target[] = {
91		[SYSTAB] = { &systab,		sizeof(systab) },
92		[MMBASE] = { &mm->phys_map,	sizeof(mm->phys_map) },
93		[MMSIZE] = { &mm->size,		sizeof(mm->size) },
94		[DCSIZE] = { &mm->desc_size,	sizeof(mm->desc_size) },
95		[DCVERS] = { &mm->desc_version,	sizeof(mm->desc_version) },
96	};
97
98	BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(name));
99	BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(dt_params[0].params));
100
101	if (!fdt)
102		return 0;
103
104	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
105		node = fdt_path_offset(fdt, dt_params[i].path);
106		if (node < 0)
107			continue;
108
109		if (efi_enabled(EFI_DBG))
110			pr_info("Getting UEFI parameters from %s in DT:\n",
111				dt_params[i].path);
112
113		for (j = 0; j < ARRAY_SIZE(target); j++) {
114			const char *pname = dt_params[i].params[j];
115
116			if (!efi_get_fdt_prop(fdt, node, pname, name[j],
117					      target[j].var, target[j].size))
118				continue;
119			if (!j)
120				goto notfound;
121			pr_err("Can't find property '%s' in DT!\n", pname);
122			return 0;
123		}
124		return systab;
125	}
126notfound:
127	pr_info("UEFI not found.\n");
128	return 0;
129}
130