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	u8		paravirt;
34	const char	params[PARAMCOUNT][26];
35} dt_params[] = {
36	{
37#ifdef CONFIG_XEN    //  <-------17------>
38		.path = "/hypervisor/uefi",
39		.paravirt = 1,
40		.params = {
41			[SYSTAB] = "xen,uefi-system-table",
42			[MMBASE] = "xen,uefi-mmap-start",
43			[MMSIZE] = "xen,uefi-mmap-size",
44			[DCSIZE] = "xen,uefi-mmap-desc-size",
45			[DCVERS] = "xen,uefi-mmap-desc-ver",
46		}
47	}, {
48#endif
49		.path = "/chosen",
50		.params = {	//  <-----------26----------->
51			[SYSTAB] = "linux,uefi-system-table",
52			[MMBASE] = "linux,uefi-mmap-start",
53			[MMSIZE] = "linux,uefi-mmap-size",
54			[DCSIZE] = "linux,uefi-mmap-desc-size",
55			[DCVERS] = "linux,uefi-mmap-desc-ver",
56		}
57	}
58};
59
60static int __init efi_get_fdt_prop(const void *fdt, int node, const char *pname,
61				   const char *rname, void *var, int size)
62{
63	const void *prop;
64	int len;
65	u64 val;
66
67	prop = fdt_getprop(fdt, node, pname, &len);
68	if (!prop)
69		return 1;
70
71	val = (len == 4) ? (u64)be32_to_cpup(prop) : get_unaligned_be64(prop);
72
73	if (size == 8)
74		*(u64 *)var = val;
75	else
76		*(u32 *)var = (val < U32_MAX) ? val : U32_MAX; // saturate
77
78	if (efi_enabled(EFI_DBG))
79		pr_info("  %s: 0x%0*llx\n", rname, size * 2, val);
80
81	return 0;
82}
83
84u64 __init efi_get_fdt_params(struct efi_memory_map_data *mm)
85{
86	const void *fdt = initial_boot_params;
87	unsigned long systab;
88	int i, j, node;
89	struct {
90		void	*var;
91		int	size;
92	} target[] = {
93		[SYSTAB] = { &systab,		sizeof(systab) },
94		[MMBASE] = { &mm->phys_map,	sizeof(mm->phys_map) },
95		[MMSIZE] = { &mm->size,		sizeof(mm->size) },
96		[DCSIZE] = { &mm->desc_size,	sizeof(mm->desc_size) },
97		[DCVERS] = { &mm->desc_version,	sizeof(mm->desc_version) },
98	};
99
100	BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(name));
101	BUILD_BUG_ON(ARRAY_SIZE(target) != ARRAY_SIZE(dt_params[0].params));
102
103	if (!fdt)
104		return 0;
105
106	for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
107		node = fdt_path_offset(fdt, dt_params[i].path);
108		if (node < 0)
109			continue;
110
111		if (efi_enabled(EFI_DBG))
112			pr_info("Getting UEFI parameters from %s in DT:\n",
113				dt_params[i].path);
114
115		for (j = 0; j < ARRAY_SIZE(target); j++) {
116			const char *pname = dt_params[i].params[j];
117
118			if (!efi_get_fdt_prop(fdt, node, pname, name[j],
119					      target[j].var, target[j].size))
120				continue;
121			if (!j)
122				goto notfound;
123			pr_err("Can't find property '%s' in DT!\n", pname);
124			return 0;
125		}
126		if (dt_params[i].paravirt)
127			set_bit(EFI_PARAVIRT, &efi.flags);
128		return systab;
129	}
130notfound:
131	pr_info("UEFI not found.\n");
132	return 0;
133}
134