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
13 enum {
14 SYSTAB,
15 MMBASE,
16 MMSIZE,
17 DCSIZE,
18 DCVERS,
19
20 PARAMCOUNT
21 };
22
23 static __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
31 static __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
efi_get_fdt_prop(const void * fdt,int node,const char * pname,const char * rname,void * var,int size)58 static 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
efi_get_fdt_params(struct efi_memory_map_data * mm)82 u64 __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 for (i = 0; i < ARRAY_SIZE(dt_params); i++) {
102 node = fdt_path_offset(fdt, dt_params[i].path);
103 if (node < 0)
104 continue;
105
106 if (efi_enabled(EFI_DBG))
107 pr_info("Getting UEFI parameters from %s in DT:\n",
108 dt_params[i].path);
109
110 for (j = 0; j < ARRAY_SIZE(target); j++) {
111 const char *pname = dt_params[i].params[j];
112
113 if (!efi_get_fdt_prop(fdt, node, pname, name[j],
114 target[j].var, target[j].size))
115 continue;
116 if (!j)
117 goto notfound;
118 pr_err("Can't find property '%s' in DT!\n", pname);
119 return 0;
120 }
121 return systab;
122 }
123 notfound:
124 pr_info("UEFI not found.\n");
125 return 0;
126 }
127
