1 // SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
2 /*
3 * Copyright(c) 2015, 2016 Intel Corporation.
4 */
5
6 #include <linux/ctype.h>
7 #include "efivar.h"
8
9 /* GUID for HFI1 variables in EFI */
10 #define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
11 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
12 /* largest EFI data size we expect */
13 #define EFI_DATA_SIZE 4096
14
15 /*
16 * Read the named EFI variable. Return the size of the actual data in *size
17 * and a kmalloc'ed buffer in *return_data. The caller must free the
18 * data. It is guaranteed that *return_data will be NULL and *size = 0
19 * if this routine fails.
20 *
21 * Return 0 on success, -errno on failure.
22 */
read_efi_var(const char * name,unsigned long * size,void ** return_data)23 static int read_efi_var(const char *name, unsigned long *size,
24 void **return_data)
25 {
26 efi_status_t status;
27 efi_char16_t *uni_name;
28 efi_guid_t guid;
29 unsigned long temp_size;
30 void *temp_buffer;
31 void *data;
32 int i;
33 int ret;
34
35 /* set failure return values */
36 *size = 0;
37 *return_data = NULL;
38
39 if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
40 return -EOPNOTSUPP;
41
42 uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
43 temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
44
45 if (!uni_name || !temp_buffer) {
46 ret = -ENOMEM;
47 goto fail;
48 }
49
50 /* input: the size of the buffer */
51 temp_size = EFI_DATA_SIZE;
52
53 /* convert ASCII to unicode - it is a 1:1 mapping */
54 for (i = 0; name[i]; i++)
55 uni_name[i] = name[i];
56
57 /* need a variable for our GUID */
58 guid = HFI1_EFIVAR_GUID;
59
60 /* call into EFI runtime services */
61 status = efi.get_variable(
62 uni_name,
63 &guid,
64 NULL,
65 &temp_size,
66 temp_buffer);
67
68 /*
69 * It would be nice to call efi_status_to_err() here, but that
70 * is in the EFIVAR_FS code and may not be compiled in.
71 * However, even that is insufficient since it does not cover
72 * EFI_BUFFER_TOO_SMALL which could be an important return.
73 * For now, just split out succces or not found.
74 */
75 ret = status == EFI_SUCCESS ? 0 :
76 status == EFI_NOT_FOUND ? -ENOENT :
77 -EINVAL;
78 if (ret)
79 goto fail;
80
81 /*
82 * We have successfully read the EFI variable into our
83 * temporary buffer. Now allocate a correctly sized
84 * buffer.
85 */
86 data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
87 if (!data) {
88 ret = -ENOMEM;
89 goto fail;
90 }
91
92 *size = temp_size;
93 *return_data = data;
94
95 fail:
96 kfree(uni_name);
97 kfree(temp_buffer);
98
99 return ret;
100 }
101
102 /*
103 * Read an HFI1 EFI variable of the form:
104 * <PCIe address>-<kind>
105 * Return an kalloc'ed array and size of the data.
106 *
107 * Returns 0 on success, -errno on failure.
108 */
read_hfi1_efi_var(struct hfi1_devdata * dd,const char * kind,unsigned long * size,void ** return_data)109 int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
110 unsigned long *size, void **return_data)
111 {
112 char prefix_name[64];
113 char name[64];
114 int result;
115 int i;
116
117 /* create a common prefix */
118 snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x",
119 pci_domain_nr(dd->pcidev->bus),
120 dd->pcidev->bus->number,
121 PCI_SLOT(dd->pcidev->devfn),
122 PCI_FUNC(dd->pcidev->devfn));
123 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
124 result = read_efi_var(name, size, return_data);
125
126 /*
127 * If reading the lowercase EFI variable fail, read the uppercase
128 * variable.
129 */
130 if (result) {
131 /* Converting to uppercase */
132 for (i = 0; prefix_name[i]; i++)
133 if (isalpha(prefix_name[i]))
134 prefix_name[i] = toupper(prefix_name[i]);
135 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
136 result = read_efi_var(name, size, return_data);
137 }
138
139 return result;
140 }
141
