1 /*
2 * Copyright(c) 2015, 2016 Intel Corporation.
3 *
4 * This file is provided under a dual BSD/GPLv2 license. When using or
5 * redistributing this file, you may do so under either license.
6 *
7 * GPL LICENSE SUMMARY
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of version 2 of the GNU General Public License as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
17 *
18 * BSD LICENSE
19 *
20 * Redistribution and use in source and binary forms, with or without
21 * modification, are permitted provided that the following conditions
22 * are met:
23 *
24 * - Redistributions of source code must retain the above copyright
25 * notice, this list of conditions and the following disclaimer.
26 * - Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in
28 * the documentation and/or other materials provided with the
29 * distribution.
30 * - Neither the name of Intel Corporation nor the names of its
31 * contributors may be used to endorse or promote products derived
32 * from this software without specific prior written permission.
33 *
34 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
35 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
36 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
37 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
38 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
39 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
40 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
41 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
42 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
43 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
44 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45 *
46 */
47
48 #include <linux/ctype.h>
49 #include "efivar.h"
50
51 /* GUID for HFI1 variables in EFI */
52 #define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
53 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
54 /* largest EFI data size we expect */
55 #define EFI_DATA_SIZE 4096
56
57 /*
58 * Read the named EFI variable. Return the size of the actual data in *size
59 * and a kmalloc'ed buffer in *return_data. The caller must free the
60 * data. It is guaranteed that *return_data will be NULL and *size = 0
61 * if this routine fails.
62 *
63 * Return 0 on success, -errno on failure.
64 */
65 static int read_efi_var(const char *name, unsigned long *size,
66 void **return_data)
67 {
68 efi_status_t status;
69 efi_char16_t *uni_name;
70 efi_guid_t guid;
71 unsigned long temp_size;
72 void *temp_buffer;
73 void *data;
74 int i;
75 int ret;
76
77 /* set failure return values */
78 *size = 0;
79 *return_data = NULL;
80
81 if (!efi_enabled(EFI_RUNTIME_SERVICES))
82 return -EOPNOTSUPP;
83
84 uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
85 temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
86
87 if (!uni_name || !temp_buffer) {
88 ret = -ENOMEM;
89 goto fail;
90 }
91
92 /* input: the size of the buffer */
93 temp_size = EFI_DATA_SIZE;
94
95 /* convert ASCII to unicode - it is a 1:1 mapping */
96 for (i = 0; name[i]; i++)
97 uni_name[i] = name[i];
98
99 /* need a variable for our GUID */
100 guid = HFI1_EFIVAR_GUID;
101
102 /* call into EFI runtime services */
103 status = efi.get_variable(
104 uni_name,
105 &guid,
106 NULL,
107 &temp_size,
108 temp_buffer);
109
110 /*
111 * It would be nice to call efi_status_to_err() here, but that
112 * is in the EFIVAR_FS code and may not be compiled in.
113 * However, even that is insufficient since it does not cover
114 * EFI_BUFFER_TOO_SMALL which could be an important return.
115 * For now, just split out succces or not found.
116 */
117 ret = status == EFI_SUCCESS ? 0 :
118 status == EFI_NOT_FOUND ? -ENOENT :
119 -EINVAL;
120 if (ret)
121 goto fail;
122
123 /*
124 * We have successfully read the EFI variable into our
125 * temporary buffer. Now allocate a correctly sized
126 * buffer.
127 */
128 data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
129 if (!data) {
130 ret = -ENOMEM;
131 goto fail;
132 }
133
134 *size = temp_size;
135 *return_data = data;
136
137 fail:
138 kfree(uni_name);
139 kfree(temp_buffer);
140
141 return ret;
142 }
143
144 /*
145 * Read an HFI1 EFI variable of the form:
146 * <PCIe address>-<kind>
147 * Return an kalloc'ed array and size of the data.
148 *
149 * Returns 0 on success, -errno on failure.
150 */
151 int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
152 unsigned long *size, void **return_data)
153 {
154 char prefix_name[64];
155 char name[64];
156 int result;
157 int i;
158
159 /* create a common prefix */
160 snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x",
161 pci_domain_nr(dd->pcidev->bus),
162 dd->pcidev->bus->number,
163 PCI_SLOT(dd->pcidev->devfn),
164 PCI_FUNC(dd->pcidev->devfn));
165 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
166 result = read_efi_var(name, size, return_data);
167
168 /*
169 * If reading the lowercase EFI variable fail, read the uppercase
170 * variable.
171 */
172 if (result) {
173 /* Converting to uppercase */
174 for (i = 0; prefix_name[i]; i++)
175 if (isalpha(prefix_name[i]))
176 prefix_name[i] = toupper(prefix_name[i]);
177 snprintf(name, sizeof(name), "%s-%s", prefix_name, kind);
178 result = read_efi_var(name, size, return_data);
179 }
180
181 return result;
182 }