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 }
183