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 "efivar.h"
49 
50 /* GUID for HFI1 variables in EFI */
51 #define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \
52 		0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4)
53 /* largest EFI data size we expect */
54 #define EFI_DATA_SIZE 4096
55 
56 /*
57  * Read the named EFI variable.  Return the size of the actual data in *size
58  * and a kmalloc'ed buffer in *return_data.  The caller must free the
59  * data.  It is guaranteed that *return_data will be NULL and *size = 0
60  * if this routine fails.
61  *
62  * Return 0 on success, -errno on failure.
63  */
64 static int read_efi_var(const char *name, unsigned long *size,
65 			void **return_data)
66 {
67 	efi_status_t status;
68 	efi_char16_t *uni_name;
69 	efi_guid_t guid;
70 	unsigned long temp_size;
71 	void *temp_buffer;
72 	void *data;
73 	int i;
74 	int ret;
75 
76 	/* set failure return values */
77 	*size = 0;
78 	*return_data = NULL;
79 
80 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
81 		return -EOPNOTSUPP;
82 
83 	uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL);
84 	temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL);
85 
86 	if (!uni_name || !temp_buffer) {
87 		ret = -ENOMEM;
88 		goto fail;
89 	}
90 
91 	/* input: the size of the buffer */
92 	temp_size = EFI_DATA_SIZE;
93 
94 	/* convert ASCII to unicode - it is a 1:1 mapping */
95 	for (i = 0; name[i]; i++)
96 		uni_name[i] = name[i];
97 
98 	/* need a variable for our GUID */
99 	guid = HFI1_EFIVAR_GUID;
100 
101 	/* call into EFI runtime services */
102 	status = efi.get_variable(
103 			uni_name,
104 			&guid,
105 			NULL,
106 			&temp_size,
107 			temp_buffer);
108 
109 	/*
110 	 * It would be nice to call efi_status_to_err() here, but that
111 	 * is in the EFIVAR_FS code and may not be compiled in.
112 	 * However, even that is insufficient since it does not cover
113 	 * EFI_BUFFER_TOO_SMALL which could be an important return.
114 	 * For now, just split out succces or not found.
115 	 */
116 	ret = status == EFI_SUCCESS   ? 0 :
117 	      status == EFI_NOT_FOUND ? -ENOENT :
118 					-EINVAL;
119 	if (ret)
120 		goto fail;
121 
122 	/*
123 	 * We have successfully read the EFI variable into our
124 	 * temporary buffer.  Now allocate a correctly sized
125 	 * buffer.
126 	 */
127 	data = kmemdup(temp_buffer, temp_size, GFP_KERNEL);
128 	if (!data) {
129 		ret = -ENOMEM;
130 		goto fail;
131 	}
132 
133 	*size = temp_size;
134 	*return_data = data;
135 
136 fail:
137 	kfree(uni_name);
138 	kfree(temp_buffer);
139 
140 	return ret;
141 }
142 
143 /*
144  * Read an HFI1 EFI variable of the form:
145  *	<PCIe address>-<kind>
146  * Return an kalloc'ed array and size of the data.
147  *
148  * Returns 0 on success, -errno on failure.
149  */
150 int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind,
151 		      unsigned long *size, void **return_data)
152 {
153 	char name[64];
154 
155 	/* create a common prefix */
156 	snprintf(name, sizeof(name), "%04x:%02x:%02x.%x-%s",
157 		 pci_domain_nr(dd->pcidev->bus),
158 		 dd->pcidev->bus->number,
159 		 PCI_SLOT(dd->pcidev->devfn),
160 		 PCI_FUNC(dd->pcidev->devfn),
161 		 kind);
162 
163 	return read_efi_var(name, size, return_data);
164 }
165