1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * PowerNV code for secure variables
4 *
5 * Copyright (C) 2019 IBM Corporation
6 * Author: Claudio Carvalho
7 * Nayna Jain
8 *
9 * APIs to access secure variables managed by OPAL.
10 */
11
12 #define pr_fmt(fmt) "secvar: "fmt
13
14 #include <linux/types.h>
15 #include <linux/of.h>
16 #include <linux/platform_device.h>
17 #include <asm/opal.h>
18 #include <asm/secvar.h>
19 #include <asm/secure_boot.h>
20
21 static int opal_status_to_err(int rc)
22 {
23 int err;
24
25 switch (rc) {
26 case OPAL_SUCCESS:
27 err = 0;
28 break;
29 case OPAL_UNSUPPORTED:
30 err = -ENXIO;
31 break;
32 case OPAL_PARAMETER:
33 err = -EINVAL;
34 break;
35 case OPAL_RESOURCE:
36 err = -ENOSPC;
37 break;
38 case OPAL_HARDWARE:
39 err = -EIO;
40 break;
41 case OPAL_NO_MEM:
42 err = -ENOMEM;
43 break;
44 case OPAL_EMPTY:
45 err = -ENOENT;
46 break;
47 case OPAL_PARTIAL:
48 err = -EFBIG;
49 break;
50 default:
51 err = -EINVAL;
52 }
53
54 return err;
55 }
56
57 static int opal_get_variable(const char *key, u64 ksize, u8 *data, u64 *dsize)
58 {
59 int rc;
60
61 if (!key || !dsize)
62 return -EINVAL;
63
64 *dsize = cpu_to_be64(*dsize);
65
66 rc = opal_secvar_get(key, ksize, data, dsize);
67
68 *dsize = be64_to_cpu(*dsize);
69
70 return opal_status_to_err(rc);
71 }
72
73 static int opal_get_next_variable(const char *key, u64 *keylen, u64 keybufsize)
74 {
75 int rc;
76
77 if (!key || !keylen)
78 return -EINVAL;
79
80 *keylen = cpu_to_be64(*keylen);
81
82 rc = opal_secvar_get_next(key, keylen, keybufsize);
83
84 *keylen = be64_to_cpu(*keylen);
85
86 return opal_status_to_err(rc);
87 }
88
89 static int opal_set_variable(const char *key, u64 ksize, u8 *data, u64 dsize)
90 {
91 int rc;
92
93 if (!key || !data)
94 return -EINVAL;
95
96 rc = opal_secvar_enqueue_update(key, ksize, data, dsize);
97
98 return opal_status_to_err(rc);
99 }
100
101 static ssize_t opal_secvar_format(char *buf, size_t bufsize)
102 {
103 ssize_t rc = 0;
104 struct device_node *node;
105 const char *format;
106
107 node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
108 if (!of_device_is_available(node)) {
109 rc = -ENODEV;
110 goto out;
111 }
112
113 rc = of_property_read_string(node, "format", &format);
114 if (rc)
115 goto out;
116
117 rc = snprintf(buf, bufsize, "%s", format);
118
119 out:
120 of_node_put(node);
121
122 return rc;
123 }
124
125 static int opal_secvar_max_size(u64 *max_size)
126 {
127 int rc;
128 struct device_node *node;
129
130 node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
131 if (!node)
132 return -ENODEV;
133
134 if (!of_device_is_available(node)) {
135 rc = -ENODEV;
136 goto out;
137 }
138
139 rc = of_property_read_u64(node, "max-var-size", max_size);
140
141 out:
142 of_node_put(node);
143 return rc;
144 }
145
146 static const struct secvar_operations opal_secvar_ops = {
147 .get = opal_get_variable,
148 .get_next = opal_get_next_variable,
149 .set = opal_set_variable,
150 .format = opal_secvar_format,
151 .max_size = opal_secvar_max_size,
152 };
153
154 static int opal_secvar_probe(struct platform_device *pdev)
155 {
156 if (!opal_check_token(OPAL_SECVAR_GET)
157 || !opal_check_token(OPAL_SECVAR_GET_NEXT)
158 || !opal_check_token(OPAL_SECVAR_ENQUEUE_UPDATE)) {
159 pr_err("OPAL doesn't support secure variables\n");
160 return -ENODEV;
161 }
162
163 return set_secvar_ops(&opal_secvar_ops);
164 }
165
166 static const struct of_device_id opal_secvar_match[] = {
167 { .compatible = "ibm,secvar-backend",},
168 {},
169 };
170
171 static struct platform_driver opal_secvar_driver = {
172 .driver = {
173 .name = "secvar",
174 .of_match_table = opal_secvar_match,
175 },
176 };
177
178 static int __init opal_secvar_init(void)
179 {
180 return platform_driver_probe(&opal_secvar_driver, opal_secvar_probe);
181 }
182 device_initcall(opal_secvar_init);
183
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