1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
4 */
5
6 #include <linux/crc32.h>
7 #include <linux/etherdevice.h>
8 #include <linux/if_ether.h>
9 #include <linux/mod_devicetable.h>
10 #include <linux/module.h>
11 #include <linux/mtd/mtd.h>
12 #include <linux/nvmem-consumer.h>
13 #include <linux/nvmem-provider.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/slab.h>
17
18 enum u_boot_env_format {
19 U_BOOT_FORMAT_SINGLE,
20 U_BOOT_FORMAT_REDUNDANT,
21 U_BOOT_FORMAT_BROADCOM,
22 };
23
24 struct u_boot_env {
25 struct device *dev;
26 struct nvmem_device *nvmem;
27 enum u_boot_env_format format;
28
29 struct mtd_info *mtd;
30 };
31
32 struct u_boot_env_image_single {
33 __le32 crc32;
34 uint8_t data[];
35 } __packed;
36
37 struct u_boot_env_image_redundant {
38 __le32 crc32;
39 u8 mark;
40 uint8_t data[];
41 } __packed;
42
43 struct u_boot_env_image_broadcom {
44 __le32 magic;
45 __le32 len;
46 __le32 crc32;
47 DECLARE_FLEX_ARRAY(uint8_t, data);
48 } __packed;
49
u_boot_env_read(void * context,unsigned int offset,void * val,size_t bytes)50 static int u_boot_env_read(void *context, unsigned int offset, void *val,
51 size_t bytes)
52 {
53 struct u_boot_env *priv = context;
54 struct device *dev = priv->dev;
55 size_t bytes_read;
56 int err;
57
58 err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
59 if (err && !mtd_is_bitflip(err)) {
60 dev_err(dev, "Failed to read from mtd: %d\n", err);
61 return err;
62 }
63
64 if (bytes_read != bytes) {
65 dev_err(dev, "Failed to read %zu bytes\n", bytes);
66 return -EIO;
67 }
68
69 return 0;
70 }
71
u_boot_env_read_post_process_ethaddr(void * context,const char * id,int index,unsigned int offset,void * buf,size_t bytes)72 static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
73 unsigned int offset, void *buf, size_t bytes)
74 {
75 u8 mac[ETH_ALEN];
76
77 if (bytes != 3 * ETH_ALEN - 1)
78 return -EINVAL;
79
80 if (!mac_pton(buf, mac))
81 return -EINVAL;
82
83 if (index)
84 eth_addr_add(mac, index);
85
86 ether_addr_copy(buf, mac);
87
88 return 0;
89 }
90
u_boot_env_add_cells(struct u_boot_env * priv,uint8_t * buf,size_t data_offset,size_t data_len)91 static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
92 size_t data_offset, size_t data_len)
93 {
94 struct nvmem_device *nvmem = priv->nvmem;
95 struct device *dev = priv->dev;
96 char *data = buf + data_offset;
97 char *var, *value, *eq;
98
99 for (var = data;
100 var < data + data_len && *var;
101 var = value + strlen(value) + 1) {
102 struct nvmem_cell_info info = {};
103
104 eq = strchr(var, '=');
105 if (!eq)
106 break;
107 *eq = '\0';
108 value = eq + 1;
109
110 info.name = devm_kstrdup(dev, var, GFP_KERNEL);
111 if (!info.name)
112 return -ENOMEM;
113 info.offset = data_offset + value - data;
114 info.bytes = strlen(value);
115 info.np = of_get_child_by_name(dev->of_node, info.name);
116 if (!strcmp(var, "ethaddr")) {
117 info.raw_len = strlen(value);
118 info.bytes = ETH_ALEN;
119 info.read_post_process = u_boot_env_read_post_process_ethaddr;
120 }
121
122 nvmem_add_one_cell(nvmem, &info);
123 }
124
125 return 0;
126 }
127
u_boot_env_parse(struct u_boot_env * priv)128 static int u_boot_env_parse(struct u_boot_env *priv)
129 {
130 struct nvmem_device *nvmem = priv->nvmem;
131 struct device *dev = priv->dev;
132 size_t crc32_data_offset;
133 size_t crc32_data_len;
134 size_t crc32_offset;
135 __le32 *crc32_addr;
136 size_t data_offset;
137 size_t data_len;
138 size_t dev_size;
139 uint32_t crc32;
140 uint32_t calc;
141 uint8_t *buf;
142 int bytes;
143 int err;
144
145 dev_size = nvmem_dev_size(nvmem);
146
147 buf = kzalloc(dev_size, GFP_KERNEL);
148 if (!buf) {
149 err = -ENOMEM;
150 goto err_out;
151 }
152
153 bytes = nvmem_device_read(nvmem, 0, dev_size, buf);
154 if (bytes < 0) {
155 err = bytes;
156 goto err_kfree;
157 } else if (bytes != dev_size) {
158 err = -EIO;
159 goto err_kfree;
160 }
161
162 switch (priv->format) {
163 case U_BOOT_FORMAT_SINGLE:
164 crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
165 crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
166 data_offset = offsetof(struct u_boot_env_image_single, data);
167 break;
168 case U_BOOT_FORMAT_REDUNDANT:
169 crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
170 crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);
171 data_offset = offsetof(struct u_boot_env_image_redundant, data);
172 break;
173 case U_BOOT_FORMAT_BROADCOM:
174 crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);
175 crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);
176 data_offset = offsetof(struct u_boot_env_image_broadcom, data);
177 break;
178 }
179
180 if (dev_size < data_offset) {
181 dev_err(dev, "Device too small for u-boot-env\n");
182 err = -EIO;
183 goto err_kfree;
184 }
185
186 crc32_addr = (__le32 *)(buf + crc32_offset);
187 crc32 = le32_to_cpu(*crc32_addr);
188 crc32_data_len = dev_size - crc32_data_offset;
189 data_len = dev_size - data_offset;
190
191 calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
192 if (calc != crc32) {
193 dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
194 err = -EINVAL;
195 goto err_kfree;
196 }
197
198 buf[dev_size - 1] = '\0';
199 err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
200
201 err_kfree:
202 kfree(buf);
203 err_out:
204 return err;
205 }
206
u_boot_env_probe(struct platform_device * pdev)207 static int u_boot_env_probe(struct platform_device *pdev)
208 {
209 struct nvmem_config config = {
210 .name = "u-boot-env",
211 .reg_read = u_boot_env_read,
212 };
213 struct device *dev = &pdev->dev;
214 struct device_node *np = dev->of_node;
215 struct u_boot_env *priv;
216
217 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
218 if (!priv)
219 return -ENOMEM;
220 priv->dev = dev;
221
222 priv->format = (uintptr_t)of_device_get_match_data(dev);
223
224 priv->mtd = of_get_mtd_device_by_node(np);
225 if (IS_ERR(priv->mtd)) {
226 dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
227 return PTR_ERR(priv->mtd);
228 }
229
230 config.dev = dev;
231 config.priv = priv;
232 config.size = priv->mtd->size;
233
234 priv->nvmem = devm_nvmem_register(dev, &config);
235 if (IS_ERR(priv->nvmem))
236 return PTR_ERR(priv->nvmem);
237
238 return u_boot_env_parse(priv);
239 }
240
241 static const struct of_device_id u_boot_env_of_match_table[] = {
242 { .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
243 { .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
244 { .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
245 { .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
246 {},
247 };
248
249 static struct platform_driver u_boot_env_driver = {
250 .probe = u_boot_env_probe,
251 .driver = {
252 .name = "u_boot_env",
253 .of_match_table = u_boot_env_of_match_table,
254 },
255 };
256 module_platform_driver(u_boot_env_driver);
257
258 MODULE_AUTHOR("Rafał Miłecki");
259 MODULE_DESCRIPTION("U-Boot environment variables support module");
260 MODULE_LICENSE("GPL");
261 MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
262