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