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/mod_devicetable.h>
8 #include <linux/module.h>
9 #include <linux/mtd/mtd.h>
10 #include <linux/nvmem-consumer.h>
11 #include <linux/nvmem-provider.h>
12 #include <linux/of_device.h>
13 #include <linux/platform_device.h>
14 #include <linux/slab.h>
15
16 enum u_boot_env_format {
17 U_BOOT_FORMAT_SINGLE,
18 U_BOOT_FORMAT_REDUNDANT,
19 };
20
21 struct u_boot_env {
22 struct device *dev;
23 enum u_boot_env_format format;
24
25 struct mtd_info *mtd;
26
27 /* Cells */
28 struct nvmem_cell_info *cells;
29 int ncells;
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
u_boot_env_read(void * context,unsigned int offset,void * val,size_t bytes)43 static int u_boot_env_read(void *context, unsigned int offset, void *val,
44 size_t bytes)
45 {
46 struct u_boot_env *priv = context;
47 struct device *dev = priv->dev;
48 size_t bytes_read;
49 int err;
50
51 err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
52 if (err && !mtd_is_bitflip(err)) {
53 dev_err(dev, "Failed to read from mtd: %d\n", err);
54 return err;
55 }
56
57 if (bytes_read != bytes) {
58 dev_err(dev, "Failed to read %zu bytes\n", bytes);
59 return -EIO;
60 }
61
62 return 0;
63 }
64
u_boot_env_add_cells(struct u_boot_env * priv,uint8_t * buf,size_t data_offset,size_t data_len)65 static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
66 size_t data_offset, size_t data_len)
67 {
68 struct device *dev = priv->dev;
69 char *data = buf + data_offset;
70 char *var, *value, *eq;
71 int idx;
72
73 priv->ncells = 0;
74 for (var = data; var < data + data_len && *var; var += strlen(var) + 1)
75 priv->ncells++;
76
77 priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
78 if (!priv->cells)
79 return -ENOMEM;
80
81 for (var = data, idx = 0;
82 var < data + data_len && *var;
83 var = value + strlen(value) + 1, idx++) {
84 eq = strchr(var, '=');
85 if (!eq)
86 break;
87 *eq = '\0';
88 value = eq + 1;
89
90 priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
91 if (!priv->cells[idx].name)
92 return -ENOMEM;
93 priv->cells[idx].offset = data_offset + value - data;
94 priv->cells[idx].bytes = strlen(value);
95 priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
96 }
97
98 if (WARN_ON(idx != priv->ncells))
99 priv->ncells = idx;
100
101 return 0;
102 }
103
u_boot_env_parse(struct u_boot_env * priv)104 static int u_boot_env_parse(struct u_boot_env *priv)
105 {
106 struct device *dev = priv->dev;
107 size_t crc32_data_offset;
108 size_t crc32_data_len;
109 size_t crc32_offset;
110 size_t data_offset;
111 size_t data_len;
112 uint32_t crc32;
113 uint32_t calc;
114 size_t bytes;
115 uint8_t *buf;
116 int err;
117
118 buf = kcalloc(1, priv->mtd->size, GFP_KERNEL);
119 if (!buf) {
120 err = -ENOMEM;
121 goto err_out;
122 }
123
124 err = mtd_read(priv->mtd, 0, priv->mtd->size, &bytes, buf);
125 if ((err && !mtd_is_bitflip(err)) || bytes != priv->mtd->size) {
126 dev_err(dev, "Failed to read from mtd: %d\n", err);
127 goto err_kfree;
128 }
129
130 switch (priv->format) {
131 case U_BOOT_FORMAT_SINGLE:
132 crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
133 crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
134 data_offset = offsetof(struct u_boot_env_image_single, data);
135 break;
136 case U_BOOT_FORMAT_REDUNDANT:
137 crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
138 crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);
139 data_offset = offsetof(struct u_boot_env_image_redundant, data);
140 break;
141 }
142 crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset));
143 crc32_data_len = priv->mtd->size - crc32_data_offset;
144 data_len = priv->mtd->size - data_offset;
145
146 calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
147 if (calc != crc32) {
148 dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
149 err = -EINVAL;
150 goto err_kfree;
151 }
152
153 buf[priv->mtd->size - 1] = '\0';
154 err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
155 if (err)
156 dev_err(dev, "Failed to add cells: %d\n", err);
157
158 err_kfree:
159 kfree(buf);
160 err_out:
161 return err;
162 }
163
u_boot_env_probe(struct platform_device * pdev)164 static int u_boot_env_probe(struct platform_device *pdev)
165 {
166 struct nvmem_config config = {
167 .name = "u-boot-env",
168 .reg_read = u_boot_env_read,
169 };
170 struct device *dev = &pdev->dev;
171 struct device_node *np = dev->of_node;
172 struct u_boot_env *priv;
173 int err;
174
175 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
176 if (!priv)
177 return -ENOMEM;
178 priv->dev = dev;
179
180 priv->format = (uintptr_t)of_device_get_match_data(dev);
181
182 priv->mtd = of_get_mtd_device_by_node(np);
183 if (IS_ERR(priv->mtd)) {
184 dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
185 return PTR_ERR(priv->mtd);
186 }
187
188 err = u_boot_env_parse(priv);
189 if (err)
190 return err;
191
192 config.dev = dev;
193 config.cells = priv->cells;
194 config.ncells = priv->ncells;
195 config.priv = priv;
196 config.size = priv->mtd->size;
197
198 return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
199 }
200
201 static const struct of_device_id u_boot_env_of_match_table[] = {
202 { .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
203 { .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
204 { .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
205 {},
206 };
207
208 static struct platform_driver u_boot_env_driver = {
209 .probe = u_boot_env_probe,
210 .driver = {
211 .name = "u_boot_env",
212 .of_match_table = u_boot_env_of_match_table,
213 },
214 };
215 module_platform_driver(u_boot_env_driver);
216
217 MODULE_AUTHOR("Rafał Miłecki");
218 MODULE_LICENSE("GPL");
219 MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
220
