1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * BCM947xx nvram variable access
4 *
5 * Copyright (C) 2005 Broadcom Corporation
6 * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
7 * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
8 */
9
10 #include <linux/io.h>
11 #include <linux/types.h>
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/string.h>
15 #include <linux/mtd/mtd.h>
16 #include <linux/bcm47xx_nvram.h>
17
18 #define NVRAM_MAGIC 0x48534C46 /* 'FLSH' */
19 #define NVRAM_SPACE 0x10000
20 #define NVRAM_MAX_GPIO_ENTRIES 32
21 #define NVRAM_MAX_GPIO_VALUE_LEN 30
22
23 #define FLASH_MIN 0x00020000 /* Minimum flash size */
24
25 struct nvram_header {
26 u32 magic;
27 u32 len;
28 u32 crc_ver_init; /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
29 u32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */
30 u32 config_ncdl; /* ncdl values for memc */
31 };
32
33 static char nvram_buf[NVRAM_SPACE];
34 static size_t nvram_len;
35 static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
36
find_nvram_size(void __iomem * end)37 static u32 find_nvram_size(void __iomem *end)
38 {
39 struct nvram_header __iomem *header;
40 int i;
41
42 for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
43 header = (struct nvram_header *)(end - nvram_sizes[i]);
44 if (header->magic == NVRAM_MAGIC)
45 return nvram_sizes[i];
46 }
47
48 return 0;
49 }
50
51 /* Probe for NVRAM header */
nvram_find_and_copy(void __iomem * iobase,u32 lim)52 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
53 {
54 struct nvram_header __iomem *header;
55 u32 off;
56 u32 size;
57
58 if (nvram_len) {
59 pr_warn("nvram already initialized\n");
60 return -EEXIST;
61 }
62
63 /* TODO: when nvram is on nand flash check for bad blocks first. */
64 off = FLASH_MIN;
65 while (off <= lim) {
66 /* Windowed flash access */
67 size = find_nvram_size(iobase + off);
68 if (size) {
69 header = (struct nvram_header *)(iobase + off - size);
70 goto found;
71 }
72 off <<= 1;
73 }
74
75 /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
76 header = (struct nvram_header *)(iobase + 4096);
77 if (header->magic == NVRAM_MAGIC) {
78 size = NVRAM_SPACE;
79 goto found;
80 }
81
82 header = (struct nvram_header *)(iobase + 1024);
83 if (header->magic == NVRAM_MAGIC) {
84 size = NVRAM_SPACE;
85 goto found;
86 }
87
88 pr_err("no nvram found\n");
89 return -ENXIO;
90
91 found:
92 __ioread32_copy(nvram_buf, header, sizeof(*header) / 4);
93 nvram_len = ((struct nvram_header *)(nvram_buf))->len;
94 if (nvram_len > size) {
95 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
96 nvram_len = size;
97 }
98 if (nvram_len >= NVRAM_SPACE) {
99 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
100 nvram_len, NVRAM_SPACE - 1);
101 nvram_len = NVRAM_SPACE - 1;
102 }
103 /* proceed reading data after header */
104 __ioread32_copy(nvram_buf + sizeof(*header), header + 1,
105 DIV_ROUND_UP(nvram_len, 4));
106 nvram_buf[NVRAM_SPACE - 1] = '\0';
107
108 return 0;
109 }
110
111 /*
112 * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
113 * subsystem to access flash. We can't even use platform device / driver to
114 * store memory offset.
115 * To handle this we provide following symbol. It's supposed to be called as
116 * soon as we get info about flash device, before any NVRAM entry is needed.
117 */
bcm47xx_nvram_init_from_mem(u32 base,u32 lim)118 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
119 {
120 void __iomem *iobase;
121 int err;
122
123 iobase = ioremap(base, lim);
124 if (!iobase)
125 return -ENOMEM;
126
127 err = nvram_find_and_copy(iobase, lim);
128
129 iounmap(iobase);
130
131 return err;
132 }
133
nvram_init(void)134 static int nvram_init(void)
135 {
136 #ifdef CONFIG_MTD
137 struct mtd_info *mtd;
138 struct nvram_header header;
139 size_t bytes_read;
140 int err;
141
142 mtd = get_mtd_device_nm("nvram");
143 if (IS_ERR(mtd))
144 return -ENODEV;
145
146 err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
147 if (!err && header.magic == NVRAM_MAGIC &&
148 header.len > sizeof(header)) {
149 nvram_len = header.len;
150 if (nvram_len >= NVRAM_SPACE) {
151 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
152 nvram_len, NVRAM_SPACE);
153 nvram_len = NVRAM_SPACE - 1;
154 }
155
156 err = mtd_read(mtd, 0, nvram_len, &nvram_len,
157 (u8 *)nvram_buf);
158 return err;
159 }
160 #endif
161
162 return -ENXIO;
163 }
164
bcm47xx_nvram_getenv(const char * name,char * val,size_t val_len)165 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
166 {
167 char *var, *value, *end, *eq;
168 int err;
169
170 if (!name)
171 return -EINVAL;
172
173 if (!nvram_len) {
174 err = nvram_init();
175 if (err)
176 return err;
177 }
178
179 /* Look for name=value and return value */
180 var = &nvram_buf[sizeof(struct nvram_header)];
181 end = nvram_buf + sizeof(nvram_buf);
182 while (var < end && *var) {
183 eq = strchr(var, '=');
184 if (!eq)
185 break;
186 value = eq + 1;
187 if (eq - var == strlen(name) &&
188 strncmp(var, name, eq - var) == 0)
189 return snprintf(val, val_len, "%s", value);
190 var = value + strlen(value) + 1;
191 }
192 return -ENOENT;
193 }
194 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
195
bcm47xx_nvram_gpio_pin(const char * name)196 int bcm47xx_nvram_gpio_pin(const char *name)
197 {
198 int i, err;
199 char nvram_var[] = "gpioXX";
200 char buf[NVRAM_MAX_GPIO_VALUE_LEN];
201
202 /* TODO: Optimize it to don't call getenv so many times */
203 for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
204 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
205 if (err <= 0)
206 continue;
207 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
208 if (err <= 0)
209 continue;
210 if (!strcmp(name, buf))
211 return i;
212 }
213 return -ENOENT;
214 }
215 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
216
bcm47xx_nvram_get_contents(size_t * nvram_size)217 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
218 {
219 int err;
220 char *nvram;
221
222 if (!nvram_len) {
223 err = nvram_init();
224 if (err)
225 return NULL;
226 }
227
228 *nvram_size = nvram_len - sizeof(struct nvram_header);
229 nvram = vmalloc(*nvram_size);
230 if (!nvram)
231 return NULL;
232 memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
233
234 return nvram;
235 }
236 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
237
238 MODULE_LICENSE("GPL v2");
239