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
25struct 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
33static char nvram_buf[NVRAM_SPACE];
34static size_t nvram_len;
35static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
36
37/**
38 * bcm47xx_nvram_is_valid - check for a valid NVRAM at specified memory
39 */
40static bool bcm47xx_nvram_is_valid(void __iomem *nvram)
41{
42 return ((struct nvram_header *)nvram)->magic == NVRAM_MAGIC;
43}
44
45/**
46 * bcm47xx_nvram_copy - copy NVRAM to internal buffer
47 */
48static void bcm47xx_nvram_copy(void __iomem *nvram_start, size_t res_size)
49{
50 struct nvram_header __iomem *header = nvram_start;
51 size_t copy_size;
52
53 copy_size = header->len;
54 if (copy_size > res_size) {
55 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
56 copy_size = res_size;
57 }
58 if (copy_size >= NVRAM_SPACE) {
59 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
60 copy_size, NVRAM_SPACE - 1);
61 copy_size = NVRAM_SPACE - 1;
62 }
63
64 __ioread32_copy(to: nvram_buf, from: nvram_start, DIV_ROUND_UP(copy_size, 4));
65 nvram_buf[NVRAM_SPACE - 1] = '\0';
66 nvram_len = copy_size;
67}
68
69/**
70 * bcm47xx_nvram_find_and_copy - find NVRAM on flash mapping & copy it
71 */
72static int bcm47xx_nvram_find_and_copy(void __iomem *flash_start, size_t res_size)
73{
74 size_t flash_size;
75 size_t offset;
76 int i;
77
78 if (nvram_len) {
79 pr_warn("nvram already initialized\n");
80 return -EEXIST;
81 }
82
83 /* TODO: when nvram is on nand flash check for bad blocks first. */
84
85 /* Try every possible flash size and check for NVRAM at its end */
86 for (flash_size = FLASH_MIN; flash_size <= res_size; flash_size <<= 1) {
87 for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
88 offset = flash_size - nvram_sizes[i];
89 if (bcm47xx_nvram_is_valid(nvram: flash_start + offset))
90 goto found;
91 }
92 }
93
94 /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
95
96 offset = 4096;
97 if (bcm47xx_nvram_is_valid(nvram: flash_start + offset))
98 goto found;
99
100 offset = 1024;
101 if (bcm47xx_nvram_is_valid(nvram: flash_start + offset))
102 goto found;
103
104 pr_err("no nvram found\n");
105 return -ENXIO;
106
107found:
108 bcm47xx_nvram_copy(nvram_start: flash_start + offset, res_size: res_size - offset);
109
110 return 0;
111}
112
113int bcm47xx_nvram_init_from_iomem(void __iomem *nvram_start, size_t res_size)
114{
115 if (nvram_len) {
116 pr_warn("nvram already initialized\n");
117 return -EEXIST;
118 }
119
120 if (!bcm47xx_nvram_is_valid(nvram: nvram_start)) {
121 pr_err("No valid NVRAM found\n");
122 return -ENOENT;
123 }
124
125 bcm47xx_nvram_copy(nvram_start, res_size);
126
127 return 0;
128}
129EXPORT_SYMBOL_GPL(bcm47xx_nvram_init_from_iomem);
130
131/*
132 * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
133 * subsystem to access flash. We can't even use platform device / driver to
134 * store memory offset.
135 * To handle this we provide following symbol. It's supposed to be called as
136 * soon as we get info about flash device, before any NVRAM entry is needed.
137 */
138int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
139{
140 void __iomem *iobase;
141 int err;
142
143 iobase = ioremap(offset: base, size: lim);
144 if (!iobase)
145 return -ENOMEM;
146
147 err = bcm47xx_nvram_find_and_copy(flash_start: iobase, res_size: lim);
148
149 iounmap(addr: iobase);
150
151 return err;
152}
153
154static int nvram_init(void)
155{
156#ifdef CONFIG_MTD
157 struct mtd_info *mtd;
158 struct nvram_header header;
159 size_t bytes_read;
160 int err;
161
162 mtd = get_mtd_device_nm(name: "nvram");
163 if (IS_ERR(ptr: mtd))
164 return -ENODEV;
165
166 err = mtd_read(mtd, from: 0, len: sizeof(header), retlen: &bytes_read, buf: (uint8_t *)&header);
167 if (!err && header.magic == NVRAM_MAGIC &&
168 header.len > sizeof(header)) {
169 nvram_len = header.len;
170 if (nvram_len >= NVRAM_SPACE) {
171 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
172 nvram_len, NVRAM_SPACE);
173 nvram_len = NVRAM_SPACE - 1;
174 }
175
176 err = mtd_read(mtd, from: 0, len: nvram_len, retlen: &nvram_len,
177 buf: (u8 *)nvram_buf);
178 return err;
179 }
180#endif
181
182 return -ENXIO;
183}
184
185int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
186{
187 char *var, *value, *end, *eq;
188 int err;
189
190 if (!name)
191 return -EINVAL;
192
193 if (!nvram_len) {
194 err = nvram_init();
195 if (err)
196 return err;
197 }
198
199 /* Look for name=value and return value */
200 var = &nvram_buf[sizeof(struct nvram_header)];
201 end = nvram_buf + sizeof(nvram_buf);
202 while (var < end && *var) {
203 eq = strchr(var, '=');
204 if (!eq)
205 break;
206 value = eq + 1;
207 if (eq - var == strlen(name) &&
208 strncmp(var, name, eq - var) == 0)
209 return snprintf(buf: val, size: val_len, fmt: "%s", value);
210 var = value + strlen(value) + 1;
211 }
212 return -ENOENT;
213}
214EXPORT_SYMBOL(bcm47xx_nvram_getenv);
215
216int bcm47xx_nvram_gpio_pin(const char *name)
217{
218 int i, err;
219 char nvram_var[] = "gpioXX";
220 char buf[NVRAM_MAX_GPIO_VALUE_LEN];
221
222 /* TODO: Optimize it to don't call getenv so many times */
223 for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
224 err = snprintf(buf: nvram_var, size: sizeof(nvram_var), fmt: "gpio%i", i);
225 if (err <= 0)
226 continue;
227 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
228 if (err <= 0)
229 continue;
230 if (!strcmp(name, buf))
231 return i;
232 }
233 return -ENOENT;
234}
235EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
236
237char *bcm47xx_nvram_get_contents(size_t *nvram_size)
238{
239 int err;
240 char *nvram;
241
242 if (!nvram_len) {
243 err = nvram_init();
244 if (err)
245 return NULL;
246 }
247
248 *nvram_size = nvram_len - sizeof(struct nvram_header);
249 nvram = vmalloc(size: *nvram_size);
250 if (!nvram)
251 return NULL;
252 memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
253
254 return nvram;
255}
256EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
257
258

source code of linux/drivers/firmware/broadcom/bcm47xx_nvram.c