1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * BCM947xx nvram variable access
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>
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>
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
23 #define FLASH_MIN 0x00020000 /* Minimum flash size */
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 */
33 static char nvram_buf[NVRAM_SPACE];
34 static size_t nvram_len;
35 static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
38 * bcm47xx_nvram_is_valid - check for a valid NVRAM at specified memory
40 static bool bcm47xx_nvram_is_valid(void __iomem *nvram)
42 return ((struct nvram_header *)nvram)->magic == NVRAM_MAGIC;
45 static u32 find_nvram_size(void __iomem *end)
49 for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
50 if (bcm47xx_nvram_is_valid(end - nvram_sizes[i]))
51 return nvram_sizes[i];
58 * bcm47xx_nvram_copy - copy NVRAM to internal buffer
60 static void bcm47xx_nvram_copy(void __iomem *nvram_start, size_t res_size)
62 struct nvram_header __iomem *header = nvram_start;
65 copy_size = header->len;
66 if (copy_size > res_size) {
67 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
70 if (copy_size >= NVRAM_SPACE) {
71 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
72 copy_size, NVRAM_SPACE - 1);
73 copy_size = NVRAM_SPACE - 1;
76 __ioread32_copy(nvram_buf, nvram_start, DIV_ROUND_UP(copy_size, 4));
77 nvram_buf[NVRAM_SPACE - 1] = '\0';
78 nvram_len = copy_size;
82 * bcm47xx_nvram_find_and_copy - find NVRAM on flash mapping & copy it
84 static int bcm47xx_nvram_find_and_copy(void __iomem *flash_start, size_t res_size)
91 pr_warn("nvram already initialized\n");
95 /* TODO: when nvram is on nand flash check for bad blocks first. */
96 for (flash_size = FLASH_MIN; flash_size <= res_size; flash_size <<= 1) {
97 /* Windowed flash access */
98 size = find_nvram_size(flash_start + flash_size);
100 offset = flash_size - size;
105 /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
108 if (bcm47xx_nvram_is_valid(flash_start + offset))
112 if (bcm47xx_nvram_is_valid(flash_start + offset))
115 pr_err("no nvram found\n");
119 bcm47xx_nvram_copy(flash_start + offset, res_size - offset);
125 * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
126 * subsystem to access flash. We can't even use platform device / driver to
127 * store memory offset.
128 * To handle this we provide following symbol. It's supposed to be called as
129 * soon as we get info about flash device, before any NVRAM entry is needed.
131 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
133 void __iomem *iobase;
136 iobase = ioremap(base, lim);
140 err = bcm47xx_nvram_find_and_copy(iobase, lim);
147 static int nvram_init(void)
150 struct mtd_info *mtd;
151 struct nvram_header header;
155 mtd = get_mtd_device_nm("nvram");
159 err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
160 if (!err && header.magic == NVRAM_MAGIC &&
161 header.len > sizeof(header)) {
162 nvram_len = header.len;
163 if (nvram_len >= NVRAM_SPACE) {
164 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
165 nvram_len, NVRAM_SPACE);
166 nvram_len = NVRAM_SPACE - 1;
169 err = mtd_read(mtd, 0, nvram_len, &nvram_len,
178 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
180 char *var, *value, *end, *eq;
192 /* Look for name=value and return value */
193 var = &nvram_buf[sizeof(struct nvram_header)];
194 end = nvram_buf + sizeof(nvram_buf);
195 while (var < end && *var) {
196 eq = strchr(var, '=');
200 if (eq - var == strlen(name) &&
201 strncmp(var, name, eq - var) == 0)
202 return snprintf(val, val_len, "%s", value);
203 var = value + strlen(value) + 1;
207 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
209 int bcm47xx_nvram_gpio_pin(const char *name)
212 char nvram_var[] = "gpioXX";
213 char buf[NVRAM_MAX_GPIO_VALUE_LEN];
215 /* TODO: Optimize it to don't call getenv so many times */
216 for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
217 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
220 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
223 if (!strcmp(name, buf))
228 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
230 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
241 *nvram_size = nvram_len - sizeof(struct nvram_header);
242 nvram = vmalloc(*nvram_size);
245 memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
249 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
251 MODULE_LICENSE("GPL v2");