firmware/broadcom/bcm47xx_nvram.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * BCM947xx nvram variable access
0004  *
0005  * Copyright (C) 2005 Broadcom Corporation
0006  * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
0007  * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
0008  */
0009
0010 #include <linux/io.h>
0011 #include <linux/types.h>
0012 #include <linux/module.h>
0013 #include <linux/kernel.h>
0014 #include <linux/string.h>
0015 #include <linux/mtd/mtd.h>
0016 #include <linux/bcm47xx_nvram.h>
0017
0018 #define NVRAM_MAGIC         0x48534C46  /* 'FLSH' */
0019 #define NVRAM_SPACE         0x10000
0020 #define NVRAM_MAX_GPIO_ENTRIES      32
0021 #define NVRAM_MAX_GPIO_VALUE_LEN    30
0022
0023 #define FLASH_MIN       0x00020000  /* Minimum flash size */
0024
0025 struct nvram_header {
0026     u32 magic;
0027     u32 len;
0028     u32 crc_ver_init;   /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
0029     u32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */
0030     u32 config_ncdl;    /* ncdl values for memc */
0031 };
0032
0033 static char nvram_buf[NVRAM_SPACE];
0034 static size_t nvram_len;
0035 static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
0036
0037 /**
0038  * bcm47xx_nvram_is_valid - check for a valid NVRAM at specified memory
0039  */
0040 static bool bcm47xx_nvram_is_valid(void __iomem *nvram)
0041 {
0042     return ((struct nvram_header *)nvram)->magic == NVRAM_MAGIC;
0043 }
0044
0045 /**
0046  * bcm47xx_nvram_copy - copy NVRAM to internal buffer
0047  */
0048 static void bcm47xx_nvram_copy(void __iomem *nvram_start, size_t res_size)
0049 {
0050     struct nvram_header __iomem *header = nvram_start;
0051     size_t copy_size;
0052
0053     copy_size = header->len;
0054     if (copy_size > res_size) {
0055         pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
0056         copy_size = res_size;
0057     }
0058     if (copy_size >= NVRAM_SPACE) {
0059         pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
0060                copy_size, NVRAM_SPACE - 1);
0061         copy_size = NVRAM_SPACE - 1;
0062     }
0063
0064     __ioread32_copy(nvram_buf, nvram_start, DIV_ROUND_UP(copy_size, 4));
0065     nvram_buf[NVRAM_SPACE - 1] = '\0';
0066     nvram_len = copy_size;
0067 }
0068
0069 /**
0070  * bcm47xx_nvram_find_and_copy - find NVRAM on flash mapping & copy it
0071  */
0072 static int bcm47xx_nvram_find_and_copy(void __iomem *flash_start, size_t res_size)
0073 {
0074     size_t flash_size;
0075     size_t offset;
0076     int i;
0077
0078     if (nvram_len) {
0079         pr_warn("nvram already initialized\n");
0080         return -EEXIST;
0081     }
0082
0083     /* TODO: when nvram is on nand flash check for bad blocks first. */
0084
0085     /* Try every possible flash size and check for NVRAM at its end */
0086     for (flash_size = FLASH_MIN; flash_size <= res_size; flash_size <<= 1) {
0087         for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
0088             offset = flash_size - nvram_sizes[i];
0089             if (bcm47xx_nvram_is_valid(flash_start + offset))
0090                 goto found;
0091         }
0092     }
0093
0094     /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
0095
0096     offset = 4096;
0097     if (bcm47xx_nvram_is_valid(flash_start + offset))
0098         goto found;
0099
0100     offset = 1024;
0101     if (bcm47xx_nvram_is_valid(flash_start + offset))
0102         goto found;
0103
0104     pr_err("no nvram found\n");
0105     return -ENXIO;
0106
0107 found:
0108     bcm47xx_nvram_copy(flash_start + offset, res_size - offset);
0109
0110     return 0;
0111 }
0112
0113 /*
0114  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
0115  * subsystem to access flash. We can't even use platform device / driver to
0116  * store memory offset.
0117  * To handle this we provide following symbol. It's supposed to be called as
0118  * soon as we get info about flash device, before any NVRAM entry is needed.
0119  */
0120 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
0121 {
0122     void __iomem *iobase;
0123     int err;
0124
0125     iobase = ioremap(base, lim);
0126     if (!iobase)
0127         return -ENOMEM;
0128
0129     err = bcm47xx_nvram_find_and_copy(iobase, lim);
0130
0131     iounmap(iobase);
0132
0133     return err;
0134 }
0135
0136 static int nvram_init(void)
0137 {
0138 #ifdef CONFIG_MTD
0139     struct mtd_info *mtd;
0140     struct nvram_header header;
0141     size_t bytes_read;
0142     int err;
0143
0144     mtd = get_mtd_device_nm("nvram");
0145     if (IS_ERR(mtd))
0146         return -ENODEV;
0147
0148     err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
0149     if (!err && header.magic == NVRAM_MAGIC &&
0150         header.len > sizeof(header)) {
0151         nvram_len = header.len;
0152         if (nvram_len >= NVRAM_SPACE) {
0153             pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
0154                 nvram_len, NVRAM_SPACE);
0155             nvram_len = NVRAM_SPACE - 1;
0156         }
0157
0158         err = mtd_read(mtd, 0, nvram_len, &nvram_len,
0159                    (u8 *)nvram_buf);
0160         return err;
0161     }
0162 #endif
0163
0164     return -ENXIO;
0165 }
0166
0167 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
0168 {
0169     char *var, *value, *end, *eq;
0170     int err;
0171
0172     if (!name)
0173         return -EINVAL;
0174
0175     if (!nvram_len) {
0176         err = nvram_init();
0177         if (err)
0178             return err;
0179     }
0180
0181     /* Look for name=value and return value */
0182     var = &nvram_buf[sizeof(struct nvram_header)];
0183     end = nvram_buf + sizeof(nvram_buf);
0184     while (var < end && *var) {
0185         eq = strchr(var, '=');
0186         if (!eq)
0187             break;
0188         value = eq + 1;
0189         if (eq - var == strlen(name) &&
0190             strncmp(var, name, eq - var) == 0)
0191             return snprintf(val, val_len, "%s", value);
0192         var = value + strlen(value) + 1;
0193     }
0194     return -ENOENT;
0195 }
0196 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
0197
0198 int bcm47xx_nvram_gpio_pin(const char *name)
0199 {
0200     int i, err;
0201     char nvram_var[] = "gpioXX";
0202     char buf[NVRAM_MAX_GPIO_VALUE_LEN];
0203
0204     /* TODO: Optimize it to don't call getenv so many times */
0205     for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
0206         err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
0207         if (err <= 0)
0208             continue;
0209         err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
0210         if (err <= 0)
0211             continue;
0212         if (!strcmp(name, buf))
0213             return i;
0214     }
0215     return -ENOENT;
0216 }
0217 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
0218
0219 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
0220 {
0221     int err;
0222     char *nvram;
0223
0224     if (!nvram_len) {
0225         err = nvram_init();
0226         if (err)
0227             return NULL;
0228     }
0229
0230     *nvram_size = nvram_len - sizeof(struct nvram_header);
0231     nvram = vmalloc(*nvram_size);
0232     if (!nvram)
0233         return NULL;
0234     memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
0235
0236     return nvram;
0237 }
0238 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
0239
0240 MODULE_LICENSE("GPL v2");