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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* BCM947xx nvram variable access
*
* Copyright (C) 2005 Broadcom Corporation
* Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
* Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
*/
#include <linux/io.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mtd/mtd.h>
#include <linux/bcm47xx_nvram.h>
#define NVRAM_MAGIC 0x48534C46 /* 'FLSH' */
#define NVRAM_SPACE 0x10000
#define NVRAM_MAX_GPIO_ENTRIES 32
#define NVRAM_MAX_GPIO_VALUE_LEN 30
#define FLASH_MIN 0x00020000 /* Minimum flash size */
struct nvram_header {
u32 magic;
u32 len;
u32 crc_ver_init; /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
u32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */
u32 config_ncdl; /* ncdl values for memc */
};
static char nvram_buf[NVRAM_SPACE];
static size_t nvram_len;
static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
static u32 find_nvram_size(void __iomem *end)
{
struct nvram_header __iomem *header;
int i;
for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
header = (struct nvram_header *)(end - nvram_sizes[i]);
if (header->magic == NVRAM_MAGIC)
return nvram_sizes[i];
}
return 0;
}
/* Probe for NVRAM header */
static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
{
struct nvram_header __iomem *header;
u32 off;
u32 size;
if (nvram_len) {
pr_warn("nvram already initialized\n");
return -EEXIST;
}
/* TODO: when nvram is on nand flash check for bad blocks first. */
off = FLASH_MIN;
while (off <= lim) {
/* Windowed flash access */
size = find_nvram_size(iobase + off);
if (size) {
header = (struct nvram_header *)(iobase + off - size);
goto found;
}
off <<= 1;
}
/* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
header = (struct nvram_header *)(iobase + 4096);
if (header->magic == NVRAM_MAGIC) {
size = NVRAM_SPACE;
goto found;
}
header = (struct nvram_header *)(iobase + 1024);
if (header->magic == NVRAM_MAGIC) {
size = NVRAM_SPACE;
goto found;
}
pr_err("no nvram found\n");
return -ENXIO;
found:
__ioread32_copy(nvram_buf, header, sizeof(*header) / 4);
nvram_len = ((struct nvram_header *)(nvram_buf))->len;
if (nvram_len > size) {
pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
nvram_len = size;
}
if (nvram_len >= NVRAM_SPACE) {
pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
nvram_len, NVRAM_SPACE - 1);
nvram_len = NVRAM_SPACE - 1;
}
/* proceed reading data after header */
__ioread32_copy(nvram_buf + sizeof(*header), header + 1,
DIV_ROUND_UP(nvram_len, 4));
nvram_buf[NVRAM_SPACE - 1] = '\0';
return 0;
}
/*
* On bcm47xx we need access to the NVRAM very early, so we can't use mtd
* subsystem to access flash. We can't even use platform device / driver to
* store memory offset.
* To handle this we provide following symbol. It's supposed to be called as
* soon as we get info about flash device, before any NVRAM entry is needed.
*/
int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
{
void __iomem *iobase;
int err;
iobase = ioremap_nocache(base, lim);
if (!iobase)
return -ENOMEM;
err = nvram_find_and_copy(iobase, lim);
iounmap(iobase);
return err;
}
static int nvram_init(void)
{
#ifdef CONFIG_MTD
struct mtd_info *mtd;
struct nvram_header header;
size_t bytes_read;
int err;
mtd = get_mtd_device_nm("nvram");
if (IS_ERR(mtd))
return -ENODEV;
err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
if (!err && header.magic == NVRAM_MAGIC &&
header.len > sizeof(header)) {
nvram_len = header.len;
if (nvram_len >= NVRAM_SPACE) {
pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
nvram_len, NVRAM_SPACE);
nvram_len = NVRAM_SPACE - 1;
}
err = mtd_read(mtd, 0, nvram_len, &nvram_len,
(u8 *)nvram_buf);
return err;
}
#endif
return -ENXIO;
}
int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
{
char *var, *value, *end, *eq;
int err;
if (!name)
return -EINVAL;
if (!nvram_len) {
err = nvram_init();
if (err)
return err;
}
/* Look for name=value and return value */
var = &nvram_buf[sizeof(struct nvram_header)];
end = nvram_buf + sizeof(nvram_buf);
while (var < end && *var) {
eq = strchr(var, '=');
if (!eq)
break;
value = eq + 1;
if (eq - var == strlen(name) &&
strncmp(var, name, eq - var) == 0)
return snprintf(val, val_len, "%s", value);
var = value + strlen(value) + 1;
}
return -ENOENT;
}
EXPORT_SYMBOL(bcm47xx_nvram_getenv);
int bcm47xx_nvram_gpio_pin(const char *name)
{
int i, err;
char nvram_var[] = "gpioXX";
char buf[NVRAM_MAX_GPIO_VALUE_LEN];
/* TODO: Optimize it to don't call getenv so many times */
for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
if (err <= 0)
continue;
err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
if (err <= 0)
continue;
if (!strcmp(name, buf))
return i;
}
return -ENOENT;
}
EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
char *bcm47xx_nvram_get_contents(size_t *nvram_size)
{
int err;
char *nvram;
if (!nvram_len) {
err = nvram_init();
if (err)
return NULL;
}
*nvram_size = nvram_len - sizeof(struct nvram_header);
nvram = vmalloc(*nvram_size);
if (!nvram)
return NULL;
memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
return nvram;
}
EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
MODULE_LICENSE("GPL v2");
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