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(nvram_buf, 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(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(flash_start + offset))
98		goto found;
99
100	offset = 1024;
101	if (bcm47xx_nvram_is_valid(flash_start + offset))
102		goto found;
103
104	pr_err("no nvram found\n");
105	return -ENXIO;
106
107found:
108	bcm47xx_nvram_copy(flash_start + offset, 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_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(base, lim);
144	if (!iobase)
145		return -ENOMEM;
146
147	err = bcm47xx_nvram_find_and_copy(iobase, lim);
148
149	iounmap(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("nvram");
163	if (IS_ERR(mtd))
164		return -ENODEV;
165
166	err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (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, 0, nvram_len, &nvram_len,
177			       (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(val, val_len, "%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(nvram_var, sizeof(nvram_var), "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(*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