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 
25 struct 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 
33 static char nvram_buf[NVRAM_SPACE];
34 static size_t nvram_len;
35 static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
36 
37 /**
38  * bcm47xx_nvram_is_valid - check for a valid NVRAM at specified memory
39  */
40 static 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  */
48 static 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  */
72 static 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 
107 found:
108 	bcm47xx_nvram_copy(flash_start + offset, res_size - offset);
109 
110 	return 0;
111 }
112 
113 int 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 }
129 EXPORT_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  */
138 int 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 
154 static 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 
185 int 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 }
214 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
215 
216 int 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 }
235 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
236 
237 char *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 }
256 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
257 
258