xref: /linux/drivers/firmware/broadcom/bcm47xx_nvram.c (revision ebf68996de0ab250c5d520eb2291ab65643e9a1e)
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 static u32 find_nvram_size(void __iomem *end)
38 {
39 	struct nvram_header __iomem *header;
40 	int i;
41 
42 	for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
43 		header = (struct nvram_header *)(end - nvram_sizes[i]);
44 		if (header->magic == NVRAM_MAGIC)
45 			return nvram_sizes[i];
46 	}
47 
48 	return 0;
49 }
50 
51 /* Probe for NVRAM header */
52 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
53 {
54 	struct nvram_header __iomem *header;
55 	u32 off;
56 	u32 size;
57 
58 	if (nvram_len) {
59 		pr_warn("nvram already initialized\n");
60 		return -EEXIST;
61 	}
62 
63 	/* TODO: when nvram is on nand flash check for bad blocks first. */
64 	off = FLASH_MIN;
65 	while (off <= lim) {
66 		/* Windowed flash access */
67 		size = find_nvram_size(iobase + off);
68 		if (size) {
69 			header = (struct nvram_header *)(iobase + off - size);
70 			goto found;
71 		}
72 		off <<= 1;
73 	}
74 
75 	/* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
76 	header = (struct nvram_header *)(iobase + 4096);
77 	if (header->magic == NVRAM_MAGIC) {
78 		size = NVRAM_SPACE;
79 		goto found;
80 	}
81 
82 	header = (struct nvram_header *)(iobase + 1024);
83 	if (header->magic == NVRAM_MAGIC) {
84 		size = NVRAM_SPACE;
85 		goto found;
86 	}
87 
88 	pr_err("no nvram found\n");
89 	return -ENXIO;
90 
91 found:
92 	__ioread32_copy(nvram_buf, header, sizeof(*header) / 4);
93 	nvram_len = ((struct nvram_header *)(nvram_buf))->len;
94 	if (nvram_len > size) {
95 		pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
96 		nvram_len = size;
97 	}
98 	if (nvram_len >= NVRAM_SPACE) {
99 		pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
100 		       nvram_len, NVRAM_SPACE - 1);
101 		nvram_len = NVRAM_SPACE - 1;
102 	}
103 	/* proceed reading data after header */
104 	__ioread32_copy(nvram_buf + sizeof(*header), header + 1,
105 			DIV_ROUND_UP(nvram_len, 4));
106 	nvram_buf[NVRAM_SPACE - 1] = '\0';
107 
108 	return 0;
109 }
110 
111 /*
112  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
113  * subsystem to access flash. We can't even use platform device / driver to
114  * store memory offset.
115  * To handle this we provide following symbol. It's supposed to be called as
116  * soon as we get info about flash device, before any NVRAM entry is needed.
117  */
118 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
119 {
120 	void __iomem *iobase;
121 	int err;
122 
123 	iobase = ioremap_nocache(base, lim);
124 	if (!iobase)
125 		return -ENOMEM;
126 
127 	err = nvram_find_and_copy(iobase, lim);
128 
129 	iounmap(iobase);
130 
131 	return err;
132 }
133 
134 static int nvram_init(void)
135 {
136 #ifdef CONFIG_MTD
137 	struct mtd_info *mtd;
138 	struct nvram_header header;
139 	size_t bytes_read;
140 	int err;
141 
142 	mtd = get_mtd_device_nm("nvram");
143 	if (IS_ERR(mtd))
144 		return -ENODEV;
145 
146 	err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
147 	if (!err && header.magic == NVRAM_MAGIC &&
148 	    header.len > sizeof(header)) {
149 		nvram_len = header.len;
150 		if (nvram_len >= NVRAM_SPACE) {
151 			pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
152 				header.len, NVRAM_SPACE);
153 			nvram_len = NVRAM_SPACE - 1;
154 		}
155 
156 		err = mtd_read(mtd, 0, nvram_len, &nvram_len,
157 			       (u8 *)nvram_buf);
158 		return err;
159 	}
160 #endif
161 
162 	return -ENXIO;
163 }
164 
165 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
166 {
167 	char *var, *value, *end, *eq;
168 	int err;
169 
170 	if (!name)
171 		return -EINVAL;
172 
173 	if (!nvram_len) {
174 		err = nvram_init();
175 		if (err)
176 			return err;
177 	}
178 
179 	/* Look for name=value and return value */
180 	var = &nvram_buf[sizeof(struct nvram_header)];
181 	end = nvram_buf + sizeof(nvram_buf);
182 	while (var < end && *var) {
183 		eq = strchr(var, '=');
184 		if (!eq)
185 			break;
186 		value = eq + 1;
187 		if (eq - var == strlen(name) &&
188 		    strncmp(var, name, eq - var) == 0)
189 			return snprintf(val, val_len, "%s", value);
190 		var = value + strlen(value) + 1;
191 	}
192 	return -ENOENT;
193 }
194 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
195 
196 int bcm47xx_nvram_gpio_pin(const char *name)
197 {
198 	int i, err;
199 	char nvram_var[] = "gpioXX";
200 	char buf[NVRAM_MAX_GPIO_VALUE_LEN];
201 
202 	/* TODO: Optimize it to don't call getenv so many times */
203 	for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
204 		err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
205 		if (err <= 0)
206 			continue;
207 		err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
208 		if (err <= 0)
209 			continue;
210 		if (!strcmp(name, buf))
211 			return i;
212 	}
213 	return -ENOENT;
214 }
215 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
216 
217 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
218 {
219 	int err;
220 	char *nvram;
221 
222 	if (!nvram_len) {
223 		err = nvram_init();
224 		if (err)
225 			return NULL;
226 	}
227 
228 	*nvram_size = nvram_len - sizeof(struct nvram_header);
229 	nvram = vmalloc(*nvram_size);
230 	if (!nvram)
231 		return NULL;
232 	memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
233 
234 	return nvram;
235 }
236 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
237 
238 MODULE_LICENSE("GPL v2");
239