1 /*
2  * BCM947xx nvram variable access
3  *
4  * Copyright (C) 2005 Broadcom Corporation
5  * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
6  * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
7  *
8  * This program is free software; you can redistribute	it and/or modify it
9  * under  the terms of	the GNU General	 Public License as published by the
10  * Free Software Foundation;  either version 2 of the  License, or (at your
11  * option) any later version.
12  */
13 
14 #include <linux/io.h>
15 #include <linux/types.h>
16 #include <linux/module.h>
17 #include <linux/kernel.h>
18 #include <linux/string.h>
19 #include <linux/mtd/mtd.h>
20 #include <linux/bcm47xx_nvram.h>
21 
22 #define NVRAM_MAGIC			0x48534C46	/* 'FLSH' */
23 #define NVRAM_SPACE			0x10000
24 #define NVRAM_MAX_GPIO_ENTRIES		32
25 #define NVRAM_MAX_GPIO_VALUE_LEN	30
26 
27 #define FLASH_MIN		0x00020000	/* Minimum flash size */
28 
29 struct nvram_header {
30 	u32 magic;
31 	u32 len;
32 	u32 crc_ver_init;	/* 0:7 crc, 8:15 ver, 16:31 sdram_init */
33 	u32 config_refresh;	/* 0:15 sdram_config, 16:31 sdram_refresh */
34 	u32 config_ncdl;	/* ncdl values for memc */
35 };
36 
37 static char nvram_buf[NVRAM_SPACE];
38 static size_t nvram_len;
39 static const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
40 
41 static u32 find_nvram_size(void __iomem *end)
42 {
43 	struct nvram_header __iomem *header;
44 	int i;
45 
46 	for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
47 		header = (struct nvram_header *)(end - nvram_sizes[i]);
48 		if (header->magic == NVRAM_MAGIC)
49 			return nvram_sizes[i];
50 	}
51 
52 	return 0;
53 }
54 
55 /* Probe for NVRAM header */
56 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
57 {
58 	struct nvram_header __iomem *header;
59 	int i;
60 	u32 off;
61 	u32 *src, *dst;
62 	u32 size;
63 
64 	if (nvram_len) {
65 		pr_warn("nvram already initialized\n");
66 		return -EEXIST;
67 	}
68 
69 	/* TODO: when nvram is on nand flash check for bad blocks first. */
70 	off = FLASH_MIN;
71 	while (off <= lim) {
72 		/* Windowed flash access */
73 		size = find_nvram_size(iobase + off);
74 		if (size) {
75 			header = (struct nvram_header *)(iobase + off - size);
76 			goto found;
77 		}
78 		off <<= 1;
79 	}
80 
81 	/* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
82 	header = (struct nvram_header *)(iobase + 4096);
83 	if (header->magic == NVRAM_MAGIC) {
84 		size = NVRAM_SPACE;
85 		goto found;
86 	}
87 
88 	header = (struct nvram_header *)(iobase + 1024);
89 	if (header->magic == NVRAM_MAGIC) {
90 		size = NVRAM_SPACE;
91 		goto found;
92 	}
93 
94 	pr_err("no nvram found\n");
95 	return -ENXIO;
96 
97 found:
98 	src = (u32 *)header;
99 	dst = (u32 *)nvram_buf;
100 	for (i = 0; i < sizeof(struct nvram_header); i += 4)
101 		*dst++ = __raw_readl(src++);
102 	header = (struct nvram_header *)nvram_buf;
103 	nvram_len = header->len;
104 	if (nvram_len > size) {
105 		pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
106 		nvram_len = size;
107 	}
108 	if (nvram_len >= NVRAM_SPACE) {
109 		pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
110 		       header->len, NVRAM_SPACE - 1);
111 		nvram_len = NVRAM_SPACE - 1;
112 	}
113 	/* proceed reading data after header */
114 	for (; i < nvram_len; i += 4)
115 		*dst++ = readl(src++);
116 	nvram_buf[NVRAM_SPACE - 1] = '\0';
117 
118 	return 0;
119 }
120 
121 /*
122  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
123  * subsystem to access flash. We can't even use platform device / driver to
124  * store memory offset.
125  * To handle this we provide following symbol. It's supposed to be called as
126  * soon as we get info about flash device, before any NVRAM entry is needed.
127  */
128 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
129 {
130 	void __iomem *iobase;
131 	int err;
132 
133 	iobase = ioremap_nocache(base, lim);
134 	if (!iobase)
135 		return -ENOMEM;
136 
137 	err = nvram_find_and_copy(iobase, lim);
138 
139 	iounmap(iobase);
140 
141 	return err;
142 }
143 
144 static int nvram_init(void)
145 {
146 #ifdef CONFIG_MTD
147 	struct mtd_info *mtd;
148 	struct nvram_header header;
149 	size_t bytes_read;
150 	int err;
151 
152 	mtd = get_mtd_device_nm("nvram");
153 	if (IS_ERR(mtd))
154 		return -ENODEV;
155 
156 	err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
157 	if (!err && header.magic == NVRAM_MAGIC &&
158 	    header.len > sizeof(header)) {
159 		nvram_len = header.len;
160 		if (nvram_len >= NVRAM_SPACE) {
161 			pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
162 				header.len, NVRAM_SPACE);
163 			nvram_len = NVRAM_SPACE - 1;
164 		}
165 
166 		err = mtd_read(mtd, 0, nvram_len, &nvram_len,
167 			       (u8 *)nvram_buf);
168 		return err;
169 	}
170 #endif
171 
172 	return -ENXIO;
173 }
174 
175 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
176 {
177 	char *var, *value, *end, *eq;
178 	int err;
179 
180 	if (!name)
181 		return -EINVAL;
182 
183 	if (!nvram_len) {
184 		err = nvram_init();
185 		if (err)
186 			return err;
187 	}
188 
189 	/* Look for name=value and return value */
190 	var = &nvram_buf[sizeof(struct nvram_header)];
191 	end = nvram_buf + sizeof(nvram_buf);
192 	while (var < end && *var) {
193 		eq = strchr(var, '=');
194 		if (!eq)
195 			break;
196 		value = eq + 1;
197 		if (eq - var == strlen(name) &&
198 		    strncmp(var, name, eq - var) == 0)
199 			return snprintf(val, val_len, "%s", value);
200 		var = value + strlen(value) + 1;
201 	}
202 	return -ENOENT;
203 }
204 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
205 
206 int bcm47xx_nvram_gpio_pin(const char *name)
207 {
208 	int i, err;
209 	char nvram_var[] = "gpioXX";
210 	char buf[NVRAM_MAX_GPIO_VALUE_LEN];
211 
212 	/* TODO: Optimize it to don't call getenv so many times */
213 	for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
214 		err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
215 		if (err <= 0)
216 			continue;
217 		err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
218 		if (err <= 0)
219 			continue;
220 		if (!strcmp(name, buf))
221 			return i;
222 	}
223 	return -ENOENT;
224 }
225 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
226 
227 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
228 {
229 	int err;
230 	char *nvram;
231 
232 	if (!nvram_len) {
233 		err = nvram_init();
234 		if (err)
235 			return NULL;
236 	}
237 
238 	*nvram_size = nvram_len - sizeof(struct nvram_header);
239 	nvram = vmalloc(*nvram_size);
240 	if (!nvram)
241 		return NULL;
242 	memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
243 
244 	return nvram;
245 }
246 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
247 
248 MODULE_LICENSE("GPL v2");
249