1/*
2 * BCM947xx nvram variable access
3 *
4 * Copyright (C) 2005 Broadcom Corporation
5 * Copyright (C) 2006 Felix Fietkau <nbd@nbd.name>
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
29struct 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
37static char nvram_buf[NVRAM_SPACE];
38static size_t nvram_len;
39static const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
40
41static 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 */
56static 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
97found:
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 */
128int 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
144static 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
175int 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}
204EXPORT_SYMBOL(bcm47xx_nvram_getenv);
205
206int 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}
225EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
226
227char *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}
246EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
247
248MODULE_LICENSE("GPLv2");
249