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
37static 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 */
52static 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
91found:
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 (%zu 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 */
118int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
119{
120	void __iomem *iobase;
121	int err;
122
123	iobase = ioremap(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
134static 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 (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
152				nvram_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
165int 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}
194EXPORT_SYMBOL(bcm47xx_nvram_getenv);
195
196int 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}
215EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
216
217char *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}
236EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
237
238MODULE_LICENSE("GPL v2");
239