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
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 const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
39
40static u32 find_nvram_size(void __iomem *end)
41{
42	struct nvram_header __iomem *header;
43	int i;
44
45	for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
46		header = (struct nvram_header *)(end - nvram_sizes[i]);
47		if (header->magic == NVRAM_MAGIC)
48			return nvram_sizes[i];
49	}
50
51	return 0;
52}
53
54/* Probe for NVRAM header */
55static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
56{
57	struct nvram_header __iomem *header;
58	int i;
59	u32 off;
60	u32 *src, *dst;
61	u32 size;
62
63	if (nvram_buf[0]) {
64		pr_warn("nvram already initialized\n");
65		return -EEXIST;
66	}
67
68	/* TODO: when nvram is on nand flash check for bad blocks first. */
69	off = FLASH_MIN;
70	while (off <= lim) {
71		/* Windowed flash access */
72		size = find_nvram_size(iobase + off);
73		if (size) {
74			header = (struct nvram_header *)(iobase + off - size);
75			goto found;
76		}
77		off <<= 1;
78	}
79
80	/* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
81	header = (struct nvram_header *)(iobase + 4096);
82	if (header->magic == NVRAM_MAGIC) {
83		size = NVRAM_SPACE;
84		goto found;
85	}
86
87	header = (struct nvram_header *)(iobase + 1024);
88	if (header->magic == NVRAM_MAGIC) {
89		size = NVRAM_SPACE;
90		goto found;
91	}
92
93	pr_err("no nvram found\n");
94	return -ENXIO;
95
96found:
97	if (header->len > size)
98		pr_err("The nvram size accoridng to the header seems to be bigger than the partition on flash\n");
99	if (header->len > NVRAM_SPACE)
100		pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
101		       header->len, NVRAM_SPACE);
102
103	src = (u32 *)header;
104	dst = (u32 *)nvram_buf;
105	for (i = 0; i < sizeof(struct nvram_header); i += 4)
106		*dst++ = __raw_readl(src++);
107	for (; i < header->len && i < NVRAM_SPACE && i < size; i += 4)
108		*dst++ = readl(src++);
109
110	return 0;
111}
112
113/*
114 * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
115 * subsystem to access flash. We can't even use platform device / driver to
116 * store memory offset.
117 * To handle this we provide following symbol. It's supposed to be called as
118 * soon as we get info about flash device, before any NVRAM entry is needed.
119 */
120int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
121{
122	void __iomem *iobase;
123	int err;
124
125	iobase = ioremap_nocache(base, lim);
126	if (!iobase)
127		return -ENOMEM;
128
129	err = nvram_find_and_copy(iobase, lim);
130
131	iounmap(iobase);
132
133	return err;
134}
135
136static int nvram_init(void)
137{
138#ifdef CONFIG_MTD
139	struct mtd_info *mtd;
140	struct nvram_header header;
141	size_t bytes_read;
142	int err;
143
144	mtd = get_mtd_device_nm("nvram");
145	if (IS_ERR(mtd))
146		return -ENODEV;
147
148	err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
149	if (!err && header.magic == NVRAM_MAGIC) {
150		u8 *dst = (uint8_t *)nvram_buf;
151		size_t len = header.len;
152
153		if (header.len > NVRAM_SPACE) {
154			pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
155				header.len, NVRAM_SPACE);
156			len = NVRAM_SPACE;
157		}
158
159		err = mtd_read(mtd, 0, len, &bytes_read, dst);
160		if (err)
161			return err;
162
163		return 0;
164	}
165#endif
166
167	return -ENXIO;
168}
169
170int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
171{
172	char *var, *value, *end, *eq;
173	int data_left, err;
174
175	if (!name)
176		return -EINVAL;
177
178	if (!nvram_buf[0]) {
179		err = nvram_init();
180		if (err)
181			return err;
182	}
183
184	/* Look for name=value and return value */
185	var = &nvram_buf[sizeof(struct nvram_header)];
186	end = nvram_buf + sizeof(nvram_buf) - 2;
187	end[0] = '\0';
188	end[1] = '\0';
189	for (; *var; var = value + strlen(value) + 1) {
190		data_left = end - var;
191
192		eq = strnchr(var, data_left, '=');
193		if (!eq)
194			break;
195		value = eq + 1;
196		if (eq - var == strlen(name) &&
197		    strncmp(var, name, eq - var) == 0)
198			return snprintf(val, val_len, "%s", value);
199	}
200	return -ENOENT;
201}
202EXPORT_SYMBOL(bcm47xx_nvram_getenv);
203
204int bcm47xx_nvram_gpio_pin(const char *name)
205{
206	int i, err;
207	char nvram_var[] = "gpioXX";
208	char buf[NVRAM_MAX_GPIO_VALUE_LEN];
209
210	/* TODO: Optimize it to don't call getenv so many times */
211	for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
212		err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
213		if (err <= 0)
214			continue;
215		err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
216		if (err <= 0)
217			continue;
218		if (!strcmp(name, buf))
219			return i;
220	}
221	return -ENOENT;
222}
223EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
224