1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2021 Rafał Miłecki <rafal@milecki.pl>
4 */
5
6 #include <linux/io.h>
7 #include <linux/mod_devicetable.h>
8 #include <linux/module.h>
9 #include <linux/nvmem-consumer.h>
10 #include <linux/nvmem-provider.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/slab.h>
14
15 #define NVRAM_MAGIC "FLSH"
16
17 struct brcm_nvram {
18 struct device *dev;
19 void __iomem *base;
20 struct nvmem_cell_info *cells;
21 int ncells;
22 };
23
24 struct brcm_nvram_header {
25 char magic[4];
26 __le32 len;
27 __le32 crc_ver_init; /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
28 __le32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */
29 __le32 config_ncdl; /* ncdl values for memc */
30 };
31
brcm_nvram_read(void * context,unsigned int offset,void * val,size_t bytes)32 static int brcm_nvram_read(void *context, unsigned int offset, void *val,
33 size_t bytes)
34 {
35 struct brcm_nvram *priv = context;
36 u8 *dst = val;
37
38 while (bytes--)
39 *dst++ = readb(priv->base + offset++);
40
41 return 0;
42 }
43
brcm_nvram_add_cells(struct brcm_nvram * priv,uint8_t * data,size_t len)44 static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
45 size_t len)
46 {
47 struct device *dev = priv->dev;
48 char *var, *value, *eq;
49 int idx;
50
51 priv->ncells = 0;
52 for (var = data + sizeof(struct brcm_nvram_header);
53 var < (char *)data + len && *var;
54 var += strlen(var) + 1) {
55 priv->ncells++;
56 }
57
58 priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
59 if (!priv->cells)
60 return -ENOMEM;
61
62 for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
63 var < (char *)data + len && *var;
64 var = value + strlen(value) + 1, idx++) {
65 eq = strchr(var, '=');
66 if (!eq)
67 break;
68 *eq = '\0';
69 value = eq + 1;
70
71 priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
72 if (!priv->cells[idx].name)
73 return -ENOMEM;
74 priv->cells[idx].offset = value - (char *)data;
75 priv->cells[idx].bytes = strlen(value);
76 priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
77 }
78
79 return 0;
80 }
81
brcm_nvram_parse(struct brcm_nvram * priv)82 static int brcm_nvram_parse(struct brcm_nvram *priv)
83 {
84 struct device *dev = priv->dev;
85 struct brcm_nvram_header header;
86 uint8_t *data;
87 size_t len;
88 int err;
89
90 memcpy_fromio(&header, priv->base, sizeof(header));
91
92 if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
93 dev_err(dev, "Invalid NVRAM magic\n");
94 return -EINVAL;
95 }
96
97 len = le32_to_cpu(header.len);
98
99 data = kzalloc(len, GFP_KERNEL);
100 memcpy_fromio(data, priv->base, len);
101 data[len - 1] = '\0';
102
103 err = brcm_nvram_add_cells(priv, data, len);
104 if (err) {
105 dev_err(dev, "Failed to add cells: %d\n", err);
106 return err;
107 }
108
109 kfree(data);
110
111 return 0;
112 }
113
brcm_nvram_probe(struct platform_device * pdev)114 static int brcm_nvram_probe(struct platform_device *pdev)
115 {
116 struct nvmem_config config = {
117 .name = "brcm-nvram",
118 .reg_read = brcm_nvram_read,
119 };
120 struct device *dev = &pdev->dev;
121 struct resource *res;
122 struct brcm_nvram *priv;
123 int err;
124
125 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
126 if (!priv)
127 return -ENOMEM;
128 priv->dev = dev;
129
130 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
131 priv->base = devm_ioremap_resource(dev, res);
132 if (IS_ERR(priv->base))
133 return PTR_ERR(priv->base);
134
135 err = brcm_nvram_parse(priv);
136 if (err)
137 return err;
138
139 config.dev = dev;
140 config.cells = priv->cells;
141 config.ncells = priv->ncells;
142 config.priv = priv;
143 config.size = resource_size(res);
144
145 return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
146 }
147
148 static const struct of_device_id brcm_nvram_of_match_table[] = {
149 { .compatible = "brcm,nvram", },
150 {},
151 };
152
153 static struct platform_driver brcm_nvram_driver = {
154 .probe = brcm_nvram_probe,
155 .driver = {
156 .name = "brcm_nvram",
157 .of_match_table = brcm_nvram_of_match_table,
158 },
159 };
160
brcm_nvram_init(void)161 static int __init brcm_nvram_init(void)
162 {
163 return platform_driver_register(&brcm_nvram_driver);
164 }
165
166 subsys_initcall_sync(brcm_nvram_init);
167
168 MODULE_AUTHOR("Rafał Miłecki");
169 MODULE_LICENSE("GPL");
170 MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);
171