GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / nvmem / brcm_nvram.c
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
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
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
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 = kcalloc(1, 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
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
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);