1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/crc8.h>
4 #include <linux/etherdevice.h>
5 #include <linux/nvmem-consumer.h>
6 #include <linux/nvmem-provider.h>
7 #include <linux/of.h>
8 #include <uapi/linux/if_ether.h>
9
10 #define SL28VPD_MAGIC 'V'
11
12 struct sl28vpd_header {
13 u8 magic;
14 u8 version;
15 } __packed;
16
17 struct sl28vpd_v1 {
18 struct sl28vpd_header header;
19 char serial_number[15];
20 u8 base_mac_address[ETH_ALEN];
21 u8 crc8;
22 } __packed;
23
sl28vpd_mac_address_pp(void * priv,const char * id,int index,unsigned int offset,void * buf,size_t bytes)24 static int sl28vpd_mac_address_pp(void *priv, const char *id, int index,
25 unsigned int offset, void *buf,
26 size_t bytes)
27 {
28 if (bytes != ETH_ALEN)
29 return -EINVAL;
30
31 if (index < 0)
32 return -EINVAL;
33
34 if (!is_valid_ether_addr(buf))
35 return -EINVAL;
36
37 eth_addr_add(buf, index);
38
39 return 0;
40 }
41
42 static const struct nvmem_cell_info sl28vpd_v1_entries[] = {
43 {
44 .name = "serial-number",
45 .offset = offsetof(struct sl28vpd_v1, serial_number),
46 .bytes = sizeof_field(struct sl28vpd_v1, serial_number),
47 },
48 {
49 .name = "base-mac-address",
50 .offset = offsetof(struct sl28vpd_v1, base_mac_address),
51 .bytes = sizeof_field(struct sl28vpd_v1, base_mac_address),
52 .read_post_process = sl28vpd_mac_address_pp,
53 },
54 };
55
sl28vpd_v1_check_crc(struct device * dev,struct nvmem_device * nvmem)56 static int sl28vpd_v1_check_crc(struct device *dev, struct nvmem_device *nvmem)
57 {
58 struct sl28vpd_v1 data_v1;
59 u8 table[CRC8_TABLE_SIZE];
60 int ret;
61 u8 crc;
62
63 crc8_populate_msb(table, 0x07);
64
65 ret = nvmem_device_read(nvmem, 0, sizeof(data_v1), &data_v1);
66 if (ret < 0)
67 return ret;
68 else if (ret != sizeof(data_v1))
69 return -EIO;
70
71 crc = crc8(table, (void *)&data_v1, sizeof(data_v1) - 1, 0);
72
73 if (crc != data_v1.crc8) {
74 dev_err(dev,
75 "Checksum is invalid (got %02x, expected %02x).\n",
76 crc, data_v1.crc8);
77 return -EINVAL;
78 }
79
80 return 0;
81 }
82
sl28vpd_add_cells(struct device * dev,struct nvmem_device * nvmem,struct nvmem_layout * layout)83 static int sl28vpd_add_cells(struct device *dev, struct nvmem_device *nvmem,
84 struct nvmem_layout *layout)
85 {
86 const struct nvmem_cell_info *pinfo;
87 struct nvmem_cell_info info = {0};
88 struct device_node *layout_np;
89 struct sl28vpd_header hdr;
90 int ret, i;
91
92 /* check header */
93 ret = nvmem_device_read(nvmem, 0, sizeof(hdr), &hdr);
94 if (ret < 0)
95 return ret;
96 else if (ret != sizeof(hdr))
97 return -EIO;
98
99 if (hdr.magic != SL28VPD_MAGIC) {
100 dev_err(dev, "Invalid magic value (%02x)\n", hdr.magic);
101 return -EINVAL;
102 }
103
104 if (hdr.version != 1) {
105 dev_err(dev, "Version %d is unsupported.\n", hdr.version);
106 return -EINVAL;
107 }
108
109 ret = sl28vpd_v1_check_crc(dev, nvmem);
110 if (ret)
111 return ret;
112
113 layout_np = of_nvmem_layout_get_container(nvmem);
114 if (!layout_np)
115 return -ENOENT;
116
117 for (i = 0; i < ARRAY_SIZE(sl28vpd_v1_entries); i++) {
118 pinfo = &sl28vpd_v1_entries[i];
119
120 info.name = pinfo->name;
121 info.offset = pinfo->offset;
122 info.bytes = pinfo->bytes;
123 info.read_post_process = pinfo->read_post_process;
124 info.np = of_get_child_by_name(layout_np, pinfo->name);
125
126 ret = nvmem_add_one_cell(nvmem, &info);
127 if (ret) {
128 of_node_put(layout_np);
129 return ret;
130 }
131 }
132
133 of_node_put(layout_np);
134
135 return 0;
136 }
137
138 static const struct of_device_id sl28vpd_of_match_table[] = {
139 { .compatible = "kontron,sl28-vpd" },
140 {},
141 };
142 MODULE_DEVICE_TABLE(of, sl28vpd_of_match_table);
143
144 static struct nvmem_layout sl28vpd_layout = {
145 .name = "sl28-vpd",
146 .of_match_table = sl28vpd_of_match_table,
147 .add_cells = sl28vpd_add_cells,
148 };
149 module_nvmem_layout_driver(sl28vpd_layout);
150
151 MODULE_LICENSE("GPL");
152 MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
153 MODULE_DESCRIPTION("NVMEM layout driver for the VPD of Kontron sl28 boards");
154
