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
12struct sl28vpd_header {
13	u8 magic;
14	u8 version;
15} __packed;
16
17struct 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
24static 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
42static 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
56static 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
83static 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
138static const struct of_device_id sl28vpd_of_match_table[] = {
139	{ .compatible = "kontron,sl28-vpd" },
140	{},
141};
142MODULE_DEVICE_TABLE(of, sl28vpd_of_match_table);
143
144static struct nvmem_layout sl28vpd_layout = {
145	.name = "sl28-vpd",
146	.of_match_table = sl28vpd_of_match_table,
147	.add_cells = sl28vpd_add_cells,
148};
149module_nvmem_layout_driver(sl28vpd_layout);
150
151MODULE_LICENSE("GPL");
152MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
153MODULE_DESCRIPTION("NVMEM layout driver for the VPD of Kontron sl28 boards");
154