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 nvmem_layout *layout)
84{
85	struct nvmem_device *nvmem = layout->nvmem;
86	struct device *dev = &layout->dev;
87	const struct nvmem_cell_info *pinfo;
88	struct nvmem_cell_info info = {0};
89	struct device_node *layout_np;
90	struct sl28vpd_header hdr;
91	int ret, i;
92
93	/* check header */
94	ret = nvmem_device_read(nvmem, 0, sizeof(hdr), &hdr);
95	if (ret < 0)
96		return ret;
97	else if (ret != sizeof(hdr))
98		return -EIO;
99
100	if (hdr.magic != SL28VPD_MAGIC) {
101		dev_err(dev, "Invalid magic value (%02x)\n", hdr.magic);
102		return -EINVAL;
103	}
104
105	if (hdr.version != 1) {
106		dev_err(dev, "Version %d is unsupported.\n", hdr.version);
107		return -EINVAL;
108	}
109
110	ret = sl28vpd_v1_check_crc(dev, nvmem);
111	if (ret)
112		return ret;
113
114	layout_np = of_nvmem_layout_get_container(nvmem);
115	if (!layout_np)
116		return -ENOENT;
117
118	for (i = 0; i < ARRAY_SIZE(sl28vpd_v1_entries); i++) {
119		pinfo = &sl28vpd_v1_entries[i];
120
121		info.name = pinfo->name;
122		info.offset = pinfo->offset;
123		info.bytes = pinfo->bytes;
124		info.read_post_process = pinfo->read_post_process;
125		info.np = of_get_child_by_name(layout_np, pinfo->name);
126
127		ret = nvmem_add_one_cell(nvmem, &info);
128		if (ret) {
129			of_node_put(layout_np);
130			return ret;
131		}
132	}
133
134	of_node_put(layout_np);
135
136	return 0;
137}
138
139static int sl28vpd_probe(struct nvmem_layout *layout)
140{
141	layout->add_cells = sl28vpd_add_cells;
142
143	return nvmem_layout_register(layout);
144}
145
146static void sl28vpd_remove(struct nvmem_layout *layout)
147{
148	nvmem_layout_unregister(layout);
149}
150
151static const struct of_device_id sl28vpd_of_match_table[] = {
152	{ .compatible = "kontron,sl28-vpd" },
153	{},
154};
155MODULE_DEVICE_TABLE(of, sl28vpd_of_match_table);
156
157static struct nvmem_layout_driver sl28vpd_layout = {
158	.driver = {
159		.owner = THIS_MODULE,
160		.name = "kontron-sl28vpd-layout",
161		.of_match_table = sl28vpd_of_match_table,
162	},
163	.probe = sl28vpd_probe,
164	.remove = sl28vpd_remove,
165};
166module_nvmem_layout_driver(sl28vpd_layout);
167
168MODULE_LICENSE("GPL");
169MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
170MODULE_DESCRIPTION("NVMEM layout driver for the VPD of Kontron sl28 boards");
171