sl28vpd.c

  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		.name = "kontron-sl28vpd-layout",
160		.of_match_table = sl28vpd_of_match_table,
161	},
162	.probe = sl28vpd_probe,
163	.remove = sl28vpd_remove,
164};
165module_nvmem_layout_driver(sl28vpd_layout);
166
167MODULE_LICENSE("GPL");
168MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
169MODULE_DESCRIPTION("NVMEM layout driver for the VPD of Kontron sl28 boards");