+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * NVMEM layout driver for MikroTik Routerboard hard config cells
+ *
+ * Copyright (C) 2024 Robert Marko <robimarko@gmail.com>
+ * Based on the sysfs hard config driver by Thibaut VARÈNE <hacks+kernel@slashdirt.org>
+ * Comments documenting the format carried over from routerboot.c
+ */
+
+#include <linux/bitfield.h>
+#include <linux/etherdevice.h>
+#include <linux/mod_devicetable.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include "rb_hardconfig.h"
+#include "routerboot.h"
+
+#define TLV_TAG_MASK GENMASK(15, 0)
+#define TLV_LEN_MASK GENMASK(31, 16)
+
+static const char *rb_tlv_cell_name(u16 tag)
+{
+ switch (tag) {
+ case RB_ID_FLASH_INFO:
+ return "flash-info";
+ case RB_ID_MAC_ADDRESS_PACK:
+ return "base-mac-address";
+ case RB_ID_BOARD_PRODUCT_CODE:
+ return "board-product-code";
+ case RB_ID_BIOS_VERSION:
+ return "booter-version";
+ case RB_ID_SERIAL_NUMBER:
+ return "board-serial";
+ case RB_ID_MEMORY_SIZE:
+ return "mem-size";
+ case RB_ID_MAC_ADDRESS_COUNT:
+ return "mac-count";
+ case RB_ID_HW_OPTIONS:
+ return "hw-options";
+ case RB_ID_WLAN_DATA:
+ return "wlan-data";
+ case RB_ID_BOARD_IDENTIFIER:
+ return "board-identifier";
+ case RB_ID_PRODUCT_NAME:
+ return "product-name";
+ case RB_ID_DEFCONF:
+ return "defconf";
+ case RB_ID_BOARD_REVISION:
+ return "board-revision";
+ default:
+ break;
+ }
+
+ return NULL;
+}
+
+static int rb_tlv_mac_read_cb(void *priv, const char *id, int index,
+ unsigned int offset, void *buf,
+ size_t bytes)
+{
+ if (index < 0)
+ return -EINVAL;
+
+ if (!is_valid_ether_addr(buf))
+ return -EINVAL;
+
+ eth_addr_add(buf, index);
+
+ return 0;
+}
+
+static nvmem_cell_post_process_t rb_tlv_read_cb(u16 tag)
+{
+ switch (tag) {
+ case RB_ID_MAC_ADDRESS_PACK:
+ return &rb_tlv_mac_read_cb;
+ default:
+ break;
+ }
+
+ return NULL;
+}
+
+static int rb_add_cells(struct device *dev, struct nvmem_device *nvmem,
+ const size_t data_len, u8 *data)
+{
+ u32 node, offset = sizeof(RB_MAGIC_HARD);
+ struct nvmem_cell_info cell = {};
+ struct device_node *layout;
+ u16 tlv_tag, tlv_len;
+ int ret;
+
+ layout = of_nvmem_layout_get_container(nvmem);
+ if (!layout)
+ return -ENOENT;
+
+ /*
+ * Routerboot tag nodes are u32 values:
+ * - The low nibble is the tag identification number,
+ * - The high nibble is the tag payload length (node excluded) in bytes.
+ * Tag nodes are CPU-endian.
+ * Tag nodes are 32bit-aligned.
+ *
+ * The payload immediately follows the tag node.
+ * Payload offset will always be aligned. while length may not end on 32bit
+ * boundary (the only known case is when parsing ERD data).
+ * The payload is CPU-endian when applicable.
+ * Tag nodes are not ordered (by ID) on flash.
+ */
+ while ((offset + sizeof(node)) <= data_len) {
+ node = *((const u32 *) (data + offset));
+ /* Tag list ends with null node */
+ if (!node)
+ break;
+
+ tlv_tag = FIELD_GET(TLV_TAG_MASK, node);
+ tlv_len = FIELD_GET(TLV_LEN_MASK, node);
+
+ offset += sizeof(node);
+ if (offset + tlv_len > data_len) {
+ dev_err(dev, "Out of bounds field (0x%x bytes at 0x%x)\n",
+ tlv_len, offset);
+ break;
+ }
+
+ cell.name = rb_tlv_cell_name(tlv_tag);
+ if (!cell.name)
+ goto skip;
+
+ cell.offset = offset;
+ /*
+ * MikroTik stores MAC-s with length of 8 bytes,
+ * but kernel expects it to be ETH_ALEN (6 bytes),
+ * so we need to make sure that is the case.
+ */
+ if (tlv_tag == RB_ID_MAC_ADDRESS_PACK)
+ cell.bytes = ETH_ALEN;
+ else
+ cell.bytes = tlv_len;
+ cell.np = of_get_child_by_name(layout, cell.name);
+ cell.read_post_process = rb_tlv_read_cb(tlv_tag);
+
+ ret = nvmem_add_one_cell(nvmem, &cell);
+ if (ret) {
+ of_node_put(layout);
+ return ret;
+ }
+
+ /*
+ * The only known situation where len may not end on 32bit
+ * boundary is within ERD data. Since we're only extracting
+ * one tag (the first and only one) from that data, we should
+ * never need to forcefully ALIGN(). Do it anyway, this is not a
+ * performance path.
+ */
+skip:
+ offset += ALIGN(tlv_len, sizeof(offset));
+ }
+
+ of_node_put(layout);
+
+ return 0;
+}
+
+static int rb_parse_table(struct nvmem_layout *layout)
+{
+ struct nvmem_device *nvmem = layout->nvmem;
+ struct device *dev = &layout->dev;
+ size_t mtd_size;
+ u8 *data;
+ u32 hdr;
+ int ret;
+
+ ret = nvmem_device_read(nvmem, 0, sizeof(hdr), &hdr);
+ if (ret < 0)
+ return ret;
+
+ if (hdr != RB_MAGIC_HARD) {
+ dev_err(dev, "Invalid header\n");
+ return -EINVAL;
+ }
+
+ mtd_size = nvmem_dev_size(nvmem);
+
+ data = devm_kmalloc(dev, mtd_size, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ ret = nvmem_device_read(nvmem, 0, mtd_size, data);
+ if (ret != mtd_size)
+ return ret;
+
+ return rb_add_cells(dev, nvmem, mtd_size, data);
+}
+
+static int rb_nvmem_probe(struct nvmem_layout *layout)
+{
+ layout->add_cells = rb_parse_table;
+
+ return nvmem_layout_register(layout);
+}
+
+static void rb_nvmem_remove(struct nvmem_layout *layout)
+{
+ nvmem_layout_unregister(layout);
+}
+
+static const struct of_device_id rb_nvmem_of_match_table[] = {
+ { .compatible = "mikrotik,routerboot-nvmem", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, rb_nvmem_of_match_table);
+
+static struct nvmem_layout_driver rb_nvmem_layout = {
+ .probe = rb_nvmem_probe,
+ .remove = rb_nvmem_remove,
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "rb_nvmem",
+ .of_match_table = rb_nvmem_of_match_table,
+ },
+};
+module_nvmem_layout_driver(rb_nvmem_layout);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Robert Marko <robimarko@gmail.com>");
+MODULE_DESCRIPTION("NVMEM layout driver for MikroTik Routerboard hard config cells");
projects / openwrt / staging / neocturne.git / commitdiff