+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Thu, 13 Jul 2023 18:29:19 +0200
+Subject: [PATCH] nvmem: core: support "mac-base" fixed layout cells
+
+Fixed layout binding allows specifying "mac-base" NVMEM cells. It's used
+for base MAC address (that can be used for calculating relative
+addresses). It can be stored in a raw binary format or as an ASCII
+string.
+---
+
+--- a/drivers/nvmem/Kconfig
++++ b/drivers/nvmem/Kconfig
+@@ -1,6 +1,7 @@
+ # SPDX-License-Identifier: GPL-2.0-only
+ menuconfig NVMEM
+ bool "NVMEM Support"
++ select GENERIC_NET_UTILS
+ help
+ Support for NVMEM(Non Volatile Memory) devices like EEPROM, EFUSES...
+
+--- a/drivers/nvmem/core.c
++++ b/drivers/nvmem/core.c
+@@ -7,9 +7,11 @@
+ */
+
+ #include <linux/device.h>
++#include <linux/etherdevice.h>
+ #include <linux/export.h>
+ #include <linux/fs.h>
+ #include <linux/idr.h>
++#include <linux/if_ether.h>
+ #include <linux/init.h>
+ #include <linux/kref.h>
+ #include <linux/module.h>
+@@ -696,6 +698,37 @@ static int nvmem_validate_keepouts(struc
+ return 0;
+ }
+
++static int nvmem_mac_base_raw_read(void *context, const char *id, int index, unsigned int offset,
++ void *buf, size_t bytes)
++{
++ if (WARN_ON(bytes != ETH_ALEN))
++ return -EINVAL;
++
++ if (index)
++ eth_addr_add(buf, index);
++
++ return 0;
++}
++
++static int nvmem_mac_base_ascii_read(void *context, const char *id, int index, unsigned int offset,
++ void *buf, size_t bytes)
++{
++ u8 mac[ETH_ALEN];
++
++ if (WARN_ON(bytes != 3 * ETH_ALEN - 1))
++ return -EINVAL;
++
++ if (!mac_pton(buf, mac))
++ return -EINVAL;
++
++ if (index)
++ eth_addr_add(mac, index);
++
++ ether_addr_copy(buf, mac);
++
++ return 0;
++}
++
+ static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_node *np)
+ {
+ struct nvmem_layout *layout = nvmem->layout;
+@@ -731,6 +764,20 @@ static int nvmem_add_cells_from_dt(struc
+ if (layout && layout->fixup_cell_info)
+ layout->fixup_cell_info(nvmem, layout, &info);
+
++ if (of_device_is_compatible(np, "fixed-layout")) {
++ if (of_device_is_compatible(child, "mac-base")) {
++ if (info.bytes == 6) {
++ info.raw_len = info.bytes;
++ info.bytes = ETH_ALEN;
++ info.read_post_process = nvmem_mac_base_raw_read;
++ } else if (info.bytes == 3 * ETH_ALEN - 1) {
++ info.raw_len = info.bytes;
++ info.bytes = ETH_ALEN;
++ info.read_post_process = nvmem_mac_base_ascii_read;
++ }
++ }
++ }
++
+ ret = nvmem_add_one_cell(nvmem, &info);
+ kfree(info.name);
+ if (ret) {