kernel: nvmem: fix "fixed-layout" & support "mac-base"

DT binding for MAC cells in fixed layout was upstream approved and
accepted. Add support for it. This can replace quite some of our
downstream hacks.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
(cherry picked from commit 61f674d)

target/linux/generic/pending-5.15/803-nvmem-core-fix-support-for-fixed-cells-NVMEM-layout.patch

@@ -0,0 +1,40 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Thu, 13 Jul 2023 17:30:59 +0200
+Subject: [PATCH] nvmem: core: fix support for fixed cells NVMEM layout
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Returning -EPROBE_DEFER for "fixed-layout" makes nvmem_register() always
+fail (that layout is supported internally with no external module). That
+makes callers (e.g. mtd_nvmem_add()) fail as well and prevents booting
+on devices with "fixed-layout" in DT.
+
+Add a quick workaround for it.
+
+Fixes: 6468a6f45148 ("nvmem: core: handle the absence of expected layouts")
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+---
+
+--- a/drivers/nvmem/core.c
++++ b/drivers/nvmem/core.c
+@@ -794,6 +794,19 @@ static struct nvmem_layout *nvmem_layout
+ 		return NULL;
+
+ 	/*
++	 * We should return -EPROBE_DEFER only when layout driver is expected to
++	 * become available later. Otherwise NVMEM will never probe successfully
++	 * for unsupported layouts. There is no known solution for that right
++	 * now.
++	 *
++	 * This problem also affects "fixed-layout". It's supported in NVMEM
++	 * core code so there never will be layout for it. We shouldn't return
++	 * -EPROBE_DEFER in such case. Add a quick workaround for that.
++	 */
++	if (of_device_is_compatible(layout_np, "fixed-layout"))
++		return NULL;
++
++	/*
+ 	 * In case the nvmem device was built-in while the layout was built as a
+ 	 * module, we shall manually request the layout driver loading otherwise
+ 	 * we'll never have any match.

target/linux/generic/pending-5.15/804-nvmem-core-support-mac-base-fixed-layout-cells.patch

@@ -0,0 +1,93 @@
+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) {