Add NVMEM support

MAINTAINERS.yml

@@ -3385,6 +3385,24 @@ NEORV32 platform:
   tests:
     - boards.neorv32
 
+NVMEM:
+  status: maintained
+  maintainers:
+    - pdgendt
+  collaborators:
+    - henrikbrixandersen
+  files:
+    - doc/services/nvmem/
+    - dts/bindings/nvmem/
+    - include/zephyr/devicetree/nvmem.h
+    - include/zephyr/nvmem.h
+    - subsys/nvmem/
+    - tests/subsys/nvmem/
+  labels:
+    - "area: NVMEM"
+  tests:
+    - nvmem
+
 NXP Platform Drivers:
   status: maintained
   maintainers:

doc/releases/release-notes-4.3.rst

@@ -193,6 +193,19 @@ New APIs and options
 
   * :kconfig:option:`CONFIG_MODEM_DEDICATED_WORKQUEUE`
 
+* NVMEM
+
+  * Introduced :ref:`Non-Volatile Memory (NVMEM)<nvmem>` subsystem
+
+    * :kconfig:option:`CONFIG_NVMEM`
+    * :kconfig:option:`CONFIG_NVMEM_EEPROM`
+    * :c:struct:`nvmem_cell`
+    * :c:func:`nvmem_cell_read`
+    * :c:func:`nvmem_cell_write`
+    * :c:func:`nvmem_cell_is_ready`
+    * :c:macro:`NVMEM_CELL_GET_BY_NAME` - and variants
+    * :c:macro:`NVMEM_CELL_GET_BY_IDX` - and variants
+
 * Networking
 
   * Sockets

doc/services/index.rst

@@ -24,6 +24,7 @@ OS Services
    resource_management/index.rst
    mem_mgmt/index.rst
    net_buf/index.rst
+   nvmem/index.rst
    modem/index.rst
    notify.rst
    pm/index.rst

doc/services/nvmem/devicetree_bindings.txt

@@ -0,0 +1,18 @@
+&eeprom0 {
+	nvmem-layout {
+		compatible = "fixed-layout";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		mac_address: mac_address@0 {
+			reg = <0x0 6>;
+			#nvmem-cell-cells = <0>;
+			read-only;
+		};
+
+		calibration_data: calibration_data@6 {
+			reg = <0x6 100>;
+			#nvmem-cell-cells = <0>;
+		};
+	};
+};

doc/services/nvmem/index.rst

@@ -0,0 +1,68 @@
+.. _nvmem:
+
+Non-Volatile Memory (NVMEM)
+###########################
+
+The NVMEM subsystem provides a generic interface for accessing non-volatile
+memory devices. It abstracts the underlying hardware and provides a unified API
+for reading and writing data.
+
+Key Concepts
+************
+
+NVMEM Provider
+==============
+
+An NVMEM provider is a driver that exposes NVMEM cells. For example, an EEPROM
+driver can be an NVMEM provider. The NVMEM provider is responsible for reading
+and writing data to the underlying hardware.
+
+NVMEM Cell
+==========
+
+An NVMEM cell is a region of non-volatile memory. It is defined in the
+devicetree and has properties like offset, size, and read-only status.
+
+NVMEM Consumer
+==============
+
+An NVMEM consumer is a driver or application that uses NVMEM cells to store or
+retrieve data.
+
+Configuration
+*************
+
+* :kconfig:option:`CONFIG_NVMEM`: Enables the NVMEM subsystem.
+* :kconfig:option:`CONFIG_NVMEM_EEPROM`: Enables NVMEM support for EEPROM devices.
+
+Devicetree Bindings
+*******************
+
+The NVMEM subsystem relies on devicetree bindings to define NVMEM cells.
+The following is an example of how to define an NVMEM provider and cells in the
+devicetree:
+
+.. literalinclude:: devicetree_bindings.txt
+   :language: dts
+
+
+A consumer can then reference the NVMEM cells like this:
+
+.. literalinclude:: my_consumer.txt
+   :language: dts
+
+
+Usage Example
+*************
+
+The following is an example of how to use the NVMEM API to read data from an
+NVMEM cell:
+
+.. literalinclude:: usage_example.txt
+   :language: c
+
+
+API Reference
+*************
+
+.. doxygengroup:: nvmem_interface

doc/services/nvmem/my_consumer.txt

@@ -0,0 +1,5 @@
+my_consumer: my-consumer {
+	compatible = "my,consumer";
+	nvmem-cells = <&mac_address>, <&calibration_data>;
+	nvmem-cell-names = "mac-address", "calibration-data";
+};

doc/services/nvmem/usage_example.txt

@@ -0,0 +1,23 @@
+#include <zephyr/nvmem.h>
+
+static const struct nvmem_cell mac_address =
+	NVMEM_CELL_GET_BY_NAME(DT_NODELABEL(my_consumer), mac_address);
+
+int main(void)
+{
+	uint8_t mac[6];
+	int ret;
+
+	if (!nvmem_cell_is_ready(&mac_address)) {
+		printk("NVMEM cell is not ready\n");
+		return -ENODEV;
+	}
+
+	ret = nvmem_cell_read(&mac_address, mac, 0, sizeof(mac));
+	if (ret < 0) {
+		printk("Failed to read MAC address: %d\n", ret);
+		return ret;
+	}
+
+	/* ... */
+}

dts/bindings/nvmem/fixed-layout.yaml

@@ -0,0 +1,46 @@
+# Copyright (c) 2025 Basalte bv
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Fixed layout for Non-Volatile memory.
+
+compatible: "fixed-layout"
+
+properties:
+  "#address-cells":
+    type: int
+    const: 1
+    description: |
+      Number of cells required to represent a child node's
+      reg property address.
+
+  "#size-cells":
+    type: int
+    const: 1
+    description: |
+      Number of cells required to represent a child node's size.
+
+child-binding:
+  description: |
+    Each child node of the NVMEM provider node represents
+    an individual NVMEM cell. These should usually
+    look like this:
+
+      cell_nodelabel: cell@START_OFFSET {
+              reg = <0xSTART_OFFSET 0xSIZE>;
+              #nvmem-cell-cells = <0>;
+      };
+
+  properties:
+    reg:
+      type: array
+      required: true
+      description: |
+        This should be in the format <OFFSET SIZE>, where OFFSET
+        is the offset of the NVMEM cell relative to the base
+        address of the parent memory, and SIZE is the size of
+        the cell in bytes.
+
+    read-only:
+      type: boolean
+      description: Set this property if the cell is read-only.

dts/bindings/nvmem/nvmem-consumer.yaml

@@ -0,0 +1,14 @@
+# Copyright (c) 2024, Andriy Gelman <[email protected]>
+# Copyright (c) 2025 Basalte bv
+# SPDX-License-Identifier: Apache-2.0
+
+properties:
+  nvmem-cell-names:
+    type: string-array
+    description:
+      Names for each nvmem-cells specified.
+
+  nvmem-cells:
+    type: phandle-array
+    description:
+      List of phandles to the nvmem data cells.

dts/bindings/test/vnd,nvmem-consumer.yaml

@@ -0,0 +1,8 @@
+# Copyright (c) 2025 Basalte bv
+# SPDX-License-Identifier: Apache-2.0
+
+description: Test NVMEM consumer node
+
+compatible: "vnd,nvmem-consumer"
+
+include: [nvmem-consumer.yaml]