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nvmem: Introduce EEPROM NVMEM support
wip Signed-off-by: Pieter De Gendt <[email protected]>
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‎dts/bindings/mtd/eeprom-base.yaml‎

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# Common fields for EEPROM devices
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include: base.yaml
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include:
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- base.yaml
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- nvmem-provider.yaml
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properties:
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size:

‎dts/bindings/mtd/nvmem-provider.yaml‎

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# SPDX-License-Identifier: Apache-2.0
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description: |
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Non-Volatile Memory (NVMEM) provider.
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NVMEM provider refers to an entity that implements methods to
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initialize, read and write the non-volatile memory.
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properties:
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"#address-cells":
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type: int
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description: |
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Number of cells required to represent a child node's
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reg property address.
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"#size-cells":
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type: int
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description: |
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Number of cells required to represent a child node's size.
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child-binding:
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description: |
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Each child node of the NVMEM provider node represents
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an individual NVMEM cell. These should usually
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look like this:
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cell_nodelabel: cell@START_OFFSET {
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reg = <0xSTART_OFFSET 0xSIZE>;
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};
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properties:
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reg:
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type: array
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required: true
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description: |
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This should be in the format <OFFSET SIZE>, where OFFSET
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is the offset of the NVMEM cell relative to the base
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address of the parent memory, and SIZE is the size of
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the cell in bytes.
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read-only:
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type: boolean
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description: Set this property if the cell is read-only.
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bits:
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type: array
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description: |
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Is pair of bit location and number of bits, which specifies
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offset in bit and number of bits within the address range
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specified by reg property. Offset takes values from 0-7.

‎include/zephyr/nvmem.h‎

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/*
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* Copyright (c) 2025 Basalte bv
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief Main header file for NVMEM API.
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* @ingroup nvmem_interface
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*/
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#ifndef ZEPHYR_INCLUDE_NVMEM_H_
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#define ZEPHYR_INCLUDE_NVMEM_H_
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/**
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* @brief Interfaces for NVMEM cells.
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* @defgroup nvmem_interface NVMEM
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* @since 4.3
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* @version 0.1.0
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* @ingroup io_interfaces
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* @{
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*/
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#include <sys/types.h>
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#include <zephyr/device.h>
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#include <zephyr/devicetree.h>
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#include <zephyr/devicetree/nvmem.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @name NVMEM cell flags
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* @anchor NVMEM_CELL_FLAGS
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* @{
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*/
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#define NVMEM_CELL_READ_ONLY BIT(0)
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/**
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* @brief Provides a type to hold NVMEM cell flags.
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*
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* @see @ref NVMEM_CELL_FLAGS.
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*/
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typedef uint8_t nvmem_cell_flags_t;
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/** @} */
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/**
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* @brief Non-Volatile Memory cell representation.
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*/
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struct nvmem_cell {
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/** NVMEM parent controller device instance. */
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const struct device *dev;
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/** Offset of the NVMEM cell relative to the parent controller's base address */
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off_t offset;
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/** Size of the NVMEM cell */
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size_t size;
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/** Bit-flags for the NVMEM cell */
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nvmem_cell_flags_t flags;
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};
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/**
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* @brief Static initializer for a struct nvmem_cell.
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*
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* This returns a static initializer for a struct nvmem_cell given a devicetree
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* node identifier and a name.
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*
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* Example devicetree fragment:
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*
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* @code{.dts}
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* mac_eeprom: mac_eeprom@2 {
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* #address-cells = <1>;
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* #size-cells = <1>;
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* mac_address: mac_address@fa {
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* reg = <0xfa 0x06>;
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* };
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* };
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*
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* eth: ethernet {
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* nvmem-cells = <&mac_address>;
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* nvmem-cell-names = "mac-address";
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* };
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* @endcode
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*
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* Example usage:
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*
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* @code{.c}
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* const struct nvmem_cell cell =;
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* NVMEM_CELL_GET_BY_NAME(DT_NODELABEL(eth), mac_address);
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*
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* // Initializes 'cell' to:
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* // {
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* // .dev = DEVICE_DT_GET(DT_NODELABEL(mac_eeprom)),
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* // .offset = 0xfa,
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* // .size = 6,
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* // }
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* @endcode
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*
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* @param node_id Devicetree node identifier.
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* @param name Lowercase-and-underscores name of an nvmem-cells element as defined by
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* the node's nvmem-cell-names property.
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*
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* @return Static initializer for a struct nvmem_cell for the property.
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*
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* @see NVMEM_CELL_INST_GET_BY_NAME
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*/
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#define NVMEM_CELL_GET_BY_NAME(node_id, name) \
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{ \
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.dev = DT_MTD_FROM_NVMEM_CELL(DT_NVMEM_CELL_BY_NAME(node_id, name)), \
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.offset = DT_REG_ADDR(DT_NVMEM_CELL_BY_NAME(nod_ide, name)), \
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.size = DT_REG_SIZE(DT_NVMEM_CELL_BY_NAME(node_id, name)), \
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.flags = COND_CODE_1(DT_PROP(DT_NVMEM_CELL_BY_NAME(node_id, name),read_only), \
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(NVMEM_CELL_READ_ONLY), (0)), \
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}
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/**
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* @brief Static initializer for a struct nvmem_cell from a DT_DRV_COMPAT
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* instance.
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*
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* @param inst DT_DRV_COMPAT instance number
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* @param name Lowercase-and-underscores name of an nvmem-cells element as defined by
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* the node's nvmem-cell-names property.
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*
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* @return Static initializer for a struct nvmem_cell for the property.
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*
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* @see NVMEM_CELL_GET_BY_NAME
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*/
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#define NVMEM_CELL_INST_GET_BY_NAME(inst, name) NVMEM_CELL_GET_BY_NAME(DT_DRV_INST(inst), name)
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/**
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* @brief Like NVMEM_CELL_GET_BY_NAME(), with a fallback to a default value.
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*
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* If the devicetree node identifier 'node_id' refers to a node with a property
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* 'nvmem-cells', this expands to <tt>NVMEM_CELL_GET_BY_NAME(node_id, name)</tt>. The
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* @p default_value parameter is not expanded in this case. Otherwise, this
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* expands to @p default_value.
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*
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* @param node_id Devicetree node identifier.
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* @param name Lowercase-and-underscores name of an nvmem-cells element as defined by
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* the node's nvmem-cell-names property.
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* @param default_value Fallback value to expand to.
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*
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* @return Static initializer for a struct nvmem_cell for the property,
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* or @p default_value if the node or property do not exist.
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*
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* @see NVMEM_CELL_INST_GET_BY_NAME_OR
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*/
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#define NVMEM_CELL_GET_BY_NAME_OR(node_id, name, default_value) \
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COND_CODE_1(DT_NODE_HAS_PROP(node_id, pwms), \
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(NVMEM_CELL_GET_BY_NAME(node_id, name)), \
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(default_value))
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/**
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* @brief Like NVMEM_CELL_INST_GET_BY_NAME(), with a fallback to a default
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* value.
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*
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* @param inst DT_DRV_COMPAT instance number
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* @param name Lowercase-and-underscores name of an nvmem-cells element as defined by
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* the node's nvmem-cell-names property.
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* @param default_value Fallback value to expand to.
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*
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* @return Static initializer for a struct nvmem_cell for the property,
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* or @p default_value if the node or property do not exist.
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*
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* @see NVMEM_CELL_GET_BY_NAME_OR
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*/
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#define NVMEM_CELL_INST_GET_BY_NAME_OR(inst, name, default_value) \
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NVMEM_CELL_GET_BY_NAME_OR(DT_DRV_INST(inst), name, default_value)
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/**
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* @brief Static initializer for a struct nvmem_cell.
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*
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* This returns a static initializer for a struct nvmem_cell given a devicetree
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* node identifier and an index.
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*
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* Example devicetree fragment:
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*
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* @code{.dts}
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* mac_eeprom: mac_eeprom@2 {
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* #address-cells = <1>;
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* #size-cells = <1>;
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* mac_address: mac_address@fa {
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* reg = <0xfa 0x06>;
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* };
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* };
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*
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* eth: ethernet {
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* nvmem-cells = <&mac_address>;
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* nvmem-cell-names = "mac-address";
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* };
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* @endcode
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*
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* Example usage:
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*
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* @code{.c}
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* const struct nvmem_cell cell =;
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* NVMEM_CELL_GET_BY_IDX(DT_NODELABEL(eth), 0);
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*
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* // Initializes 'cell' to:
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* // {
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* // .dev = DEVICE_DT_GET(DT_NODELABEL(mac_eeprom)),
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* // .offset = 0xfa,
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* // .size = 6,
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* // }
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* @endcode
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*
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* @param node_id Devicetree node identifier.
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* @param idx Logical index into 'nvmem-cells' property.
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*
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* @return Static initializer for a struct nvmem_cell for the property.
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*
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* @see NVMEM_CELL_INST_GET_BY_IDX
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*/
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#define NVMEM_CELL_GET_BY_IDX(node_id, idx) \
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{ \
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.dev = DT_MTD_FROM_NVMEM_CELL(DT_NVMEM_CELL_BY_IDX(node_id, idx)), \
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.offset = DT_REG_ADDR(DT_NVMEM_CELL_BY_IDX(node_id, idx)), \
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.size = DT_REG_SIZE(DT_NVMEM_CELL_BY_IDX(node_id, idx)), \
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.flags = COND_CODE_1(DT_PROP(DT_NVMEM_CELL_BY_IDX(node_id, idx),read_only), \
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(NVMEM_CELL_READ_ONLY), (0)), \
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}
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/**
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* @brief Static initializer for a struct nvmem_cell from a DT_DRV_COMPAT
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* instance.
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*
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* @param inst DT_DRV_COMPAT instance number
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* @param idx Logical index into 'nvmem-cells' property.
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*
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* @return Static initializer for a struct nvmem_cell for the property.
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*
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* @see NVMEM_CELL_GET_BY_IDX
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*/
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#define NVMEM_CELL_INST_GET_BY_IDX(inst, idx) NVMEM_CELL_GET_BY_IDX(DT_DRV_INST(inst), idx)
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/**
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* @brief Like NVMEM_CELL_GET_BY_IDX(), with a fallback to a default value.
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*
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* If the devicetree node identifier 'node_id' refers to a node with a property
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* 'nvmem-cells', this expands to <tt>NVMEM_CELL_GET_BY_IDX(node_id, idx)</tt>. The
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* @p default_value parameter is not expanded in this case. Otherwise, this
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* expands to @p default_value.
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*
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* @param node_id Devicetree node identifier.
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* @param idx Logical index into 'nvmem-cells' property.
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* @param default_value Fallback value to expand to.
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*
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* @return Static initializer for a struct nvmem_cell for the property,
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* or @p default_value if the node or property do not exist.
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*
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* @see NVMEM_CELL_INST_GET_BY_IDX_OR
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*/
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#define NVMEM_CELL_GET_BY_IDX_OR(node_id, idx, default_value) \
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COND_CODE_1(DT_NODE_HAS_PROP(node_id, nvmem_cells), \
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(NVMEM_CELL_GET_BY_IDX(node_id, idx)), \
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(default_value))
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/**
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* @brief Like NVMEM_CELL_INST_GET_BY_IDX(), with a fallback to a default
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* value.
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*
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* @param inst DT_DRV_COMPAT instance number
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* @param idx Logical index into 'nvmem-cells' property.
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* @param default_value Fallback value to expand to.
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*
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* @return Static initializer for a struct nvmem_cell for the property,
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* or @p default_value if the node or property do not exist.
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*
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* @see NVMEM_CELL_GET_BY_IDX_OR
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*/
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#define NVMEM_CELL_INST_GET_BY_IDX_OR(inst, idx, default_value) \
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NVMEM_CELL_GET_BY_IDX_OR(DT_DRV_INST(inst), idx, default_value)
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/**
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* @brief Read data from NVMEM cell.
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*
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* @param cell The NVMEM cell.
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* @param data Buffer to store read data.
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* @param len Number of bytes to read.
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*
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* @return 0 on success, negative errno code on failure.
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*/
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int nvmem_cell_read(const struct nvmem_cell *cell, void *data, size_t len);
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/**
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* @brief Write data to NVMEM cell.
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*
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* @param cell The NVMEM cell.
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* @param data Buffer with data to write.
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* @param len Number of bytes to write.
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*
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* @return 0 on success, negative errno code on failure.
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*/
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int nvmem_cell_write(const struct nvmem_cell *cell, const void *data, size_t len);
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#ifdef __cplusplus
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}
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#endif
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/**
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* @}
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*/
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#endif /* ZEPHYR_INCLUDE_NVMEM_H_ */

‎subsys/CMakeLists.txt‎

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add_subdirectory_ifdef(CONFIG_LLEXT llext)
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add_subdirectory_ifdef(CONFIG_MODEM_MODULES modem)
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add_subdirectory_ifdef(CONFIG_NETWORKING net)
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add_subdirectory_ifdef(CONFIG_NVMEM nvmem)
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add_subdirectory_ifdef(CONFIG_PROFILING profiling)
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add_subdirectory_ifdef(CONFIG_RETENTION retention)
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add_subdirectory_ifdef(CONFIG_SECURE_STORAGE secure_storage)

‎subsys/Kconfig‎

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source "subsys/modbus/Kconfig"
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source "subsys/modem/Kconfig"
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source "subsys/net/Kconfig"
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source "subsys/nvmem/Kconfig"
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source "subsys/pm/Kconfig"
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source "subsys/pmci/Kconfig"
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source "subsys/portability/Kconfig"

‎subsys/nvmem/CMakeLists.txt‎

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# SPDX-License-Identifier: Apache-2.0
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zephyr_library()
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zephyr_library_sources(nvmem.c)

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