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Luna Pes
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drivers: eeprom: fm25xxx: add support for infineon fm25xxx FRAM
This driver adds support for the Infineon FM25XXX series of chips. Has been tested on Infineon FM25CL64B-G. Signed-off-by: Luna Pes <[email protected]>
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‎drivers/eeprom/CMakeLists.txt‎

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@@ -26,3 +26,5 @@ zephyr_library_sources_ifdef(CONFIG_EEPROM_AT2X_EMUL eeprom_at2x_emul.c)
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zephyr_library_sources_ifdef(CONFIG_EEPROM_MB85RCXX eeprom_mb85rcxx.c)
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zephyr_library_sources_ifdef(CONFIG_EEPROM_MB85RSXX eeprom_mb85rsxx.c)
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zephyr_library_sources_ifdef(CONFIG_EEPROM_FM25XXX eeprom_fm25xxx.c)

‎drivers/eeprom/Kconfig‎

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@@ -100,6 +100,7 @@ source "drivers/eeprom/Kconfig.tmp11x"
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source "drivers/eeprom/Kconfig.xec"
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source "drivers/eeprom/Kconfig.mb85rcxx"
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source "drivers/eeprom/Kconfig.mb85rsxx"
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source "drivers/eeprom/Kconfig.fm25xxx"
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config EEPROM_SIMULATOR
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bool "Simulated EEPROM driver"

‎drivers/eeprom/Kconfig.fm25xxx‎

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# Copyright (c) 2025 Luna Pes <[email protected]>
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# SPDX-License-Identifier: Apache-2.0
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config EEPROM_FM25XXX
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bool "Infineon FM25XXX SPI FRAM"
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default y
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depends on DT_HAS_INFINEON_FM25XXX_ENABLED
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select SPI
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help
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Enable Infineon FM25XXX SPI FRAM

‎drivers/eeprom/eeprom_fm25xxx.c‎

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/*
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* Copyright (c) 2025 Luna Pes <[email protected]>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/* This file implements the Infineon AN304 SPI Guide for F-RAM */
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#include "zephyr/devicetree.h"
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#include "zephyr/kernel.h"
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#include "zephyr/sys/byteorder.h"
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#include "zephyr/sys/util.h"
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#include <zephyr/device.h>
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#include <zephyr/drivers/eeprom.h>
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#include <zephyr/drivers/spi.h>
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#include <zephyr/logging/log.h>
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#define DT_DRV_COMPAT infineon_fm25xxx
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LOG_MODULE_REGISTER(fm25xxx, CONFIG_EEPROM_LOG_LEVEL);
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/* Registers */
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#define FM25XXX_WREN 0x06
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#define FM25XXX_WRDI 0x04
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#define FM25XXX_RDSR 0x05
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#define FM25XXX_WRSR 0x01
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#define FM25XXX_READ 0x03
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#define FM25XXX_WRITE 0x02
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struct fm25xxx_config {
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struct spi_dt_spec spi;
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size_t size;
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bool readonly;
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};
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struct fm25xxx_data {
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struct k_mutex lock;
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};
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static uint8_t eeprom_fm25xxx_size_to_addr_bytes(size_t size)
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{
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if (size <= 500) {
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return 1;
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} else if (size <= 64000) {
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return 2;
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} else {
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return 3;
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}
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}
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static int eeprom_fm25xxx_set_enable_write(const struct device *dev, bool enable_writes)
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{
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const struct fm25xxx_config *config = dev->config;
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uint8_t op = enable_writes ? FM25XXX_WREN : FM25XXX_WRDI;
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const struct spi_buf tx_bufs[] = {{
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.buf = &op,
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.len = sizeof(op),
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}};
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const struct spi_buf_set tx_buf_set = {
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.buffers = tx_bufs,
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.count = ARRAY_SIZE(tx_bufs),
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};
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spi_write_dt(&config->spi, &tx_buf_set);
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return 0;
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}
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int eeprom_fm25xxx_read(const struct device *dev, off_t offset, void *data, size_t len)
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{
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int ret;
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const struct fm25xxx_config *config = dev->config;
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struct fm25xxx_data *dev_data = dev->data;
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if (offset + len > config->size) {
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LOG_ERR("Can not read more data than the device size");
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return -EINVAL;
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}
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if (len == 0) {
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return 0;
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}
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uint8_t read_op[4] = {FM25XXX_READ};
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size_t addr_bytes = eeprom_fm25xxx_size_to_addr_bytes(config->size);
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size_t op_len = 1 + addr_bytes;
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switch (addr_bytes) {
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case 1:
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read_op[1] = offset & 0xff;
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break;
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case 2:
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sys_put_be16(offset, &read_op[1]);
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break;
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case 3:
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sys_put_be24(offset, &read_op[1]);
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break;
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default:
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LOG_ERR("Invalid number of address bytes %u", addr_bytes);
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return -EINVAL;
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}
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LOG_HEXDUMP_WRN(read_op, 4, "Read op");
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const struct spi_buf tx_bufs[] = {{
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.buf = &read_op,
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.len = op_len,
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}};
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const struct spi_buf_set tx_buf_set = {
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.buffers = tx_bufs,
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.count = ARRAY_SIZE(tx_bufs),
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};
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const struct spi_buf rx_bufs[2] = {
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{
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.buf = NULL,
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.len = op_len,
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},
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{
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.buf = data,
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.len = len,
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},
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};
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const struct spi_buf_set rx_buf_set = {
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.buffers = rx_bufs,
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.count = ARRAY_SIZE(rx_bufs),
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};
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ret = spi_transceive_dt(&config->spi, &tx_buf_set, &rx_buf_set);
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if (ret != 0) {
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LOG_ERR("Failed to read from FRAM");
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return ret;
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}
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return 0;
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}
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int eeprom_fm25xxx_write(const struct device *dev, off_t offset, const void *data, size_t len)
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{
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int ret;
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const struct fm25xxx_config *config = dev->config;
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struct fm25xxx_data *dev_data = dev->data;
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if (config->readonly) {
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LOG_ERR("Can not write to a readonly device");
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return -EACCES;
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}
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if (offset + len > config->size) {
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LOG_ERR("Can not write more data than the device size");
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return -EINVAL;
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}
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if (len == 0) {
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return 0;
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}
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uint8_t write_op[4] = {FM25XXX_WRITE};
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size_t addr_bytes = eeprom_fm25xxx_size_to_addr_bytes(config->size);
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size_t op_len = 1 + addr_bytes;
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switch (addr_bytes) {
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case 1:
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write_op[1] = offset & 0xff;
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break;
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case 2:
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sys_put_be16(offset, &write_op[1]);
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break;
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case 3:
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sys_put_be24(offset, &write_op[1]);
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break;
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default:
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LOG_ERR("Invalid number of address bytes %u", addr_bytes);
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return -EINVAL;
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}
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const struct spi_buf tx_bufs[] = {
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{
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.buf = &write_op,
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.len = op_len,
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},
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{
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.buf = (void *)data,
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.len = len,
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},
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};
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const struct spi_buf_set tx_buf_set = {
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.buffers = tx_bufs,
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.count = ARRAY_SIZE(tx_bufs),
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};
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k_mutex_lock(&dev_data->lock, K_FOREVER);
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ret = eeprom_fm25xxx_set_enable_write(dev, true);
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if (ret != 0) {
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k_mutex_unlock(&dev_data->lock);
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LOG_ERR("Could not enable writes");
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return ret;
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}
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ret = spi_write_dt(&config->spi, &tx_buf_set);
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if (ret != 0) {
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k_mutex_unlock(&dev_data->lock);
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LOG_ERR("Failed to write to FRAM");
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return ret;
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}
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ret = eeprom_fm25xxx_set_enable_write(dev, false);
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if (ret != 0) {
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k_mutex_unlock(&dev_data->lock);
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LOG_ERR("Could not disable writes");
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return ret;
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}
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k_mutex_unlock(&dev_data->lock);
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return 0;
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}
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size_t eeprom_fm25xxx_get_size(const struct device *dev)
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{
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const struct fm25xxx_config *config = dev->config;
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return config->size;
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}
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static int eeprom_fm25xxx_init(const struct device *dev)
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{
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const struct fm25xxx_config *config = dev->config;
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struct fm25xxx_data *data = dev->data;
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k_mutex_init(&data->lock);
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if (!spi_is_ready_dt(&config->spi)) {
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LOG_ERR("SPI bus not ready");
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return -ENODEV;
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}
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return 0;
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}
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static DEVICE_API(eeprom, eeprom_fm25xxx_api) = {
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.read = &eeprom_fm25xxx_read,
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.write = &eeprom_fm25xxx_write,
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.size = &eeprom_fm25xxx_get_size,
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};
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#define FM25XXX_INIT(inst) \
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static struct fm25xxx_data fm25xxx_data_##inst; \
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static const struct fm25xxx_config fm25xxx_config_##inst = { \
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.spi = SPI_DT_SPEC_INST_GET(inst, SPI_OP_MODE_MASTER | SPI_WORD_SET(8), 0), \
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.size = DT_INST_PROP(inst, size), \
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.readonly = DT_INST_PROP(inst, read_only), \
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}; \
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\
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DEVICE_DT_INST_DEFINE(inst, eeprom_fm25xxx_init, NULL, &fm25xxx_data_##inst, \
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&fm25xxx_config_##inst, POST_KERNEL, CONFIG_EEPROM_INIT_PRIORITY, \
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&eeprom_fm25xxx_api);
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DT_INST_FOREACH_STATUS_OKAY(FM25XXX_INIT)

‎dts/bindings/mtd/infineon,fm25xxx.yaml‎

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# Copyright (c) 2025 Luna Pes <[email protected]>
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# SPDX-License-Identifier: Apache-2.0
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description: Infineon FM25XXX SPI FRAM
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compatible: "infineon,fm25xxx"
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include: ["eeprom-base.yaml", spi-device.yaml]
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properties:
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size:
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required: true
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description: Total FRAM size in bytes.

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