subsys/retention/retention.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2023, Nordic Semiconductor ASA
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #define DT_DRV_COMPAT zephyr_retention

 #include <string.h>
 #include <sys/types.h>
 #include <zephyr/kernel.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/sys/crc.h>
 #include <zephyr/device.h>
 #include <zephyr/devicetree.h>
 #include <zephyr/drivers/retained_mem.h>
 #include <zephyr/retention/retention.h>
 #include <zephyr/logging/log.h>

 LOG_MODULE_REGISTER(retention, CONFIG_RETENTION_LOG_LEVEL);

 #define DATA_VALID_VALUE 1

 #define INST_HAS_CHECKSUM(n) DT_INST_PROP(n, checksum) ||

 #define INST_HAS_PREFIX(n) COND_CODE_1(DT_INST_NODE_HAS_PROP(n, prefix), (1), (0)) ||

 #if (DT_INST_FOREACH_STATUS_OKAY(INST_HAS_CHECKSUM) 0)
 #define ANY_HAS_CHECKSUM
 #endif

 #if (DT_INST_FOREACH_STATUS_OKAY(INST_HAS_PREFIX) 0)
 #define ANY_HAS_PREFIX
 #endif

 enum {
 	CHECKSUM_NONE = 0,
 	CHECKSUM_CRC8,
 	CHECKSUM_CRC16,
 	CHECKSUM_UNUSED,
 	CHECKSUM_CRC32,
 };

 struct retention_data {
 	bool header_written;
 #ifdef CONFIG_RETENTION_MUTEXES
 	struct k_mutex lock;
 #endif
 };

 struct retention_config {
 	const struct device *parent;
 	size_t offset;
 	size_t size;
 	size_t reserved_size;
 	uint8_t checksum_size;
 	uint8_t prefix_len;
 	uint8_t prefix[];
 };

 static inline void retention_lock_take(const struct device *dev)
 {
 #ifdef CONFIG_RETENTION_MUTEXES
 	struct retention_data *data = dev->data;

 	k_mutex_lock(&data->lock, K_FOREVER);
 #else
 	ARG_UNUSED(dev);
 #endif
 }

 static inline void retention_lock_release(const struct device *dev)
 {
 #ifdef CONFIG_RETENTION_MUTEXES
 	struct retention_data *data = dev->data;

 	k_mutex_unlock(&data->lock);
 #else
 	ARG_UNUSED(dev);
 #endif
 }

 #ifdef ANY_HAS_CHECKSUM
 static int retention_checksum(const struct device *dev, uint32_t *output)
 {
 	const struct retention_config *config = dev->config;
 	int rc = -ENOSYS;

 	if (config->checksum_size == CHECKSUM_CRC8 ||
 	    config->checksum_size == CHECKSUM_CRC16 ||
 	    config->checksum_size == CHECKSUM_CRC32) {
 		size_t pos = config->offset + config->prefix_len;
 		size_t end = config->offset + config->size - config->checksum_size;
 		uint8_t buffer[CONFIG_RETENTION_BUFFER_SIZE];

 		*output = 0;

 		while (pos < end) {
 			uint16_t read_size = MIN((end - pos), sizeof(buffer));

 			rc = retained_mem_read(config->parent, pos, buffer, read_size);

 			if (rc < 0) {
 				goto finish;
 			}

 			if (config->checksum_size == CHECKSUM_CRC8) {
 				*output = (uint32_t)crc8(buffer, read_size, 0x12,
 							 (uint8_t)*output, false);
 			} else if (config->checksum_size == CHECKSUM_CRC16) {
 				*output = (uint32_t)crc16_itu_t((uint16_t)*output,
 								buffer, read_size);
 			} else if (config->checksum_size == CHECKSUM_CRC32) {
 				*output = crc32_ieee_update(*output, buffer, read_size);
 			}

 			pos += read_size;
 		}
 	}

 finish:
 	return rc;
 }
 #endif

 static int retention_init(const struct device *dev)
 {
 	const struct retention_config *config = dev->config;
 #ifdef CONFIG_RETENTION_MUTEXES
 	struct retention_data *data = dev->data;
 #endif
 	ssize_t area_size;

 	if (!device_is_ready(config->parent)) {
 		LOG_ERR("Parent device is not ready");
 		return -ENODEV;
 	}

 	/* Ensure backend has a large enough storage area for the requirements of
 	 * this retention area
 	 */
 	area_size = retained_mem_size(config->parent);

 	if (area_size < 0) {
 		LOG_ERR("Parent initialisation failure: %d", area_size);
 		return area_size;
 	}

 	if ((config->offset + config->size) > area_size) {
 		/* Backend storage is insufficient */
 		LOG_ERR("Underlying area size is insufficient, requires: 0x%x, has: 0x%x",
 			(config->offset + config->size), area_size);
 		return -EINVAL;
 	}

 #ifdef CONFIG_RETENTION_MUTEXES
 	k_mutex_init(&data->lock);
 #endif

 	return 0;
 }

 ssize_t retention_size(const struct device *dev)
 {
 	const struct retention_config *config = dev->config;

 	return (config->size - config->reserved_size);
 }

 int retention_is_valid(const struct device *dev)
 {
 	const struct retention_config *config = dev->config;
 	int rc = 0;

 	retention_lock_take(dev);

 	/* If neither the header or checksum are enabled, return a not supported error */
 	if (config->prefix_len == 0 && config->checksum_size == 0) {
 		rc = -ENOTSUP;
 		goto finish;
 	}

 #ifdef ANY_HAS_PREFIX
 	if (config->prefix_len != 0) {
 		/* Check magic header is present at the start of the section */
 		struct retention_data *data = dev->data;
 		uint8_t buffer[CONFIG_RETENTION_BUFFER_SIZE];
 		off_t pos = 0;

 		while (pos < config->prefix_len) {
 			uint16_t read_size = MIN((config->prefix_len - pos), sizeof(buffer));

 			rc = retained_mem_read(config->parent, (config->offset + pos), buffer,
 					       read_size);

 			if (rc < 0) {
 				goto finish;
 			}

 			if (memcmp(&config->prefix[pos], buffer, read_size) != 0) {
 				/* If the magic header does not match, do not check the rest of
 				 * the validity of the data, assume it is invalid
 				 */
 				data->header_written = false;
 				rc = 0;
 				goto finish;
 			}

 			pos += read_size;
 		}

 		/* Header already exists so no need to re-write it again */
 		data->header_written = true;
 	}
 #endif

 #ifdef ANY_HAS_CHECKSUM
 	if (config->checksum_size != 0) {
 		/* Check the checksum validity, for this all the data must be read out */
 		uint32_t checksum = 0;
 		uint32_t expected_checksum = 0;
 		ssize_t data_size = config->size - config->checksum_size;

 		rc = retention_checksum(dev, &checksum);

 		if (rc < 0) {
 			goto finish;
 		}

 		if (config->checksum_size == CHECKSUM_CRC8) {
 			uint8_t read_checksum;

 			rc = retained_mem_read(config->parent, (config->offset + data_size),
 					       (void *)&read_checksum, sizeof(read_checksum));
 			expected_checksum = (uint32_t)read_checksum;
 		} else if (config->checksum_size == CHECKSUM_CRC16) {
 			uint16_t read_checksum;

 			rc = retained_mem_read(config->parent, (config->offset + data_size),
 					       (void *)&read_checksum, sizeof(read_checksum));
 			expected_checksum = (uint32_t)read_checksum;
 		} else if (config->checksum_size == CHECKSUM_CRC32) {
 			rc = retained_mem_read(config->parent, (config->offset + data_size),
 					       (void *)&expected_checksum,
 					       sizeof(expected_checksum));
 		}

 		if (rc < 0) {
 			goto finish;
 		}

 		if (checksum != expected_checksum) {
 			goto finish;
 		}
 	}
 #endif

 	/* At this point, checks have passed (if enabled), mark data as being valid */
 	rc = DATA_VALID_VALUE;

 finish:
 	retention_lock_release(dev);

 	return rc;
 }

 int retention_read(const struct device *dev, off_t offset, uint8_t *buffer, size_t size)
 {
 	const struct retention_config *config = dev->config;
 	int rc;

 	if (offset < 0 || ((size_t)offset + size) > (config->size - config->reserved_size)) {
 		/* Disallow reading past the virtual data size or before it */
 		return -EINVAL;
 	}

 	retention_lock_take(dev);

 	rc = retained_mem_read(config->parent, (config->offset + config->prefix_len +
 			       (size_t)offset), buffer, size);

 	retention_lock_release(dev);

 	return rc;
 }

 int retention_write(const struct device *dev, off_t offset, const uint8_t *buffer, size_t size)
 {
 	const struct retention_config *config = dev->config;
 	int rc;

 #ifdef ANY_HAS_PREFIX
 	struct retention_data *data = dev->data;
 #endif

 	retention_lock_take(dev);

 	if (offset < 0 || ((size_t)offset + size) > (config->size - config->reserved_size)) {
 		/* Disallow writing past the virtual data size or before it */
 		rc = -EINVAL;
 		goto finish;
 	}

 	rc = retained_mem_write(config->parent, (config->offset + config->prefix_len +
 				(size_t)offset), buffer, size);

 	if (rc < 0) {
 		goto finish;
 	}

 #ifdef ANY_HAS_PREFIX
 	/* Write optional header and footer information, these are done last to ensure data
 	 * validity before marking it as being valid
 	 */
 	if (config->prefix_len != 0 && data->header_written == false) {
 		rc = retained_mem_write(config->parent, config->offset, (void *)config->prefix,
 					config->prefix_len);

 		if (rc < 0) {
 			goto finish;
 		}

 		data->header_written = true;
 	}
 #endif

 #ifdef ANY_HAS_CHECKSUM
 	if (config->checksum_size != 0) {
 		/* Generating a checksum requires reading out all the data in the region */
 		uint32_t checksum = 0;

 		rc = retention_checksum(dev, &checksum);

 		if (rc < 0) {
 			goto finish;
 		}

 		if (config->checksum_size == CHECKSUM_CRC8) {
 			uint8_t output_checksum = (uint8_t)checksum;

 			rc = retained_mem_write(config->parent,
 					(config->offset + config->size - config->checksum_size),
 					(void *)&output_checksum, sizeof(output_checksum));
 		} else if (config->checksum_size == CHECKSUM_CRC16) {
 			uint16_t output_checksum = (uint16_t)checksum;

 			rc = retained_mem_write(config->parent,
 					(config->offset + config->size - config->checksum_size),
 					(void *)&output_checksum, sizeof(output_checksum));
 		} else if (config->checksum_size == CHECKSUM_CRC32) {
 			rc = retained_mem_write(config->parent,
 					(config->offset + config->size - config->checksum_size),
 					(void *)&checksum, sizeof(checksum));
 		}
 	}
 #endif

 finish:
 	retention_lock_release(dev);

 	return rc;
 }

 int retention_clear(const struct device *dev)
 {
 	const struct retention_config *config = dev->config;
 	struct retention_data *data = dev->data;
 	int rc = 0;
 	uint8_t buffer[CONFIG_RETENTION_BUFFER_SIZE];
 	off_t pos = 0;

 	memset(buffer, 0, sizeof(buffer));

 	retention_lock_take(dev);

 	data->header_written = false;

 	while (pos < config->size) {
 		rc = retained_mem_write(config->parent, (config->offset + pos), buffer,
 					MIN((config->size - pos), sizeof(buffer)));

 		if (rc < 0) {
 			goto finish;
 		}

 		pos += MIN((config->size - pos), sizeof(buffer));
 	}

 finish:
 	retention_lock_release(dev);

 	return rc;
 }

 #define RETENTION_DEVICE(inst)									\
 	static struct retention_data								\
 		retention_data_##inst = {							\
 		.header_written = false,							\
 	};											\
 	static const struct retention_config							\
 		retention_config_##inst = {							\
 		.parent = DEVICE_DT_GET(DT_PARENT(DT_INST(inst, DT_DRV_COMPAT))),		\
 		.checksum_size = DT_INST_PROP(inst, checksum),					\
 		.offset = DT_INST_REG_ADDR(inst),						\
 		.size = DT_INST_REG_SIZE(inst),							\
 		.reserved_size = (COND_CODE_1(DT_INST_NODE_HAS_PROP(inst, prefix),		\
 					      (DT_INST_PROP_LEN(inst, prefix)), (0)) +		\
 				  DT_INST_PROP(inst, checksum)),				\
 		.prefix_len = COND_CODE_1(DT_INST_NODE_HAS_PROP(inst, prefix),			\
 					  (DT_INST_PROP_LEN(inst, prefix)), (0)),		\
 		.prefix = DT_INST_PROP_OR(inst, prefix, {0}),					\
 	};											\
 	DEVICE_DT_INST_DEFINE(inst,								\
 			      &retention_init,							\
 			      NULL,								\
 			      &retention_data_##inst,						\
 			      &retention_config_##inst,						\
 			      POST_KERNEL,							\
 			      CONFIG_RETENTION_INIT_PRIORITY,					\
 			      NULL);

 DT_INST_FOREACH_STATUS_OKAY(RETENTION_DEVICE)
	/*
	* Copyright (c) 2023, Nordic Semiconductor ASA
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#define DT_DRV_COMPAT zephyr_retention

	#include <string.h>
	#include <sys/types.h>
	#include <zephyr/kernel.h>
	#include <zephyr/sys/util.h>
	#include <zephyr/sys/crc.h>
	#include <zephyr/device.h>
	#include <zephyr/devicetree.h>
	#include <zephyr/drivers/retained_mem.h>
	#include <zephyr/retention/retention.h>
	#include <zephyr/logging/log.h>

	LOG_MODULE_REGISTER(retention, CONFIG_RETENTION_LOG_LEVEL);

	#define DATA_VALID_VALUE 1

	#define INST_HAS_CHECKSUM(n) DT_INST_PROP(n, checksum) \|\|

	#define INST_HAS_PREFIX(n) COND_CODE_1(DT_INST_NODE_HAS_PROP(n, prefix), (1), (0)) \|\|

	#if (DT_INST_FOREACH_STATUS_OKAY(INST_HAS_CHECKSUM) 0)
	#define ANY_HAS_CHECKSUM
	#endif

	#if (DT_INST_FOREACH_STATUS_OKAY(INST_HAS_PREFIX) 0)
	#define ANY_HAS_PREFIX
	#endif

	enum {
	CHECKSUM_NONE = 0,
	CHECKSUM_CRC8,
	CHECKSUM_CRC16,
	CHECKSUM_UNUSED,
	CHECKSUM_CRC32,
	};

	struct retention_data {
	bool header_written;
	#ifdef CONFIG_RETENTION_MUTEXES
	struct k_mutex lock;
	#endif
	};

	struct retention_config {
	const struct device *parent;
	size_t offset;
	size_t size;
	size_t reserved_size;
	uint8_t checksum_size;
	uint8_t prefix_len;
	uint8_t prefix[];
	};

	static inline void retention_lock_take(const struct device *dev)
	{
	#ifdef CONFIG_RETENTION_MUTEXES
	struct retention_data *data = dev->data;

	k_mutex_lock(&data->lock, K_FOREVER);
	#else
	ARG_UNUSED(dev);
	#endif
	}

	static inline void retention_lock_release(const struct device *dev)
	{
	#ifdef CONFIG_RETENTION_MUTEXES
	struct retention_data *data = dev->data;

	k_mutex_unlock(&data->lock);
	#else
	ARG_UNUSED(dev);
	#endif
	}

	#ifdef ANY_HAS_CHECKSUM
	static int retention_checksum(const struct device dev, uint32_t output)
	{
	const struct retention_config *config = dev->config;
	int rc = -ENOSYS;

	if (config->checksum_size == CHECKSUM_CRC8 \|\|
	config->checksum_size == CHECKSUM_CRC16 \|\|
	config->checksum_size == CHECKSUM_CRC32) {
	size_t pos = config->offset + config->prefix_len;
	size_t end = config->offset + config->size - config->checksum_size;
	uint8_t buffer[CONFIG_RETENTION_BUFFER_SIZE];

	*output = 0;

	while (pos < end) {
	uint16_t read_size = MIN((end - pos), sizeof(buffer));

	rc = retained_mem_read(config->parent, pos, buffer, read_size);

	if (rc < 0) {
	goto finish;
	}

	if (config->checksum_size == CHECKSUM_CRC8) {
	*output = (uint32_t)crc8(buffer, read_size, 0x12,
	(uint8_t)*output, false);
	} else if (config->checksum_size == CHECKSUM_CRC16) {
	output = (uint32_t)crc16_itu_t((uint16_t)output,
	buffer, read_size);
	} else if (config->checksum_size == CHECKSUM_CRC32) {
	output = crc32_ieee_update(output, buffer, read_size);
	}

	pos += read_size;
	}
	}

	finish:
	return rc;
	}
	#endif

	static int retention_init(const struct device *dev)
	{
	const struct retention_config *config = dev->config;
	#ifdef CONFIG_RETENTION_MUTEXES
	struct retention_data *data = dev->data;
	#endif
	ssize_t area_size;

	if (!device_is_ready(config->parent)) {
	LOG_ERR("Parent device is not ready");
	return -ENODEV;
	}

	/* Ensure backend has a large enough storage area for the requirements of
	* this retention area
	*/
	area_size = retained_mem_size(config->parent);

	if (area_size < 0) {
	LOG_ERR("Parent initialisation failure: %d", area_size);
	return area_size;
	}

	if ((config->offset + config->size) > area_size) {
	/* Backend storage is insufficient */
	LOG_ERR("Underlying area size is insufficient, requires: 0x%x, has: 0x%x",
	(config->offset + config->size), area_size);
	return -EINVAL;
	}

	#ifdef CONFIG_RETENTION_MUTEXES
	k_mutex_init(&data->lock);
	#endif

	return 0;
	}

	ssize_t retention_size(const struct device *dev)
	{
	const struct retention_config *config = dev->config;

	return (config->size - config->reserved_size);
	}

	int retention_is_valid(const struct device *dev)
	{
	const struct retention_config *config = dev->config;
	int rc = 0;

	retention_lock_take(dev);

	/* If neither the header or checksum are enabled, return a not supported error */
	if (config->prefix_len == 0 && config->checksum_size == 0) {
	rc = -ENOTSUP;
	goto finish;
	}

	#ifdef ANY_HAS_PREFIX
	if (config->prefix_len != 0) {
	/* Check magic header is present at the start of the section */
	struct retention_data *data = dev->data;
	uint8_t buffer[CONFIG_RETENTION_BUFFER_SIZE];
	off_t pos = 0;

	while (pos < config->prefix_len) {
	uint16_t read_size = MIN((config->prefix_len - pos), sizeof(buffer));

	rc = retained_mem_read(config->parent, (config->offset + pos), buffer,
	read_size);

	if (rc < 0) {
	goto finish;
	}

	if (memcmp(&config->prefix[pos], buffer, read_size) != 0) {
	/* If the magic header does not match, do not check the rest of
	* the validity of the data, assume it is invalid
	*/
	data->header_written = false;
	rc = 0;
	goto finish;
	}

	pos += read_size;
	}

	/* Header already exists so no need to re-write it again */
	data->header_written = true;
	}
	#endif

	#ifdef ANY_HAS_CHECKSUM
	if (config->checksum_size != 0) {
	/* Check the checksum validity, for this all the data must be read out */
	uint32_t checksum = 0;
	uint32_t expected_checksum = 0;
	ssize_t data_size = config->size - config->checksum_size;

	rc = retention_checksum(dev, &checksum);

	if (rc < 0) {
	goto finish;
	}

	if (config->checksum_size == CHECKSUM_CRC8) {
	uint8_t read_checksum;

	rc = retained_mem_read(config->parent, (config->offset + data_size),
	(void *)&read_checksum, sizeof(read_checksum));
	expected_checksum = (uint32_t)read_checksum;
	} else if (config->checksum_size == CHECKSUM_CRC16) {
	uint16_t read_checksum;

	rc = retained_mem_read(config->parent, (config->offset + data_size),
	(void *)&read_checksum, sizeof(read_checksum));
	expected_checksum = (uint32_t)read_checksum;
	} else if (config->checksum_size == CHECKSUM_CRC32) {
	rc = retained_mem_read(config->parent, (config->offset + data_size),
	(void *)&expected_checksum,
	sizeof(expected_checksum));
	}

	if (rc < 0) {
	goto finish;
	}

	if (checksum != expected_checksum) {
	goto finish;
	}
	}
	#endif

	/* At this point, checks have passed (if enabled), mark data as being valid */
	rc = DATA_VALID_VALUE;

	finish:
	retention_lock_release(dev);

	return rc;
	}

	int retention_read(const struct device dev, off_t offset, uint8_t buffer, size_t size)
	{
	const struct retention_config *config = dev->config;
	int rc;

	if (offset < 0 \|\| ((size_t)offset + size) > (config->size - config->reserved_size)) {
	/* Disallow reading past the virtual data size or before it */
	return -EINVAL;
	}

	retention_lock_take(dev);

	rc = retained_mem_read(config->parent, (config->offset + config->prefix_len +
	(size_t)offset), buffer, size);

	retention_lock_release(dev);

	return rc;
	}

	int retention_write(const struct device dev, off_t offset, const uint8_t buffer, size_t size)
	{
	const struct retention_config *config = dev->config;
	int rc;

	#ifdef ANY_HAS_PREFIX
	struct retention_data *data = dev->data;
	#endif

	retention_lock_take(dev);

	if (offset < 0 \|\| ((size_t)offset + size) > (config->size - config->reserved_size)) {
	/* Disallow writing past the virtual data size or before it */
	rc = -EINVAL;
	goto finish;
	}

	rc = retained_mem_write(config->parent, (config->offset + config->prefix_len +
	(size_t)offset), buffer, size);

	if (rc < 0) {
	goto finish;
	}

	#ifdef ANY_HAS_PREFIX
	/* Write optional header and footer information, these are done last to ensure data
	* validity before marking it as being valid
	*/
	if (config->prefix_len != 0 && data->header_written == false) {
	rc = retained_mem_write(config->parent, config->offset, (void *)config->prefix,
	config->prefix_len);

	if (rc < 0) {
	goto finish;
	}

	data->header_written = true;
	}
	#endif

	#ifdef ANY_HAS_CHECKSUM
	if (config->checksum_size != 0) {
	/* Generating a checksum requires reading out all the data in the region */
	uint32_t checksum = 0;

	rc = retention_checksum(dev, &checksum);

	if (rc < 0) {
	goto finish;
	}

	if (config->checksum_size == CHECKSUM_CRC8) {
	uint8_t output_checksum = (uint8_t)checksum;

	rc = retained_mem_write(config->parent,
	(config->offset + config->size - config->checksum_size),
	(void *)&output_checksum, sizeof(output_checksum));
	} else if (config->checksum_size == CHECKSUM_CRC16) {
	uint16_t output_checksum = (uint16_t)checksum;

	rc = retained_mem_write(config->parent,
	(config->offset + config->size - config->checksum_size),
	(void *)&output_checksum, sizeof(output_checksum));
	} else if (config->checksum_size == CHECKSUM_CRC32) {
	rc = retained_mem_write(config->parent,
	(config->offset + config->size - config->checksum_size),
	(void *)&checksum, sizeof(checksum));
	}
	}
	#endif

	finish:
	retention_lock_release(dev);

	return rc;
	}

	int retention_clear(const struct device *dev)
	{
	const struct retention_config *config = dev->config;
	struct retention_data *data = dev->data;
	int rc = 0;
	uint8_t buffer[CONFIG_RETENTION_BUFFER_SIZE];
	off_t pos = 0;

	memset(buffer, 0, sizeof(buffer));

	retention_lock_take(dev);

	data->header_written = false;

	while (pos < config->size) {
	rc = retained_mem_write(config->parent, (config->offset + pos), buffer,
	MIN((config->size - pos), sizeof(buffer)));

	if (rc < 0) {
	goto finish;
	}

	pos += MIN((config->size - pos), sizeof(buffer));
	}

	finish:
	retention_lock_release(dev);

	return rc;
	}

	#define RETENTION_DEVICE(inst) \
	static struct retention_data \
	retention_data_##inst = { \
	.header_written = false, \
	}; \
	static const struct retention_config \
	retention_config_##inst = { \
	.parent = DEVICE_DT_GET(DT_PARENT(DT_INST(inst, DT_DRV_COMPAT))), \
	.checksum_size = DT_INST_PROP(inst, checksum), \
	.offset = DT_INST_REG_ADDR(inst), \
	.size = DT_INST_REG_SIZE(inst), \
	.reserved_size = (COND_CODE_1(DT_INST_NODE_HAS_PROP(inst, prefix), \
	(DT_INST_PROP_LEN(inst, prefix)), (0)) + \
	DT_INST_PROP(inst, checksum)), \
	.prefix_len = COND_CODE_1(DT_INST_NODE_HAS_PROP(inst, prefix), \
	(DT_INST_PROP_LEN(inst, prefix)), (0)), \
	.prefix = DT_INST_PROP_OR(inst, prefix, {0}), \
	}; \
	DEVICE_DT_INST_DEFINE(inst, \
	&retention_init, \
	NULL, \
	&retention_data_##inst, \
	&retention_config_##inst, \
	POST_KERNEL, \
	CONFIG_RETENTION_INIT_PRIORITY, \
	NULL);

	DT_INST_FOREACH_STATUS_OKAY(RETENTION_DEVICE)