mtd: api for mtd devices

Enable support of mtd devices and partitions on flash. Provide support
for mtd on eeprom and retained_ram.

Modified flash_map_default.c to avoid generating non flash partitions in
the default_flash_map structure.

Performed some optimisation in finding the mtd_dev_cfg and offset on the
device.

Reworked to make the read, write and erase functions on the device part
of the mtd_dev_cfg struct.

Made the library more modular to allow easier addition of new backends

Signed-off-by: Laczen JMS <laczenjms@gmail.com>

dts/bindings/mtd/zephyr,mtd-eeprom.yaml

@@ -0,0 +1,6 @@
+# Copyright (c) 2023 Laczen
+# SPDX-License-Identifier: Apache-2.0
+
+# Compatible used to describe mtd on eeprom
+
+include: base.yaml

dts/bindings/mtd/zephyr,mtd-flash.yaml

@@ -0,0 +1,6 @@
+# Copyright (c) 2023 Laczen
+# SPDX-License-Identifier: Apache-2.0
+
+# Compatible used to describe mtd on flash
+
+include: base.yaml

dts/bindings/mtd/zephyr,mtd-retained-mem.yaml

@@ -0,0 +1,6 @@
+# Copyright (c) 2023 Laczen
+# SPDX-License-Identifier: Apache-2.0
+
+# Compatible used to describe mtd on retained_mem
+
+include: base.yaml

include/zephyr/mtd/mtd.h

@@ -0,0 +1,207 @@
+/*
+ * Copyright (c) 2023 Laczen
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ * @brief Public API for memory technology devices (mtd) partitions
+ */
+
+#ifndef ZEPHYR_INCLUDE_MTD_H_
+#define ZEPHYR_INCLUDE_MTD_H_
+
+/**
+ * @brief Abstraction over mtd devices and partitions on mtd devices and their
+ *        drivers
+ *
+ * @defgroup mtd_part_api mtd interface
+ * @{
+ */
+
+/*
+ * This API makes it possible to operate on mtd devices and partitions on mtd
+ * devices easily and effectively.
+ */
+
+#include <sys/types.h>
+#include <zephyr/device.h>
+#include <zephyr/devicetree.h>
+#include <zephyr/drivers/flash.h>
+#include <zephyr/drivers/eeprom.h>
+#include <zephyr/drivers/retained_mem.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * The MTD subsystem provide an abstraction layer between hardware-specific
+ * device drivers and higher-level applications for mtd devices. On mtd devices
+ * 3 routines for operation are used: read, write and erase. Before data can be
+ * written the write location needs to be erased. The MTD subsystem also
+ * provides an adaptation layer for devices that are generally not considered
+ * mtd devices (e.g. eeprom and retained_mem).
+ *
+ * Both the MTD device as partitions on a MTD device are created by the
+ * subsystem.
+ *
+ */
+
+/**
+ * @brief Retrieve a pointer to the MTD info struct of a MTD.
+ *
+ * A mtd with nodelabel "flash0" is retrieved as:
+ * const struct mtd_info *mtd = MTD_GET(flash0)
+ * A mtd partition nodelabel "storage_partition" is retrieved as:
+ * const struct mtd_info *mtd = MTD_GET(storage_partition)
+ *
+ * @param nodelabel of the mtd device.
+ */
+#define MTD_GET(nodelabel) &UTIL_CAT(mtd_info_, DT_NODELABEL(nodelabel))
+
+enum mtd_type {UNKNOWN, FLASH, EEPROM, RETAINED_MEM};
+
+struct mtd_dev_cfg;
+
+/** @brief mtd_dev_cfg represents the configuration of a mtd device */
+struct mtd_dev_cfg {
+	/** device used as mtd backend */
+	const struct device *dev;
+	/** type of device used as mtd backend */
+	const enum mtd_type type;
+	/** backend routines */
+	int (* const read)(const struct mtd_dev_cfg *dev_cfg, off_t off,
+			   void *dst, size_t len);
+	int (* const write)(const struct mtd_dev_cfg *dev_cfg, off_t off,
+			    const void *src, size_t len);
+	int (* const erase)(const struct mtd_dev_cfg *dev_cfg, off_t off,
+			    size_t len);
+};
+
+struct mtd_info;
+
+/**
+ * @brief mtd_info represents a mtd item.
+ */
+struct mtd_info {
+	/** mtd device configuration (is NULL for a mtd partition) */
+	const struct mtd_dev_cfg *dev_cfg;
+	/** mtd parent (is NULL for a mtd device) */
+	const struct mtd_info *parent;
+	/** mtd offset on parent */
+	const off_t off;
+	const size_t size;
+	const bool read_only;
+};
+
+/**
+ * @brief Get the size of a mtd item.
+ *
+ * @param[in] info MTD item
+ * @return the size.
+ */
+size_t mtd_get_size(const struct mtd_info *info);
+
+/**
+ * @brief Get the device that is used by a mtd item.
+ *
+ * @param[in] info MTD item
+ * @return the device.
+ */
+const struct device *mtd_get_device(const struct mtd_info *info);
+
+/**
+ * @brief Get the offset of the mtd item on the device.
+ *
+ * @param[in] info MTD item
+ * @return the offsetdevice.
+ */
+off_t mtd_get_device_offset(const struct mtd_info *info);
+
+/**
+ * @brief Get the device type of a mtd item.
+ *
+ * @param[in] info MTD item
+ * @return the device type.
+ */
+enum mtd_type mtd_get_device_type(const struct mtd_info *info);
+
+/**
+ * @brief Read data from mtd item. Read boundaries are verified before read
+ * request is executed.
+ *
+ * @param[in] info MTD item
+ * @param[in] off Offset relative from beginning of mtd item to read
+ * @param[out] dst Buffer to store read data
+ * @param[in] len Number of bytes to read
+ *
+ * @return  0 on success, negative errno code on fail.
+ */
+int mtd_read(const struct mtd_info *info, off_t off, void *dst, size_t len);
+
+/**
+ * @brief Write data to mtd item. Write boundaries are verified before write
+ * request is executed.
+ *
+ * @param[in] info MTD item
+ * @param[in] off Offset relative from beginning of mtd item to write
+ * @param[out] src Buffer with data to be written
+ * @param[in] len Number of bytes to write
+ *
+ * @return  0 on success, negative errno code on fail.
+ */
+int mtd_write(const struct mtd_info *info, off_t off, const void *src,
+	      size_t len);
+
+/**
+ * @brief Erase range on mtd item. Erase boundaries are verified before erase
+ * is executed.
+ *
+ * @param[in] info MTD item
+ * @param[in] off Offset relative from beginning of mtd item.
+ * @param[in] len Number of bytes to be erase
+ *
+ * @return  0 on success, negative errno code on fail.
+ */
+int mtd_erase(const struct mtd_info *info, off_t off, size_t len);
+
+/** @cond INTERNAL_HIDDEN */
+
+#define MTD_DECLARE(n) extern const struct mtd_info mtd_info_##n;
+
+#define MTD_FIXED_PARTITIONS_DECLARE(n, _compat)				\
+	COND_CODE_0(DT_NODE_HAS_COMPAT(DT_PARENT(n), _compat), (),		\
+		(DT_FOREACH_CHILD(n, MTD_DECLARE)))
+
+#define MTD_COMPATIBLE_PARTITIONS_DECLARE(_compatible)				\
+	DT_FOREACH_STATUS_OKAY_VARGS(fixed_partitions,                          \
+		MTD_FIXED_PARTITIONS_DECLARE, _compatible)
+
+#ifdef CONFIG_MTD_FLASH
+DT_FOREACH_STATUS_OKAY(zephyr_mtd_flash, MTD_DECLARE)
+MTD_COMPATIBLE_PARTITIONS_DECLARE(zephyr_mtd_flash)
+#endif
+
+#ifdef CONFIG_MTD_EEPROM
+DT_FOREACH_STATUS_OKAY(zephyr_mtd_eeprom, MTD_DECLARE)
+MTD_COMPATIBLE_PARTITIONS_DECLARE(zephyr_mtd_eeprom)
+#endif
+
+#ifdef CONFIG_MTD_RETAINED_MEM
+DT_FOREACH_STATUS_OKAY(zephyr_mtd_retained_mem, MTD_DECLARE)
+MTD_COMPATIBLE_PARTITIONS_DECLARE(zephyr_mtd_retained_mem)
+#endif
+
+/** @endcond */
+
+#ifdef __cplusplus
+}
+#endif
+
+/**
+ * @}
+ */
+
+#endif /* ZEPHYR_INCLUDE_MTD_H_ */

subsys/CMakeLists.txt

@@ -41,6 +41,8 @@ add_subdirectory_ifdef(CONFIG_IMG_MANAGER dfu)
 add_subdirectory_ifdef(CONFIG_INPUT input)
 add_subdirectory_ifdef(CONFIG_JWT jwt)
 add_subdirectory_ifdef(CONFIG_MODEM_MODULES modem)
+add_subdirectory_ifdef(CONFIG_LORAWAN lorawan)
+add_subdirectory_ifdef(CONFIG_MTD mtd)
 add_subdirectory_ifdef(CONFIG_NET_BUF net)
 add_subdirectory_ifdef(CONFIG_RETENTION retention)
 add_subdirectory_ifdef(CONFIG_SENSING sensing)

subsys/Kconfig

@@ -25,6 +25,7 @@ source "subsys/lorawan/Kconfig"
 source "subsys/mgmt/Kconfig"
 source "subsys/modbus/Kconfig"
 source "subsys/modem/Kconfig"
+source "subsys/mtd/Kconfig"
 source "subsys/net/Kconfig"
 source "subsys/pm/Kconfig"
 source "subsys/portability/Kconfig"

subsys/mtd/CMakeLists.txt

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(mtd.c)
+zephyr_library_sources_ifdef(CONFIG_MTD_FLASH mtd_flash.c)
+zephyr_library_sources_ifdef(CONFIG_MTD_EEPROM mtd_eeprom.c)
+zephyr_library_sources_ifdef(CONFIG_MTD_RETAINED_MEM mtd_retained_mem.c)

subsys/mtd/Kconfig

@@ -0,0 +1,53 @@
+# Copyright (c) 2023, Laczen
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig MTD
+	bool "mtd support"
+	help
+	  Enables support for the mtd system, which enables using generic mtd
+	  routines to read/write and erase mtd devices. Supported mtd devices
+	  are flash, but also eeprom, bbram and retained_mem over an adaptation
+	  layer.
+
+if MTD
+
+config MTD_FLASH
+	bool "mtd support for flash devices"
+	default y
+	depends on FLASH
+	help
+	  Enables mtd support for flash devices.
+
+config MTD_EEPROM
+	bool "mtd support for eeprom devices"
+	default y
+	depends on EEPROM
+	help
+	  Enables mtd support for eeprom devices.
+
+config MTD_RETAINED_MEM
+	bool "mtd support for retained_mem devices"
+	default y
+	depends on RETAINED_MEM
+	help
+	  Enables mtd support for retained_mem devices.
+
+config MTD_ERASE_BUFSIZE
+	int "mtd erase bufsize"
+	default 64
+	range 16 256
+	help
+	  Size of the buffer used to erase when mtd is used on non-flash
+	  devices.
+
+config MTD_ERASE_VALUE
+	hex "mtd erase value"
+	default 0xff
+	help
+	  Value used to erase when mtd is used on non-flash devices.
+
+module = MTD
+module-str = mtd
+source "subsys/logging/Kconfig.template.log_config"
+
+endif # MTD