drivers: add support for MTDs emulated in RAM

drivers/include/mtd.h

@@ -33,7 +33,7 @@
  * * A **sector** is the device's erase unit. Calls to @ref mtd_erase need to
  *   work in alignment with this number (commonly somewhere around 1kiB).
  *
- *   (Note that this corresponse to the term "page" as used in the flashpage
+ *   (Note that this corresponds to the term "page" as used in the flashpage
  *   API, and the term "eraseblock" in Linux's MTD).
  *
  * * A **page** is the largest a device can write in one transfer.
@@ -108,7 +108,7 @@ typedef struct mtd_desc mtd_desc_t;
 typedef struct {
     const mtd_desc_t *driver;  /**< MTD driver */
     uint32_t sector_count;     /**< Number of sector in the MTD */
-    uint32_t pages_per_sector; /**< Number of pages by sector in the MTD */
+    uint32_t pages_per_sector; /**< Number of pages per sector in the MTD */
     uint32_t page_size;        /**< Size of the pages in the MTD */
     uint32_t write_size;       /**< Minimum size and alignment of writes to the device */
 #if defined(MODULE_MTD_WRITE_PAGE) || DOXYGEN
@@ -324,8 +324,8 @@ int mtd_read(mtd_dev_t *mtd, void *dest, uint32_t addr, uint32_t count);
  * @param[in]  offset   offset from the start of the page (in bytes)
  * @param[in]  size     the number of bytes to read
  *
- * @return 0 on success
- * @return < 0 if an error occurred
+ * @return number of bytes read on success
+ * @return < 0 value on error
  * @return -ENODEV if @p mtd is not a valid device
  * @return -ENOTSUP if operation is not supported on @p mtd
  * @return -EOVERFLOW if @p addr or @p count are not valid, i.e. outside memory
@@ -373,8 +373,8 @@ int mtd_write(mtd_dev_t *mtd, const void *src, uint32_t addr, uint32_t count);
  * @param[in]  offset   byte offset from the start of the page
  * @param[in]  size     the number of bytes to write
  *
- * @return 0 on success
- * @return < 0 if an error occurred
+ * @return number of bytes written on success
+ * @return < 0 value on error
  * @return -ENODEV if @p mtd is not a valid device
  * @return -ENOTSUP if operation is not supported on @p mtd
  * @return -EOVERFLOW if @p addr or @p count are not valid, i.e. outside memory,
@@ -403,8 +403,8 @@ int mtd_write_page_raw(mtd_dev_t *mtd, const void *src, uint32_t page,
  * @param[in]  offset   byte offset from the start of the page
  * @param[in]  size     the number of bytes to write
  *
- * @return 0 on success
- * @return < 0 if an error occurred
+ * @return number of bytes written on success
+ * @return < 0 value on error
  * @return -ENODEV if @p mtd is not a valid device
  * @return -ENOTSUP if operation is not supported on @p mtd
  * @return -EOVERFLOW if @p addr or @p count are not valid, i.e. outside memory,

drivers/include/mtd_default.h

@@ -18,27 +18,51 @@
 #define MTD_DEFAULT_H
 
 #include "board.h"
+#include "modules.h"
 #include "mtd.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/**
- * @brief   Number of MTD devices
- */
-#ifndef MTD_NUMOF
+#if defined(MODULE_MTD_SDCARD_DEFAULT)
+#include "mtd_sdcard.h"
+#endif
+
+#if defined(MODULE_MTD_EMULATED)
+#include "mtd_emulated.h"
+#endif
+
+#if !defined(MTD_NUMOF) && !DOXYGEN
+
 #if defined(MTD_3)
-#define MTD_NUMOF 4
+#define MTD_BOARD_NUMOF     4
 #elif defined(MTD_2)
-#define MTD_NUMOF 3
+#define MTD_BOARD_NUMOF     3
 #elif defined(MTD_1)
-#define MTD_NUMOF 2
+#define MTD_BOARD_NUMOF     2
 #elif defined(MTD_0)
-#define MTD_NUMOF 1
+#define MTD_BOARD_NUMOF     1
 #else
-#define MTD_NUMOF 0
+#define MTD_BOARD_NUMOF     0
+#endif
+
+#define MTD_SDCARD_NUMOF    IS_USED(MODULE_MTD_SDCARD_DEFAULT)
+#define MTD_EMULATED_NUMOF  IS_USED(MODULE_MTD_EMULATED)
+
+/**
+ * @brief   Number of MTD devices
+ */
+#define MTD_NUMOF           (MTD_BOARD_NUMOF + MTD_SDCARD_NUMOF + MTD_EMULATED_NUMOF)
+
+#endif /*  !defined(MTD_NUMOF) && !DOXYGEN */
+
+#if defined(MODULE_MTD_SDCARD_DEFAULT)
+extern mtd_sdcard_t mtd_sdcard_dev0;
 #endif
+
+#if defined(MODULE_MTD_EMULATED)
+extern mtd_emulated_t mtd_emulated_dev0;
 #endif
 
 /**
@@ -52,20 +76,25 @@ extern "C" {
 static inline mtd_dev_t *mtd_default_get_dev(unsigned idx)
 {
     switch (idx) {
-#ifdef MTD_0
+#if MTD_BOARD_NUMOF > 0
     case 0: return MTD_0;
 #endif
-#ifdef MTD_1
+#if MTD_BOARD_NUMOF > 1
     case 1: return MTD_1;
 #endif
-#ifdef MTD_2
+#if MTD_BOARD_NUMOF > 2
     case 2: return MTD_2;
 #endif
-#ifdef MTD_3
+#if MTD_BOARD_NUMOF > 3
     case 3: return MTD_3;
+#endif
+#if MTD_SDCARD_NUMOF > 0
+    case MTD_BOARD_NUMOF: return (mtd_dev_t *)&mtd_sdcard_dev0;
+#endif
+#if MTD_EMULATED_NUMOF > 0
+    case MTD_BOARD_NUMOF + MTD_SDCARD_NUMOF: return (mtd_dev_t *)&mtd_emulated_dev0;
 #endif
     }
-
     return NULL;
 }
 

drivers/include/mtd_emulated.h

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2023 Gunar Schorcht
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     drivers_mtd
+ * @{
+ * @brief       MTD device that is emulated in RAM for test purposes
+ *
+ * Helpers for using emulated MTDs.
+ *
+ * @author      Gunar Schorcht <gunar@schorcht.net>
+ */
+#ifndef MTD_EMULATED_H
+#define MTD_EMULATED_H
+
+#include <stdbool.h>
+
+#include "board.h"
+#include "macros/utils.h"
+#include "mtd.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Macro to define an emulated MTD
+ *
+ * This macro creates a MTD device that is emulated in RAM. For example, using
+ * ```
+ * MTD_EMULATED_DEV(0, 16, 4, 64)
+ * ```
+ * creates the emulated MTD device `mtd_emulated_dev0` with 16 sectors, 4 pages
+ * per sector and a page size of 64 bytes. The write size is always 1 byte.
+ *
+ * @param   n   index of the emulated MTD (results into symbol `mtd_emulated_devn`)
+ * @param   sc  sectors of the emulated MTD
+ * @param   pps pages per sector of the emulated MTD
+ * @param   ps  page size in bytes
+ */
+#define MTD_EMULATED_DEV(n, sc, pps, ps)                \
+    uint8_t _mtd_emulated_memory ## n[sc * pps * ps];   \
+                                                        \
+    mtd_emulated_t mtd_emulated_dev ## n = {            \
+        .base = {                                       \
+            .driver = &_mtd_emulated_driver,            \
+            .sector_count = sc,                         \
+            .pages_per_sector = pps,                    \
+            .page_size = ps,                            \
+            .write_size = 1,                            \
+        },                                              \
+        .size = sc * pps * ps,                          \
+        .memory = _mtd_emulated_memory ## n,            \
+        .init_done = false,                             \
+    }                                                   \
+
+#if MODULE_VFS_AUTO_MOUNT || DOXYGEN
+/**
+ * @brief   Macro to define an automatic VFS mount point for an emulated MTD.
+ *
+ * For example, using
+ * ```
+ * MTD_EMULATED_DEV_FS(0, 2, fatfs);
+ * ```
+ * automatically mounts the emulated MTD `mtd_emulated_dev0` with FAT file
+ * system under mount point `/mtde0` with unique index 2.
+ *
+ * @param   n   index of the emulated MTD (symbol `mtd_emulated_devn`, mount point `/mtde0`)
+ * @param   m   unique overall index of VFS mount point
+ * @param   fs  filesystem type used
+ */
+#define MTD_EMULATED_DEV_FS(n, m, fs) \
+    VFS_AUTO_MOUNT(fs, VFS_MTD(mtd_emulated_dev ## n), "/mtde" # n, m)
+
+#endif /* MODULE_VFS || DOXYGEN */
+
+/**
+ * @brief   Device descriptor for a MTD device that is emulated in RAM
+ */
+typedef struct {
+    mtd_dev_t base;     /**< inherit from mtd_dev_t object */
+    size_t size;        /**< total size of the MTD device in bytes */
+    uint8_t *memory;    /**< RAM that is used for the emulated MTD device */
+    bool init_done;     /**< indicates whether initialization is already done */
+} mtd_emulated_t;
+
+/**
+ * @brief   Emulated MTD device operations table for mtd
+ */
+extern const mtd_desc_t _mtd_emulated_driver;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* MTD_EMULATED_H */
+/** @} */

drivers/mtd/Kconfig

@@ -105,6 +105,9 @@ config MODULE_MTD_SDCARD
     bool "MTD interface for SPI SD-Card"
     depends on MODULE_SDCARD_SPI
 
+config MODULE_MTD_EMULATED
+    bool "MTD interface for MTD emulated in RAM"
+
 config MODULE_SAM0_SDHC
     bool "MTD interface for SAM0 SD Host Controller"
     depends on CPU_COMMON_SAM0

drivers/mtd_emulated/Makefile

@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base