storage/flash_map: Make flash_area.fa_dev_name optional

With switch to compile time resolved device object and usage of
flash_area.fa_dev, the filed flash_area.fa_dev_name becomes optional
as there are no more device_get_binding calls within flash_map
that rely on that filed, or any other references to that field.

The added Kconfig option, FLASH_MAP_DEV_NAME_IN_FLASH_AREA, allows
to remove the flash_area.fa_dev_name field, when disabled.
The option is set to y by default to support external code that may
relay on the existence of flash_area.fa_dev_name.

Configurations for samples and tests that require the fa_dev_name
have been altered to have proper Kconfig options enabled.

Signed-off-by: Dominik Ermel <[email protected]>

include/storage/flash_map.h

@@ -60,11 +60,13 @@ struct flash_area {
  off_t fa_off;
  /** Total size */
  size_t fa_size;
+#if defined(CONFIG_FLASH_MAP_DEV_NAME_IN_FLASH_AREA)
  /**
  * Name of the flash device, suitable for passing to
  * device_get_binding().
  */
  const char *fa_dev_name;
+#endif
 #if defined(CONFIG_FLASH_MAP_DEV_IN_FLASH_AREA)
  /**
  * Pointer to device structure for the flash device.

subsys/settings/Kconfig

@@ -60,6 +60,7 @@ config SETTINGS_NVS
  bool "NVS non-volatile storage support"
  depends on NVS
  depends on FLASH_MAP
+ depends on FLASH_MAP_DEV_NAME_IN_FLASH_AREA
  help
  Enables NVS storage support
 

subsys/storage/flash_map/Kconfig

@@ -18,8 +18,12 @@ if FLASH_MAP
 config FLASH_MAP_SHELL
  bool "Enable flash map shell interface"
  depends on SHELL
+ select FLASH_MAP_DEV_NAME_IN_FLASH_AREA
  help
  This enables shell commands to list and test flash maps.
+ The option depends on FLASH_MAP_DEV_NAME_IN_FLASH_AREA being selected, even when
+ FLASH_MAP_DEV_IN_FLASH_AREA is enabled, to be able to list names of devices tied to
+ flash areas, as the names need to be accessible from flash_area structure.
 
 config FLASH_MAP_DEV_IN_FLASH_AREA
  bool "Switch flash map to use compile time evaluated devices objects"
@@ -36,6 +40,26 @@ config FLASH_MAP_DEV_IN_FLASH_AREA
  custom map populates the flash_area.fa_dev areas you may want to set this option to
  improve flash map performance.
 
+if FLASH_MAP_DEV_IN_FLASH_AREA
+config FLASH_MAP_DEV_NAME_IN_FLASH_AREA
+ bool "Keep fa_dev_name filed to flash_area structure"
+ default y
+ help
+ The options allows storage of string name of flash device that is tied to the flash area
+ record. This may be useful when device_get_binding is used for obtaining device object
+ for the flash_area or when in need to have such information at run-time.
+ The flash map does not use flash_area.fa_dev_name internally when
+ FLASH_MAP_USE_DEV_IN_FLASH_AREA is enabled, and in such case, unless used by other code,
+ this can be safely disabled and will reduce size of flash_area structure by size of
+ a pointer.
+endif
+
+if !FLASH_MAP_DEV_IN_FLASH_AREA
+config FLASH_MAP_DEV_NAME_IN_FLASH_AREA
+ bool
+ default y
+endif
+
 config FLASH_MAP_CUSTOM
  bool "Custom flash map description"
  help

subsys/storage/flash_map/flash_map_default.c

@@ -14,7 +14,10 @@
 #define FLASH_AREA_FOO(part) \
  {.fa_id = DT_FIXED_PARTITION_ID(part), \
  .fa_off = DT_REG_ADDR(part), \
- .fa_dev_name = DT_LABEL(DT_MTD_FROM_FIXED_PARTITION(part)), \
+ COND_CODE_1(CONFIG_FLASH_MAP_DEV_NAME_IN_FLASH_AREA, \
+ (.fa_dev_name = DT_LABEL(DT_MTD_FROM_FIXED_PARTITION(part)),), \
+ () \
+ ) \
  COND_CODE_1(CONFIG_FLASH_MAP_DEV_IN_FLASH_AREA, \
  (.fa_dev = DEVICE_DT_GET(DT_MTD_FROM_FIXED_PARTITION(part)),), \
  () \