flash_map: add function to iterate over areas

A new foreach iterator to go over all flash areas in a flash map.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

include/flash_map.h

@@ -172,6 +172,24 @@ u8_t flash_area_align(const struct flash_area *fa);
 int flash_area_get_sectors(int fa_id, u32_t *count,
 			   struct flash_sector *sectors);
 
+/**
+ * Flash map iteration callback
+ *
+ * @param fa flash area
+ * @param user_data User supplied data
+ *
+ */
+typedef void (*flash_area_cb_t)(const struct flash_area *fa,
+				void *user_data);
+
+/**
+ * Iterate over flash map
+ *
+ * @param user_cb User callback
+ * @param user_data User supplied data
+ */
+void flash_area_foreach(flash_area_cb_t user_cb, void *user_data);
+
 /**
  * Check whether given flash area has supporting flash driver
  * in the system.

subsys/storage/flash_map/flash_map.c

@@ -41,6 +41,13 @@ static struct flash_area const *get_flash_area_from_id(int idx)
 	return NULL;
 }
 
+void flash_area_foreach(flash_area_cb_t user_cb, void *user_data)
+{
+	for (int i = 0; i < flash_map_entries; i++) {
+		user_cb(&flash_map[i], user_data);
+	}
+}
+
 int flash_area_open(u8_t id, const struct flash_area **fap)
 {
 	const struct flash_area *area;