esp8266: Implement vfs.rom_ioctl with support for external flash.

Not enabled by default on any board.  For a board to enable ROMFS it must:

- Add `#define MICROPY_VFS_ROM (1)` to its `mpconfigboard.h` file.

- Add a FLASH_ROMFS partition to the linker script and expose the partition
  with:

    _micropy_hw_romfs_start = ORIGIN(FLASH_ROMFS);
    _micropy_hw_romfs_size = LENGTH(FLASH_ROMFS);

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/ports/esp8266/modesp.c b/ports/esp8266/modesp.c
index f303da1a3..c88022945 100644
--- a/ports/esp8266/modesp.c
+++ b/ports/esp8266/modesp.c
@@ -164,9 +164,16 @@ static MP_DEFINE_CONST_FUN_OBJ_0(esp_flash_size_obj, esp_flash_size);
 #define IS_OTA_FIRMWARE() ((*(uint32_t *)0x40200000 & 0xff00) == 0x100)
 
 extern byte _firmware_size[];
+#if MICROPY_VFS_ROM_IOCTL
+extern uint8_t _micropy_hw_romfs_size;
+#endif
 
 static mp_obj_t esp_flash_user_start(void) {
-    return MP_OBJ_NEW_SMALL_INT((uint32_t)_firmware_size);
+    uint32_t flash_user_start = (uint32_t)_firmware_size;
+    #if MICROPY_VFS_ROM_IOCTL
+    flash_user_start += (uint32_t)&_micropy_hw_romfs_size;
+    #endif
+    return MP_OBJ_NEW_SMALL_INT(flash_user_start);
 }
 static MP_DEFINE_CONST_FUN_OBJ_0(esp_flash_user_start_obj, esp_flash_user_start);