zephyr: Enable fatfs.

Enables the fatfs filesystem in the zephyr port.

Example usage with an SD card on the mimxrt1050_evk board:

import zephyr, os
bdev = zephyr.DiskAccess('SDHC')
os.VfsFat.mkfs(bdev)
os.mount(bdev, '/sd')
with open('/sd/hello.txt','w') as f:
    f.write('Hello world')
print(open('/sd/hello.txt').read())

ports/zephyr/Makefile

@@ -17,6 +17,8 @@ OUTDIR_PREFIX = $(BOARD)
 MICROPY_HEAP_SIZE = 16384
 FROZEN_DIR = scripts
 
+MICROPY_VFS_FAT ?= 1
+
 # Default target
 all:
 
@@ -48,6 +50,7 @@ SRC_C = main.c \
 	machine_pin.c \
 	uart_core.c \
 	zephyr_storage.c \
+	lib/timeutils/timeutils.c \
 	lib/utils/stdout_helpers.c \
 	lib/utils/printf.c \
 	lib/utils/pyexec.c \
@@ -61,7 +64,7 @@ SRC_QSTR += $(SRC_C)
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 CFLAGS = $(Z_CFLAGS) \
-	 -std=gnu99 -fomit-frame-pointer -DNDEBUG -DMICROPY_HEAP_SIZE=$(MICROPY_HEAP_SIZE) $(CFLAGS_EXTRA) $(INC)
+	 -std=gnu99 -fomit-frame-pointer -DNDEBUG -DMICROPY_HEAP_SIZE=$(MICROPY_HEAP_SIZE) $(CFLAGS_MOD) $(CFLAGS_EXTRA) $(INC)
 
 include $(TOP)/py/mkrules.mk
 

ports/zephyr/moduos.c

@@ -28,6 +28,10 @@
 
 #include "extmod/vfs.h"
 
+#if MICROPY_VFS_FAT
+#include "extmod/vfs_fat.h"
+#endif
+
 #if MICROPY_PY_UOS
 
 STATIC const mp_rom_map_elem_t uos_module_globals_table[] = {
@@ -47,6 +51,9 @@ STATIC const mp_rom_map_elem_t uos_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_mount), MP_ROM_PTR(&mp_vfs_mount_obj) },
     { MP_ROM_QSTR(MP_QSTR_umount), MP_ROM_PTR(&mp_vfs_umount_obj) },
     #endif
+    #if MICROPY_VFS_FAT
+    { MP_ROM_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
+    #endif
 };
 STATIC MP_DEFINE_CONST_DICT(uos_module_globals, uos_module_globals_table);
 

ports/zephyr/mpconfigport.h

@@ -84,6 +84,13 @@
 #define MICROPY_VFS                 (1)
 #define MICROPY_READER_VFS          (MICROPY_VFS)
 
+// fatfs configuration used in ffconf.h
+#define MICROPY_FATFS_ENABLE_LFN       (1)
+#define MICROPY_FATFS_LFN_CODE_PAGE    437 /* 1=SFN/ANSI 437=LFN/U.S.(OEM) */
+#define MICROPY_FATFS_USE_LABEL        (1)
+#define MICROPY_FATFS_RPATH            (2)
+#define MICROPY_FATFS_NORTC            (1)
+
 // Saving extra crumbs to make sure binary fits in 128K
 #define MICROPY_COMP_CONST_FOLDING  (0)
 #define MICROPY_COMP_CONST (0)