zephyr/boards: Setup rpi_pico to use Zephyr FS instead of MPY FS.

Use new Zephyr FS, and be a demonstration of that configuration.

This is still on-disk compatible with existing filesystems on the internal
flash.

Signed-off-by: Vdragon <mail@massdriver.space>

Author: VynDragon

ports/zephyr/boards/rpi_pico.conf

@@ -18,3 +18,13 @@ CONFIG_SPI=y
 
 # MicroPython config.
 CONFIG_MICROPY_HEAP_SIZE=196608
+
+# File System Configuration
+CONFIG_FILE_SYSTEM=y
+CONFIG_FILE_SYSTEM_LITTLEFS=y
+CONFIG_FILE_SYSTEM_MKFS=y
+CONFIG_MICROPY_VFS_FAT=n
+CONFIG_MICROPY_VFS_LFS1=n
+CONFIG_MICROPY_VFS_LFS2=n
+# Default heap for littlefs is too small
+CONFIG_FS_LITTLEFS_FC_HEAP_SIZE=8192

ports/zephyr/boards/rpi_pico.overlay

@@ -9,6 +9,20 @@
 		/* Use USB CDC ACM as the console. */
 		zephyr,console = &cdc_acm_uart0;
 	};
+
+	fstab {
+		compatible = "zephyr,fstab";
+		lfs: lfs {
+			compatible = "zephyr,fstab,littlefs";
+			mount-point = "/flash";
+			partition = <&storage_partition>;
+			read-size=<16>;
+			prog-size=<256>;
+			cache-size=<1024>;
+			lookahead-size=<32>;
+			block-cycles=<4>;
+		};
+	};
 };
 
 /* Delete defined partitions and make a layout matching the rp2 port RPI_PICO configuration. */