添加rtt的驱动框架，实现了一部分接口函数，支持了Kconfig.

.config

@@ -0,0 +1,72 @@
+CONFIG_RTT_DIR="./"
+
+#
+# DFS: device virtual file system
+#
+CONFIG_RT_USING_DFS=y
+CONFIG_DFS_USING_POSIX=y
+CONFIG_DFS_USING_WORKDIR=y
+# CONFIG_RT_USING_DFS_MNTTABLE is not set
+CONFIG_DFS_FD_MAX=16
+CONFIG_RT_USING_DFS_V1=y
+# CONFIG_RT_USING_DFS_V2 is not set
+CONFIG_DFS_FILESYSTEMS_MAX=4
+CONFIG_DFS_FILESYSTEM_TYPES_MAX=4
+# CONFIG_RT_USING_DFS_ELMFAT is not set
+CONFIG_RT_USING_DFS_DEVFS=y
+# CONFIG_RT_USING_DFS_ROMFS is not set
+# CONFIG_RT_USING_DFS_CROMFS is not set
+# CONFIG_RT_USING_DFS_RAMFS is not set
+# CONFIG_RT_USING_DFS_TMPFS is not set
+# CONFIG_RT_USING_DFS_MQUEUE is not set
+# end of DFS: device virtual file system
+
+#
+# Device Drivers
+#
+# CONFIG_RT_USING_DM is not set
+CONFIG_RT_USING_DEVICE_IPC=y
+CONFIG_RT_UNAMED_PIPE_NUMBER=64
+# CONFIG_RT_USING_SYSTEM_WORKQUEUE is not set
+CONFIG_RT_USING_SERIAL=y
+CONFIG_RT_USING_SERIAL_V1=y
+# CONFIG_RT_USING_SERIAL_V2 is not set
+CONFIG_RT_SERIAL_USING_DMA=y
+CONFIG_RT_SERIAL_RB_BUFSZ=64
+# CONFIG_RT_USING_CAN is not set
+# CONFIG_RT_USING_HWTIMER is not set
+# CONFIG_RT_USING_CPUTIME is not set
+# CONFIG_RT_USING_I2C is not set
+# CONFIG_RT_USING_PHY is not set
+CONFIG_RT_USING_PIN=y
+# CONFIG_RT_USING_ADC is not set
+# CONFIG_RT_USING_DAC is not set
+# CONFIG_RT_USING_NULL is not set
+# CONFIG_RT_USING_ZERO is not set
+# CONFIG_RT_USING_RANDOM is not set
+# CONFIG_RT_USING_PWM is not set
+# CONFIG_RT_USING_MTD_NOR is not set
+# CONFIG_RT_USING_MTD_NAND is not set
+# CONFIG_RT_USING_PM is not set
+# CONFIG_RT_USING_RTC is not set
+# CONFIG_RT_USING_SDIO is not set
+# CONFIG_RT_USING_SPI is not set
+# CONFIG_RT_USING_WDT is not set
+# CONFIG_RT_USING_AUDIO is not set
+# CONFIG_RT_USING_SENSOR is not set
+# CONFIG_RT_USING_TOUCH is not set
+# CONFIG_RT_USING_LCD is not set
+# CONFIG_RT_USING_HWCRYPTO is not set
+# CONFIG_RT_USING_PULSE_ENCODER is not set
+# CONFIG_RT_USING_INPUT_CAPTURE is not set
+# CONFIG_RT_USING_DEV_BUS is not set
+# CONFIG_RT_USING_WIFI is not set
+# CONFIG_RT_USING_VIRTIO is not set
+
+#
+# Using USB
+#
+# CONFIG_RT_USING_USB_HOST is not set
+# CONFIG_RT_USING_USB_DEVICE is not set
+# end of Using USB
+# end of Device Drivers