[libcpu][asm9260t] Add new BSP for AlphaScale ASM9260T

bsp/asm9260t/drivers/SConscript

@@ -0,0 +1,21 @@
+Import('RTT_ROOT')
+Import('rtconfig')
+from building import *
+
+cwd = os.path.join(str(Dir('#')), 'drivers')
+
+# add the general drvers.
+src = Split("""
+board.c
+usart.c
+""")
+
+# add Ethernet drvers.
+if GetDepend('RT_USING_LED'):
+    src += ['led.c']
+
+CPPPATH = [cwd]
+
+group = DefineGroup('Drivers', src, depend = [''], CPPPATH = CPPPATH)
+
+Return('group')