hwstub: Add support for rk27xx lradc block

Change-Id: I8fe15ad8207ac7098944bb85d6b66b91b9858e8f

utils/hwstub/tools/lua/rk27xx.lua

@@ -0,0 +1,8 @@
+---
+--- Chip Identification
+---
+
+RK27XX = {}
+
+hwstub.soc:select("rk27xx")
+require 'rk27xx/lcdif'

utils/hwstub/tools/lua/rk27xx/lradc.lua

@@ -0,0 +1,12 @@
+RK27XX.adc = {}
+
+function RK27XX.adc.init()
+    -- setup ADC clock divider to reach max 1MHz
+    HW.SCU.DIVCON1.write(bit32.replace(HW.SCU.DIVCON1.read(), 49, 10, 8))
+end
+
+function RK27XX.adc.read(channel)
+    HW.ADC.CTRL.write(bit32.bor(bit32.lshift(1,4), bit32.lshift(1,3), bit32.band(channel,3)))
+    -- udelay(20)
+    return bit32.band(HW.ADC.DATA.read(), 0x3ff)
+end