hw/misc/mps2-scc: Add "QEMU interface" comment

The MPS2 SCC device doesn't have any documentation of its properties;
add a "QEMU interface" format comment describing them.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210504120912.23094-2-peter.maydell@linaro.org

include/hw/misc/mps2-scc.h

@@ -9,6 +9,18 @@
  *  (at your option) any later version.
  */
 
+/*
+ * This is a model of the Serial Communication Controller (SCC)
+ * block found in most MPS FPGA images.
+ *
+ * QEMU interface:
+ *  + sysbus MMIO region 0: the register bank
+ *  + QOM property "scc-cfg4": value of the read-only CFG4 register
+ *  + QOM property "scc-aid": value of the read-only SCC_AID register
+ *  + QOM property "scc-id": value of the read-only SCC_ID register
+ *  + QOM property array "oscclk": reset values of the OSCCLK registers
+ *    (which are accessed via the SYS_CFG channel provided by this device)
+ */
 #ifndef MPS2_SCC_H
 #define MPS2_SCC_H