Hi Beuh .
I have built an engine using this cycle of operations . It is a 2 stroke engine and it completes all 4 cycles in one revolution of the crankshaft . There are two valves .The inlet is atmospherically operated and the exhaust which is located about half way down the stroke is spring loaded by a very ling spring and is opened by exhaust pressure when the piston passes the port and then closes when the pressure has dropped the remainder of the stroke is the intake and once the piston starts moving up again you have the compression stroke with some possible losses out the exhaust valve till the piston has past the exhaust port and when the piston nears TDC you have ignition and the cycle begins again.
This is a link to one I built .