core: add edge-triggered irq signal for command completion

Author: gsomlo

litesdcard/core.py

@@ -24,6 +24,7 @@ class SDCore(LiteXModule):
     def __init__(self, phy):
         self.sink   = stream.Endpoint([("data", 8)])
         self.source = stream.Endpoint([("data", 8)])
+        self.irq = Signal()
 
         # Cmd Registers.
         self.cmd_argument = CSRStorage(32, description="SDCard Cmd Argument.")
@@ -115,6 +116,11 @@ def __init__(self, phy):
             crc7_inserter.enable.eq(1),
         ]
 
+        # IRQ / Generate IRQ on CMD done rising edge
+        done_d     = Signal()
+        self.sync += done_d.eq(cmd_done)
+        self.sync += self.irq.eq(cmd_done & ~done_d)
+
         # Main FSM ---------------------------------------------------------------------------------
         self.fsm = fsm = FSM()
         fsm.act("IDLE",