X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=src%2Fsoc%2Fsimple%2Fissuer.py;h=ad4fd0a9112680cffbe08d3aecdf94dd8e928f81;hb=c83043ee58e86a1b1da7b76a2b2d34e1667923dc;hp=0515611938d21afd4268f4c8355b40c251f79d53;hpb=f2a1daea5d49cfcbe0eca08db961d59e0a86b901;p=soc.git

diff --git a/src/soc/simple/issuer.py b/src/soc/simple/issuer.py
index 05156119..ad4fd0a9 100644
--- a/src/soc/simple/issuer.py
+++ b/src/soc/simple/issuer.py
@@ -135,20 +135,24 @@ class TestIssuer(Elaboratable):
 
         # read the PC
         pc = Signal(64, reset_less=True)
+        pc_ok_delay = Signal()
+        sync += pc_ok_delay.eq(~self.pc_i.ok)
         with m.If(self.pc_i.ok):
             # incoming override (start from pc_i)
             comb += pc.eq(self.pc_i.data)
         with m.Else():
-            # otherwise read StateRegs regfile for PC
+            # otherwise read StateRegs regfile for PC...
             comb += self.state_r_pc.ren.eq(1<<StateRegs.PC)
+        # ... but on a 1-clock delay
+        with m.If(pc_ok_delay):
             comb += pc.eq(self.state_r_pc.data_o)
 
         # don't write pc every cycle
-        sync += self.state_w_pc.wen.eq(0)
-        sync += self.state_w_pc.data_i.eq(0)
+        comb += self.state_w_pc.wen.eq(0)
+        comb += self.state_w_pc.data_i.eq(0)
 
         # don't read msr every cycle
-        sync += self.state_r_msr.ren.eq(0)
+        comb += self.state_r_msr.ren.eq(0)
 
         # connect up debug signals
         # TODO comb += core.icache_rst_i.eq(dbg.icache_rst_o)
@@ -187,14 +191,15 @@ class TestIssuer(Elaboratable):
                     comb += self.imem.f_valid_i.eq(1)
                     sync += cur_state.pc.eq(pc)
 
-                    # read MSR, latch it, and put it in decode "state"
-                    sync += self.state_r_msr.ren.eq(1<<StateRegs.MSR)
-                    sync += cur_state.msr.eq(self.state_r_msr.data_o)
+                    # initiate read of MSR
+                    comb += self.state_r_msr.ren.eq(1<<StateRegs.MSR)
 
                     m.next = "INSN_READ" # move to "wait for bus" phase
 
             # dummy pause to find out why simulation is not keeping up
             with m.State("INSN_READ"):
+                # one cycle later, msr read arrives
+                sync += cur_state.msr.eq(self.state_r_msr.data_o)
                 with m.If(self.imem.f_busy_o): # zzz...
                     # busy: stay in wait-read
                     comb += self.imem.a_valid_i.eq(1)
@@ -232,14 +237,13 @@ class TestIssuer(Elaboratable):
                     # this just blithely overwrites whatever pipeline
                     # updated the PC
                     with m.If(~pc_changed):
-                        sync += self.state_w_pc.wen.eq(1<<StateRegs.PC)
-                        sync += self.state_w_pc.data_i.eq(nia)
+                        comb += self.state_w_pc.wen.eq(1<<StateRegs.PC)
+                        comb += self.state_w_pc.data_i.eq(nia)
                     sync += core.e.eq(0)
                     m.next = "IDLE" # back to idle
 
         # this bit doesn't have to be in the FSM: connect up to read
         # regfiles on demand from DMI
-
         with m.If(d_reg.req): # request for regfile access being made
             # TODO: error-check this
             # XXX should this be combinatorial?  sync better?
@@ -248,6 +252,10 @@ class TestIssuer(Elaboratable):
             else:
                 comb += self.int_r.addr.eq(d_reg.addr)
                 comb += self.int_r.ren.eq(1)
+        d_reg_delay  = Signal()
+        sync += d_reg_delay.eq(d_reg.req)
+        with m.If(d_reg_delay):
+            # data arrives one clock later
             comb += d_reg.data.eq(self.int_r.data_o)
             comb += d_reg.ack.eq(1)
 
@@ -275,7 +283,7 @@ class TestIssuer(Elaboratable):
                                     ] + \
                 list(self.dbg.dmi.ports()) + \
                 list(self.imem.ibus.fields.values()) + \
-                list(self.core.l0.cmpi.lsmem.lsi.dbus.fields.values())
+                list(self.core.l0.cmpi.lsmem.lsi.slavebus.fields.values())
 
     def ports(self):
         return list(self)