# hack method of keeping an eye on whether branch/trap set the PC
self.state_nia = self.core.regs.rf['state'].w_ports['nia']
self.state_nia.wen.name = 'state_nia_wen'
+ # and whether SPR pipeline sets DEC or TB
+ self.state_spr = self.core.regs.rf['state'].w_ports['state1']
# pulse to synchronize the simulator at instruction end
self.insn_done = Signal()
m.submodules["sram4k_%d" % i] = csd(sram)
comb += sram.enable.eq(self.wb_sram_en)
- # terrible hack to stop a potential race condition. if core
- # is doing any operation (at all) pause the DEC/TB FSM
- comb += self.pause_dec_tb.eq(core.pause_dec_tb)
-
# XICS interrupt handler
if self.xics:
m.submodules.xics_icp = icp = csd(self.xics_icp)
dbg_sync = ClockDomain(self.dbg_domain)
m.domains += dbg_sync
+ # create a delay, but remember it is in the power-on-reset clock domain!
ti_rst = Signal(reset_less=True)
delay = Signal(range(4), reset=3)
+ stop_delay = Signal(range(16), reset=5)
with m.If(delay != 0):
- m.d.por += delay.eq(delay - 1)
+ m.d.por += delay.eq(delay - 1) # decrement... in POR domain!
+ with m.If(stop_delay != 0):
+ m.d.por += stop_delay.eq(stop_delay - 1) # likewise
comb += cd_por.clk.eq(ClockSignal())
# power-on reset delay
else:
with m.If(delay != 0 | dbg.core_rst_o):
comb += core_rst.eq(1)
+ with m.If(stop_delay != 0):
+ # run DMI core-stop as well but on an extra couple of cycles
+ comb += dbg.core_stopped_i.eq(1)
# connect external reset signal to DMI Reset
if self.dbg_domain != "sync":
comb += pdecode2.dec.bigendian.eq(self.core_bigendian_i)
# temporary hack: says "go" immediately for both address gen and ST
+ # XXX: st.go_i is set to 1 cycle delay to reduce combinatorial chains
l0 = core.l0
ldst = core.fus.fus['ldst0']
st_go_edge = rising_edge(m, ldst.st.rel_o)
# link addr-go direct to rel
m.d.comb += ldst.ad.go_i.eq(ldst.ad.rel_o)
- m.d.comb += ldst.st.go_i.eq(st_go_edge) # link store-go to rising rel
+ m.d.sync += ldst.st.go_i.eq(st_go_edge) # link store-go to rising rel
def do_dmi(self, m, dbg):
"""deals with DMI debug requests
fetch_failed = Const(0, 1)
flush_needed = False
+ # create a register with pc+4 as a way to reduce combinatorial chains
+ pc4 = Signal.like(cur_state.pc)
+ sync += pc4.eq(cur_state.pc + 4)
+
# set priv / virt mode on I-Cache, sigh
if isinstance(self.imem, ICache):
comb += self.imem.i_in.priv_mode.eq(~msr[MSR.PR])
with m.FSM(name='fetch_fsm'):
+ # allow fetch to not run at startup due to I-Cache reset not
+ # having time to settle. power-on-reset holds dbg.core_stopped_i
+ with m.State("PRE_IDLE"):
+ with m.If(~dbg.core_stopped_i & ~dbg.core_stop_o):
+ m.next = "IDLE"
+
# waiting (zzz)
with m.State("IDLE"):
# fetch allowed if not failed and stopped but not stepping
m.next = "INSN_READY"
with m.Else():
# fetch the rest of the instruction from memory
- comb += self.imem.a_pc_i.eq(cur_state.pc + 4)
+ comb += self.imem.a_pc_i.eq(pc4)
comb += self.imem.a_i_valid.eq(1)
comb += self.imem.f_i_valid.eq(1)
m.next = "INSN_READ2"
# blech, icache returns actual instruction
insn = self.imem.f_instr_o
else:
- insn = get_insn(self.imem.f_instr_o, cur_state.pc+4)
+ insn = get_insn(self.imem.f_instr_o, pc4)
sync += dec_opcode_i.eq(insn)
m.next = "INSN_READY"
# TODO: probably can start looking at pdecode2.rm_dec
# instruction started: must wait till it finishes
with m.State("INSN_ACTIVE"):
- # note changes to MSR, PC and SVSTATE
- # XXX oops, really must monitor *all* State Regfile write
- # ports looking for changes!
+ # note changes to MSR, PC and SVSTATE, and DEC/TB
+ # these last two are done together, and passed to the
+ # DEC/TB FSM
with m.If(self.state_nia.wen & (1 << StateRegs.SVSTATE)):
sync += self.sv_changed.eq(1)
with m.If(self.state_nia.wen & (1 << StateRegs.MSR)):
sync += self.msr_changed.eq(1)
with m.If(self.state_nia.wen & (1 << StateRegs.PC)):
sync += self.pc_changed.eq(1)
+ with m.If((self.state_spr.wen &
+ ((1 << StateRegs.DEC) | (1 << StateRegs.TB))).bool()):
+ comb += self.pause_dec_tb.eq(1)
with m.If(~core_busy_o): # instruction done!
comb += exec_pc_o_valid.eq(1)
with m.If(exec_pc_i_ready):
projects / soc.git / blobdiff