+"""
+Based on microwatt mmu.vhdl
+
+* https://bugs.libre-soc.org/show_bug.cgi?id=491
+* https://bugs.libre-soc.org/show_bug.cgi?id=450
+"""
+
from nmigen import Elaboratable, Module, Signal, Shape, unsigned, Cat, Mux
+from nmigen import Record, Memory
+from nmigen import Const
from soc.fu.mmu.pipe_data import MMUInputData, MMUOutputData, MMUPipeSpec
from nmutil.singlepipe import ControlBase
+from nmutil.util import rising_edge
+
+from soc.experiment.mmu import MMU
+
+from openpower.consts import MSR
+from openpower.decoder.power_fields import DecodeFields
+from openpower.decoder.power_fieldsn import SignalBitRange
+from openpower.decoder.power_decoder2 import decode_spr_num
+from openpower.decoder.power_enums import MicrOp
+
+from soc.experiment.mem_types import LoadStore1ToMMUType
+from soc.experiment.mem_types import MMUToLoadStore1Type
+
+from soc.fu.ldst.loadstore import LoadStore1, TestSRAMLoadStore1
+from nmutil.util import Display
class FSMMMUStage(ControlBase):
+ """FSM MMU
+
+ FSM-based MMU: must call set_ldst_interface and pass in an instance
+ of a LoadStore1. this to comply with the ConfigMemoryPortInterface API
+
+ this Function Unit is extremely unusual in that it actually stores a
+ "thing" rather than "processes inputs and produces outputs". hence
+ why it has to be a FSM. linking up LD/ST however is going to have
+ to be done back in Issuer (or Core). sorted: call set_ldst_interface
+ """
def __init__(self, pspec):
super().__init__()
self.pspec = pspec
+
# set up p/n data
- self.p.data_i = MMUInputData(pspec)
- self.n.data_o = MMUOutputData(pspec)
+ self.p.i_data = MMUInputData(pspec)
+ self.n.o_data = MMUOutputData(pspec)
+ self.exc_o = self.n.o_data.exception # AllFunctionUnits needs this
+
+ self.mmu = MMU()
+
+ # debugging output for gtkw
+ self.debug0 = Signal(4)
+ self.illegal = Signal()
+
+ # for SPR field number access
+ i = self.p.i_data
+ self.fields = DecodeFields(SignalBitRange, [i.ctx.op.insn])
+ self.fields.create_specs()
+
+ def set_ldst_interface(self, ldst):
+ """must be called back in Core, after FUs have been set up.
+ one of those will be the MMU (us!) but the LoadStore1 instance
+ must be set up in ConfigMemoryPortInterface. sigh.
+ """
+ # incoming PortInterface
+ self.ldst = ldst
+ self.dcache = self.ldst.dcache
+ self.icache = self.ldst.icache
+ self.pi = self.ldst.pi
def elaborate(self, platform):
+ assert hasattr(self, "dcache"), "remember to call set_ldst_interface"
m = super().elaborate(platform)
- data_i = self.p.data_i
- data_o = self.n.data_o
+ comb, sync = m.d.comb, m.d.sync
+ dcache, icache = self.dcache, self.icache
+ ldst = self.ldst # managed externally: do not add here
+
+ # link mmu, dcache and icache together
+ m.submodules.mmu = mmu = self.mmu
+ m.d.comb += dcache.m_in.eq(mmu.d_out) # MMUToDCacheType
+ m.d.comb += mmu.d_in.eq(dcache.m_out) # DCacheToMMUType
+ m.d.comb += icache.m_in.eq(mmu.i_out) # MMUToICacheType
+
+ l_in, l_out = mmu.l_in, mmu.l_out
+ d_in, d_out = dcache.d_in, dcache.d_out
+
+ # link ldst and MMU together
+ comb += l_in.eq(ldst.m_out)
+ comb += ldst.m_in.eq(l_out)
+
+ i_data, o_data = self.p.i_data, self.n.o_data
+ op = i_data.ctx.op
+ cia_i = op.cia
+ msr_i = op.msr
+ a_i, b_i, spr1_i = i_data.ra, i_data.rb, i_data.spr1
+ o, exc_o, spr1_o = o_data.o, o_data.exception, o_data.spr1
- m.d.comb += self.n.valid_o.eq(~self.empty & self.div_state_next.o.done)
- m.d.comb += self.p.ready_o.eq(self.empty)
- m.d.sync += self.saved_state.eq(self.div_state_next.o)
+ # busy/done signals
+ busy = Signal(name="mmu_fsm_busy")
+ done = Signal(name="mmu_fsm_done")
+ m.d.comb += self.n.o_valid.eq(busy & done)
+ m.d.comb += self.p.o_ready.eq(~busy)
- with m.If(self.empty):
- with m.If(self.p.valid_i):
- m.d.sync += self.empty.eq(0)
- m.d.sync += self.saved_input_data.eq(data_i)
+ # take copy of X-Form SPR field
+ x_fields = self.fields.FormXFX
+ spr = Signal(len(x_fields.SPR))
+ comb += spr.eq(decode_spr_num(x_fields.SPR))
+
+ # ok so we have to "pulse" the MMU (or dcache) rather than
+ # hold the valid hi permanently. guess what this does...
+ valid = Signal()
+ blip = Signal()
+ m.d.comb += blip.eq(rising_edge(m, valid))
+
+ with m.If(~busy):
+ with m.If(self.p.i_valid):
+ sync += busy.eq(1)
with m.Else():
- m.d.comb += [
- with m.If(self.n.ready_i & self.n.valid_o):
- m.d.sync += self.empty.eq(1)
+
+ # based on the Micro-Op, we work out which of MMU or DCache
+ # should "action" the operation. one of MMU or DCache gets
+ # enabled ("valid") and we twiddle our thumbs until it
+ # responds ("done").
+
+ # WIP: properly implement MicrOp.OP_MTSPR and MicrOp.OP_MFSPR
+
+ with m.Switch(op.insn_type):
+
+ ##########
+ # OP_MTSPR
+ ##########
+
+ with m.Case(MicrOp.OP_MTSPR):
+ comb += Display("MMUTEST: OP_MTSPR: spr=%i", spr)
+ # despite redirection this FU **MUST** behave exactly
+ # like the SPR FU. this **INCLUDES** updating the SPR
+ # regfile because the CSV file entry for OP_MTSPR
+ # categorically defines and requires the expectation
+ # that the CompUnit **WILL** write to the regfile.
+ comb += spr1_o.data.eq(a_i)
+ comb += spr1_o.ok.eq(1)
+ # subset SPR: first check a few bits
+ # XXX NOTE this must now cover **FOUR** values: this
+ # test might not be adequate. DSISR, DAR, PGTBL and PID
+ # must ALL be covered here.
+ with m.If(~spr[9] & ~spr[5]):
+ comb += self.debug0.eq(3)
+ #if matched update local cached value
+ #commented out because there is a driver conflict
+ comb += ldst.sprval_in.eq(a_i)
+ comb += ldst.mmu_set_spr.eq(1)
+ with m.If(spr[0]):
+ comb += ldst.mmu_set_dar.eq(1)
+ with m.Else():
+ comb += ldst.mmu_set_dsisr.eq(1)
+ comb += done.eq(1)
+ # pass it over to the MMU instead
+ with m.Else():
+ # PGTBL and PID
+ comb += self.debug0.eq(4)
+ # blip the MMU and wait for it to complete
+ comb += valid.eq(1) # start "pulse"
+ comb += l_in.valid.eq(blip) # start
+ comb += l_in.mtspr.eq(1) # mtspr mode
+ comb += l_in.sprn.eq(spr) # which SPR
+ comb += l_in.rs.eq(a_i) # incoming operand (RS)
+ comb += done.eq(1) # FIXME l_out.done
+
+ ##########
+ # OP_MFSPR
+ ##########
+
+ with m.Case(MicrOp.OP_MFSPR):
+ comb += Display("MMUTEST: OP_MFSPR: spr=%i returns=%i",
+ spr, spr1_i)
+ # partial SPR number decoding perfectly fine
+ with m.If(spr[9] | spr[5]):
+ # identified as an MMU OP_MFSPR, contact the MMU.
+ # interestingly, the read is combinatorial: no need
+ # to set "valid", just set the SPR number
+ comb += l_in.sprn.eq(spr) # which SPR
+ comb += o.data.eq(l_out.sprval)
+ with m.Else():
+ # identified as DSISR or DAR. again: read the SPR
+ # directly, combinatorial access
+ with m.If(spr[0]):
+ comb += o.data.eq(ldst.dar)
+ with m.Else():
+ comb += o.data.eq(ldst.dsisr)
+
+ comb += o.ok.eq(1)
+ comb += done.eq(1)
+
+ ##########
+ # OP_TLBIE
+ ##########
+
+ with m.Case(MicrOp.OP_TLBIE):
+ comb += Display("MMUTEST: OP_TLBIE: insn_bits=%i", spr)
+ # pass TLBIE request to MMU (spec: v3.0B p1034)
+ # note that the spr is *not* an actual spr number, it's
+ # just that those bits happen to match with field bits
+ # RIC, PRS, R
+ comb += Display("TLBIE: %i %i", spr, l_out.done)
+ comb += valid.eq(1) # start "pulse"
+ comb += l_in.valid.eq(blip) # start
+ comb += l_in.tlbie.eq(1) # mtspr mode
+ comb += l_in.sprn.eq(spr) # use sprn to send insn bits
+ comb += l_in.addr.eq(b_i) # incoming operand (RB)
+ comb += done.eq(l_out.done) # zzzz
+ comb += self.debug0.eq(2)
+
+ ##########
+ # OP_FETCH_FAILED
+ ##########
+
+ with m.Case(MicrOp.OP_FETCH_FAILED):
+ comb += Display("MMUTEST: OP_FETCH_FAILED: @%x", cia_i)
+ # trigger an instruction fetch failed MMU event.
+ # PowerDecoder2 drops svstate.pc into NIA for us
+ # really, this should be direct communication with the
+ # MMU, rather than going through LoadStore1. but, doing
+ # so allows for the opportunity to prevent LoadStore1
+ # from accepting any other LD/ST requests.
+ comb += valid.eq(1) # start "pulse"
+ comb += ldst.instr_fault.eq(blip)
+ comb += ldst.priv_mode.eq(~msr_i[MSR.PR])
+ comb += ldst.maddr.eq(cia_i)
+ # XXX should not access this!
+ comb += done.eq(ldst.done)
+ comb += self.debug0.eq(3)
+ # LDST unit contains exception data, which (messily)
+ # is copied over, here. not ideal but it will do for now
+ comb += exc_o.eq(ldst.pi.exc_o)
+
+ ############
+ # OP_ILLEGAL
+ ############
+
+ with m.Case(MicrOp.OP_ILLEGAL):
+ comb += self.illegal.eq(1)
+
+ with m.If(self.n.i_ready & self.n.o_valid):
+ sync += busy.eq(0)
return m
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