src/soc/fu/ldst/loadstore.py

   1 from nmigen import (Elaboratable, Module, Signal, Shape, unsigned, Cat, Mux,
   2                     Record, Memory,
   3                     Const)
   4 from nmutil.util import rising_edge
   5 from enum import Enum, unique
   6
   7 from soc.experiment.dcache import DCache
   8 from soc.experiment.pimem import PortInterfaceBase
   9 from soc.experiment.mem_types import LoadStore1ToMMUType
  10 from soc.experiment.mem_types import MMUToLoadStore1Type
  11
  12 from soc.minerva.wishbone import make_wb_layout
  13 from soc.bus.sram import SRAM
  14
  15
  16 @unique
  17 class State(Enum):
  18     IDLE = 0       # ready for instruction
  19     SECOND_REQ = 1 # send 2nd request of unaligned xfer
  20     ACK_WAIT = 2   # waiting for ack from dcache
  21     MMU_LOOKUP = 3 # waiting for MMU to look up translation
  22     TLBIE_WAIT = 4 # waiting for MMU to finish doing a tlbie
  23     FINISH_LFS = 5 # write back converted SP data for lfs*
  24     COMPLETE = 6   # extra cycle to complete an operation
  25
  26
  27 # glue logic for microwatt mmu and dcache
  28 class LoadStore1(PortInterfaceBase):
  29     def __init__(self, pspec):
  30         self.pspec = pspec
  31         self.disable_cache = (hasattr(pspec, "disable_cache") and
  32                               pspec.disable_cache == True)
  33         regwid = pspec.reg_wid
  34         addrwid = pspec.addr_wid
  35
  36         super().__init__(regwid, addrwid)
  37         self.dcache = DCache()
  38         self.d_in  = self.dcache.d_in
  39         self.d_out = self.dcache.d_out
  40         self.l_in  = LoadStore1ToMMUType()
  41         self.l_out = MMUToLoadStore1Type()
  42         # TODO microwatt
  43         self.mmureq = Signal()
  44         self.derror = Signal()
  45
  46         # TODO, convert dcache wb_in/wb_out to "standard" nmigen Wishbone bus
  47         self.dbus = Record(make_wb_layout(pspec))
  48
  49         # for creating a single clock blip to DCache
  50         self.d_valid = Signal()
  51         self.d_w_valid = Signal()
  52         self.d_validblip = Signal()
  53
  54         # DSISR and DAR cached values.  note that the MMU FSM is where
  55         # these are accessed by OP_MTSPR/OP_MFSPR, on behalf of LoadStore1.
  56         # by contrast microwatt has the spr set/get done *in* loadstore1.vhdl
  57         self.dsisr = Signal(64)
  58         self.dar = Signal(64)
  59
  60         # state info for LD/ST
  61         self.done          = Signal()
  62         # latch most of the input request
  63         self.load          = Signal()
  64         self.tlbie         = Signal()
  65         self.dcbz          = Signal()
  66         self.addr          = Signal(64)
  67         self.store_data    = Signal(64)
  68         self.load_data     = Signal(64)
  69         self.byte_sel      = Signal(8)
  70         self.update        = Signal()
  71         #self.xerc         : xer_common_t;
  72         #self.reserve       = Signal()
  73         #self.atomic        = Signal()
  74         #self.atomic_last   = Signal()
  75         #self.rc            = Signal()
  76         self.nc            = Signal()              # non-cacheable access
  77         self.virt_mode     = Signal()
  78         self.priv_mode     = Signal()
  79         self.state        = Signal(State)
  80         self.instr_fault   = Signal()
  81         self.align_intr    = Signal()
  82         self.busy          = Signal()
  83         self.wait_dcache   = Signal()
  84         self.wait_mmu      = Signal()
  85         #self.mode_32bit    = Signal()
  86         self.wr_sel        = Signal(2)
  87         self.interrupt     = Signal()
  88         #self.intr_vec     : integer range 0 to 16#fff#;
  89         #self.nia           = Signal(64)
  90         #self.srr1          = Signal(16)
  91
  92     def set_wr_addr(self, m, addr, mask):
  93         m.d.comb += self.load.eq(0) # store operation
  94
  95         m.d.comb += self.d_in.load.eq(0)
  96         m.d.comb += self.byte_sel.eq(mask)
  97         m.d.comb += self.addr.eq(addr)
  98         # option to disable the cache entirely for write
  99         if self.disable_cache:
 100             m.d.comb += self.nc.eq(1)
 101         return None
 102
 103     def set_rd_addr(self, m, addr, mask):
 104         m.d.comb += self.d_valid.eq(1)
 105         m.d.comb += self.d_in.valid.eq(self.d_validblip)
 106         m.d.comb += self.load.eq(1) # load operation
 107         m.d.comb += self.d_in.load.eq(1)
 108         m.d.comb += self.byte_sel.eq(mask)
 109         m.d.comb += self.addr.eq(addr)
 110         # BAD HACK! disable cacheing on LD when address is 0xCxxx_xxxx
 111         # this is for peripherals. same thing done in Microwatt loadstore1.vhdl
 112         with m.If(addr[28:] == Const(0xc, 4)):
 113             m.d.comb += self.nc.eq(1)
 114         # option to disable the cache entirely for read
 115         if self.disable_cache:
 116             m.d.comb += self.nc.eq(1)
 117         return None #FIXME return value
 118
 119     def set_wr_data(self, m, data, wen):
 120         # do the "blip" on write data
 121         m.d.comb += self.d_valid.eq(1)
 122         m.d.comb += self.d_in.valid.eq(self.d_validblip)
 123         # put data into comb which is picked up in main elaborate()
 124         m.d.comb += self.d_w_valid.eq(1)
 125         m.d.comb += self.store_data.eq(data)
 126         #m.d.sync += self.d_in.byte_sel.eq(wen) # this might not be needed
 127         st_ok = self.done # TODO indicates write data is valid
 128         #st_ok = Const(1, 1)
 129         return st_ok
 130
 131     def get_rd_data(self, m):
 132         ld_ok = self.done     # indicates read data is valid
 133         data = self.load_data # actual read data
 134         return data, ld_ok
 135
 136     """
 137     if d_in.error = '1' then
 138                 if d_in.cache_paradox = '1' then
 139                     -- signal an interrupt straight away
 140                     exception := '1';
 141                     dsisr(63 - 38) := not r2.req.load;
 142                     -- XXX there is no architected bit for this
 143                     -- (probably should be a machine check in fact)
 144                     dsisr(63 - 35) := d_in.cache_paradox;
 145                 else
 146                     -- Look up the translation for TLB miss
 147                     -- and also for permission error and RC error
 148                     -- in case the PTE has been updated.
 149                     mmureq := '1';
 150                     v.state := MMU_LOOKUP;
 151                     v.stage1_en := '0';
 152                 end if;
 153             end if;
 154     """
 155
 156     def elaborate(self, platform):
 157         m = super().elaborate(platform)
 158         comb, sync = m.d.comb, m.d.sync
 159
 160         # create dcache module
 161         m.submodules.dcache = dcache = self.dcache
 162
 163         # temp vars
 164         d_in, d_out, l_out, dbus = self.d_in, self.d_out, self.l_out, self.dbus
 165
 166         with m.If(d_out.error):
 167             with m.If(d_out.cache_paradox):
 168                 sync += self.derror.eq(1)
 169                 sync += self.dsisr[63 - 38].eq(~self.load)
 170                 # XXX there is no architected bit for this
 171                 # (probably should be a machine check in fact)
 172                 sync += self.dsisr[63 - 35].eq(d_out.cache_paradox)
 173
 174             with m.Else():
 175                 # Look up the translation for TLB miss
 176                 # and also for permission error and RC error
 177                 # in case the PTE has been updated.
 178                 sync += self.mmureq.eq(1)
 179                 sync += self.state.eq(State.MMU_LOOKUP)
 180
 181         exc = self.pi.exc_o
 182
 183         # happened, alignment, instr_fault, invalid,
 184         comb += exc.happened.eq(d_out.error | l_out.err)
 185         comb += exc.invalid.eq(l_out.invalid)
 186
 187         # badtree, perm_error, rc_error, segment_fault
 188         comb += exc.badtree.eq(l_out.badtree)
 189         comb += exc.perm_error.eq(l_out.perm_error)
 190         comb += exc.rc_error.eq(l_out.rc_error)
 191         comb += exc.segment_fault.eq(l_out.segerr)
 192
 193         # TODO some exceptions set SPRs
 194
 195         # TODO, connect dcache wb_in/wb_out to "standard" nmigen Wishbone bus
 196         comb += dbus.adr.eq(dcache.wb_out.adr)
 197         comb += dbus.dat_w.eq(dcache.wb_out.dat)
 198         comb += dbus.sel.eq(dcache.wb_out.sel)
 199         comb += dbus.cyc.eq(dcache.wb_out.cyc)
 200         comb += dbus.stb.eq(dcache.wb_out.stb)
 201         comb += dbus.we.eq(dcache.wb_out.we)
 202
 203         comb += dcache.wb_in.dat.eq(dbus.dat_r)
 204         comb += dcache.wb_in.ack.eq(dbus.ack)
 205         if hasattr(dbus, "stall"):
 206             comb += dcache.wb_in.stall.eq(dbus.stall)
 207
 208         # create a blip (single pulse) on valid read/write request
 209         m.d.comb += self.d_validblip.eq(rising_edge(m, self.d_valid))
 210
 211         # write out d data only when flag set
 212         with m.If(self.d_w_valid):
 213             m.d.sync += self.d_in.data.eq(self.store_data)
 214         with m.Else():
 215             m.d.sync += self.d_in.data.eq(0)
 216
 217         m.d.comb += self.d_in.load.eq(self.load)
 218         m.d.comb += self.d_in.byte_sel.eq(self.byte_sel)
 219         m.d.comb += self.d_in.addr.eq(self.addr)
 220         m.d.comb += self.d_in.nc.eq(self.nc)
 221         m.d.comb += self.done.eq(self.d_out.valid)
 222         m.d.comb += self.load_data.eq(d_out.data)
 223
 224         return m
 225
 226     def ports(self):
 227         yield from super().ports()
 228         # TODO: memory ports
 229
 230
 231 class TestSRAMLoadStore1(LoadStore1):
 232     def __init__(self, pspec):
 233         super().__init__(pspec)
 234         pspec = self.pspec
 235         # small 32-entry Memory
 236         if (hasattr(pspec, "dmem_test_depth") and
 237                 isinstance(pspec.dmem_test_depth, int)):
 238             depth = pspec.dmem_test_depth
 239         else:
 240             depth = 32
 241         print("TestSRAMBareLoadStoreUnit depth", depth)
 242
 243         self.mem = Memory(width=pspec.reg_wid, depth=depth)
 244
 245     def elaborate(self, platform):
 246         m = super().elaborate(platform)
 247         comb = m.d.comb
 248         m.submodules.sram = sram = SRAM(memory=self.mem, granularity=8,
 249                                         features={'cti', 'bte', 'err'})
 250         dbus = self.dbus
 251
 252         # directly connect the wishbone bus of LoadStoreUnitInterface to SRAM
 253         # note: SRAM is a target (slave), dbus is initiator (master)
 254         fanouts = ['dat_w', 'sel', 'cyc', 'stb', 'we', 'cti', 'bte']
 255         fanins = ['dat_r', 'ack', 'err']
 256         for fanout in fanouts:
 257             print("fanout", fanout, getattr(sram.bus, fanout).shape(),
 258                   getattr(dbus, fanout).shape())
 259             comb += getattr(sram.bus, fanout).eq(getattr(dbus, fanout))
 260             comb += getattr(sram.bus, fanout).eq(getattr(dbus, fanout))
 261         for fanin in fanins:
 262             comb += getattr(dbus, fanin).eq(getattr(sram.bus, fanin))
 263         # connect address
 264         comb += sram.bus.adr.eq(dbus.adr)
 265
 266         return m
 267