c4m/nmigen/jtag/tap.py

   1 #!/usr/bin/env python3
   2 import os, textwrap
   3 from enum import Enum, auto
   4
   5 from nmigen import (Elaboratable, Signal, Module, ClockDomain, Cat, Record,
   6                     Const, Mux)
   7 from nmigen.hdl.rec import Direction, Layout
   8 from nmigen.tracer import get_var_name
   9
  10 from nmigen_soc.wishbone import Interface as WishboneInterface
  11
  12 from .bus import Interface, DMIInterface
  13
  14 __all__ = [
  15     "TAP", "ShiftReg", "IOType", "IOConn",
  16 ]
  17
  18
  19 class _FSM(Elaboratable):
  20     """TAP subblock for the FSM"""
  21     def __init__(self, *, bus):
  22         self.isir = Signal()
  23         self.isdr = Signal()
  24         self.capture = Signal()
  25         self.shift = Signal()
  26         self.update = Signal()
  27
  28         # JTAG uses both edges of the incoming clock (TCK). set them up here
  29         self.posjtag = ClockDomain("posjtag", local=True)
  30         self.negjtag = ClockDomain("negjtag", local=True, clk_edge="neg")
  31
  32         self._bus = bus
  33
  34     def elaborate(self, platform):
  35         m = Module()
  36
  37         rst = Signal()
  38         m.d.comb += [
  39             self.posjtag.clk.eq(self._bus.tck),
  40             self.posjtag.rst.eq(rst),
  41             self.negjtag.clk.eq(self._bus.tck),
  42             self.negjtag.rst.eq(rst),
  43         ]
  44
  45         # Make local clock domain optionally using trst of JTAG bus as reset
  46         if hasattr(self._bus, "trst"):
  47             m.domains.local = local = ClockDomain(local=True)
  48             m.d.comb += local.rst.eq(self._bus.trst)
  49         else:
  50             m.domains.local = local = ClockDomain(local=True, reset_less=True)
  51         m.d.comb += local.clk.eq(self._bus.tck)
  52
  53         with m.FSM(domain="local") as fsm:
  54             with m.State("TestLogicReset"):
  55                 # Be sure to reset isir, isdr
  56                 m.d.local += [
  57                     self.isir.eq(0),
  58                     self.isdr.eq(0),
  59                 ]
  60                 with m.If(self._bus.tms == 0):
  61                     m.next = "RunTestIdle"
  62             with m.State("RunTestIdle"):
  63                 # Be sure to reset isir, isdr
  64                 m.d.local += [
  65                     self.isir.eq(0),
  66                     self.isdr.eq(0),
  67                 ]
  68                 with m.If(self._bus.tms == 1):
  69                     m.next = "SelectDRScan"
  70             with m.State("SelectDRScan"):
  71                 with m.If(self._bus.tms == 0):
  72                     m.d.local += self.isdr.eq(1)
  73                     m.next = "CaptureState"
  74                 with m.Else():
  75                     m.next = "SelectIRScan"
  76             with m.State("SelectIRScan"):
  77                 with m.If(self._bus.tms == 0):
  78                     m.d.local += self.isir.eq(1)
  79                     m.next = "CaptureState"
  80                 with m.Else():
  81                     m.next = "TestLogicReset"
  82             with m.State("CaptureState"):
  83                 with m.If(self._bus.tms == 0):
  84                     m.next = "ShiftState"
  85                 with m.Else():
  86                     m.next = "Exit1"
  87             with m.State("ShiftState"):
  88                 with m.If(self._bus.tms == 1):
  89                     m.next = "Exit1"
  90             with m.State("Exit1"):
  91                 with m.If(self._bus.tms == 0):
  92                     m.next = "Pause"
  93                 with m.Else():
  94                     m.next = "UpdateState"
  95             with m.State("Pause"):
  96                 with m.If(self._bus.tms == 1):
  97                     m.next = "Exit2"
  98             with m.State("Exit2"):
  99                 with m.If(self._bus.tms == 0):
 100                     m.next = "ShiftState"
 101                 with m.Else():
 102                     m.next = "UpdateState"
 103             with m.State("UpdateState"):
 104                 m.d.local += [
 105                     self.isir.eq(0),
 106                     self.isdr.eq(0),
 107                 ]
 108                 with m.If(self._bus.tms == 0):
 109                     m.next = "RunTestIdle"
 110                 with m.Else():
 111                     m.next = "SelectDRScan"
 112
 113             m.d.comb += [
 114                 rst.eq(fsm.ongoing("TestLogicReset")),
 115                 self.capture.eq(fsm.ongoing("CaptureState")),
 116                 self.shift.eq(fsm.ongoing("ShiftState")),
 117                 self.update.eq(fsm.ongoing("UpdateState")),
 118             ]
 119
 120         return m
 121
 122
 123 class _IRBlock(Elaboratable):
 124     """TAP subblock for handling the IR shift register"""
 125     def __init__(self, *, ir_width, cmd_idcode,
 126                  tdi, capture, shift, update,
 127                  name):
 128         self.name = name
 129         self.ir = Signal(ir_width, reset=cmd_idcode)
 130         self.tdo = Signal()
 131
 132         self._tdi = tdi
 133         self._capture = capture
 134         self._shift = shift
 135         self._update = update
 136
 137     def elaborate(self, platform):
 138         m = Module()
 139
 140         shift_ir = Signal(len(self.ir), reset_less=True)
 141
 142         m.d.comb += self.tdo.eq(self.ir[0])
 143         with m.If(self._capture):
 144             m.d.posjtag += shift_ir.eq(self.ir)
 145         with m.Elif(self._shift):
 146             m.d.posjtag += shift_ir.eq(Cat(shift_ir[1:], self._tdi))
 147         with m.Elif(self._update):
 148             # For ir we only update it on the rising edge of clock
 149             # to avoid that we already have the new ir value when still in
 150             # Update state
 151             m.d.posjtag += self.ir.eq(shift_ir)
 152
 153         return m
 154
 155
 156 class IOType(Enum):
 157     In = auto()
 158     Out = auto()
 159     TriOut = auto()
 160     InTriOut = auto()
 161
 162
 163 class IOConn(Record):
 164     lengths = {
 165         IOType.In: 1,
 166         IOType.Out: 1,
 167         IOType.TriOut: 2,
 168         IOType.InTriOut: 3,
 169     }
 170
 171     """TAP subblock representing the interface for an JTAG IO cell.
 172     It contains signal to connect to the core and to the pad
 173
 174     This object is normally only allocated and returned from ``TAP.add_io``
 175     It is a Record subclass.
 176
 177     Attributes
 178     ----------
 179     core: subrecord with signals for the core
 180         i: Signal(1), present only for IOType.In and IOType.InTriOut.
 181             Signal input to core with pad input value.
 182         o: Signal(1), present only for IOType.Out, IOType.TriOut and
 183             IOType.InTriOut.
 184             Signal output from core with the pad output value.
 185         oe: Signal(1), present only for IOType.TriOut and IOType.InTriOut.
 186             Signal output from core with the pad output enable value.
 187     pad: subrecord with for the pad
 188         i: Signal(1), present only for IOType.In and IOType.InTriOut
 189             Output from pad with pad input value for core.
 190         o: Signal(1), present only for IOType.Out, IOType.TriOut and
 191             IOType.InTriOut.
 192             Input to pad with pad output value.
 193         oe: Signal(1), present only for IOType.TriOut and IOType.InTriOut.
 194             Input to pad with pad output enable value.
 195     """
 196     @staticmethod
 197     def layout(iotype):
 198         sigs = []
 199         if iotype in (IOType.In, IOType.InTriOut):
 200             sigs.append(("i", 1))
 201         if iotype in (IOType.Out, IOType.TriOut, IOType.InTriOut):
 202             sigs.append(("o", 1))
 203         if iotype in (IOType.TriOut, IOType.InTriOut):
 204             sigs.append(("oe", 1))
 205
 206         return Layout((("core", sigs), ("pad", sigs)))
 207
 208     def __init__(self, *, iotype, name=None, src_loc_at=0):
 209         super().__init__(self.__class__.layout(iotype), name=name,
 210                          src_loc_at=src_loc_at+1)
 211
 212         self._iotype = iotype
 213
 214
 215 class _IDBypassBlock(Elaboratable):
 216     """TAP subblock for the ID shift register"""
 217     def __init__(self, *, manufacturer_id, part_number, version,
 218                  tdi, capture, shift, update, bypass,
 219                  name):
 220         self.name = name
 221         if (not isinstance(manufacturer_id, Const) and
 222             len(manufacturer_id) != 11):
 223             raise ValueError("manufacturer_id has to be Const of length 11")
 224         if not isinstance(part_number, Const) and len(manufacturer_id) != 16:
 225             raise ValueError("part_number has to be Const of length 16")
 226         if not isinstance(version, Const) and len(version) != 4:
 227             raise ValueError("version has to be Const of length 4")
 228         self._id = Cat(Const(1,1), manufacturer_id, part_number, version)
 229
 230         self.tdo = Signal(name=name+"_tdo")
 231
 232         self._tdi = tdi
 233         self._capture = capture
 234         self._shift = shift
 235         self._update = update
 236         self._bypass = bypass
 237
 238     def elaborate(self, platform):
 239         m = Module()
 240
 241         sr = Signal(32, reset_less=True, name=self.name+"_sr")
 242
 243         # Local signals for the module
 244         _tdi = Signal()
 245         _capture = Signal()
 246         _shift = Signal()
 247         _update = Signal()
 248         _bypass = Signal()
 249
 250         m.d.comb += [
 251             _tdi.eq(self._tdi),
 252             _capture.eq(self._capture),
 253             _shift.eq(self._shift),
 254             _update.eq(self._update),
 255             _bypass.eq(self._bypass),
 256             self.tdo.eq(sr[0]),
 257         ]
 258
 259         with m.If(_capture):
 260             m.d.posjtag += sr.eq(self._id)
 261         with m.Elif(_shift):
 262             with m.If(_bypass):
 263                 m.d.posjtag += sr[0].eq(_tdi)
 264             with m.Else():
 265                 m.d.posjtag += sr.eq(Cat(sr[1:], _tdi))
 266
 267         return m
 268
 269
 270 class ShiftReg(Record):
 271     """Object with interface for extra shift registers on a TAP.
 272
 273     Parameters
 274     ----------
 275     sr_length : int
 276     cmds : int, default=1
 277         The number of corresponding JTAG instructions
 278
 279     This object is normally only allocated and returned from ``TAP.add_shiftreg``
 280     It is a Record subclass.
 281
 282     Attributes
 283     ----------
 284     i: length=sr_length, FANIN
 285         The input data sampled during capture state of the TAP
 286     ie: length=cmds, FANOUT
 287         Indicates that data is to be sampled by the JTAG TAP and
 288         should be held stable. The bit indicates the corresponding
 289         instruction for which data is asked.
 290         This signal is kept high for a whole JTAG TAP clock cycle
 291         and may thus be kept higher for more than one clock cycle
 292         on the domain where ShiftReg is used.
 293         The JTAG protocol does not allow insertion of wait states
 294         so data need to be provided before ie goes down. The speed
 295         of the response will determine the max. frequency for the
 296         JTAG interface.
 297     o: length=sr_length, FANOUT
 298         The value of the shift register.
 299     oe: length=cmds, FANOUT
 300         Indicates that output is stable and can be sampled downstream because
 301         JTAG TAP is in the Update state. The bit indicates the corresponding
 302         instruction. The bit is only kept high for one clock cycle.
 303     """
 304     def __init__(self, *, sr_length, cmds=1, name=None, src_loc_at=0):
 305         layout = [
 306             ("i", sr_length, Direction.FANIN),
 307             ("ie", cmds, Direction.FANOUT),
 308             ("o", sr_length, Direction.FANOUT),
 309             ("oe", cmds, Direction.FANOUT),
 310         ]
 311         super().__init__(layout, name=name, src_loc_at=src_loc_at+1)
 312
 313
 314 class TAP(Elaboratable):
 315     #TODO: Document TAP
 316     def __init__(self, *, with_reset=False, ir_width=None,
 317                  manufacturer_id=Const(0b10001111111, 11),
 318                  part_number=Const(1, 16),
 319                  version=Const(0, 4),
 320                  name=None, src_loc_at=0):
 321         assert((ir_width is None) or (isinstance(ir_width, int) and
 322                ir_width >= 2))
 323         assert(len(version) == 4)
 324
 325         if name is None:
 326             name = get_var_name(depth=src_loc_at+2, default="TAP")
 327         self.name = name
 328         self.bus = Interface(with_reset=with_reset, name=self.name+"_bus",
 329                              src_loc_at=src_loc_at+1)
 330
 331         ##
 332
 333         self._ir_width = ir_width
 334         self._manufacturer_id = manufacturer_id
 335         self._part_number = part_number
 336         self._version = version
 337
 338         self._ircodes = [0, 1, 2] # Already taken codes, all ones added at end
 339
 340         self._ios = []
 341         self._srs = []
 342         self._wbs = []
 343         self._dmis = []
 344
 345     def elaborate(self, platform):
 346         m = Module()
 347
 348         # Determine ir_width if not fixed.
 349         ir_max = max(self._ircodes) + 1 # One extra code needed with all ones
 350         ir_width = len("{:b}".format(ir_max))
 351         if self._ir_width is not None:
 352             assert self._ir_width >= ir_width, "Specified JTAG IR width " \
 353                    "not big enough for allocated shiift registers"
 354             ir_width = self._ir_width
 355
 356         # TODO: Make commands numbers configurable
 357         cmd_extest = 0
 358         cmd_intest = 0
 359         cmd_idcode = 1
 360         cmd_sample = 2
 361         cmd_preload = 2
 362         cmd_bypass = 2**ir_width - 1 # All ones
 363
 364         m.submodules._fsm = fsm = _FSM(bus=self.bus)
 365         m.domains.posjtag = fsm.posjtag
 366         m.domains.negjtag = fsm.negjtag
 367
 368         # IR block
 369         select_ir = fsm.isir
 370         m.submodules._irblock = irblock = _IRBlock(
 371             ir_width=ir_width, cmd_idcode=cmd_idcode, tdi=self.bus.tdi,
 372             capture=(fsm.isir & fsm.capture),
 373             shift=(fsm.isir & fsm.shift),
 374             update=(fsm.isir & fsm.update),
 375             name=self.name+"_ir",
 376         )
 377         ir = irblock.ir
 378
 379         # ID block
 380         select_id = Signal()
 381         id_bypass = Signal()
 382         m.d.comb += select_id.eq(fsm.isdr &
 383                                  ((ir == cmd_idcode) | (ir == cmd_bypass)))
 384         m.d.comb += id_bypass.eq(ir == cmd_bypass)
 385         m.submodules._idblock = idblock = _IDBypassBlock(
 386             manufacturer_id=self._manufacturer_id,
 387             part_number=self._part_number,
 388             version=self._version, tdi=self.bus.tdi,
 389             capture=(select_id & fsm.capture),
 390             shift=(select_id & fsm.shift),
 391             update=(select_id & fsm.update),
 392             bypass=id_bypass,
 393             name=self.name+"_id",
 394         )
 395
 396         # IO (Boundary scan) block
 397         io_capture = Signal()
 398         io_shift = Signal()
 399         io_update = Signal()
 400         io_bd2io = Signal()
 401         io_bd2core = Signal()
 402         sample = (ir == cmd_extest) | (ir == cmd_sample)
 403         preload = (ir == cmd_preload)
 404         select_io = fsm.isdr & (sample | preload)
 405         m.d.comb += [
 406             io_capture.eq(sample & fsm.capture), # Don't capture if not sample
 407                                                  # (like for PRELOAD)
 408             io_shift.eq(select_io & fsm.shift),
 409             io_update.eq(select_io & fsm.update),
 410             io_bd2io.eq(ir == cmd_extest),
 411             io_bd2core.eq(ir == cmd_intest),
 412         ]
 413         io_tdo = self._elaborate_ios(
 414             m=m,
 415             capture=io_capture, shift=io_shift, update=io_update,
 416             bd2io=io_bd2io, bd2core=io_bd2core,
 417         )
 418
 419         # chain tdo: select as appropriate, to go into into shiftregs
 420         tdo = Signal(name=self.name+"_tdo")
 421         with m.If(select_ir):
 422             m.d.comb += tdo.eq(irblock.tdo)
 423         with m.Elif(select_id):
 424             m.d.comb += tdo.eq(idblock.tdo)
 425         with m.Elif(select_io):
 426             m.d.comb += tdo.eq(io_tdo)
 427
 428         # shiftregs block
 429         self._elaborate_shiftregs(
 430             m, capture=fsm.capture, shift=fsm.shift, update=fsm.update,
 431             ir=irblock.ir, tdo_jtag=tdo
 432         )
 433
 434         # wishbone
 435         self._elaborate_wishbones(m)
 436
 437         # DMI (Debug Memory Interface)
 438         self._elaborate_dmis(m)
 439
 440         return m
 441
 442     def add_dmi(self, *, ircodes, address_width=8, data_width=64,
 443                      domain="sync", name=None):
 444         """Add a DMI interface
 445
 446         * writing to DMIADDR will automatically trigger a DMI READ.
 447           the DMI address does not alter (so writes can be done at that addr)
 448         * reading from DMIREAD triggers a DMI READ at the current DMI addr
 449           the address is automatically incremented by 1 after.
 450         * writing to DMIWRITE triggers a DMI WRITE at the current DMI addr
 451           the address is automatically incremented by 1 after.
 452
 453         Parameters:
 454         -----------
 455         ircodes: sequence of three integer for the JTAG IR codes;
 456                  they represent resp. DMIADDR, DMIREAD and DMIWRITE.
 457                  First code has a shift register of length 'address_width',
 458                  the two other codes share a shift register of length
 459                 data_width.
 460
 461         address_width: width of the address
 462         data_width: width of the data
 463
 464         Returns:
 465         dmi: soc.debug.dmi.DMIInterface
 466             The DMI interface
 467         """
 468         if len(ircodes) != 3:
 469             raise ValueError("3 IR Codes have to be provided")
 470
 471         if name is None:
 472             name = "dmi" + str(len(self._dmis))
 473
 474         # add 2 shift registers: one for addr, one for data.
 475         sr_addr = self.add_shiftreg(ircode=ircodes[0], length=address_width,
 476                                      domain=domain, name=name+"_addrsr")
 477         sr_data = self.add_shiftreg(ircode=ircodes[1:], length=data_width,
 478                                     domain=domain, name=name+"_datasr")
 479
 480         dmi = DMIInterface(name=name)
 481         self._dmis.append((sr_addr, sr_data, dmi, domain))
 482
 483         return dmi
 484
 485     def _elaborate_dmis(self, m):
 486         for sr_addr, sr_data, dmi, domain in self._dmis:
 487             cd = m.d[domain]
 488             m.d.comb += sr_addr.i.eq(dmi.addr_i)
 489
 490             with m.FSM(domain=domain) as ds:
 491
 492                 # detect mode based on whether jtag addr or data read/written
 493                 with m.State("IDLE"):
 494                     with m.If(sr_addr.oe): # DMIADDR code
 495                         cd += dmi.addr_i.eq(sr_addr.o)
 496                         m.next = "READ"
 497                     with m.Elif(sr_data.oe[0]): # DMIREAD code
 498                         # If data is
 499                         cd += dmi.addr_i.eq(dmi.addr_i + 1)
 500                         m.next = "READ"
 501                     with m.Elif(sr_data.oe[1]): # DMIWRITE code
 502                         cd += dmi.din.eq(sr_data.o)
 503                         m.next = "WRRD"
 504
 505                 # req_i raises for 1 clock
 506                 with m.State("READ"):
 507                     m.next = "READACK"
 508
 509                 # wait for read ack
 510                 with m.State("READACK"):
 511                     with m.If(dmi.ack_o):
 512                         # Store read data in sr_data.i hold till next read
 513                         cd += sr_data.i.eq(dmi.dout)
 514                         m.next = "IDLE"
 515
 516                 # req_i raises for 1 clock
 517                 with m.State("WRRD"):
 518                     m.next = "WRRDACK"
 519
 520                 # wait for write ack
 521                 with m.State("WRRDACK"):
 522                     with m.If(dmi.ack_o):
 523                         cd += dmi.addr_i.eq(dmi.addr_i + 1)
 524                         m.next = "READ" # for readwrite
 525
 526                 # set DMI req and write-enable based on ongoing FSM states
 527                 m.d.comb += [
 528                     dmi.req_i.eq(ds.ongoing("READ") | ds.ongoing("WRRD")),
 529                     dmi.we_i.eq(ds.ongoing("WRRD")),
 530                 ]
 531
 532     def add_io(self, *, iotype, name=None, src_loc_at=0):
 533         """Add a io cell to the boundary scan chain
 534
 535         Parameters:
 536         - iotype: :class:`IOType` enum.
 537
 538         Returns:
 539         - :class:`IOConn`
 540         """
 541         if name is None:
 542             name = "ioconn" + str(len(self._ios))
 543
 544         ioconn = IOConn(iotype=iotype, name=name, src_loc_at=src_loc_at+1)
 545         self._ios.append(ioconn)
 546         return ioconn
 547
 548     def _elaborate_ios(self, *, m, capture, shift, update, bd2io, bd2core):
 549         length = sum(IOConn.lengths[conn._iotype] for conn in self._ios)
 550         if length == 0:
 551             return self.bus.tdi
 552
 553         io_sr = Signal(length)
 554         io_bd = Signal(length)
 555
 556         # Boundary scan "capture" mode.  makes I/O status available via SR
 557         with m.If(capture):
 558             iol = []
 559             idx = 0
 560             for conn in self._ios:
 561                 # in appropriate sequence: In/TriOut has pad.i,
 562                 # Out.InTriOut has everything, Out and TriOut have core.o
 563                 if conn._iotype in [IOType.In, IOType.InTriOut]:
 564                     iol.append(conn.pad.i)
 565                 if conn._iotype in [IOType.Out, IOType.InTriOut]:
 566                     iol.append(conn.core.o)
 567                 if conn._iotype in [IOType.TriOut, IOType.InTriOut]:
 568                     iol.append(conn.core.oe)
 569                 # length double-check
 570                 idx += IOConn.lengths[conn._iotype] # fails if wrong type
 571             assert idx == length, "Internal error"
 572             m.d.posjtag += io_sr.eq(Cat(*iol)) # assigns all io_sr in one hit
 573
 574         # "Shift" mode (sends out captured data on tdo, sets incoming from tdi)
 575         with m.Elif(shift):
 576             m.d.posjtag += io_sr.eq(Cat(self.bus.tdi, io_sr[:-1]))
 577
 578         # "Update" mode
 579         with m.Elif(update):
 580             m.d.negjtag += io_bd.eq(io_sr)
 581
 582         # sets up IO (pad<->core) or in testing mode depending on requested
 583         # mode, via Muxes controlled by bd2core and bd2io
 584         idx = 0
 585         for conn in self._ios:
 586             if conn._iotype == IOType.In:
 587                 m.d.comb += conn.core.i.eq(Mux(bd2core, io_bd[idx], conn.pad.i))
 588                 idx += 1
 589             elif conn._iotype == IOType.Out:
 590                 m.d.comb += conn.pad.o.eq(Mux(bd2io, io_bd[idx], conn.core.o))
 591                 idx += 1
 592             elif conn._iotype == IOType.TriOut:
 593                 m.d.comb += [
 594                     conn.pad.o.eq(Mux(bd2io, io_bd[idx], conn.core.o)),
 595                     conn.pad.oe.eq(Mux(bd2io, io_bd[idx+1], conn.core.oe)),
 596                 ]
 597                 idx += 2
 598             elif conn._iotype == IOType.InTriOut:
 599                 m.d.comb += [
 600                     conn.core.i.eq(Mux(bd2core, io_bd[idx], conn.pad.i)),
 601                     conn.pad.o.eq(Mux(bd2io, io_bd[idx+1], conn.core.o)),
 602                     conn.pad.oe.eq(Mux(bd2io, io_bd[idx+2], conn.core.oe)),
 603                 ]
 604                 idx += 3
 605             else:
 606                 raise("Internal error")
 607         assert idx == length, "Internal error"
 608
 609         return io_sr[-1]
 610
 611     def add_shiftreg(self, *, ircode, length, domain="sync", name=None,
 612                      src_loc_at=0):
 613         """Add a shift register to the JTAG interface
 614
 615         Parameters:
 616         - ircode: code(s) for the IR; int or sequence of ints. In the latter
 617           case this shiftreg is shared between different IR codes.
 618         - length: the length of the shift register
 619         - domain: the domain on which the signal will be used"""
 620
 621         try:
 622             ir_it = iter(ircode)
 623             ircodes = ircode
 624         except TypeError:
 625             ir_it = ircodes = (ircode,)
 626         for _ircode in ir_it:
 627             if not isinstance(_ircode, int) or _ircode <= 0:
 628                 raise ValueError("IR code '{}' is not an int "
 629                                  "greater than 0".format(_ircode))
 630             if _ircode in self._ircodes:
 631                 raise ValueError("IR code '{}' already taken".format(_ircode))
 632
 633         self._ircodes.extend(ircodes)
 634
 635         if name is None:
 636             name = "sr{}".format(len(self._srs))
 637         sr = ShiftReg(sr_length=length, cmds=len(ircodes), name=name,
 638                       src_loc_at=src_loc_at+1)
 639         self._srs.append((ircodes, domain, sr))
 640
 641         return sr
 642
 643     def _elaborate_shiftregs(self, m, capture, shift, update, ir, tdo_jtag):
 644         # tdos is tuple of (tdo, tdo_en) for each shiftreg
 645         tdos = []
 646         for ircodes, domain, sr in self._srs:
 647             reg = Signal(len(sr.o), name=sr.name+"_reg")
 648             m.d.comb += sr.o.eq(reg)
 649
 650             isir = Signal(len(ircodes), name=sr.name+"_isir")
 651             sr_capture = Signal(name=sr.name+"_capture")
 652             sr_shift = Signal(name=sr.name+"_shift")
 653             sr_update = Signal(name=sr.name+"_update")
 654             m.d.comb += [
 655                 isir.eq(Cat(ir == ircode for ircode in ircodes)),
 656                 sr_capture.eq((isir != 0) & capture),
 657                 sr_shift.eq((isir != 0) & shift),
 658                 sr_update.eq((isir != 0) & update),
 659             ]
 660
 661             # update signal is on the JTAG clockdomain, sr.oe is on `domain`
 662             # clockdomain latch update in `domain` clockdomain and see when
 663             # it has falling edge.
 664             # At that edge put isir in sr.oe for one `domain` clockdomain
 665             update_core = Signal(name=sr.name+"_update_core")
 666             update_core_prev = Signal(name=sr.name+"_update_core_prev")
 667             m.d[domain] += [
 668                 update_core.eq(sr_update), # This is CDC from JTAG domain
 669                                            # to given domain
 670                 update_core_prev.eq(update_core)
 671             ]
 672             with m.If(update_core_prev & ~update_core):
 673                 # Falling edge of update
 674                 m.d[domain] += sr.oe.eq(isir)
 675             with m.Else():
 676                 m.d[domain] += sr.oe.eq(0)
 677
 678             with m.If(sr_shift):
 679                 m.d.posjtag += reg.eq(Cat(reg[1:], self.bus.tdi))
 680             with m.If(sr_capture):
 681                 m.d.posjtag += reg.eq(sr.i)
 682
 683             # tdo = reg[0], tdo_en = shift
 684             tdos.append((reg[0], sr_shift))
 685
 686
 687         # Assign the right tdo to the bus tdo
 688         for i, (tdo, tdo_en) in enumerate(tdos):
 689             if i == 0:
 690                 with m.If(tdo_en):
 691                     m.d.comb += self.bus.tdo.eq(tdo)
 692             else:
 693                 with m.Elif(tdo_en):
 694                     m.d.comb += self.bus.tdo.eq(tdo)
 695
 696         if len(tdos) > 0:
 697             with m.Else():
 698                 m.d.comb += self.bus.tdo.eq(tdo_jtag)
 699         else:
 700             # Always connect tdo_jtag to
 701             m.d.comb += self.bus.tdo.eq(tdo_jtag)
 702
 703
 704     def add_wishbone(self, *, ircodes, address_width, data_width,
 705                      granularity=None, domain="sync", features=None,
 706                      name=None, src_loc_at=0):
 707         """Add a wishbone interface
 708
 709         In order to allow high JTAG clock speed, data will be cached.
 710         This means that if data is output the value of the next address
 711         will be read automatically.
 712
 713         Parameters:
 714         -----------
 715         ircodes: sequence of three integer for the JTAG IR codes;
 716           they represent resp. WBADDR, WBREAD and WBREADWRITE. First code
 717           has a shift register of length 'address_width', the two other codes
 718           share a shift register of length data_width.
 719         address_width: width of the address
 720         data_width: width of the data
 721         features: features required.  defaults to stall, lock, err, rty
 722
 723         Returns:
 724         wb: nmigen_soc.wishbone.bus.Interface
 725             The Wishbone interface, is pipelined and has stall field.
 726         """
 727         if len(ircodes) != 3:
 728             raise ValueError("3 IR Codes have to be provided")
 729
 730         if features is None:
 731             features={"stall", "lock", "err", "rty"}
 732         if name is None:
 733             name = "wb" + str(len(self._wbs))
 734         sr_addr = self.add_shiftreg(
 735             ircode=ircodes[0], length=address_width, domain=domain,
 736             name=name+"_addrsr"
 737         )
 738         sr_data = self.add_shiftreg(
 739             ircode=ircodes[1:], length=data_width, domain=domain,
 740             name=name+"_datasr"
 741         )
 742
 743         wb = WishboneInterface(data_width=data_width, addr_width=address_width,
 744                                granularity=granularity, features=features,
 745                                name=name, src_loc_at=src_loc_at+1)
 746
 747         self._wbs.append((sr_addr, sr_data, wb, domain))
 748
 749         return wb
 750
 751     def _elaborate_wishbones(self, m):
 752         for sr_addr, sr_data, wb, domain in self._wbs:
 753             m.d.comb += sr_addr.i.eq(wb.adr)
 754
 755             if hasattr(wb, "sel"):
 756                 # Always selected
 757                 m.d.comb += [s.eq(1) for s in wb.sel]
 758
 759             with m.FSM(domain=domain) as fsm:
 760                 with m.State("IDLE"):
 761                     with m.If(sr_addr.oe): # WBADDR code
 762                         m.d[domain] += wb.adr.eq(sr_addr.o)
 763                         m.next = "READ"
 764                     with m.Elif(sr_data.oe[0]): # WBREAD code
 765                         # If data is
 766                         m.d[domain] += wb.adr.eq(wb.adr + 1)
 767                         m.next = "READ"
 768                     with m.Elif(sr_data.oe[1]): # WBWRITE code
 769                         m.d[domain] += wb.dat_w.eq(sr_data.o)
 770                         m.next = "WRITEREAD"
 771                 with m.State("READ"):
 772                     if not hasattr(wb, "stall"):
 773                         m.next = "READACK"
 774                     else:
 775                         with m.If(~wb.stall):
 776                             m.next = "READACK"
 777                 with m.State("READACK"):
 778                     with m.If(wb.ack):
 779                         # Store read data in sr_data.i
 780                         # and keep it there til next read
 781                         m.d[domain] += sr_data.i.eq(wb.dat_r)
 782                         m.next = "IDLE"
 783                 with m.State("WRITEREAD"):
 784                     if not hasattr(wb, "stall"):
 785                         m.next = "WRITEREADACK"
 786                     else:
 787                         with m.If(~wb.stall):
 788                             m.next = "WRITEREADACK"
 789                 with m.State("WRITEREADACK"):
 790                     with m.If(wb.ack):
 791                         m.d[domain] += wb.adr.eq(wb.adr + 1)
 792                         m.next = "READ"
 793
 794                 m.d.comb += [
 795                     wb.cyc.eq(~fsm.ongoing("IDLE")),
 796                     wb.stb.eq(fsm.ongoing("READ") | fsm.ongoing("WRITEREAD")),
 797                     wb.we.eq(fsm.ongoing("WRITEREAD")),
 798                 ]