3 This first version is intended for prototyping and test purposes:
4 it has "direct" access to Memory.
6 The intention is that this version remains an integral part of the
7 test infrastructure, and, just as with minerva's memory arrangement,
8 a dynamic runtime config *selects* alternative memory arrangements
9 rather than *replaces and discards* this code.
13 * https://bugs.libre-soc.org/show_bug.cgi?id=216
14 * https://libre-soc.org/3d_gpu/architecture/memory_and_cache/
15 * https://bugs.libre-soc.org/show_bug.cgi?id=465 - exception handling
19 from nmigen
.compat
.sim
import run_simulation
, Settle
20 from nmigen
.cli
import rtlil
21 from nmigen
import Module
, Signal
, Mux
, Elaboratable
, Cat
, Const
22 from nmutil
.iocontrol
import RecordObject
23 from nmigen
.utils
import log2_int
25 from nmutil
.latch
import SRLatch
, latchregister
26 from nmutil
.util
import rising_edge
27 from openpower
.decoder
.power_decoder2
import Data
28 from soc
.scoreboard
.addr_match
import LenExpand
29 from soc
.experiment
.mem_types
import LDSTException
31 # for testing purposes
32 from soc
.experiment
.testmem
import TestMemory
33 #from soc.scoreboard.addr_split import LDSTSplitter
34 from nmutil
.util
import Display
35 from collections
import namedtuple
36 MSRSpec
= namedtuple("MSRSpec", ["dr", "pr", "sf"]) # used in unit tests
41 class PortInterface(RecordObject
):
44 defines the interface - the API - that the LDSTCompUnit connects
45 to. note that this is NOT a "fire-and-forget" interface. the
46 LDSTCompUnit *must* be kept appraised that the request is in
47 progress, and only when it has a 100% successful completion
48 can the notification be given (busy dropped).
50 The interface FSM rules are as follows:
52 * if busy_o is asserted, a LD/ST is in progress. further
53 requests may not be made until busy_o is deasserted.
55 * only one of is_ld_i or is_st_i may be asserted. busy_o
56 will immediately be asserted and remain asserted.
58 * addr.ok is to be asserted when the LD/ST address is known.
59 addr.data is to be valid on the same cycle.
61 addr.ok and addr.data must REMAIN asserted until busy_o
62 is de-asserted. this ensures that there is no need
63 for the L0 Cache/Buffer to have an additional address latch
64 (because the LDSTCompUnit already has it)
66 * addr_ok_o (or exception.happened) must be waited for. these will
67 be asserted *only* for one cycle and one cycle only.
69 * exception.happened will be asserted if there is no chance that the
70 memory request may be fulfilled.
72 busy_o is deasserted on the same cycle as exception.happened is asserted.
74 * conversely: addr_ok_o must *ONLY* be asserted if there is a
75 HUNDRED PERCENT guarantee that the memory request will be
78 * for a LD, ld.ok will be asserted - for only one clock cycle -
79 at any point in the future that is acceptable to the underlying
80 Memory subsystem. the recipient MUST latch ld.data on that cycle.
82 busy_o is deasserted on the same cycle as ld.ok is asserted.
84 * for a ST, st.ok may be asserted only after addr_ok_o had been
85 asserted, alongside valid st.data at the same time. st.ok
86 must only be asserted for one cycle.
88 the underlying Memory is REQUIRED to pick up that data and
89 guarantee its delivery. no back-acknowledgement is required.
91 busy_o is deasserted on the cycle AFTER st.ok is asserted.
94 def __init__(self
, name
=None, regwid
=64, addrwid
=48):
97 self
._addrwid
= addrwid
99 RecordObject
.__init
__(self
, name
=name
)
101 # distinguish op type (ld/st)
102 self
.is_ld_i
= Signal(reset_less
=True)
103 self
.is_st_i
= Signal(reset_less
=True)
105 # LD/ST data length (TODO: other things may be needed)
106 self
.data_len
= Signal(4, reset_less
=True)
109 self
.busy_o
= Signal(reset_less
=True) # do not use if busy
110 self
.go_die_i
= Signal(reset_less
=True) # back to reset
111 self
.addr
= Data(addrwid
, "addr_i") # addr/addr-ok
112 # addr is valid (TLB, L1 etc.)
113 self
.addr_ok_o
= Signal(reset_less
=True)
114 self
.exc_o
= LDSTException("exc")
117 self
.ld
= Data(regwid
, "ld_data_o") # ok to be set by L0 Cache/Buf
118 self
.st
= Data(regwid
, "st_data_i") # ok to be set by CompUnit
121 self
.is_nc
= Signal() # no cacheing
123 #only priv_mode = not msr_pr is used currently
124 # TODO: connect signals
125 self
.virt_mode
= Signal() # ctrl.msr(MSR_DR);
126 self
.priv_mode
= Signal() # not ctrl.msr(MSR_PR);
127 self
.mode_32bit
= Signal() # not ctrl.msr(MSR_SF);
129 self
.is_dcbz_i
= Signal(reset_less
=True)
132 self
.mmu_done
= Signal() # keep for now
135 self
.ldst_error
= Signal()
136 ## Signalling ld/st error - NC cache hit, TLB miss, prot/RC failure
137 self
.cache_paradox
= Signal()
139 def connect_port(self
, inport
):
140 print("connect_port", self
, inport
)
141 return [self
.is_ld_i
.eq(inport
.is_ld_i
),
142 self
.is_st_i
.eq(inport
.is_st_i
),
143 self
.is_nc
.eq(inport
.is_nc
),
144 self
.is_dcbz_i
.eq(inport
.is_dcbz_i
),
145 self
.data_len
.eq(inport
.data_len
),
146 self
.go_die_i
.eq(inport
.go_die_i
),
147 self
.addr
.data
.eq(inport
.addr
.data
),
148 self
.addr
.ok
.eq(inport
.addr
.ok
),
149 self
.st
.eq(inport
.st
),
150 self
.virt_mode
.eq(inport
.virt_mode
),
151 self
.priv_mode
.eq(inport
.priv_mode
),
152 self
.mode_32bit
.eq(inport
.mode_32bit
),
153 inport
.ld
.eq(self
.ld
),
154 inport
.busy_o
.eq(self
.busy_o
),
155 inport
.addr_ok_o
.eq(self
.addr_ok_o
),
156 inport
.exc_o
.eq(self
.exc_o
),
157 inport
.mmu_done
.eq(self
.mmu_done
),
158 inport
.ldst_error
.eq(self
.ldst_error
),
159 inport
.cache_paradox
.eq(self
.cache_paradox
)
163 class PortInterfaceBase(Elaboratable
):
166 Base class for PortInterface-compliant Memory read/writers
169 def __init__(self
, regwid
=64, addrwid
=4):
171 self
.addrwid
= addrwid
172 self
.pi
= PortInterface("ldst_port0", regwid
, addrwid
)
176 return log2_int(self
.regwid
//8)
178 def splitaddr(self
, addr
):
179 """split the address into top and bottom bits of the memory granularity
181 return addr
[:self
.addrbits
], addr
[self
.addrbits
:]
183 def connect_port(self
, inport
):
184 return self
.pi
.connect_port(inport
)
186 def set_wr_addr(self
, m
, addr
, mask
, misalign
, msr
, is_dcbz
): pass
187 def set_rd_addr(self
, m
, addr
, mask
, misalign
, msr
): pass
188 def set_wr_data(self
, m
, data
, wen
): pass
189 def get_rd_data(self
, m
): pass
191 def elaborate(self
, platform
):
193 comb
, sync
= m
.d
.comb
, m
.d
.sync
195 # state-machine latches
196 m
.submodules
.st_active
= st_active
= SRLatch(False, name
="st_active")
197 m
.submodules
.st_done
= st_done
= SRLatch(False, name
="st_done")
198 m
.submodules
.ld_active
= ld_active
= SRLatch(False, name
="ld_active")
199 m
.submodules
.reset_l
= reset_l
= SRLatch(True, name
="reset")
200 m
.submodules
.adrok_l
= adrok_l
= SRLatch(False, name
="addr_acked")
201 m
.submodules
.busy_l
= busy_l
= SRLatch(False, name
="busy")
202 m
.submodules
.cyc_l
= cyc_l
= SRLatch(True, name
="cyc")
206 sync
+= st_done
.s
.eq(0)
207 comb
+= st_done
.r
.eq(0)
208 comb
+= st_active
.r
.eq(0)
209 comb
+= ld_active
.r
.eq(0)
210 comb
+= cyc_l
.s
.eq(0)
211 comb
+= cyc_l
.r
.eq(0)
212 comb
+= busy_l
.s
.eq(0)
213 comb
+= busy_l
.r
.eq(0)
214 sync
+= adrok_l
.s
.eq(0)
215 comb
+= adrok_l
.r
.eq(0)
217 # expand ld/st binary length/addr[:3] into unary bitmap
218 m
.submodules
.lenexp
= lenexp
= LenExpand(4, 8)
220 lds
= Signal(reset_less
=True)
221 sts
= Signal(reset_less
=True)
223 comb
+= lds
.eq(pi
.is_ld_i
) # ld-req signals
224 comb
+= sts
.eq(pi
.is_st_i
) # st-req signals
228 busy_delay
= Signal()
230 sync
+= busy_delay
.eq(pi
.busy_o
)
231 comb
+= busy_edge
.eq(pi
.busy_o
& ~busy_delay
)
233 # misalignment detection: bits at end of lenexpand are set.
234 # when using the L0CacheBuffer "data expander" which splits requests
235 # into *two* PortInterfaces, this acts as a "safety check".
237 comb
+= misalign
.eq(lenexp
.lexp_o
[8:].bool())
240 # activate mode: only on "edge"
241 comb
+= ld_active
.s
.eq(rising_edge(m
, lds
)) # activate LD mode
242 comb
+= st_active
.s
.eq(rising_edge(m
, sts
)) # activate ST mode
244 # LD/ST requested activates "busy" (only if not already busy)
245 with m
.If(self
.pi
.is_ld_i | self
.pi
.is_st_i
):
246 comb
+= busy_l
.s
.eq(~busy_delay
)
247 with m
.If(self
.pi
.exc_o
.happened
):
248 sync
+= Display("fast exception")
250 # if now in "LD" mode: wait for addr_ok, then send the address out
251 # to memory, acknowledge address, and send out LD data
252 with m
.If(ld_active
.q
):
253 # set up LenExpander with the LD len and lower bits of addr
254 lsbaddr
, msbaddr
= self
.splitaddr(pi
.addr
.data
)
255 comb
+= lenexp
.len_i
.eq(pi
.data_len
)
256 comb
+= lenexp
.addr_i
.eq(lsbaddr
)
257 with m
.If(pi
.addr
.ok
& adrok_l
.qn
):
258 self
.set_rd_addr(m
, pi
.addr
.data
, lenexp
.lexp_o
, misalign
, pr
)
259 comb
+= pi
.addr_ok_o
.eq(1) # acknowledge addr ok
260 sync
+= adrok_l
.s
.eq(1) # and pull "ack" latch
262 # if now in "ST" mode: likewise do the same but with "ST"
263 # to memory, acknowledge address, and send out LD data
264 with m
.If(st_active
.q
):
265 # set up LenExpander with the ST len and lower bits of addr
266 lsbaddr
, msbaddr
= self
.splitaddr(pi
.addr
.data
)
267 comb
+= lenexp
.len_i
.eq(pi
.data_len
)
268 comb
+= lenexp
.addr_i
.eq(lsbaddr
)
269 with m
.If(pi
.addr
.ok
):
270 self
.set_wr_addr(m
, pi
.addr
.data
, lenexp
.lexp_o
, misalign
, pr
,
272 with m
.If(adrok_l
.qn
& self
.pi
.exc_o
.happened
==0):
273 comb
+= pi
.addr_ok_o
.eq(1) # acknowledge addr ok
274 sync
+= adrok_l
.s
.eq(1) # and pull "ack" latch
276 # for LD mode, when addr has been "ok'd", assume that (because this
277 # is a "Memory" test-class) the memory read data is valid.
278 comb
+= reset_l
.s
.eq(0)
279 comb
+= reset_l
.r
.eq(0)
280 lddata
= Signal(self
.regwid
, reset_less
=True)
281 data
, ldok
= self
.get_rd_data(m
)
282 comb
+= lddata
.eq((data
& lenexp
.rexp_o
) >>
284 with m
.If(ld_active
.q
& adrok_l
.q
):
285 # shift data down before pushing out. requires masking
286 # from the *byte*-expanded version of LenExpand output
287 comb
+= pi
.ld
.data
.eq(lddata
) # put data out
288 comb
+= pi
.ld
.ok
.eq(ldok
) # indicate data valid
289 comb
+= reset_l
.s
.eq(ldok
) # reset mode after 1 cycle
291 # for ST mode, when addr has been "ok'd", wait for incoming "ST ok"
292 sync
+= st_done
.s
.eq(0) # store done trigger
293 with m
.If(st_active
.q
& pi
.st
.ok
):
294 # shift data up before storing. lenexp *bit* version of mask is
295 # passed straight through as byte-level "write-enable" lines.
296 stdata
= Signal(self
.regwid
, reset_less
=True)
297 comb
+= stdata
.eq(pi
.st
.data
<< (lenexp
.addr_i
*8))
298 # TODO: replace with link to LoadStoreUnitInterface.x_store_data
299 # and also handle the ready/stall/busy protocol
300 stok
= self
.set_wr_data(m
, stdata
, lenexp
.lexp_o
)
301 sync
+= st_done
.s
.eq(~self
.pi
.exc_o
.happened
) # store done trigger
302 with m
.If(st_done
.q
):
303 comb
+= reset_l
.s
.eq(stok
) # reset mode after 1 cycle
305 # ugly hack, due to simultaneous addr req-go acknowledge
306 reset_delay
= Signal(reset_less
=True)
307 sync
+= reset_delay
.eq(reset_l
.q
)
308 with m
.If(reset_delay
):
309 comb
+= adrok_l
.r
.eq(1) # address reset
311 # after waiting one cycle (reset_l is "sync" mode), reset the port
312 with m
.If(reset_l
.q
):
313 comb
+= ld_active
.r
.eq(1) # leave the LD active for 1 cycle
314 comb
+= st_active
.r
.eq(1) # leave the ST active for 1 cycle
315 comb
+= reset_l
.r
.eq(1) # clear reset
316 comb
+= adrok_l
.r
.eq(1) # address reset
317 comb
+= st_done
.r
.eq(1) # store done reset
319 # monitor for an exception, clear busy immediately
320 with m
.If(self
.pi
.exc_o
.happened
):
321 comb
+= busy_l
.r
.eq(1)
322 comb
+= reset_l
.s
.eq(1) # also reset whole unit
324 # however ST needs one cycle before busy is reset
325 #with m.If(self.pi.st.ok | self.pi.ld.ok):
326 with m
.If(reset_l
.s
):
327 comb
+= cyc_l
.s
.eq(1)
330 comb
+= cyc_l
.r
.eq(1)
331 comb
+= busy_l
.r
.eq(1)
333 # busy latch outputs to interface
334 if hasattr(self
, "external_busy"):
335 # when there is an extra (external) busy, include that here.
336 # this is used e.g. in LoadStore1 when an instruction fault
337 # is being processed (instr_fault) and stops Load/Store requests
338 # from being made until it's done
339 comb
+= pi
.busy_o
.eq(busy_l
.q | self
.external_busy(m
))
341 comb
+= pi
.busy_o
.eq(busy_l
.q
)
346 yield from self
.pi
.ports()
349 class TestMemoryPortInterface(PortInterfaceBase
):
350 """TestMemoryPortInterface
352 This is a test class for simple verification of the LDSTCompUnit
353 and for the simple core, to be able to run unit tests rapidly and
354 with less other code in the way.
356 Versions of this which are *compatible* (conform with PortInterface)
357 will include augmented-Wishbone Bus versions, including ones that
358 connect to L1, L2, MMU etc. etc. however this is the "base lowest
359 possible version that complies with PortInterface".
362 def __init__(self
, regwid
=64, addrwid
=4):
363 super().__init
__(regwid
, addrwid
)
364 # hard-code memory addressing width to 6 bits
365 self
.mem
= TestMemory(regwid
, 5, granularity
=regwid
//8, init
=False)
367 def set_wr_addr(self
, m
, addr
, mask
, misalign
, msr
, is_dcbz
):
368 lsbaddr
, msbaddr
= self
.splitaddr(addr
)
369 m
.d
.comb
+= self
.mem
.wrport
.addr
.eq(msbaddr
)
371 def set_rd_addr(self
, m
, addr
, mask
, misalign
, msr
):
372 lsbaddr
, msbaddr
= self
.splitaddr(addr
)
373 m
.d
.comb
+= self
.mem
.rdport
.addr
.eq(msbaddr
)
375 def set_wr_data(self
, m
, data
, wen
):
376 m
.d
.comb
+= self
.mem
.wrport
.data
.eq(data
) # write st to mem
377 m
.d
.comb
+= self
.mem
.wrport
.en
.eq(wen
) # enable writes
380 def get_rd_data(self
, m
):
381 return self
.mem
.rdport
.data
, Const(1, 1)
383 def elaborate(self
, platform
):
384 m
= super().elaborate(platform
)
386 # add TestMemory as submodule
387 m
.submodules
.mem
= self
.mem
392 yield from super().ports()