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
39 class PortInterface(RecordObject
):
42 defines the interface - the API - that the LDSTCompUnit connects
43 to. note that this is NOT a "fire-and-forget" interface. the
44 LDSTCompUnit *must* be kept appraised that the request is in
45 progress, and only when it has a 100% successful completion
46 can the notification be given (busy dropped).
48 The interface FSM rules are as follows:
50 * if busy_o is asserted, a LD/ST is in progress. further
51 requests may not be made until busy_o is deasserted.
53 * only one of is_ld_i or is_st_i may be asserted. busy_o
54 will immediately be asserted and remain asserted.
56 * addr.ok is to be asserted when the LD/ST address is known.
57 addr.data is to be valid on the same cycle.
59 addr.ok and addr.data must REMAIN asserted until busy_o
60 is de-asserted. this ensures that there is no need
61 for the L0 Cache/Buffer to have an additional address latch
62 (because the LDSTCompUnit already has it)
64 * addr_ok_o (or exception.happened) must be waited for. these will
65 be asserted *only* for one cycle and one cycle only.
67 * exception.happened will be asserted if there is no chance that the
68 memory request may be fulfilled.
70 busy_o is deasserted on the same cycle as exception.happened is asserted.
72 * conversely: addr_ok_o must *ONLY* be asserted if there is a
73 HUNDRED PERCENT guarantee that the memory request will be
76 * for a LD, ld.ok will be asserted - for only one clock cycle -
77 at any point in the future that is acceptable to the underlying
78 Memory subsystem. the recipient MUST latch ld.data on that cycle.
80 busy_o is deasserted on the same cycle as ld.ok is asserted.
82 * for a ST, st.ok may be asserted only after addr_ok_o had been
83 asserted, alongside valid st.data at the same time. st.ok
84 must only be asserted for one cycle.
86 the underlying Memory is REQUIRED to pick up that data and
87 guarantee its delivery. no back-acknowledgement is required.
89 busy_o is deasserted on the cycle AFTER st.ok is asserted.
92 def __init__(self
, name
=None, regwid
=64, addrwid
=48):
95 self
._addrwid
= addrwid
97 RecordObject
.__init
__(self
, name
=name
)
99 # distinguish op type (ld/st)
100 self
.is_ld_i
= Signal(reset_less
=True)
101 self
.is_st_i
= Signal(reset_less
=True)
103 # LD/ST data length (TODO: other things may be needed)
104 self
.data_len
= Signal(4, reset_less
=True)
107 self
.busy_o
= Signal(reset_less
=True) # do not use if busy
108 self
.go_die_i
= Signal(reset_less
=True) # back to reset
109 self
.addr
= Data(addrwid
, "addr_i") # addr/addr-ok
110 # addr is valid (TLB, L1 etc.)
111 self
.addr_ok_o
= Signal(reset_less
=True)
112 self
.exc_o
= LDSTException("exc")
113 self
.dar_o
= Signal(64, reset_less
=True)
116 self
.ld
= Data(regwid
, "ld_data_o") # ok to be set by L0 Cache/Buf
117 self
.st
= Data(regwid
, "st_data_i") # ok to be set by CompUnit
120 self
.is_nc
= Signal() # no cacheing
121 self
.msr_pr
= Signal() # 1==virtual, 0==privileged
122 self
.is_dcbz_i
= Signal(reset_less
=True)
125 self
.mmu_done
= Signal() # keep for now
128 self
.ldst_error
= Signal()
129 ## Signalling ld/st error - NC cache hit, TLB miss, prot/RC failure
130 self
.cache_paradox
= Signal()
132 def connect_port(self
, inport
):
133 print("connect_port", self
, inport
)
134 return [self
.is_ld_i
.eq(inport
.is_ld_i
),
135 self
.is_st_i
.eq(inport
.is_st_i
),
136 self
.is_nc
.eq(inport
.is_nc
),
137 self
.is_dcbz_i
.eq(inport
.is_dcbz_i
),
138 self
.data_len
.eq(inport
.data_len
),
139 self
.go_die_i
.eq(inport
.go_die_i
),
140 self
.addr
.data
.eq(inport
.addr
.data
),
141 self
.addr
.ok
.eq(inport
.addr
.ok
),
142 self
.st
.eq(inport
.st
),
143 self
.msr_pr
.eq(inport
.msr_pr
),
144 inport
.ld
.eq(self
.ld
),
145 inport
.busy_o
.eq(self
.busy_o
),
146 inport
.addr_ok_o
.eq(self
.addr_ok_o
),
147 inport
.exc_o
.eq(self
.exc_o
),
148 inport
.dar_o
.eq(self
.dar_o
),
149 inport
.mmu_done
.eq(self
.mmu_done
),
150 inport
.ldst_error
.eq(self
.ldst_error
),
151 inport
.cache_paradox
.eq(self
.cache_paradox
)
155 class PortInterfaceBase(Elaboratable
):
158 Base class for PortInterface-compliant Memory read/writers
161 def __init__(self
, regwid
=64, addrwid
=4):
163 self
.addrwid
= addrwid
164 self
.pi
= PortInterface("ldst_port0", regwid
, addrwid
)
168 return log2_int(self
.regwid
//8)
170 def splitaddr(self
, addr
):
171 """split the address into top and bottom bits of the memory granularity
173 return addr
[:self
.addrbits
], addr
[self
.addrbits
:]
175 def connect_port(self
, inport
):
176 return self
.pi
.connect_port(inport
)
178 def set_wr_addr(self
, m
, addr
, mask
, misalign
, msr_pr
, is_dcbz
): pass
179 def set_rd_addr(self
, m
, addr
, mask
, misalign
, msr_pr
): pass
180 def set_wr_data(self
, m
, data
, wen
): pass
181 def get_rd_data(self
, m
): pass
183 def elaborate(self
, platform
):
185 comb
, sync
= m
.d
.comb
, m
.d
.sync
187 # state-machine latches
188 m
.submodules
.st_active
= st_active
= SRLatch(False, name
="st_active")
189 m
.submodules
.st_done
= st_done
= SRLatch(False, name
="st_done")
190 m
.submodules
.ld_active
= ld_active
= SRLatch(False, name
="ld_active")
191 m
.submodules
.reset_l
= reset_l
= SRLatch(True, name
="reset")
192 m
.submodules
.adrok_l
= adrok_l
= SRLatch(False, name
="addr_acked")
193 m
.submodules
.busy_l
= busy_l
= SRLatch(False, name
="busy")
194 m
.submodules
.cyc_l
= cyc_l
= SRLatch(True, name
="cyc")
198 sync
+= st_done
.s
.eq(0)
199 comb
+= st_done
.r
.eq(0)
200 comb
+= st_active
.r
.eq(0)
201 comb
+= ld_active
.r
.eq(0)
202 comb
+= cyc_l
.s
.eq(0)
203 comb
+= cyc_l
.r
.eq(0)
204 comb
+= busy_l
.s
.eq(0)
205 comb
+= busy_l
.r
.eq(0)
206 sync
+= adrok_l
.s
.eq(0)
207 comb
+= adrok_l
.r
.eq(0)
209 # expand ld/st binary length/addr[:3] into unary bitmap
210 m
.submodules
.lenexp
= lenexp
= LenExpand(4, 8)
212 lds
= Signal(reset_less
=True)
213 sts
= Signal(reset_less
=True)
215 comb
+= lds
.eq(pi
.is_ld_i
) # ld-req signals
216 comb
+= sts
.eq(pi
.is_st_i
) # st-req signals
217 pr
= pi
.msr_pr
# MSR problem state: PR=1 ==> virt, PR==0 ==> priv
220 busy_delay
= Signal()
222 sync
+= busy_delay
.eq(pi
.busy_o
)
223 comb
+= busy_edge
.eq(pi
.busy_o
& ~busy_delay
)
225 # misalignment detection: bits at end of lenexpand are set.
226 # when using the L0CacheBuffer "data expander" which splits requests
227 # into *two* PortInterfaces, this acts as a "safety check".
229 comb
+= misalign
.eq(lenexp
.lexp_o
[8:].bool())
232 # activate mode: only on "edge"
233 comb
+= ld_active
.s
.eq(rising_edge(m
, lds
)) # activate LD mode
234 comb
+= st_active
.s
.eq(rising_edge(m
, sts
)) # activate ST mode
236 # LD/ST requested activates "busy" (only if not already busy)
237 with m
.If(self
.pi
.is_ld_i | self
.pi
.is_st_i
):
238 comb
+= busy_l
.s
.eq(~busy_delay
)
240 # if now in "LD" mode: wait for addr_ok, then send the address out
241 # to memory, acknowledge address, and send out LD data
242 with m
.If(ld_active
.q
):
243 # set up LenExpander with the LD len and lower bits of addr
244 lsbaddr
, msbaddr
= self
.splitaddr(pi
.addr
.data
)
245 comb
+= lenexp
.len_i
.eq(pi
.data_len
)
246 comb
+= lenexp
.addr_i
.eq(lsbaddr
)
247 with m
.If(pi
.addr
.ok
& adrok_l
.qn
):
248 self
.set_rd_addr(m
, pi
.addr
.data
, lenexp
.lexp_o
, misalign
, pr
)
249 comb
+= pi
.addr_ok_o
.eq(1) # acknowledge addr ok
250 sync
+= adrok_l
.s
.eq(1) # and pull "ack" latch
252 # if now in "ST" mode: likewise do the same but with "ST"
253 # to memory, acknowledge address, and send out LD data
254 with m
.If(st_active
.q
):
255 # set up LenExpander with the ST len and lower bits of addr
256 lsbaddr
, msbaddr
= self
.splitaddr(pi
.addr
.data
)
257 comb
+= lenexp
.len_i
.eq(pi
.data_len
)
258 comb
+= lenexp
.addr_i
.eq(lsbaddr
)
259 with m
.If(pi
.addr
.ok
):
260 self
.set_wr_addr(m
, pi
.addr
.data
, lenexp
.lexp_o
, misalign
, pr
,
262 with m
.If(adrok_l
.qn
):
263 comb
+= pi
.addr_ok_o
.eq(1) # acknowledge addr ok
264 sync
+= adrok_l
.s
.eq(1) # and pull "ack" latch
266 # for LD mode, when addr has been "ok'd", assume that (because this
267 # is a "Memory" test-class) the memory read data is valid.
268 comb
+= reset_l
.s
.eq(0)
269 comb
+= reset_l
.r
.eq(0)
270 lddata
= Signal(self
.regwid
, reset_less
=True)
271 data
, ldok
= self
.get_rd_data(m
)
272 comb
+= lddata
.eq((data
& lenexp
.rexp_o
) >>
274 with m
.If(ld_active
.q
& adrok_l
.q
):
275 # shift data down before pushing out. requires masking
276 # from the *byte*-expanded version of LenExpand output
277 comb
+= pi
.ld
.data
.eq(lddata
) # put data out
278 comb
+= pi
.ld
.ok
.eq(ldok
) # indicate data valid
279 comb
+= reset_l
.s
.eq(ldok
) # reset mode after 1 cycle
281 # for ST mode, when addr has been "ok'd", wait for incoming "ST ok"
282 with m
.If(st_active
.q
& pi
.st
.ok
):
283 # shift data up before storing. lenexp *bit* version of mask is
284 # passed straight through as byte-level "write-enable" lines.
285 stdata
= Signal(self
.regwid
, reset_less
=True)
286 comb
+= stdata
.eq(pi
.st
.data
<< (lenexp
.addr_i
*8))
287 # TODO: replace with link to LoadStoreUnitInterface.x_store_data
288 # and also handle the ready/stall/busy protocol
289 stok
= self
.set_wr_data(m
, stdata
, lenexp
.lexp_o
)
290 sync
+= st_done
.s
.eq(1) # store done trigger
291 with m
.If(st_done
.q
):
292 comb
+= reset_l
.s
.eq(stok
) # reset mode after 1 cycle
294 # ugly hack, due to simultaneous addr req-go acknowledge
295 reset_delay
= Signal(reset_less
=True)
296 sync
+= reset_delay
.eq(reset_l
.q
)
297 with m
.If(reset_delay
):
298 comb
+= adrok_l
.r
.eq(1) # address reset
300 # after waiting one cycle (reset_l is "sync" mode), reset the port
301 with m
.If(reset_l
.q
):
302 comb
+= ld_active
.r
.eq(1) # leave the LD active for 1 cycle
303 comb
+= st_active
.r
.eq(1) # leave the ST active for 1 cycle
304 comb
+= reset_l
.r
.eq(1) # clear reset
305 comb
+= adrok_l
.r
.eq(1) # address reset
306 comb
+= st_done
.r
.eq(1) # store done reset
308 # monitor for an exception, clear busy immediately
309 with m
.If(self
.pi
.exc_o
.happened
):
310 comb
+= busy_l
.r
.eq(1)
312 # however ST needs one cycle before busy is reset
313 #with m.If(self.pi.st.ok | self.pi.ld.ok):
314 with m
.If(reset_l
.s
):
315 comb
+= cyc_l
.s
.eq(1)
318 comb
+= cyc_l
.r
.eq(1)
319 comb
+= busy_l
.r
.eq(1)
321 # busy latch outputs to interface
322 comb
+= pi
.busy_o
.eq(busy_l
.q
)
327 yield from self
.pi
.ports()
330 class TestMemoryPortInterface(PortInterfaceBase
):
331 """TestMemoryPortInterface
333 This is a test class for simple verification of the LDSTCompUnit
334 and for the simple core, to be able to run unit tests rapidly and
335 with less other code in the way.
337 Versions of this which are *compatible* (conform with PortInterface)
338 will include augmented-Wishbone Bus versions, including ones that
339 connect to L1, L2, MMU etc. etc. however this is the "base lowest
340 possible version that complies with PortInterface".
343 def __init__(self
, regwid
=64, addrwid
=4):
344 super().__init
__(regwid
, addrwid
)
345 # hard-code memory addressing width to 6 bits
346 self
.mem
= TestMemory(regwid
, 5, granularity
=regwid
//8, init
=False)
348 def set_wr_addr(self
, m
, addr
, mask
, misalign
, msr_pr
, is_dcbz
):
349 lsbaddr
, msbaddr
= self
.splitaddr(addr
)
350 m
.d
.comb
+= self
.mem
.wrport
.addr
.eq(msbaddr
)
352 def set_rd_addr(self
, m
, addr
, mask
, misalign
, msr_pr
):
353 lsbaddr
, msbaddr
= self
.splitaddr(addr
)
354 m
.d
.comb
+= self
.mem
.rdport
.addr
.eq(msbaddr
)
356 def set_wr_data(self
, m
, data
, wen
):
357 m
.d
.comb
+= self
.mem
.wrport
.data
.eq(data
) # write st to mem
358 m
.d
.comb
+= self
.mem
.wrport
.en
.eq(wen
) # enable writes
361 def get_rd_data(self
, m
):
362 return self
.mem
.rdport
.data
, Const(1, 1)
364 def elaborate(self
, platform
):
365 m
= super().elaborate(platform
)
367 # add TestMemory as submodule
368 m
.submodules
.mem
= self
.mem
373 yield from super().ports()