9dc133abf0a436e6960bc1102095cdee75f8d564
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")
115 self
.ld
= Data(regwid
, "ld_data_o") # ok to be set by L0 Cache/Buf
116 self
.st
= Data(regwid
, "st_data_i") # ok to be set by CompUnit
119 self
.is_nc
= Signal() # no cacheing
120 self
.msr_pr
= Signal() # 1==virtual, 0==privileged
121 self
.is_dcbz_i
= Signal(reset_less
=True)
124 self
.mmu_done
= Signal() # keep for now
127 self
.ldst_error
= Signal()
128 ## Signalling ld/st error - NC cache hit, TLB miss, prot/RC failure
129 self
.cache_paradox
= Signal()
131 def connect_port(self
, inport
):
132 print("connect_port", self
, inport
)
133 return [self
.is_ld_i
.eq(inport
.is_ld_i
),
134 self
.is_st_i
.eq(inport
.is_st_i
),
135 self
.is_nc
.eq(inport
.is_nc
),
136 self
.is_dcbz_i
.eq(inport
.is_dcbz_i
),
137 self
.data_len
.eq(inport
.data_len
),
138 self
.go_die_i
.eq(inport
.go_die_i
),
139 self
.addr
.data
.eq(inport
.addr
.data
),
140 self
.addr
.ok
.eq(inport
.addr
.ok
),
141 self
.st
.eq(inport
.st
),
142 self
.msr_pr
.eq(inport
.msr_pr
),
143 inport
.ld
.eq(self
.ld
),
144 inport
.busy_o
.eq(self
.busy_o
),
145 inport
.addr_ok_o
.eq(self
.addr_ok_o
),
146 inport
.exc_o
.eq(self
.exc_o
),
147 inport
.mmu_done
.eq(self
.mmu_done
),
148 inport
.ldst_error
.eq(self
.ldst_error
),
149 inport
.cache_paradox
.eq(self
.cache_paradox
)
153 class PortInterfaceBase(Elaboratable
):
156 Base class for PortInterface-compliant Memory read/writers
159 def __init__(self
, regwid
=64, addrwid
=4):
161 self
.addrwid
= addrwid
162 self
.pi
= PortInterface("ldst_port0", regwid
, addrwid
)
166 return log2_int(self
.regwid
//8)
168 def splitaddr(self
, addr
):
169 """split the address into top and bottom bits of the memory granularity
171 return addr
[:self
.addrbits
], addr
[self
.addrbits
:]
173 def connect_port(self
, inport
):
174 return self
.pi
.connect_port(inport
)
176 def set_wr_addr(self
, m
, addr
, mask
, misalign
, msr_pr
, is_dcbz
): pass
177 def set_rd_addr(self
, m
, addr
, mask
, misalign
, msr_pr
): pass
178 def set_wr_data(self
, m
, data
, wen
): pass
179 def get_rd_data(self
, m
): pass
181 def elaborate(self
, platform
):
183 comb
, sync
= m
.d
.comb
, m
.d
.sync
185 # state-machine latches
186 m
.submodules
.st_active
= st_active
= SRLatch(False, name
="st_active")
187 m
.submodules
.st_done
= st_done
= SRLatch(False, name
="st_done")
188 m
.submodules
.ld_active
= ld_active
= SRLatch(False, name
="ld_active")
189 m
.submodules
.reset_l
= reset_l
= SRLatch(True, name
="reset")
190 m
.submodules
.adrok_l
= adrok_l
= SRLatch(False, name
="addr_acked")
191 m
.submodules
.busy_l
= busy_l
= SRLatch(False, name
="busy")
192 m
.submodules
.cyc_l
= cyc_l
= SRLatch(True, name
="cyc")
196 sync
+= st_done
.s
.eq(0)
197 comb
+= st_done
.r
.eq(0)
198 comb
+= st_active
.r
.eq(0)
199 comb
+= ld_active
.r
.eq(0)
200 comb
+= cyc_l
.s
.eq(0)
201 comb
+= cyc_l
.r
.eq(0)
202 comb
+= busy_l
.s
.eq(0)
203 comb
+= busy_l
.r
.eq(0)
204 sync
+= adrok_l
.s
.eq(0)
205 comb
+= adrok_l
.r
.eq(0)
207 # expand ld/st binary length/addr[:3] into unary bitmap
208 m
.submodules
.lenexp
= lenexp
= LenExpand(4, 8)
210 lds
= Signal(reset_less
=True)
211 sts
= Signal(reset_less
=True)
213 comb
+= lds
.eq(pi
.is_ld_i
) # ld-req signals
214 comb
+= sts
.eq(pi
.is_st_i
) # st-req signals
215 pr
= pi
.msr_pr
# MSR problem state: PR=1 ==> virt, PR==0 ==> priv
218 busy_delay
= Signal()
220 sync
+= busy_delay
.eq(pi
.busy_o
)
221 comb
+= busy_edge
.eq(pi
.busy_o
& ~busy_delay
)
223 # misalignment detection: bits at end of lenexpand are set.
224 # when using the L0CacheBuffer "data expander" which splits requests
225 # into *two* PortInterfaces, this acts as a "safety check".
227 comb
+= misalign
.eq(lenexp
.lexp_o
[8:].bool())
230 # activate mode: only on "edge"
231 comb
+= ld_active
.s
.eq(rising_edge(m
, lds
)) # activate LD mode
232 comb
+= st_active
.s
.eq(rising_edge(m
, sts
)) # activate ST mode
234 # LD/ST requested activates "busy" (only if not already busy)
235 with m
.If(self
.pi
.is_ld_i | self
.pi
.is_st_i
):
236 comb
+= busy_l
.s
.eq(~busy_delay
)
238 # if now in "LD" mode: wait for addr_ok, then send the address out
239 # to memory, acknowledge address, and send out LD data
240 with m
.If(ld_active
.q
):
241 # set up LenExpander with the LD len and lower bits of addr
242 lsbaddr
, msbaddr
= self
.splitaddr(pi
.addr
.data
)
243 comb
+= lenexp
.len_i
.eq(pi
.data_len
)
244 comb
+= lenexp
.addr_i
.eq(lsbaddr
)
245 with m
.If(pi
.addr
.ok
& adrok_l
.qn
):
246 self
.set_rd_addr(m
, pi
.addr
.data
, lenexp
.lexp_o
, misalign
, pr
)
247 comb
+= pi
.addr_ok_o
.eq(1) # acknowledge addr ok
248 sync
+= adrok_l
.s
.eq(1) # and pull "ack" latch
250 # if now in "ST" mode: likewise do the same but with "ST"
251 # to memory, acknowledge address, and send out LD data
252 with m
.If(st_active
.q
):
253 # set up LenExpander with the ST 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
):
258 self
.set_wr_addr(m
, pi
.addr
.data
, lenexp
.lexp_o
, misalign
, pr
,
260 with m
.If(adrok_l
.qn
):
261 comb
+= pi
.addr_ok_o
.eq(1) # acknowledge addr ok
262 sync
+= adrok_l
.s
.eq(1) # and pull "ack" latch
264 # for LD mode, when addr has been "ok'd", assume that (because this
265 # is a "Memory" test-class) the memory read data is valid.
266 comb
+= reset_l
.s
.eq(0)
267 comb
+= reset_l
.r
.eq(0)
268 lddata
= Signal(self
.regwid
, reset_less
=True)
269 data
, ldok
= self
.get_rd_data(m
)
270 comb
+= lddata
.eq((data
& lenexp
.rexp_o
) >>
272 with m
.If(ld_active
.q
& adrok_l
.q
):
273 # shift data down before pushing out. requires masking
274 # from the *byte*-expanded version of LenExpand output
275 comb
+= pi
.ld
.data
.eq(lddata
) # put data out
276 comb
+= pi
.ld
.ok
.eq(ldok
) # indicate data valid
277 comb
+= reset_l
.s
.eq(ldok
) # reset mode after 1 cycle
279 # for ST mode, when addr has been "ok'd", wait for incoming "ST ok"
280 with m
.If(st_active
.q
& pi
.st
.ok
):
281 # shift data up before storing. lenexp *bit* version of mask is
282 # passed straight through as byte-level "write-enable" lines.
283 stdata
= Signal(self
.regwid
, reset_less
=True)
284 comb
+= stdata
.eq(pi
.st
.data
<< (lenexp
.addr_i
*8))
285 # TODO: replace with link to LoadStoreUnitInterface.x_store_data
286 # and also handle the ready/stall/busy protocol
287 stok
= self
.set_wr_data(m
, stdata
, lenexp
.lexp_o
)
288 sync
+= st_done
.s
.eq(1) # store done trigger
289 with m
.If(st_done
.q
):
290 comb
+= reset_l
.s
.eq(stok
) # reset mode after 1 cycle
292 # ugly hack, due to simultaneous addr req-go acknowledge
293 reset_delay
= Signal(reset_less
=True)
294 sync
+= reset_delay
.eq(reset_l
.q
)
295 with m
.If(reset_delay
):
296 comb
+= adrok_l
.r
.eq(1) # address reset
298 # after waiting one cycle (reset_l is "sync" mode), reset the port
299 with m
.If(reset_l
.q
):
300 comb
+= ld_active
.r
.eq(1) # leave the LD active for 1 cycle
301 comb
+= st_active
.r
.eq(1) # leave the ST active for 1 cycle
302 comb
+= reset_l
.r
.eq(1) # clear reset
303 comb
+= adrok_l
.r
.eq(1) # address reset
304 comb
+= st_done
.r
.eq(1) # store done reset
306 # monitor for an exception, clear busy immediately
307 with m
.If(self
.pi
.exc_o
.happened
):
308 comb
+= busy_l
.r
.eq(1)
310 # however ST needs one cycle before busy is reset
311 #with m.If(self.pi.st.ok | self.pi.ld.ok):
312 with m
.If(reset_l
.s
):
313 comb
+= cyc_l
.s
.eq(1)
316 comb
+= cyc_l
.r
.eq(1)
317 comb
+= busy_l
.r
.eq(1)
319 # busy latch outputs to interface
320 comb
+= pi
.busy_o
.eq(busy_l
.q
)
325 yield from self
.pi
.ports()
328 class TestMemoryPortInterface(PortInterfaceBase
):
329 """TestMemoryPortInterface
331 This is a test class for simple verification of the LDSTCompUnit
332 and for the simple core, to be able to run unit tests rapidly and
333 with less other code in the way.
335 Versions of this which are *compatible* (conform with PortInterface)
336 will include augmented-Wishbone Bus versions, including ones that
337 connect to L1, L2, MMU etc. etc. however this is the "base lowest
338 possible version that complies with PortInterface".
341 def __init__(self
, regwid
=64, addrwid
=4):
342 super().__init
__(regwid
, addrwid
)
343 # hard-code memory addressing width to 6 bits
344 self
.mem
= TestMemory(regwid
, 5, granularity
=regwid
//8, init
=False)
346 def set_wr_addr(self
, m
, addr
, mask
, misalign
, msr_pr
, is_dcbz
):
347 lsbaddr
, msbaddr
= self
.splitaddr(addr
)
348 m
.d
.comb
+= self
.mem
.wrport
.addr
.eq(msbaddr
)
350 def set_rd_addr(self
, m
, addr
, mask
, misalign
, msr_pr
):
351 lsbaddr
, msbaddr
= self
.splitaddr(addr
)
352 m
.d
.comb
+= self
.mem
.rdport
.addr
.eq(msbaddr
)
354 def set_wr_data(self
, m
, data
, wen
):
355 m
.d
.comb
+= self
.mem
.wrport
.data
.eq(data
) # write st to mem
356 m
.d
.comb
+= self
.mem
.wrport
.en
.eq(wen
) # enable writes
359 def get_rd_data(self
, m
):
360 return self
.mem
.rdport
.data
, Const(1, 1)
362 def elaborate(self
, platform
):
363 m
= super().elaborate(platform
)
365 # add TestMemory as submodule
366 m
.submodules
.mem
= self
.mem
371 yield from super().ports()