lasmi: simplify usage for the user (it's the job of the controller to…

… manage write/read latencies on acks)
m-labs · Mar 1, 2015 · 6d83a11 · 6d83a11
1 parent f58394f
commit 6d83a11
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Showing 3 changed files with 43 additions and 25 deletions.
diff --git a/misoclib/mem/sdram/bus/lasmibus.py b/misoclib/mem/sdram/bus/lasmibus.py
@@ -14,12 +14,13 @@ def __init__(self, aw, dw, nbanks, req_queue_size, read_latency, write_latency):
 		self.write_latency = write_latency
 
 		bank_layout = [
-			("adr",		aw,		DIR_M_TO_S),
-			("we",		1,		DIR_M_TO_S),
-			("stb",		1,		DIR_M_TO_S),
-			("req_ack",	1,		DIR_S_TO_M),
-			("dat_ack",	1,		DIR_S_TO_M),
-			("lock",	1,		DIR_S_TO_M)
+			("adr",			aw,		DIR_M_TO_S),
+			("we",			1,		DIR_M_TO_S),
+			("stb",			1,		DIR_M_TO_S),
+			("req_ack",		1,		DIR_S_TO_M),
+			("dat_w_ack",	1,		DIR_S_TO_M),
+			("dat_r_ack",	1,		DIR_S_TO_M),
+			("lock",		1,		DIR_S_TO_M)
 		]
 		if nbanks > 1:
 			layout = [("bank"+str(i), bank_layout) for i in range(nbanks)]
@@ -77,7 +78,9 @@ def do_finalize(self):
 			else:
 				controller_selected = [1]*nmasters
 			master_req_acks = [0]*nmasters
-			master_dat_acks = [0]*nmasters
+			master_dat_w_acks = [0]*nmasters
+			master_dat_r_acks = [0]*nmasters
+
 			rrs = [roundrobin.RoundRobin(nmasters, roundrobin.SP_CE) for n in range(self._nbanks)]
 			self.submodules += rrs
 			for nb, rr in enumerate(rrs):
@@ -109,11 +112,28 @@ def do_finalize(self):
 				]
 				master_req_acks = [master_req_ack | ((rr.grant == nm) & bank_selected[nm] & bank.req_ack)
 					for nm, master_req_ack in enumerate(master_req_acks)]
-				master_dat_acks = [master_dat_ack | ((rr.grant == nm) & bank.dat_ack)
-					for nm, master_dat_ack in enumerate(master_dat_acks)]
+				master_dat_w_acks = [master_dat_w_ack | ((rr.grant == nm) & bank.dat_w_ack)
+					for nm, master_dat_w_ack in enumerate(master_dat_w_acks)]
+				master_dat_r_acks = [master_dat_r_ack | ((rr.grant == nm) & bank.dat_r_ack)
+					for nm, master_dat_r_ack in enumerate(master_dat_r_acks)]
+
+			for nm, master_dat_w_ack in enumerate(master_dat_w_acks):
+					for i in range(self._write_latency):
+						new_master_dat_w_ack = Signal()
+						self.sync += new_master_dat_w_ack.eq(master_dat_w_ack)
+						master_dat_w_ack = new_master_dat_w_ack
+					master_dat_w_acks[nm] = master_dat_w_ack
+
+			for nm, master_dat_r_ack in enumerate(master_dat_r_acks):
+					for i in range(self._read_latency):
+						new_master_dat_r_ack = Signal()
+						self.sync += new_master_dat_r_ack.eq(master_dat_r_ack)
+						master_dat_r_ack = new_master_dat_r_ack
+					master_dat_r_acks[nm] = master_dat_r_ack
 
 			self.comb += [master.req_ack.eq(master_req_ack) for master, master_req_ack in zip(self._masters, master_req_acks)]
-			self.comb += [master.dat_ack.eq(master_dat_ack) for master, master_dat_ack in zip(self._masters, master_dat_acks)]
+			self.comb += [master.dat_w_ack.eq(master_dat_w_ack) for master, master_dat_w_ack in zip(self._masters, master_dat_w_acks)]
+			self.comb += [master.dat_r_ack.eq(master_dat_r_ack) for master, master_dat_r_ack in zip(self._masters, master_dat_r_acks)]
 
 			# route data writes
 			controller_selected_wl = controller_selected

diff --git a/misoclib/mem/sdram/bus/wishbone2lasmi.py b/misoclib/mem/sdram/bus/wishbone2lasmi.py
@@ -105,8 +105,6 @@ def word_is_last(word):
 		fsm = FSM(reset_state="IDLE")
 		self.submodules += fsm
 
-		fsm.delayed_enter("EVICT_DATAD", "EVICT_DATA", lasmim.write_latency-1)
-		fsm.delayed_enter("REFILL_DATAD", "REFILL_DATA", lasmim.read_latency-1)
 
 		fsm.act("IDLE",
 			If(self.wishbone.cyc & self.wishbone.stb, NextState("TEST_HIT"))
@@ -135,7 +133,7 @@ def word_is_last(word):
 			If(lasmim.req_ack, NextState("EVICT_WAIT_DATA_ACK"))
 		)
 		fsm.act("EVICT_WAIT_DATA_ACK",
-			If(lasmim.dat_ack, NextState("EVICT_DATAD"))
+			If(lasmim.dat_w_ack, NextState("EVICT_DATA"))
 		)
 		fsm.act("EVICT_DATA",
 			write_to_lasmi.eq(1),
@@ -155,17 +153,16 @@ def word_is_last(word):
 		)
 		fsm.act("REFILL_REQUEST",
 			lasmim.stb.eq(1),
-			If(lasmim.req_ack, NextState("REFILL_WAIT_DATA_ACK"))
-		)
-		fsm.act("REFILL_WAIT_DATA_ACK",
-			If(lasmim.dat_ack, NextState("REFILL_DATAD"))
+			If(lasmim.req_ack, NextState("REFILL_DATA"))
 		)
 		fsm.act("REFILL_DATA",
-			write_from_lasmi.eq(1),
-			word_inc.eq(1),
-			If(word_is_last(word),
-				NextState("TEST_HIT"),
-			).Else(
-				NextState("REFILL_REQUEST")
+			If(lasmim.dat_r_ack,
+				write_from_lasmi.eq(1),
+				word_inc.eq(1),
+				If(word_is_last(word),
+					NextState("TEST_HIT"),
+				).Else(
+					NextState("REFILL_REQUEST")
+				)
 			)
 		)
diff --git a/misoclib/mem/sdram/lasmicon/bankmachine.py b/misoclib/mem/sdram/lasmicon/bankmachine.py
@@ -41,7 +41,7 @@ def __init__(self, geom_settings, timing_settings, address_align, bankn, req):
 			self.req_fifo.we.eq(req.stb),
 			req.req_ack.eq(self.req_fifo.writable),
 
-			self.req_fifo.re.eq(req.dat_ack),
+			self.req_fifo.re.eq(req.dat_w_ack | req.dat_r_ack),
 			req.lock.eq(self.req_fifo.readable)
 		]
 		reqf = self.req_fifo.dout
@@ -100,7 +100,8 @@ def __init__(self, geom_settings, timing_settings, address_align, bankn, req):
 					If(hit,
 						# NB: write-to-read specification is enforced by multiplexer
 						self.cmd.stb.eq(1),
-						req.dat_ack.eq(self.cmd.ack),
+						req.dat_w_ack.eq(self.cmd.ack & reqf.we),
+						req.dat_r_ack.eq(self.cmd.ack & ~reqf.we),
 						self.cmd.is_read.eq(~reqf.we),
 						self.cmd.is_write.eq(reqf.we),
 						self.cmd.cas_n.eq(0),