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frontend/avalon: Improve decoupling in START state.

This commit is contained in:
Florent Kermarrec 2023-05-31 10:42:21 +02:00 committed by Hans Baier
parent b0503f1b00
commit f1f5f637e7
1 changed files with 22 additions and 24 deletions
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46
litedram/frontend/avalon.py
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@ -46,12 +46,11 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
# Internal Signals.
burst_count = Signal(9)
burst_start = Signal()
address = Signal(port.address_width)
address_offset = Signal(port.address_width)
byteenable = Signal(avalon_data_width//8)
writedata = Signal(avalon_data_width)
start = Signal()
latch = Signal()
cmd_ready_seen = Signal()
cmd_ready_count = Signal(9)
@ -65,7 +64,7 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
]
self.sync += [
If(start,
If(latch,
byteenable.eq(avalon.byteenable),
writedata.eq(avalon.writedata),
burst_count.eq(avalon.burstcount),
@ -77,31 +76,30 @@ class LiteDRAMAvalonMM2Native(LiteXModule):
self.fsm = fsm = FSM(reset_state="START")
fsm.act("START",
avalon.waitrequest.eq(1),
If(avalon.burstcount <= 1,
port.cmd.addr.eq(avalon.address - address_offset),
port.cmd.we.eq(avalon.write),
port.cmd.valid.eq(avalon.read | avalon.write)
),
# Start of Access.
If(avalon.read | avalon.write,
If((avalon.burstcount > 1) | (downconvert == True) | port.cmd.ready,
start.eq(1),
If((downconvert == False) & (avalon.burstcount <= 1),
avalon.waitrequest.eq(0)
),
latch.eq(1),
# Burst Access.
If(avalon.burstcount > 1,
If(avalon.write,
If(avalon.burstcount > 1,
NextState("BURST_WRITE")
).Else(
port.cmd.last.eq(1),
NextState("BURST_WRITE")
),
If(avalon.read,
avalon.waitrequest.eq(0),
NextValue(cmd_ready_count, avalon.burstcount),
NextState("BURST_READ")
)
# Single Access.
).Else(
port.cmd.addr.eq(avalon.address - address_offset),
port.cmd.we.eq(avalon.write),
port.cmd.valid.eq(1),
port.cmd.last.eq(1),
If((downconvert == True) | port.cmd.ready,
avalon.waitrequest.eq(downconvert == True),
If(port.cmd.we,
NextState("SINGLE_WRITE")
)
).Elif(avalon.read,
If(avalon.burstcount > 1,
avalon.waitrequest.eq(0),
NextValue(cmd_ready_count, avalon.burstcount),
NextState("BURST_READ")
).Else(
port.cmd.last.eq(1),
NextState("SINGLE_READ")
)
)