From 93bcc94b539d8a422d3ae5f9139763fb7d56668d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C4=99drzej=20Boczar?= Date: Thu, 16 Jul 2020 10:21:43 +0200 Subject: [PATCH] soc/interconnect/axi: implement AXILite down-converter --- litex/soc/interconnect/axi.py | 159 ++++++++++++++++++++++++++- test/test_axi.py | 200 +++++++++++++++++++++++++++++++++- 2 files changed, 353 insertions(+), 6 deletions(-) diff --git a/litex/soc/interconnect/axi.py b/litex/soc/interconnect/axi.py index 02002a58e..160b08f93 100644 --- a/litex/soc/interconnect/axi.py +++ b/litex/soc/interconnect/axi.py @@ -172,13 +172,14 @@ class AXILiteInterface: yield while not (yield self.aw.ready): yield + yield self.aw.valid.eq(0) while not (yield self.w.ready): yield + yield self.w.valid.eq(0) + yield self.b.ready.eq(1) while not (yield self.b.valid): yield - yield self.b.ready.eq(1) resp = (yield self.b.resp) - yield yield self.b.ready.eq(0) return resp @@ -188,12 +189,12 @@ class AXILiteInterface: yield while not (yield self.ar.ready): yield + yield self.ar.valid.eq(0) + yield self.r.ready.eq(1) while not (yield self.r.valid): yield - yield self.r.ready.eq(1) data = (yield self.r.data) resp = (yield self.r.resp) - yield yield self.r.ready.eq(0) return (data, resp) @@ -679,6 +680,152 @@ class AXILiteSRAM(Module): # AXILite Data Width Converter --------------------------------------------------------------------- +class AXILiteDownConverter(Module): + def __init__(self, master, slave): + assert isinstance(master, AXILiteInterface) and isinstance(slave, AXILiteInterface) + dw_from = len(master.r.data) + dw_to = len(slave.r.data) + ratio = dw_from//dw_to + + # # # + + skip = Signal() + counter = Signal(max=ratio) + do_read = Signal() + do_write = Signal() + last_was_read = Signal() + aw_ready = Signal() + w_ready = Signal() + + # Slave address counter + master_align = log2_int(master.data_width//8) + slave_align = log2_int(slave.data_width//8) + addr_counter = Signal(master_align) + self.comb += addr_counter[slave_align:].eq(counter) + + # Write path + self.comb += [ + slave.aw.addr.eq(Cat(addr_counter, master.aw.addr[master_align:])), + Case(counter, {i: slave.w.data.eq(master.w.data[i*dw_to:]) for i in range(ratio)}), + Case(counter, {i: slave.w.strb.eq(master.w.strb[i*dw_to//8:]) for i in range(ratio)}), + master.b.resp.eq(RESP_OKAY), # FIXME: error handling? + ] + + # Read path + # shift the data word + r_data = Signal(dw_from, reset_less=True) + self.sync += If(slave.r.ready, r_data.eq(master.r.data)) + self.comb += master.r.data.eq(Cat(r_data[dw_to:], slave.r.data)) + # address, resp + self.comb += [ + slave.ar.addr.eq(Cat(addr_counter, master.ar.addr[master_align:])), + master.r.resp.eq(RESP_OKAY), # FIXME: error handling? + ] + + # Control Path + fsm = FSM(reset_state="IDLE") + fsm = ResetInserter()(fsm) + self.submodules.fsm = fsm + self.comb += fsm.reset.eq(~(master.aw.valid | master.ar.valid)) + + fsm.act("IDLE", + NextValue(counter, 0), + # If the last access was a read, do a write, and vice versa + If(master.aw.valid & master.ar.valid, + do_write.eq(last_was_read), + do_read.eq(~last_was_read), + ).Else( + do_write.eq(master.aw.valid), + do_read.eq(master.ar.valid), + ), + # Start reading/writing immediately not to waste a cycle + If(do_write & master.w.valid, + NextValue(last_was_read, 0), + NextState("WRITE") + ).Elif(do_read, + NextValue(last_was_read, 1), + NextState("READ") + ) + ) + + # Write conversion + fsm.act("WRITE", + skip.eq(slave.w.strb == 0), + slave.aw.valid.eq(~skip & ~aw_ready), + slave.w.valid.eq(~skip & ~w_ready), + If(slave.aw.ready, + NextValue(aw_ready, 1) + ), + If(slave.w.ready, + NextValue(w_ready, 1) + ), + # When skipping, we just increment the counter + If(skip, + NextValue(counter, counter + 1), + # Corner-case: when the last word is being skipped, we must send the response + If(counter == (ratio - 1), + master.aw.ready.eq(1), + master.w.ready.eq(1), + NextState("WRITE-RESPONSE-MASTER") + ) + # Write current word and wait for write response + ).Elif((slave.aw.ready | aw_ready) & (slave.w.ready | w_ready), + NextState("WRITE-RESPONSE-SLAVE") + ) + ) + fsm.act("WRITE-RESPONSE-SLAVE", + NextValue(aw_ready, 0), + NextValue(w_ready, 0), + If(slave.b.valid, + slave.b.ready.eq(1), + If(counter == (ratio - 1), + master.aw.ready.eq(1), + master.w.ready.eq(1), + NextState("WRITE-RESPONSE-MASTER") + ).Else( + NextValue(counter, counter + 1), + NextState("WRITE") + ) + ) + ) + fsm.act("WRITE-RESPONSE-MASTER", + NextValue(aw_ready, 0), + NextValue(w_ready, 0), + master.b.valid.eq(1), + If(master.b.ready, + NextState("IDLE") + ) + ) + + # Read conversion + fsm.act("READ", + slave.ar.valid.eq(1), + If(slave.ar.ready, + NextState("READ-RESPONSE-SLAVE") + ) + ) + fsm.act("READ-RESPONSE-SLAVE", + If(slave.r.valid, + # On last word acknowledge ar and hold slave.r.valid until we get master.r.ready + If(counter == (ratio - 1), + master.ar.ready.eq(1), + NextState("READ-RESPONSE-MASTER") + # Acknowledge the response and continue conversion + ).Else( + slave.r.ready.eq(1), + NextValue(counter, counter + 1), + NextState("READ") + ) + ) + ) + fsm.act("READ-RESPONSE-MASTER", + master.r.valid.eq(1), + If(master.r.ready, + slave.r.ready.eq(1), + NextState("IDLE") + ) + ) + class AXILiteConverter(Module): """AXILite data width converter""" def __init__(self, master, slave): @@ -690,8 +837,10 @@ class AXILiteConverter(Module): dw_from = len(master.r.data) dw_to = len(slave.r.data) if dw_from > dw_to: - raise NotImplementedError + print("AXILiteConverter (Down): {} -> {}".format(master.data_width, slave.data_width)) + self.submodules += AXILiteDownConverter(master, slave) elif dw_from < dw_to: + print("AXILiteConverter (Up): {} -> {}".format(master.data_width, slave.data_width)) raise NotImplementedError else: self.comb += master.connect(slave) diff --git a/test/test_axi.py b/test/test_axi.py index fa694e412..84b2b52e1 100644 --- a/test/test_axi.py +++ b/test/test_axi.py @@ -51,7 +51,7 @@ class Write(Access): class Read(Access): pass -# Tests -------------------------------------------------------------------------------------------- +# TestAXI ------------------------------------------------------------------------------------------ class TestAXI(unittest.TestCase): def test_burst2beat(self): @@ -327,6 +327,71 @@ class TestAXI(unittest.TestCase): r_ready_random = 90 ) +# TestAXILite -------------------------------------------------------------------------------------- + +class AXILiteChecker: + def __init__(self, latency=None, rdata_generator=None): + self.latency = latency or (lambda: 0) + self.rdata_generator = rdata_generator or (lambda adr: 0xbaadc0de) + self.writes = [] + self.reads = [] + + def delay(self): + for _ in range(self.latency()): + yield + + def handle_write(self, axi_lite): + while not (yield axi_lite.aw.valid): + yield + yield from self.delay() + addr = (yield axi_lite.aw.addr) + yield axi_lite.aw.ready.eq(1) + yield + yield axi_lite.aw.ready.eq(0) + while not (yield axi_lite.w.valid): + yield + yield from self.delay() + data = (yield axi_lite.w.data) + strb = (yield axi_lite.w.strb) + yield axi_lite.w.ready.eq(1) + yield + yield axi_lite.w.ready.eq(0) + yield axi_lite.b.valid.eq(1) + yield axi_lite.b.resp.eq(RESP_OKAY) + yield + while not (yield axi_lite.b.ready): + yield + yield axi_lite.b.valid.eq(0) + self.writes.append((addr, data, strb)) + + def handle_read(self, axi_lite): + while not (yield axi_lite.ar.valid): + yield + yield from self.delay() + addr = (yield axi_lite.ar.addr) + yield axi_lite.ar.ready.eq(1) + yield + yield axi_lite.ar.ready.eq(0) + data = self.rdata_generator(addr) + yield axi_lite.r.valid.eq(1) + yield axi_lite.r.resp.eq(RESP_OKAY) + yield axi_lite.r.data.eq(data) + yield + while not (yield axi_lite.r.ready): + yield + yield axi_lite.r.valid.eq(0) + self.reads.append((addr, data)) + + @passive + def handler(self, axi_lite): + while True: + if (yield axi_lite.aw.valid): + yield from self.handle_write(axi_lite) + if (yield axi_lite.ar.valid): + yield from self.handle_read(axi_lite) + yield + +class TestAXILite(unittest.TestCase): def test_wishbone2axi2wishbone(self): class DUT(Module): def __init__(self): @@ -439,3 +504,136 @@ class TestAXI(unittest.TestCase): dut = DUT(size=len(init)*4, init=[v for v in init]) run_simulation(dut, [generator(dut, init)]) self.assertEqual(dut.errors, 0) + + def converter_test(self, width_from, width_to, + write_pattern=None, write_expected=None, + read_pattern=None, read_expected=None): + assert not (write_pattern is None and read_pattern is None) + + if write_pattern is None: + write_pattern = [] + write_expected = [] + elif len(write_pattern[0]) == 2: + # add w.strb + write_pattern = [(adr, data, 2**(width_from//8)-1) for adr, data in write_pattern] + + if read_pattern is None: + read_pattern = [] + read_expected = [] + + class DUT(Module): + def __init__(self, width_from, width_to): + self.master = AXILiteInterface(data_width=width_from) + self.slave = AXILiteInterface(data_width=width_to) + self.submodules.converter = AXILiteConverter(self.master, self.slave) + + def generator(axi_lite): + for addr, data, strb in write_pattern or []: + resp = (yield from axi_lite.write(addr, data, strb)) + self.assertEqual(resp, RESP_OKAY) + for _ in range(16): + yield + + for addr, refdata in read_pattern or []: + data, resp = (yield from axi_lite.read(addr)) + self.assertEqual(resp, RESP_OKAY) + self.assertEqual(data, refdata) + for _ in range(4): + yield + + def rdata_generator(adr): + for a, v in read_expected: + if a == adr: + return v + return 0xbaadc0de + + _latency = 0 + def latency(): + nonlocal _latency + _latency = (_latency + 1) % 3 + return _latency + + dut = DUT(width_from=width_from, width_to=width_to) + checker = AXILiteChecker(latency, rdata_generator) + run_simulation(dut, [generator(dut.master), checker.handler(dut.slave)], vcd_name='sim.vcd') + self.assertEqual(checker.writes, write_expected) + self.assertEqual(checker.reads, read_expected) + + def test_axilite_down_converter_32to16(self): + write_pattern = [ + (0x00000000, 0x22221111), + (0x00000004, 0x44443333), + (0x00000008, 0x66665555), + (0x00000100, 0x88887777), + ] + write_expected = [ + (0x00000000, 0x1111, 0b11), + (0x00000002, 0x2222, 0b11), + (0x00000004, 0x3333, 0b11), + (0x00000006, 0x4444, 0b11), + (0x00000008, 0x5555, 0b11), + (0x0000000a, 0x6666, 0b11), + (0x00000100, 0x7777, 0b11), + (0x00000102, 0x8888, 0b11), + ] + read_pattern = write_pattern + read_expected = [(adr, data) for (adr, data, _) in write_expected] + self.converter_test(width_from=32, width_to=16, + write_pattern=write_pattern, write_expected=write_expected, + read_pattern=read_pattern, read_expected=read_expected) + + def test_axilite_down_converter_32to8(self): + write_pattern = [ + (0x00000000, 0x44332211), + (0x00000004, 0x88776655), + ] + write_expected = [ + (0x00000000, 0x11, 0b1), + (0x00000001, 0x22, 0b1), + (0x00000002, 0x33, 0b1), + (0x00000003, 0x44, 0b1), + (0x00000004, 0x55, 0b1), + (0x00000005, 0x66, 0b1), + (0x00000006, 0x77, 0b1), + (0x00000007, 0x88, 0b1), + ] + read_pattern = write_pattern + read_expected = [(adr, data) for (adr, data, _) in write_expected] + self.converter_test(width_from=32, width_to=8, + write_pattern=write_pattern, write_expected=write_expected, + read_pattern=read_pattern, read_expected=read_expected) + + def test_axilite_down_converter_64to32(self): + write_pattern = [ + (0x00000000, 0x2222222211111111), + (0x00000008, 0x4444444433333333), + ] + write_expected = [ + (0x00000000, 0x11111111, 0b1111), + (0x00000004, 0x22222222, 0b1111), + (0x00000008, 0x33333333, 0b1111), + (0x0000000c, 0x44444444, 0b1111), + ] + read_pattern = write_pattern + read_expected = [(adr, data) for (adr, data, _) in write_expected] + self.converter_test(width_from=64, width_to=32, + write_pattern=write_pattern, write_expected=write_expected, + read_pattern=read_pattern, read_expected=read_expected) + + def test_axilite_down_converter_strb(self): + write_pattern = [ + (0x00000000, 0x22221111, 0b1100), + (0x00000004, 0x44443333, 0b1111), + (0x00000008, 0x66665555, 0b1011), + (0x00000100, 0x88887777, 0b0011), + ] + write_expected = [ + (0x00000002, 0x2222, 0b11), + (0x00000004, 0x3333, 0b11), + (0x00000006, 0x4444, 0b11), + (0x00000008, 0x5555, 0b11), + (0x0000000a, 0x6666, 0b10), + (0x00000100, 0x7777, 0b11), + ] + self.converter_test(width_from=32, width_to=16, + write_pattern=write_pattern, write_expected=write_expected)