litedram/test/test_bist.py

import unittest
import random

from litex.gen import *

from litex.soc.interconnect.stream import *

from litedram.common import LiteDRAMWritePort, LiteDRAMReadPort
from litedram.frontend.bist import LiteDRAMBISTGenerator
from litedram.frontend.bist import LiteDRAMBISTChecker
from litedram.frontend.bist import LiteDRAMBISTCheckerScope

from test.common import *


class DUT(Module):
    def __init__(self):
        self.write_port = LiteDRAMWritePort(aw=32, dw=32)
        self.read_port = LiteDRAMReadPort(aw=32, dw=32)
        self.submodules.generator = LiteDRAMBISTGenerator(self.write_port, True)
        self.submodules.checker = LiteDRAMBISTChecker(self.read_port, True)
        self.submodules.checker_scope = LiteDRAMBISTCheckerScope(self.checker)


def main_generator(dut, mem):
    # Populate memory with random data
    random.seed(0)
    for i in range(0, len(mem.mem)):
        mem.mem[i] = random.randint(0, 2**mem.width)

    # write
    yield from reset_bist_module(dut.generator)

    yield dut.generator.base.storage.eq(16)
    yield dut.generator.length.storage.eq(64)
    for i in range(8):
        yield
    yield dut.generator.start.re.eq(1)
    yield
    yield dut.generator.start.re.eq(0)
    for i in range(8):
        yield
    while((yield dut.generator.done.status) == 0):
        yield
    done = yield dut.generator.done.status
    assert done, done

    # read with no errors
    yield from reset_bist_module(dut.checker)
    errors = yield dut.checker.err_count.status
    assert errors == 0, errors

    yield dut.checker.base.storage.eq(16)
    yield dut.checker.length.storage.eq(64)
    for i in range(8):
        yield
    yield from toggle_re(dut.checker.start)
    for i in range(8):
        yield
    while((yield dut.checker.done.status) == 0):
        yield
    done = yield dut.checker.done.status
    assert done, done
    errors = yield dut.checker.err_count.status
    assert errors == 0, errors

    yield
    yield

    # read with one error
    yield from reset_bist_module(dut.checker)
    errors = yield dut.checker.err_count.status
    assert errors == 0, errors

    print("mem.mem[20]", hex(mem.mem[20]))
    assert mem.mem[20] == 0xffff000f, hex(mem.mem[20])
    mem.mem[20] = 0x200  # Make position 20 an error

    yield dut.checker.base.storage.eq(16)
    yield dut.checker.length.storage.eq(64)
    for i in range(8):
        yield
    yield from toggle_re(dut.checker.start)
    for i in range(8):
        yield
    while((yield dut.checker.done.status) == 0):
        yield
    done = yield dut.checker.done.status
    assert done, done
    errors = yield dut.checker.err_count.status
    assert errors == 1, errors

    yield
    yield

    # read with two errors
    yield from reset_bist_module(dut.checker)
    errors = yield dut.checker.err_count.status
    assert errors == 0, errors

    print("mem.mem[21]", hex(mem.mem[21]))
    assert mem.mem[21] == 0xfff1ff1f, hex(mem.mem[21])
    mem.mem[21] = 0x210 # Make position 21 an error

    yield dut.checker.base.storage.eq(16)
    yield dut.checker.length.storage.eq(64)
    for i in range(8):
        yield
    yield from toggle_re(dut.checker.start)
    for i in range(8):
        yield
    while((yield dut.checker.done.status) == 0):
        yield
    done = yield dut.checker.done.status
    assert done, done
    errors = yield dut.checker.err_count.status
    assert errors == 2, errors

    yield
    yield

    # check the scoped signals
    yield from reset_bist_module(dut.checker)
    errors = yield dut.checker.err_count.status
    assert errors == 0, errors

    yield dut.checker.base.storage.eq(16)
    yield dut.checker.length.storage.eq(64)
    for i in range(8):
        yield
    yield from toggle_re(dut.checker.start)
    for i in range(8):
        yield
    while((yield dut.checker_scope.data_error) == 0):
        yield

    err_addr = yield dut.checker_scope.data_address
    assert err_addr == 20, err_addr
    err_expect = yield dut.checker_scope.data_expected
    assert err_expect == 0xffff000f, hex(err_expect)
    err_actual = yield dut.checker_scope.data_actual
    assert err_actual == 0x200, err_actual
    yield
    errors = yield dut.checker.core.err_count
    assert errors == 1, errors

    while((yield dut.checker_scope.data_error) == 0):
        yield

    err_addr = yield dut.checker_scope.data_address
    assert err_addr == 21, err_addr
    err_expect = yield dut.checker_scope.data_expected
    assert err_expect == 0xfff1ff1f, hex(err_expect)
    err_actual = yield dut.checker_scope.data_actual
    assert err_actual == 0x210, hex(err_actual)
    yield
    errors = yield dut.checker.core.err_count
    assert errors == 2, errors

    while((yield dut.checker.done.status) == 0):
        yield

    done = yield dut.checker.done.status
    assert done, done
    errors = yield dut.checker.err_count.status
    assert errors == 2, errors

    yield
    yield


class TestBIST(unittest.TestCase):
    def test(self):
        dut = DUT()
        mem = DRAMMemory(32, 128)
        generators = {
            "sys" : [
                main_generator(dut, mem),
                mem.write_generator(dut.write_port),
                mem.read_generator(dut.read_port)
            ]
        }
        clocks = {"sys": 10}
        run_simulation(dut, generators, clocks, vcd_name="sim.vcd")