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# Copyright (c) 2012-2020 ARM Limited
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#
# The license below extends only to copyright in the software and shall
# not be construed as granting a license to any other intellectual
# property including but not limited to intellectual property relating
# to a hardware implementation of the functionality of the software
# licensed hereunder. You may use the software subject to the license
# terms below provided that you ensure that this notice is replicated
# unmodified and in its entirety in all distributions of the software,
# modified or unmodified, in source code or in binary form.
#
# Copyright (c) 2013 Amin Farmahini-Farahani
# Copyright (c) 2015 University of Kaiserslautern
# Copyright (c) 2015 The University of Bologna
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met: redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer;
# redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution;
# neither the name of the copyright holders nor the names of its
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# this software without specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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from m5.params import *
from m5.proxy import *
from m5.objects.AbstractMemory import AbstractMemory
# Enum for the address mapping. With Ch, Ra, Ba, Ro and Co denoting
# channel, rank, bank, row and column, respectively, and going from
# MSB to LSB. Available are RoRaBaChCo and RoRaBaCoCh, that are
# suitable for an open-page policy, optimising for sequential accesses
# hitting in the open row. For a closed-page policy, RoCoRaBaCh
# maximises parallelism.
class AddrMap(Enum):
vals = ["RoRaBaChCo", "RoRaBaCoCh", "RoCoRaBaCh"]
class MemInterface(AbstractMemory):
type = "MemInterface"
abstract = True
cxx_header = "mem/mem_interface.hh"
cxx_class = "gem5::memory::MemInterface"
# Allow the interface to set required controller buffer sizes
# each entry corresponds to a burst for the specific memory channel
# configuration (e.g. x32 with burst length 8 is 32 bytes) and not
# the cacheline size or request/packet size
write_buffer_size = Param.Unsigned(64, "Number of write queue entries")
read_buffer_size = Param.Unsigned(32, "Number of read queue entries")
# scheduler, address map
addr_mapping = Param.AddrMap("RoRaBaCoCh", "Address mapping policy")
# size of memory device in Bytes
device_size = Param.MemorySize("Size of memory device")
# the physical organisation of the memory
device_bus_width = Param.Unsigned(
"data bus width in bits for each " "memory device/chip"
)
burst_length = Param.Unsigned("Burst lenght (BL) in beats")
device_rowbuffer_size = Param.MemorySize(
"Page (row buffer) size per " "device/chip"
)
devices_per_rank = Param.Unsigned("Number of devices/chips per rank")
ranks_per_channel = Param.Unsigned("Number of ranks per channel")
banks_per_rank = Param.Unsigned("Number of banks per rank")
# timing behaviour and constraints - all in nanoseconds
# the base clock period of the memory
tCK = Param.Latency("Clock period")
# time to complete a burst transfer, typically the burst length
# divided by two due to the DDR bus, but by making it a parameter
# it is easier to also evaluate SDR memories like WideIO and new
# interfaces, emerging technologies.
# This parameter has to account for burst length.
# Read/Write requests with data size larger than one full burst are broken
# down into multiple requests in the controller
tBURST = Param.Latency(
"Burst duration " "(typically burst length / 2 cycles)"
)
# write-to-read, same rank turnaround penalty
tWTR = Param.Latency("Write to read, same rank switching time")
# read-to-write, same rank turnaround penalty
tRTW = Param.Latency("Read to write, same rank switching time")
# rank-to-rank bus delay penalty
# this does not correlate to a memory timing parameter and encompasses:
# 1) RD-to-RD, 2) WR-to-WR, 3) RD-to-WR, and 4) WR-to-RD
# different rank bus delay
tCS = Param.Latency("Rank to rank switching time")