path: root/src/mem/SimpleDRAM.py

# Copyright (c) 2012-2013 ARM Limited
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# property including but not limited to intellectual property relating
# to a hardware implementation of the functionality of the software
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# 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
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#
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# modification, are permitted provided that the following conditions are
# met: redistributions of source code must retain the above copyright
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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# Authors: Andreas Hansson
#          Ani Udipi

from m5.params import *
from AbstractMemory import *

# Enum for memory scheduling algorithms, currently First-Come
# First-Served and a First-Row Hit then First-Come First-Served
class MemSched(Enum): vals = ['fcfs', 'frfcfs']

# Enum for the address mapping. With Ra, Co, Ba and Ch denoting rank,
# column, bank and channel, respectively, and going from MSB to LSB.
# Available are RaBaChCo and RaBaCoCh, that are suitable for an
# open-page policy, optimising for sequential accesses hitting in the
# open row. For a closed-page policy, CoRaBaCh maximises parallelism.
class AddrMap(Enum): vals = ['RaBaChCo', 'RaBaCoCh', 'CoRaBaCh']

# Enum for the page policy, either open or close.
class PageManage(Enum): vals = ['open', 'close']

# SimpleDRAM is a single-channel single-ported DRAM controller model
# that aims to model the most important system-level performance
# effects of a DRAM without getting into too much detail of the DRAM
# itself.
class SimpleDRAM(AbstractMemory):
    type = 'SimpleDRAM'
    cxx_header = "mem/simple_dram.hh"

    # single-ported on the system interface side, instantiate with a
    # bus in front of the controller for multiple ports
    port = SlavePort("Slave port")

    # the basic configuration of the controller architecture
    write_buffer_size = Param.Unsigned(32, "Number of write queue entries")
    read_buffer_size = Param.Unsigned(32, "Number of read queue entries")

    # threshold in percent for when to trigger writes and start
    # emptying the write buffer as it starts to get full
    write_high_thresh_perc = Param.Percent(70, "Threshold to trigger writes")

    # threshold in percentage for when to stop writes if the read
    # queue has an entry. An optimisaton to give reads priority if
    # sufficient number of writes are scheduled and write queue has
    # sufficient number of free entries
    write_low_thresh_perc = Param.Percent(0, "Threshold to stop writes")

    # scheduler, address map and page policy
    mem_sched_policy = Param.MemSched('frfcfs', "Memory scheduling policy")
    addr_mapping = Param.AddrMap('RaBaChCo', "Address mapping policy")
    page_policy = Param.PageManage('open', "Page closure management policy")

    # pipeline latency of the controller and PHY, split into a
    # frontend part and a backend part, with reads and writes serviced
    # by the queues only seeing the frontend contribution, and reads
    # serviced by the memory seeing the sum of the two
    static_frontend_latency = Param.Latency("10ns", "Static frontend latency")
    static_backend_latency = Param.Latency("10ns", "Static backend latency")

    # the physical organisation of the DRAM
    device_bus_width = Param.Unsigned("data bus width in bits for each DRAM "\
                                      "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")
    # only used for the address mapping as the controller by
    # construction is a single channel and multiple controllers have
    # to be instantiated for a multi-channel configuration
    channels = Param.Unsigned(1, "Number of channels")

    # timing behaviour and constraints - all in nanoseconds

    # the amount of time in nanoseconds from issuing an activate command
    # to the data being available in the row buffer for a read/write
    tRCD = Param.Latency("RAS to CAS delay")

    # the time from issuing a read/write command to seeing the actual data
    tCL = Param.Latency("CAS latency")

    # minimum time between a precharge and subsequent activate
    tRP = Param.Latency("Row precharge time")

    # minimum time between an activate and a precharge to the same row
    tRAS = Param.Latency("ACT to PRE delay")

    # 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.
    # 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 SimpleDRAM controller
    tBURST = Param.Latency("Burst duration (for DDR burst length / 2 cycles)")

    # time taken to complete one refresh cycle (N rows in all banks)
    tRFC = Param.Latency("Refresh cycle time")

    # refresh command interval, how often a "ref" command needs
    # to be sent. It is 7.8 us for a 64ms refresh requirement
    tREFI = Param.Latency("Refresh command interval")

    # write-to-read turn around penalty, assumed same as read-to-write
    tWTR = Param.Latency("Write to read switching time")

    # minimum row activate to row activate delay time
    tRRD = Param.Latency("ACT to ACT delay")

    # time window in which a maximum number of activates are allowed
    # to take place, set to 0 to disable
    tXAW = Param.Latency("X activation window")
    activation_limit = Param.Unsigned("Max number of activates in window")

    # Currently rolled into other params
    ######################################################################

    # tRC  - assumed to be tRAS + tRP

# A single DDR3 x64 interface (one command and address bus), with
# default timings based on DDR3-1600 4 Gbit parts in an 8x8
# configuration, which would amount to 4 Gbyte of memory.
class DDR3_1600_x64(SimpleDRAM):
    # 8x8 configuration, 8 devices each with an 8-bit interface
    device_bus_width = 8

    # DDR3 is a BL8 device
    burst_length = 8

    # Each device has a page (row buffer) size of 1KB
    # (this depends on the memory density)
    device_rowbuffer_size = '1kB'

    # 8x8 configuration, so 8 devices
    devices_per_rank = 8

    # Use two ranks
    ranks_per_channel = 2

    # DDR3 has 8 banks in all configurations
    banks_per_rank = 8

    # DDR3-1600 11-11-11-28
    tRCD = '13.75ns'
    tCL = '13.75ns'
    tRP = '13.75ns'
    tRAS = '35ns'

    # 8 beats across an x64 interface translates to 4 clocks @ 800 MHz.
    # Note this is a BL8 DDR device.
    tBURST = '5ns'

    # DDR3, 4 Gbit has a tRFC of 240 CK and tCK = 1.25 ns
    tRFC = '300ns'

    # DDR3, <=85C, half for >85C
    tREFI = '7.8us'

    # Greater of 4 CK or 7.5 ns, 4 CK @ 800 MHz = 5 ns
    tWTR = '7.5ns'

    # Assume 5 CK for activate to activate for different banks
    tRRD = '6.25ns'

    # With a 2kbyte page size, DDR3-1600 lands around 40 ns
    tXAW = '40ns'
    activation_limit = 4


# A single LPDDR2-S4 x32 interface (one command/address bus), with
# default timings based on a LPDDR2-1066 4 Gbit part in a 1x32
# configuration.
class LPDDR2_S4_1066_x32(SimpleDRAM):
    # 1x32 configuration, 1 device with a 32-bit interface
    device_bus_width = 32

    # LPDDR2_S4 is a BL4 and BL8 device
    burst_length = 8

    # Each device has a page (row buffer) size of 1KB
    # (this depends on the memory density)
    device_rowbuffer_size = '1kB'

    # 1x32 configuration, so 1 device
    devices_per_rank = 1

    # Use a single rank
    ranks_per_channel = 1

    # LPDDR2-S4 has 8 banks in all configurations
    banks_per_rank = 8

    # Fixed at 15 ns
    tRCD = '15ns'

    # 8 CK read latency, 4 CK write latency @ 533 MHz, 1.876 ns cycle time
    tCL = '15ns'

    # Pre-charge one bank 15 ns (all banks 18 ns)
    tRP = '15ns'

    tRAS = '42ns'

    # 8 beats across an x32 DDR interface translates to 4 clocks @ 533 MHz.
    # Note this is a BL8 DDR device.
    # Requests larger than 32 bytes are broken down into multiple requests
    # in the SimpleDRAM controller
    tBURST = '7.5ns'

    # LPDDR2-S4, 4 Gbit
    tRFC = '130ns'
    tREFI = '3.9us'

    # Irrespective of speed grade, tWTR is 7.5 ns
    tWTR = '7.5ns'

    # Activate to activate irrespective of density and speed grade
    tRRD = '10.0ns'

    # Irrespective of density, tFAW is 50 ns
    tXAW = '50ns'
    activation_limit = 4

# A single WideIO x128 interface (one command and address bus), with
# default timings based on an estimated WIO-200 8 Gbit part.
class WideIO_200_x128(SimpleDRAM):
    # 1x128 configuration, 1 device with a 128-bit interface
    device_bus_width = 128

    # This is a BL4 device
    burst_length = 4

    # Each device has a page (row buffer) size of 4KB
    # (this depends on the memory density)
    device_rowbuffer_size = '4kB'

    # 1x128 configuration, so 1 device
    devices_per_rank = 1

    # Use one rank for a one-high die stack
    ranks_per_channel = 1

    # WideIO has 4 banks in all configurations
    banks_per_rank = 4

    # WIO-200
    tRCD = '18ns'
    tCL = '18ns'
    tRP = '18ns'
    tRAS = '42ns'

    # 4 beats across an x128 SDR interface translates to 4 clocks @ 200 MHz.
    # Note this is a BL4 SDR device.
    tBURST = '20ns'

    # WIO 8 Gb
    tRFC = '210ns'

    # WIO 8 Gb, <=85C, half for >85C
    tREFI = '3.9us'

    # Greater of 2 CK or 15 ns, 2 CK @ 200 MHz = 10 ns
    tWTR = '15ns'

    # Activate to activate irrespective of density and speed grade
    tRRD = '10.0ns'

    # Two instead of four activation window
    tXAW = '50ns'
    activation_limit = 2

# A single LPDDR3 x32 interface (one command/address bus), with
# default timings based on a LPDDR3-1600 4 Gbit part in a 1x32
# configuration
class LPDDR3_1600_x32(SimpleDRAM):
    # 1x32 configuration, 1 device with a 32-bit interface
    device_bus_width = 32

    # LPDDR3 is a BL8 device
    burst_length = 8

    # Each device has a page (row buffer) size of 1KB
    # (this depends on the memory density)
    device_rowbuffer_size = '1kB'

    # 1x32 configuration, so 1 device
    devices_per_rank = 1

    # Use a single rank
    ranks_per_channel = 1

    # LPDDR3 has 8 banks in all configurations
    banks_per_rank = 8

    # Fixed at 15 ns
    tRCD = '15ns'

    # 12 CK read latency, 6 CK write latency @ 800 MHz, 1.25 ns cycle time
    tCL = '15ns'

    tRAS = '42ns'

    # Pre-charge one bank 15 ns (all banks 18 ns)
    tRP = '15ns'

    # 8 beats across a x32 DDR interface translates to 4 clocks @ 800 MHz.
    # Note this is a BL8 DDR device.
    # Requests larger than 32 bytes are broken down into multiple requests
    # in the SimpleDRAM controller
    tBURST = '5ns'

    # LPDDR3, 4 Gb
    tRFC = '130ns'
    tREFI = '3.9us'

    # Irrespective of speed grade, tWTR is 7.5 ns
    tWTR = '7.5ns'

    # Activate to activate irrespective of density and speed grade
    tRRD = '10.0ns'

    # Irrespective of size, tFAW is 50 ns
    tXAW = '50ns'
    activation_limit = 4