arm, dev: Add a NAND flash timing model

This adds a NAND flash timing model. This model takes the number of
planes into account and is ultimately intended to be used as a
high-level performance model for any device using flash. To access the
memory, use either readMemory or writeMemory.

To make use of the model you will need an interface model
such as UFSHostDevice, which is part of a separate patch.

At the moment the flash device is part of the ARM device tree since
the only use if the UFSHostDevice, and that in turn relies on the ARM
GIC.

6 files changed, 1065 insertions, 0 deletions

diff --git a/src/dev/arm/AbstractNVM.py b/src/dev/arm/AbstractNVM.py
new file mode 100644
index 000000000..2a50e76c3
--- /dev/null
+++ b/src/dev/arm/AbstractNVM.py
@@ -0,0 +1,46 @@
+# Copyright (c) 2013-2015 ARM Limited
+# All rights reserved.
+#
+# 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.
+#
+# 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
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Rene de Jong
+#
+
+from m5.params import *
+from m5.proxy import *
+from m5.SimObject import SimObject
+
+class AbstractNVM(SimObject):
+    type = 'AbstractNVM'
+    abstract = True
+    cxx_header = "dev/arm/abstract_nvm.hh"
diff --git a/src/dev/arm/FlashDevice.py b/src/dev/arm/FlashDevice.py
new file mode 100644
index 000000000..ed3b9d04d
--- /dev/null
+++ b/src/dev/arm/FlashDevice.py
@@ -0,0 +1,74 @@
+# Copyright (c) 2013-2015 ARM Limited
+# All rights reserved.
+#
+# 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.
+#
+# 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
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Authors: Rene de Jong
+#
+
+from m5.params import *
+from m5.proxy import *
+from AbstractNVM import *
+
+#Distribution of the data.
+#sequential: sequential (address n+1 is likely to be on the same plane as n)
+#Random: @TODO Not yet implemented
+#stripe: striping over all the planes
+class DataDistribution(Enum): vals = ['sequential', 'stripe']
+
+class FlashDevice(AbstractNVM):
+    type = 'FlashDevice'
+    cxx_header = "dev/arm/flash_device.hh"
+    # default blocksize is 128 kB.This seems to be the most common size in
+    # mobile devices (not the image blocksize)
+    blk_size = Param.MemorySize("128kB", "Size of one disk block")
+    # disk page size is 2 kB. This is the most commonly used page size in
+    # flash devices
+    page_size = Param.MemorySize("2kB", "Size of one disk page")
+    # There are many GC flavours. It is impossible to cover them all; this
+    # parameter enables the approximation of different GC algorithms
+    GC_active = Param.Percent(50, "Percentage of the time (in whole numbers) \
+        that the GC is activated if a block is full")
+    # Access latencies. Different devices will have different latencies, but
+    # the latencies will be around the default values.
+    read_lat = Param.Latency("25us", "Read Latency")
+    write_lat = Param.Latency("200us", "Write Latency")
+    erase_lat = Param.Latency("1500us", "Erase Delay")
+    # Number of planes ought to be a power of two according to ONFI standard
+    num_planes = Param.UInt32(1, "Number of planes per die")
+    # Data distribution. Default is none. It is adviced to switch to stripe
+    # when more than one plane is used.
+    data_distribution = Param.DataDistribution('sequential', "Distribution \
+        of the data in the adress table; Stripe needed for multiple\
+        planes; otherwise use: sequential")
+
diff --git a/src/dev/arm/SConscript b/src/dev/arm/SConscript
index 7ed85a587..09ee7b4e5 100644
--- a/src/dev/arm/SConscript
+++ b/src/dev/arm/SConscript
@@ -40,6 +40,8 @@
 Import('*')
 
 if env['TARGET_ISA'] == 'arm':
+    SimObject('AbstractNVM.py')
+    SimObject('FlashDevice.py')
     SimObject('Gic.py')
     SimObject('RealView.py')
     SimObject('EnergyCtrl.py')
@@ -48,6 +50,7 @@ if env['TARGET_ISA'] == 'arm':
     Source('amba_device.cc')
     Source('amba_fake.cc')
     Source('base_gic.cc')
+    Source('flash_device.cc')
     Source('generic_timer.cc')
     Source('gic_pl390.cc')
     Source('gic_v2m.cc')
@@ -64,6 +67,7 @@ if env['TARGET_ISA'] == 'arm':
     Source('energy_ctrl.cc')
 
     DebugFlag('AMBA')
+    DebugFlag('FlashDevice')
     DebugFlag('HDLcd')
     DebugFlag('PL111')
     DebugFlag('GICV2M')
diff --git a/src/dev/arm/abstract_nvm.hh b/src/dev/arm/abstract_nvm.hh
new file mode 100644
index 000000000..0882df215
--- /dev/null
+++ b/src/dev/arm/abstract_nvm.hh
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2013-2015 ARM Limited
+ * All rights reserved
+ *
+ * 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.
+ *
+ * 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
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Rene de Jong
+ */
+
+#ifndef __DEV_ARM_ABSTRACT_NVM_HH__
+#define __DEV_ARM_ABSTRACT_NVM_HH__
+
+#include "base/callback.hh"
+#include "params/AbstractNVM.hh"
+#include "sim/sim_object.hh"
+
+/**
+ * This is an interface between the disk interface (which will handle the disk
+ * data transactions) and the timing model. The timing model only takes care
+ * of calculating the appropriate delay to the disk, and calling back a
+ * function when the action has completed. All the other associated actions
+ * (such as getting data from A to B) should be taken care of by the disk
+ * interface.
+ */
+class AbstractNVM : public SimObject
+{
+
+  public:
+    AbstractNVM(const AbstractNVMParams* p): SimObject(p) {};
+    virtual ~AbstractNVM() {};
+
+    /**
+     * Initialize Memory.
+     * This function is used to set the memory device dimensions to the
+     * dimensions that it controls. For instance, One can imagine that the
+     * memory is one disk, e.g. the /data partition of Android, which means
+     * that the data handling part will have an image of /data. On the other
+     * hand one might want to set up a Raid like configuration, without
+     * wanting to create multiple disk images. In that case one can choose to
+     * devide the image over multiple memory devices in any way he wants
+     * (i.e. higher layers can implement some division based on logical
+     * addresses, or intelligent file system interpretation analysis; to
+     * effectively devide the disk over the devices; enabling object oriented
+     * storage devices).
+     * Moving this function outside of the constructor allows you the
+     * flexibility to make this decision once the image is loaded.
+     *
+     * @param disk_size disksize in sectors; value can be obtained from the
+     * disk image
+     * @param sector_size size of one sector in bytes; value is defined in
+     * disk_image.hh
+     */
+    virtual void initializeMemory(uint64_t disk_size, uint32_t sector_size) =
+        0;
+
+    /**
+     * Access functions
+     * Access function to simulate a read/write access to the memory. Once
+     * the action has completed, the Callback event should be called. Putting
+     * a NULL pointer as callback is valid syntax, and should result in the
+     * simulation of the access, but with no callback to the higher layer.
+     * This may be used to occupy the device, such that next actions will be
+     * delayed. The read/write function will schedule the incoming requests
+     * on a first come first serve basis.
+     *
+     * @param address The logical address to a location in the Non-volatile
+     * memory.
+     * @param amount The amount of data transfered from the NVM in bytes
+     * @param event A pointer to a callback function that will perform the
+     * actions taken by the disk controller on successfull completion of the
+     * data transfer between the disk and the disk controller.
+     */
+    virtual void readMemory(uint64_t address, uint32_t amount,
+                            Callback *event) = 0;
+    virtual void writeMemory(uint64_t address, uint32_t amount,
+                             Callback *event) = 0;
+};
+
+#endif //__DEV_ARM_ABSTRACT_NVM_HH__
diff --git a/src/dev/arm/flash_device.cc b/src/dev/arm/flash_device.cc
new file mode 100644
index 000000000..eaa839178
--- /dev/null
+++ b/src/dev/arm/flash_device.cc
@@ -0,0 +1,630 @@
+/*
+ * Copyright (c) 2013-2015 ARM Limited
+ * All rights reserved
+ *
+ * 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.
+ *
+ * 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
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Rene de Jong
+ */
+
+/** @file
+ * This simplistic flash model is designed to model managed SLC NAND flash.
+ * This device will need an interface module (such as NVMe or UFS); Note that
+ * this model only calculates the delay and does not perform the actual
+ * transaction.
+ *
+ * To access the memory, use either readMemory or writeMemory. This will
+ * schedule an event at the tick where the action will finish. If a callback
+ * has been given as argument then that function will be called on completion
+ * of that event. Note that this does not guarantee that there are no other
+ * actions pending in the flash device.
+ *
+ * IMPORTANT: number of planes should be a power of 2.
+ */
+
+#include "dev/arm/flash_device.hh"
+
+#include "debug/Drain.hh"
+
+/**
+ * Create this device
+ */
+
+FlashDevice*
+FlashDeviceParams::create()
+{
+    return new FlashDevice(this);
+}
+
+
+/**
+ * Flash Device constructor and destructor
+ */
+
+FlashDevice::FlashDevice(const FlashDeviceParams* p):
+    AbstractNVM(p),
+    diskSize(0),
+    blockSize(p->blk_size),
+    pageSize(p->page_size),
+    GCActivePercentage(p->GC_active),
+    readLatency(p->read_lat),
+    writeLatency(p->write_lat),
+    eraseLatency(p->erase_lat),
+    dataDistribution(p->data_distribution),
+    numPlanes(p->num_planes),
+    pagesPerBlock(0),
+    pagesPerDisk(0),
+    blocksPerDisk(0),
+    planeMask(numPlanes - 1),
+    drainManager(NULL),
+    planeEventQueue(numPlanes),
+    planeEvent(this)
+{
+
+    /*
+     * Let 'a' be a power of two of n bits, written such that a-n is the msb
+     * and a-0 is the lsb. Since it is a power of two, only one bit (a-x,
+     * with 0 <= x <= n) is set. If we subtract one from this number the bits
+     * a-(x-1) to a-0 are set and all the other bits are cleared. Hence a
+     * bitwise AND with those two numbers results in an integer with all bits
+     * cleared.
+     */
+    if(numPlanes & planeMask)
+        fatal("Number of planes is not a power of 2 in flash device.\n");
+}
+
+/**
+ * Initiates all the flash functions: initializes the lookup tables, age of
+ * the device, etc. This can only be done once the disk image is known.
+ * Thats why it can't be done in the constructor.
+ */
+void
+FlashDevice::initializeFlash(uint64_t disk_size, uint32_t sector_size)
+{
+    diskSize = disk_size * sector_size;
+    pagesPerBlock = blockSize / pageSize;
+    pagesPerDisk = diskSize / pageSize;
+    blocksPerDisk = diskSize / blockSize;
+
+    /** Sanity information: check flash configuration */
+    DPRINTF(FlashDevice, "diskSize: %d Bytes; %d pages per block, %d pages "
+            "per disk\n", diskSize, pagesPerBlock, pagesPerDisk);
+
+    locationTable.resize(pagesPerDisk);
+
+    /**Garbage collection related*/
+    blockValidEntries.resize(blocksPerDisk, 0);
+    blockEmptyEntries.resize(blocksPerDisk, pagesPerBlock);
+
+    /**
+     * This is a bitmap. Every bit is a page
+     * unknownPages is a vector of 32 bit integers. If every page was an
+     * integer, the total size would be pagesPerDisk; since we can map one
+     * page per bit we need ceil(pagesPerDisk/32) entries. 32 = 1 << 5 hence
+     * it will do to just shift pagesPerDisk five positions and add one. This
+     * will allocate one integer to many for this data structure in the worst
+     * case.
+     */
+    unknownPages.resize((pagesPerDisk >> 5) + 1, 0xFFFFFFFF);
+
+    for (uint32_t count = 0; count < pagesPerDisk; count++) {
+        //setup lookup table + physical aspects
+
+        if (dataDistribution == Enums::stripe) {
+            locationTable[count].page = count / blocksPerDisk;
+            locationTable[count].block = count % blocksPerDisk;
+
+        } else {
+            locationTable[count].page = count % pagesPerBlock;
+            locationTable[count].block = count / pagesPerBlock;
+        }
+    }
+}
+
+FlashDevice::~FlashDevice()
+{
+    DPRINTF(FlashDevice, "Remove FlashDevice\n");
+}
+
+/**
+ * Handles the accesses to the device.
+ * The function determines when certain actions are scheduled and schedules
+ * an event that uses the callback function on completion of the action.
+ */
+void
+FlashDevice::accessDevice(uint64_t address, uint32_t amount, Callback *event,
+                          Actions action)
+{
+    DPRINTF(FlashDevice, "Flash calculation for %d bytes in %d pages\n"
+            , amount, pageSize);
+
+    std::vector<Tick> time(numPlanes, 0);
+    uint64_t logic_page_addr = address / pageSize;
+    uint32_t plane_address = 0;
+
+    /**
+     * The access will be broken up in a number of page accesses. The number
+     * of page accesses depends on the amount that needs to be transfered.
+     * The assumption here is that the interface is completely ignorant of
+     * the page size and that this model has to figure out all of the
+     * transaction characteristics.
+     */
+    for (uint32_t count = 0; amount > (count * pageSize); count++) {
+        uint32_t index = (locationTable[logic_page_addr].block *
+                          pagesPerBlock) + (logic_page_addr % pagesPerBlock);
+
+        DPRINTF(FlashDevice, "Index 0x%8x, Block 0x%8x, pages/block %d,"
+                " logic address 0x%8x\n", index,
+                locationTable[logic_page_addr].block, pagesPerBlock,
+                logic_page_addr);
+        DPRINTF(FlashDevice, "Page %d; %d bytes up to this point\n", count,
+                (count * pageSize));
+
+        plane_address = locationTable[logic_page_addr].block & planeMask;
+
+        if (action == ActionRead) {
+            //lookup
+            //call accessTimes
+            time[plane_address] += accessTimes(locationTable[logic_page_addr]
+                                               .block, ActionRead);
+
+            /*stats*/
+            stats.readAccess.sample(logic_page_addr);
+            stats.readLatency.sample(time[plane_address]);
+        } else { //write
+            //lookup
+            //call accessTimes if appropriate, page may be unknown, so lets
+            //give it the benefit of the doubt
+
+            if (getUnknownPages(index))
+                time[plane_address] += accessTimes
+                    (locationTable[logic_page_addr].block, ActionWrite);
+
+            else //A remap is needed
+                time[plane_address] += remap(logic_page_addr);
+
+            /*stats*/
+            stats.writeAccess.sample(logic_page_addr);
+            stats.writeLatency.sample(time[plane_address]);
+        }
+
+        /**
+         * Check if the page is known and used. unknownPages is a bitmap of
+         * all the pages. It tracks wether we can be sure that the
+         * information of this page is taken into acount in the model (is it
+         * considered in blockValidEntries and blockEmptyEntries?). If it has
+         * been used in the past, then it is known.
+         */
+        if (getUnknownPages(index)) {
+            clearUnknownPages(index);
+            --blockEmptyEntries[locationTable[logic_page_addr].block];
+            ++blockValidEntries[locationTable[logic_page_addr].block];
+        }
+
+        stats.fileSystemAccess.sample(address);
+        ++logic_page_addr;
+    }
+
+    /**
+     * previous part of the function found the times spend in different
+     * planes, now lets find the maximum to know when to callback the disk
+     */
+    for (uint32_t count = 0; count < numPlanes; count++){
+        plane_address = (time[plane_address] > time[count]) ? plane_address
+            : count;
+
+        DPRINTF(FlashDevice, "Plane %d is busy for %d ticks\n", count,
+                time[count]);
+
+        if  (time[count] != 0) {
+
+            struct CallBackEntry cbe;
+            /**
+             * If there are no events for this plane, then add the current
+             * time to the occupation time; otherwise, plan it after the
+             * last event. If by chance that event is handled in this tick,
+             * then we would still end up with the same result.
+             */
+            if (planeEventQueue[count].empty())
+                cbe.time = time[count] + curTick();
+            else
+                cbe.time = time[count] +
+                           planeEventQueue[count].back().time;
+            cbe.function = NULL;
+            planeEventQueue[count].push_back(cbe);
+
+            DPRINTF(FlashDevice, "scheduled at: %ld\n", cbe.time);
+
+            if (!planeEvent.scheduled())
+                schedule(planeEvent, planeEventQueue[count].back().time);
+            else if (planeEventQueue[count].back().time < planeEvent.when())
+                reschedule(planeEvent,
+                    planeEventQueue[plane_address].back().time, true);
+        }
+    }
+
+    //worst case two plane finish at the same time, each triggers an event
+    //and this callback will be called once. Maybe before the other plane
+    //could execute its event, but in the same tick.
+    planeEventQueue[plane_address].back().function = event;
+    DPRINTF(FlashDevice, "Callback queued for plane %d; %d in queue\n",
+            plane_address, planeEventQueue[plane_address].size());
+    DPRINTF(FlashDevice, "first event @ %d\n", planeEvent.when());
+}
+
+/**
+ * When a plane completes its action, this event is triggered. When a
+ * callback function was associated with that event, it will be called.
+ */
+
+void
+FlashDevice::actionComplete()
+{
+    DPRINTF(FlashDevice, "Plane action completed\n");
+    uint8_t plane_address = 0;
+
+    uint8_t next_event = 0;
+
+    /**Search for a callback that is supposed to happen in this Tick*/
+    for (plane_address = 0; plane_address < numPlanes; plane_address++) {
+        if (!planeEventQueue[plane_address].empty()) {
+            /**
+             * Invariant: All queued events are scheduled in the present
+             *  or future.
+             */
+            assert(planeEventQueue[plane_address].front().time >= curTick());
+
+            if (planeEventQueue[plane_address].front().time == curTick()) {
+                /**
+                 * To ensure that the follow-up action is executed correctly,
+                 * the callback entry first need to be cleared before it can
+                 * be called.
+                 */
+                Callback *temp = planeEventQueue[plane_address].front().
+                                 function;
+                planeEventQueue[plane_address].pop_front();
+
+                /**Found a callback, lets make it happen*/
+                if (temp != NULL) {
+                    DPRINTF(FlashDevice, "Callback, %d\n", plane_address);
+                    temp->process();
+                }
+            }
+        }
+    }
+
+    /** Find when to schedule the planeEvent next */
+    for (plane_address = 0; plane_address < numPlanes; plane_address++) {
+        if (!planeEventQueue[plane_address].empty())
+            if (planeEventQueue[next_event].empty() ||
+                    (planeEventQueue[plane_address].front().time <
+                     planeEventQueue[next_event].front().time))
+                next_event = plane_address;
+    }
+
+    /**Schedule the next plane that will be ready (if any)*/
+    if (!planeEventQueue[next_event].empty()) {
+        DPRINTF(FlashDevice, "Schedule plane: %d\n", plane_address);
+        reschedule(planeEvent, planeEventQueue[next_event].front().time, true);
+    }
+
+    checkDrain();
+
+    DPRINTF(FlashDevice, "returing from flash event\n");
+    DPRINTF(FlashDevice, "first event @ %d\n", planeEvent.when());
+}
+
+/**
+ * Handles the remapping of the pages. It is a (I hope) sensible statistic
+ * approach. asumption: garbage collection happens when a clean is needed
+ * (may become stochastic function).
+ */
+Tick
+FlashDevice::remap(uint64_t logic_page_addr)
+{
+    /**
+     * Are there any empty left in this Block, or do we need to do an erase
+     */
+    if (blockEmptyEntries[locationTable[logic_page_addr].block] > 0) {
+        //just a remap
+        //update tables
+        --blockEmptyEntries[locationTable[logic_page_addr].block];
+        //access to this table won't be sequential anymore
+        locationTable[logic_page_addr].page = pagesPerBlock + 2;
+        //access new block
+        Tick time = accessTimes(locationTable[logic_page_addr].block,
+                                ActionWrite);
+
+        DPRINTF(FlashDevice, "Remap returns %d ticks\n", time);
+        return time;
+
+    } else {
+        //calculate how much time GC would have taken
+        uint32_t block = locationTable[logic_page_addr].block;
+        Tick time = ((GCActivePercentage *
+                       (accessTimes(block, ActionCopy) +
+                        accessTimes(block, ActionErase)))
+                     / 100);
+
+        //use block as the logical start address of the block
+        block = locationTable[logic_page_addr].block * pagesPerBlock;
+
+        //assumption: clean will improve locality
+        for (uint32_t count = 0; count < pageSize; count++) {
+            locationTable[block + count].page = (block + count) %
+                pagesPerBlock;
+            ++count;
+        }
+
+        blockEmptyEntries[locationTable[logic_page_addr].block] =
+            pagesPerBlock;
+        /*stats*/
+        ++stats.totalGCActivations;
+
+        DPRINTF(FlashDevice, "Remap with erase action returns %d ticks\n",
+                time);
+
+        return time;
+    }
+
+}
+
+/**
+ * Calculates the accesstime per operation needed
+ */
+Tick
+FlashDevice::accessTimes(uint64_t block, Actions action)
+{
+    Tick time = 0;
+
+    switch(action) {
+      case ActionRead: {
+          /**Just read the page*/
+          time = readLatency;
+      } break;
+
+      case ActionWrite: {
+          /**Write the page, and read the result*/
+          time = writeLatency + readLatency;
+      } break;
+
+      case ActionErase: {
+          /**Erase and check wether it was successfull*/
+          time = eraseLatency + readLatency;
+      } break;
+
+      case ActionCopy: {
+          /**Copy every valid page*/
+          uint32_t validpages = blockValidEntries[block];
+          time = validpages * (readLatency + writeLatency);
+      } break;
+
+      default: break;
+    }
+
+    //Used to determine sequential action.
+    DPRINTF(FlashDevice, "Access returns %d ticks\n", time);
+    return time;
+}
+
+/**
+ * clearUnknownPages. defines that a page is known and used
+ * unknownPages is a bitmap of all the pages. It tracks wether we can be sure
+ * that the information of this page is taken into acount in the model (is it
+ * considered in blockValidEntries and blockEmptyEntries?). If it has been
+ * used in the past, then it is known. But it needs to be tracked to make
+ * decisions about write accesses, and indirectly about copy actions. one
+ * unknownPage entry is a 32 bit integer. So if we have a page index, then
+ * that means that we need entry floor(index/32) (index >> 5) and we need to
+ * select the bit which number is equal to the remainder of index/32
+ * (index%32). The bit is cleared to make sure that we see it as considered
+ * in the future.
+ */
+
+inline
+void
+FlashDevice::clearUnknownPages(uint32_t index)
+{
+    unknownPages[index >> 5] &= ~(0x01 << (index % 32));
+}
+
+/**
+ * getUnknownPages. Verify wether a page is known
+ */
+
+inline
+bool
+FlashDevice::getUnknownPages(uint32_t index)
+{
+    return unknownPages[index >> 5] & (0x01 << (index % 32));
+}
+
+void
+FlashDevice::regStats()
+{
+    using namespace Stats;
+
+    std::string fd_name = name() + ".FlashDevice";
+
+    // Register the stats
+    /** Amount of GC activations*/
+    stats.totalGCActivations
+        .name(fd_name + ".totalGCActivations")
+        .desc("Number of Garbage collector activations")
+        .flags(none);
+
+    /** Histogram of address accesses*/
+    stats.writeAccess
+        .init(2)
+        .name(fd_name + ".writeAccessHist")
+        .desc("Histogram of write addresses")
+        .flags(pdf);
+    stats.readAccess
+        .init(2)
+        .name(fd_name + ".readAccessHist")
+        .desc("Histogram of read addresses")
+        .flags(pdf);
+    stats.fileSystemAccess
+        .init(100)
+        .name(fd_name + ".fileSystemAccessHist")
+        .desc("Histogram of file system accesses")
+        .flags(pdf);
+
+    /** Histogram of access latencies*/
+    stats.writeLatency
+        .init(100)
+        .name(fd_name + ".writeLatencyHist")
+        .desc("Histogram of write latency")
+        .flags(pdf);
+    stats.readLatency
+        .init(100)
+        .name(fd_name + ".readLatencyHist")
+        .desc("Histogram of read latency")
+        .flags(pdf);
+}
+
+/**
+ * Serialize; needed to create checkpoints
+ */
+
+void
+FlashDevice::serialize(std::ostream &os)
+{
+    SERIALIZE_SCALAR(planeMask);
+
+    int unknown_pages_size = unknownPages.size();
+    SERIALIZE_SCALAR(unknown_pages_size);
+    for (uint32_t count = 0; count < unknownPages.size(); count++)
+        SERIALIZE_SCALAR(unknownPages[count]);
+
+    int location_table_size = locationTable.size();
+    SERIALIZE_SCALAR(location_table_size);
+    for (uint32_t count = 0; count < location_table_size; count++) {
+        SERIALIZE_SCALAR(locationTable[count].page);
+        SERIALIZE_SCALAR(locationTable[count].block);
+        }
+
+    int block_valid_entries_size = blockValidEntries.size();
+    SERIALIZE_SCALAR(block_valid_entries_size);
+    for (uint32_t count = 0; count < blockValidEntries.size(); count++)
+        SERIALIZE_SCALAR(blockValidEntries[count]);
+
+    int block_empty_entries_size = blockEmptyEntries.size();
+    SERIALIZE_SCALAR(block_empty_entries_size);
+    for (uint32_t count = 0; count < blockEmptyEntries.size(); count++)
+        SERIALIZE_SCALAR(blockEmptyEntries[count]);
+
+};
+
+/**
+ * Unserialize; needed to restore from checkpoints
+ */
+
+void
+FlashDevice::unserialize(Checkpoint *cp, const std::string &section)
+{
+    UNSERIALIZE_SCALAR(planeMask);
+
+    int unknown_pages_size;
+    UNSERIALIZE_SCALAR(unknown_pages_size);
+    unknownPages.resize(unknown_pages_size);
+    for (uint32_t count = 0; count < unknown_pages_size; count++)
+        UNSERIALIZE_SCALAR(unknownPages[count]);
+
+    int location_table_size;
+    UNSERIALIZE_SCALAR(location_table_size);
+    locationTable.resize(location_table_size);
+    for (uint32_t count = 0; count < location_table_size; count++) {
+        UNSERIALIZE_SCALAR(locationTable[count].page);
+        UNSERIALIZE_SCALAR(locationTable[count].block);
+        }
+
+    int block_valid_entries_size;
+    UNSERIALIZE_SCALAR(block_valid_entries_size);
+    blockValidEntries.resize(block_valid_entries_size);
+    for (uint32_t count = 0; count < block_valid_entries_size; count++)
+        UNSERIALIZE_SCALAR(blockValidEntries[count]);
+
+    int block_empty_entries_size;
+    UNSERIALIZE_SCALAR(block_empty_entries_size);
+    blockEmptyEntries.resize(block_empty_entries_size);
+    for (uint32_t count = 0; count < block_empty_entries_size; count++)
+        UNSERIALIZE_SCALAR(blockEmptyEntries[count]);
+
+};
+
+/**
+ * Drain; needed to enable checkpoints
+ */
+
+unsigned int
+FlashDevice::drain(DrainManager *dm)
+{
+    unsigned int count = 0;
+
+    if (planeEvent.scheduled()) {
+        count = 1;
+        drainManager = dm;
+    } else {
+        DPRINTF(Drain, "Flash device in drained state\n");
+    }
+
+    if (count) {
+        DPRINTF(Drain, "Flash device is draining...\n");
+        setDrainState(Drainable::Draining);
+    } else {
+        DPRINTF(Drain, "Flash device drained\n");
+        setDrainState(Drainable::Drained);
+    }
+    return count;
+}
+
+/**
+ * Checkdrain; needed to enable checkpoints
+ */
+
+void
+FlashDevice::checkDrain()
+{
+    if (drainManager == NULL) {
+        return;
+    }
+
+    if (planeEvent.when() > curTick()) {
+        DPRINTF(Drain, "Flash device is still draining\n");
+    } else {
+        DPRINTF(Drain, "Flash device is done draining\n");
+        drainManager->signalDrainDone();
+        drainManager = NULL;
+    }
+}
diff --git a/src/dev/arm/flash_device.hh b/src/dev/arm/flash_device.hh
new file mode 100644
index 000000000..8dc4ba04a
--- /dev/null
+++ b/src/dev/arm/flash_device.hh
@@ -0,0 +1,202 @@
+/*
+ * Copyright (c) 2013-2015 ARM Limited
+ * All rights reserved
+ *
+ * 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.
+ *
+ * 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
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Rene de Jong
+ */
+#ifndef __DEV_ARM_FLASH_DEVICE_HH__
+#define __DEV_ARM_FLASH_DEVICE_HH__
+
+#include <deque>
+
+#include "base/statistics.hh"
+#include "debug/FlashDevice.hh"
+#include "dev/arm/abstract_nvm.hh"
+#include "enums/DataDistribution.hh"
+#include "params/FlashDevice.hh"
+#include "sim/serialize.hh"
+
+/**
+ * Flash Device model
+ * The Flash Device model is a timing model for a NAND flash device.
+ * It doesn't tranfer any data
+ */
+class FlashDevice : public AbstractNVM
+{
+  public:
+
+    /** Initialize functions*/
+    FlashDevice(const FlashDeviceParams*);
+    ~FlashDevice();
+
+    /** Checkpoint functions*/
+    unsigned int drain(DrainManager *dm);
+    void checkDrain();
+    void serialize(std::ostream &os);
+    void unserialize(Checkpoint *cp, const std::string &section);
+
+  private:
+    /** Defines the possible actions to the flash*/
+    enum Actions {
+        ActionRead,
+        ActionWrite,
+        ActionErase,
+        /**
+         * A copy involves taking all the used pages from a block and store
+         *  it in another
+         */
+        ActionCopy
+    };
+
+    /** Every logical address maps to a physical block and a physical page*/
+    struct PageMapEntry {
+        uint32_t page;
+        uint32_t block;
+    };
+
+    struct CallBackEntry {
+        Tick time;
+        Callback *function;
+    };
+
+    struct FlashDeviceStats {
+        /** Amount of GC activations*/
+        Stats::Scalar totalGCActivations;
+
+        /** Histogram of address accesses*/
+        Stats::Histogram writeAccess;
+        Stats::Histogram readAccess;
+        Stats::Histogram fileSystemAccess;
+
+        /** Histogram of access latencies*/
+        Stats::Histogram writeLatency;
+        Stats::Histogram readLatency;
+    };
+
+    /** Device access functions Inherrited from AbstractNVM*/
+    virtual void initializeMemory(uint64_t disk_size, uint32_t sector_size)
+    {
+        initializeFlash(disk_size, sector_size);
+    }
+
+    virtual void readMemory(uint64_t address, uint32_t amount,
+                            Callback *event)
+    {
+        accessDevice(address, amount, event, ActionRead);
+    }
+    virtual void writeMemory(uint64_t address, uint32_t amount,
+                             Callback *event)
+    {
+        accessDevice(address, amount, event, ActionWrite);
+    }
+
+    /**Initialization function; called when all disk specifics are known*/
+    void initializeFlash(uint64_t disk_size, uint32_t sector_size);
+
+    /**Flash action function*/
+    void accessDevice(uint64_t address, uint32_t amount, Callback *event,
+                      Actions action);
+
+    /** Event rescheduler*/
+    void actionComplete();
+
+    /** FTL functionality */
+    Tick remap(uint64_t logic_page_addr);
+
+    /** Access time calculator*/
+    Tick accessTimes(uint64_t address, Actions accesstype);
+
+    /** Function to indicate that a page is known*/
+    void clearUnknownPages(uint32_t index);
+
+    /** Function to test if a page is known*/
+    bool getUnknownPages(uint32_t index);
+
+    /**Stats register function*/
+    void regStats();
+
+    /** Disk sizes in bytes */
+    uint64_t diskSize;
+    const uint32_t blockSize;
+    const uint32_t pageSize;
+
+    /** Garbage collection algorithm emulator */
+    const uint32_t GCActivePercentage;
+
+    /** Access latencies */
+    const Tick readLatency;
+    const Tick writeLatency;
+    const Tick eraseLatency;
+
+    /** Flash organization */
+    const Enums::DataDistribution dataDistribution;
+    const uint32_t numPlanes;
+
+    /** RequestHandler stats */
+    struct FlashDeviceStats stats;
+
+    /** Disk dimensions in pages and blocks */
+    uint32_t pagesPerBlock;
+    uint32_t pagesPerDisk;
+    uint32_t blocksPerDisk;
+
+    uint32_t planeMask;
+
+    /**
+     * drain manager
+     * Needed to be able to implement checkpoint functionality
+     */
+
+    DrainManager *drainManager;
+
+    /**
+     * when the disk is first started we are unsure of the number of
+     * used pages, this variable will help determining what we do know.
+     */
+    std::vector<uint32_t> unknownPages;
+    /** address to logic place has a block and a page field*/
+    std::vector<struct PageMapEntry> locationTable;
+    /** number of valid entries per block*/
+    std::vector<uint32_t> blockValidEntries;
+    /** number of empty entries*/
+    std::vector<uint32_t> blockEmptyEntries;
+
+    /**This vector of queues keeps track of all the callbacks per plane*/
+    std::vector<std::deque<struct CallBackEntry> > planeEventQueue;
+
+    /** Completion event */
+    EventWrapper<FlashDevice, &FlashDevice::actionComplete> planeEvent;
+};
+#endif //__DEV_ARM_FLASH_DEVICE_HH__