energy: Memory-mapped Energy Controller component

This patch provides an Energy Controller device that provides software
(driver) access to a DVFS handler. The device is currently residing in
the dev/arm tree, but there is nothing inherently ARM specific in the
behaviour. It is currently only tested and supported for ARM Linux,
hence the location.

1 files changed, 264 insertions, 0 deletions

diff --git a/src/dev/arm/energy_ctrl.cc b/src/dev/arm/energy_ctrl.cc
new file mode 100644
index 000000000..cbfa5aa79
--- /dev/null
+++ b/src/dev/arm/energy_ctrl.cc
@@ -0,0 +1,264 @@
+/*
+ * Copyright (c) 2012-2014 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: Vasileios Spiliopoulos
+ *          Akash Bagdia
+ *          Stephan Diestelhorst
+ */
+
+#include "debug/EnergyCtrl.hh"
+#include "dev/arm/energy_ctrl.hh"
+#include "mem/packet.hh"
+#include "mem/packet_access.hh"
+#include "params/EnergyCtrl.hh"
+#include "sim/dvfs_handler.hh"
+
+EnergyCtrl::EnergyCtrl(const Params *p)
+    : BasicPioDevice(p, PIO_NUM_FIELDS * 4),        // each field is 32 bit
+      dvfsHandler(p->dvfs_handler),
+      domainID(0),
+      domainIDIndexToRead(0),
+      perfLevelAck(0),
+      perfLevelToRead(0),
+      updateAckEvent(this)
+{
+    fatal_if(!p->dvfs_handler, "EnergyCtrl: Needs a DVFSHandler for a "
+             "functioning system.\n");
+}
+
+Tick
+EnergyCtrl::read(PacketPtr pkt)
+{
+    assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize);
+    assert(pkt->getSize() == 4);
+    pkt->allocate();
+
+    Addr daddr = pkt->getAddr() - pioAddr;
+    assert((daddr & 3) == 0);
+    Registers reg = Registers(daddr / 4);
+
+    if (!dvfsHandler->isEnabled()) {
+        // NB: Zero is a good response if the handler is disabled
+        pkt->set<uint32_t>(0);
+        warn_once("EnergyCtrl: Disabled handler, ignoring read from reg %i\n",
+                  reg);
+        DPRINTF(EnergyCtrl, "dvfs handler disabled, return 0 for read from "\
+                "reg %i\n", reg);
+        pkt->makeAtomicResponse();
+        return pioDelay;
+    }
+
+    uint32_t result = 0;
+    Tick period;
+    double voltage;
+
+    switch(reg) {
+      case DVFS_HANDLER_STATUS:
+        result = 1;
+        DPRINTF(EnergyCtrl, "dvfs handler enabled\n");
+        break;
+      case DVFS_NUM_DOMAINS:
+        result = dvfsHandler->numDomains();
+        DPRINTF(EnergyCtrl, "reading number of domains %d\n", result);
+        break;
+      case DVFS_DOMAINID_AT_INDEX:
+        result = dvfsHandler->domainID(domainIDIndexToRead);
+        DPRINTF(EnergyCtrl, "reading domain id at index %d as %d\n",
+                domainIDIndexToRead, result);
+        break;
+      case DVFS_HANDLER_TRANS_LATENCY:
+        // Return transition latency in nanoseconds
+        result = dvfsHandler->transLatency() / SimClock::Int::ns;
+        DPRINTF(EnergyCtrl, "reading dvfs handler trans latency %d ns\n",
+                result);
+        break;
+      case DOMAIN_ID:
+        result = domainID;
+        DPRINTF(EnergyCtrl, "reading domain id:%d\n", result);
+        break;
+      case PERF_LEVEL:
+        result = dvfsHandler->perfLevel(domainID);
+        DPRINTF(EnergyCtrl, "reading domain %d perf level: %d\n",
+                domainID, result);
+        break;
+      case PERF_LEVEL_ACK:
+        result = perfLevelAck;
+        DPRINTF(EnergyCtrl, "reading ack:%d\n", result);
+        // Signal is set for a single read only
+        if (result == 1)
+            perfLevelAck = 0;
+        break;
+      case NUM_OF_PERF_LEVELS:
+        result = dvfsHandler->numPerfLevels(domainID);
+        DPRINTF(EnergyCtrl, "reading num of perf level:%d\n", result);
+        break;
+      case FREQ_AT_PERF_LEVEL:
+        period = dvfsHandler->clkPeriodAtPerfLevel(domainID, perfLevelToRead);
+        result = ticksTokHz(period);
+        DPRINTF(EnergyCtrl, "reading freq %d KHz at perf level: %d\n",
+                result, perfLevelToRead);
+        break;
+      case VOLT_AT_PERF_LEVEL:
+        voltage = dvfsHandler->voltageAtPerfLevel(domainID, perfLevelToRead);
+        result = toMicroVolt(voltage);
+        DPRINTF(EnergyCtrl, "reading voltage %d u-volt at perf level: %d\n",
+                result, perfLevelToRead);
+        break;
+      default:
+        panic("Tried to read EnergyCtrl at offset %#x / reg %i\n", daddr,
+              reg);
+    }
+    pkt->set<uint32_t>(result);
+    pkt->makeAtomicResponse();
+    return pioDelay;
+}
+
+Tick
+EnergyCtrl::write(PacketPtr pkt)
+{
+    assert(pkt->getAddr() >= pioAddr && pkt->getAddr() < pioAddr + pioSize);
+    assert(pkt->getSize() == 4);
+
+    uint32_t data;
+    data = pkt->get<uint32_t>();
+
+    Addr daddr = pkt->getAddr() - pioAddr;
+    assert((daddr & 3) == 0);
+    Registers reg = Registers(daddr / 4);
+
+    if (!dvfsHandler->isEnabled()) {
+        // Ignore writes to a disabled controller
+        warn_once("EnergyCtrl: Disabled handler, ignoring write %u to "\
+                  "reg %i\n", data, reg);
+        DPRINTF(EnergyCtrl, "dvfs handler disabled, ignoring write %u to "\
+                "reg %i\n", data, reg);
+        pkt->makeAtomicResponse();
+        return pioDelay;
+    }
+
+    switch(reg) {
+      case DVFS_DOMAINID_AT_INDEX:
+        domainIDIndexToRead = data;
+        DPRINTF(EnergyCtrl, "writing domain id index:%d\n",
+                domainIDIndexToRead);
+        break;
+      case DOMAIN_ID:
+        // Extra check to ensure that a valid domain ID is being queried
+        if (dvfsHandler->validDomainID(data)) {
+            domainID = data;
+            DPRINTF(EnergyCtrl, "writing domain id:%d\n", domainID);
+        } else {
+           DPRINTF(EnergyCtrl, "invalid domain id:%d\n", domainID);
+        }
+        break;
+      case PERF_LEVEL:
+        if (dvfsHandler->perfLevel(domainID, data)) {
+            if (updateAckEvent.scheduled()) {
+                // The OS driver is trying to change the perf level while
+                // another change is in flight.  This is fine, but only a
+                // single acknowledgment will be sent.
+                DPRINTF(EnergyCtrl, "descheduling previous pending ack "\
+                        "event\n");
+                deschedule(updateAckEvent);
+            }
+            schedule(updateAckEvent, curTick() + dvfsHandler->transLatency());
+            DPRINTF(EnergyCtrl, "writing domain %d perf level: %d\n",
+                    domainID, data);
+        } else {
+            DPRINTF(EnergyCtrl, "invalid / ineffective perf level:%d for "\
+                    "domain:%d\n", data, domainID);
+        }
+        break;
+      case PERF_LEVEL_TO_READ:
+        perfLevelToRead = data;
+        DPRINTF(EnergyCtrl, "writing perf level to read opp at: %d\n",
+                data);
+        break;
+      default:
+        panic("Tried to write EnergyCtrl at offset %#x\n", daddr);
+        break;
+    }
+
+    pkt->makeAtomicResponse();
+    return pioDelay;
+}
+
+void
+EnergyCtrl::serialize(std::ostream &os)
+{
+    SERIALIZE_SCALAR(domainID);
+    SERIALIZE_SCALAR(domainIDIndexToRead);
+    SERIALIZE_SCALAR(perfLevelToRead);
+    SERIALIZE_SCALAR(perfLevelAck);
+
+    Tick next_event = updateAckEvent.scheduled() ? updateAckEvent.when() : 0;
+    SERIALIZE_SCALAR(next_event);
+}
+
+void
+EnergyCtrl::unserialize(Checkpoint *cp, const std::string &section)
+{
+    UNSERIALIZE_SCALAR(domainID);
+    UNSERIALIZE_SCALAR(domainIDIndexToRead);
+    UNSERIALIZE_SCALAR(perfLevelToRead);
+    UNSERIALIZE_SCALAR(perfLevelAck);
+    Tick next_event = 0;
+    UNSERIALIZE_SCALAR(next_event);
+
+    // restore scheduled events
+    if (next_event != 0) {
+        schedule(updateAckEvent, next_event);
+    }
+}
+
+EnergyCtrl * EnergyCtrlParams::create()
+{
+    return new EnergyCtrl(this);
+}
+
+void
+EnergyCtrl::startup()
+{
+    if (!dvfsHandler->isEnabled()) {
+        warn("Existing EnergyCtrl, but no enabled DVFSHandler found.\n");
+    }
+}
+
+void
+EnergyCtrl::init()
+{
+    BasicPioDevice::init();
+}