dev-arm: add Watchdog Module SP805 model

This provides a model of the Arm Watchdog Module SP805. This is based
on the public TRM rev. r1p0 (ARM DDI 0270B). Integration test harness
is not supported. Auto-generation of device tree entries is provided.

Change-Id: I6157cec2212d0a1d2685bcfa983d2acbae1f3377
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24205
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

4 files changed, 439 insertions, 0 deletions

diff --git a/src/dev/arm/RealView.py b/src/dev/arm/RealView.py
index e773096b7..73f654ddf 100644
--- a/src/dev/arm/RealView.py
+++ b/src/dev/arm/RealView.py
@@ -402,6 +402,34 @@ class Sp804(AmbaPioDevice):
     clock1 = Param.Clock('1MHz', "Clock speed of the input")
     amba_id = 0x00141804
 
+class Sp805(AmbaIntDevice):
+    """
+Arm Watchdog Module (SP805)
+Reference:
+    Arm Watchdog Module (SP805) - Technical Reference Manual - rev. r1p0
+    Doc. ID: ARM DDI 0270B
+    """
+
+    type = 'Sp805'
+    cxx_header = 'dev/arm/watchdog_sp805.hh'
+
+    amba_id = 0x00141805
+
+    def generateDeviceTree(self, state):
+        node = self.generateBasicPioDeviceNode(state, 'watchdog',
+            self.pio_addr, 0x1000, [int(self.int_num)])
+        node.appendCompatible(['arm,sp805', 'arm,primecell'])
+        clocks = [state.phandle(self.clk_domain.unproxy(self))]
+        clock_names = ['wdogclk']
+        platform = self._parent.unproxy(self)
+        if self in platform._off_chip_devices():
+            clocks.append(state.phandle(platform.dcc.osc_smb))
+            clock_names.append('apb_pclk')
+        node.append(FdtPropertyWords('clocks', clocks))
+        node.append(FdtPropertyStrings('clock-names', clock_names))
+
+        yield node
+
 class A9GlobalTimer(BasicPioDevice):
     type = 'A9GlobalTimer'
     cxx_header = "dev/arm/timer_a9global.hh"
diff --git a/src/dev/arm/SConscript b/src/dev/arm/SConscript
index c2df3ef51..66a368df0 100644
--- a/src/dev/arm/SConscript
+++ b/src/dev/arm/SConscript
@@ -81,6 +81,7 @@ if env['TARGET_ISA'] == 'arm':
     Source('smmu_v3_slaveifc.cc');
     Source('smmu_v3_transl.cc');
     Source('timer_sp804.cc')
+    Source('watchdog_sp805.cc')
     Source('gpu_nomali.cc')
     Source('pci_host.cc')
     Source('rv_ctrl.cc')
@@ -104,6 +105,7 @@ if env['TARGET_ISA'] == 'arm':
     DebugFlag('RVCTRL')
     DebugFlag('SMMUv3')
     DebugFlag('SMMUv3Hazard')
+    DebugFlag('Sp805')
     DebugFlag('EnergyCtrl')
     DebugFlag('UFSHostDevice')
     DebugFlag('VGIC')
diff --git a/src/dev/arm/watchdog_sp805.cc b/src/dev/arm/watchdog_sp805.cc
new file mode 100644
index 000000000..1cf4a3643
--- /dev/null
+++ b/src/dev/arm/watchdog_sp805.cc
@@ -0,0 +1,274 @@
+/*
+ * Copyright (c) 2020 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: Adrian Herrera
+ */
+
+#include "dev/arm/watchdog_sp805.hh"
+
+#include "base/logging.hh"
+#include "debug/Sp805.hh"
+#include "mem/packet_access.hh"
+#include "params/Sp805.hh"
+
+Sp805::Sp805(Sp805Params const* params)
+    : AmbaIntDevice(params, 0x1000),
+      timeoutInterval(0xffffffff),
+      timeoutStartTick(MaxTick),
+      persistedValue(timeoutInterval),
+      enabled(false),
+      resetEnabled(false),
+      intRaised(false),
+      writeAccessEnabled(true),
+      integrationTestEnabled(false),
+      timeoutEvent([this] { timeoutExpired(); }, name())
+{
+}
+
+Tick
+Sp805::read(PacketPtr pkt)
+{
+    const Addr addr = pkt->getAddr() - pioAddr;
+    const size_t size = pkt->getSize();
+    panic_if(size != 4, "Sp805::read: Invalid size %i\n", size);
+
+    uint64_t resp = 0;
+    switch (addr) {
+      case WDOGLOAD:
+        resp = timeoutInterval;
+        break;
+      case WDOGVALUE:
+        resp = value();
+        break;
+      case WDOGCONTROL:
+        resp = enabled | (resetEnabled << 1);
+        break;
+      case WDOGINTCLR:
+        warn("Sp805::read: WO reg (0x%x) [WDOGINTCLR]\n", addr);
+        break;
+      case WDOGRIS:
+        resp = intRaised;
+        break;
+      case WDOGMIS:
+        resp = intRaised & enabled;
+        break;
+      case WDOGLOCK:
+        resp = writeAccessEnabled;
+        break;
+      case WDOGITCR:
+        resp = integrationTestEnabled;
+        break;
+      case WDOGITOP:
+        warn("Sp805::read: WO reg (0x%x) [WDOGITOP]\n", addr);
+        break;
+      default:
+        if (readId(pkt, ambaId, pioAddr))
+            resp = pkt->getUintX(LittleEndianByteOrder);
+        else
+            warn("Sp805::read: Unexpected address (0x%x:%i), assuming RAZ\n",
+                 addr, size);
+    }
+
+    DPRINTF(Sp805, "Sp805::read: 0x%x<-0x%x(%i)\n", resp, addr, size);
+
+    pkt->setUintX(resp, LittleEndianByteOrder);
+    pkt->makeResponse();
+    return pioDelay;
+}
+
+Tick
+Sp805::write(PacketPtr pkt)
+{
+    const Addr addr = pkt->getAddr() - pioAddr;
+    const size_t size = pkt->getSize();
+    panic_if(size != 4, "Sp805::write: Invalid size %i\n", size);
+
+    uint64_t data = pkt->getUintX(LittleEndianByteOrder);
+    switch (addr) {
+      case WDOGLOAD:
+        if (writeAccessEnabled) {
+            // When WdogLoad is written 0x0, immediately trigger an interrupt
+            if (!timeoutInterval)
+                sendInt();
+            else
+                timeoutInterval = data;
+            if (enabled)
+                restartCounter();
+        }
+        break;
+      case WDOGVALUE:
+        warn("Sp805::write: RO reg (0x%x) [WDOGVALUE]\n", addr);
+        break;
+      case WDOGCONTROL:
+        if (writeAccessEnabled) {
+            bool was_enabled = enabled;
+            enabled = bits(data, 0);
+            resetEnabled = bits(data, 1);
+            // If watchdog becomes enabled, restart the counter
+            if (!was_enabled && enabled)
+                restartCounter();
+            // If watchdog becomes disabled, stop the counter
+            else if (timeoutEvent.scheduled() && !enabled)
+                stopCounter();
+        }
+        break;
+      case WDOGINTCLR:
+        if (writeAccessEnabled) {
+            // Clear the interrupt and restart the counter if enabled
+            clearInt();
+            if (enabled)
+                restartCounter();
+        }
+        break;
+      case WDOGRIS:
+        warn("Sp805::write: RO reg (0x%x) [WDOGRIS]\n", addr);
+        break;
+      case WDOGMIS:
+        warn("Sp805::write: RO reg (0x%x) [WDOGMIS]\n", addr);
+        break;
+      case WDOGLOCK:
+        writeAccessEnabled = (data == WDOGLOCK_MAGIC);
+        break;
+      case WDOGITCR ... WDOGITOP:
+        warn("Sp805::write: No support for integration test harness\n");
+        break;
+      default:
+        warn("Sp805::write: Unexpected address (0x%x:%i), assuming WI\n",
+             addr, size);
+    }
+
+    DPRINTF(Sp805, "Sp805::write: 0x%x->0x%x(%i)\n", data, addr, size);
+
+    pkt->makeResponse();
+    return pioDelay;
+}
+
+uint32_t
+Sp805::value() const
+{
+    return timeoutEvent.scheduled() ? timeoutInterval -
+           ((timeoutEvent.when() - timeoutStartTick) / clockPeriod())
+           : persistedValue;
+}
+
+void
+Sp805::timeoutExpired()
+{
+    timeoutStartTick = MaxTick;
+    sendInt();
+    restartCounter();
+}
+
+void
+Sp805::restartCounter()
+{
+    reschedule(timeoutEvent, clockEdge(Cycles(timeoutInterval)), true);
+    timeoutStartTick = curTick();
+}
+
+void
+Sp805::stopCounter()
+{
+    persistedValue = value();
+    deschedule(timeoutEvent);
+    timeoutStartTick = MaxTick;
+}
+
+void
+Sp805::sendInt()
+{
+    // If the previously sent interrupt has not been served,
+    // assert system reset if enabled
+    if (intRaised & enabled) {
+        if (resetEnabled)
+            warn("Watchdog timed out, system reset asserted\n");
+    } else {
+        intRaised = true;
+        gic->sendInt(intNum);
+    }
+}
+
+void
+Sp805::clearInt()
+{
+    intRaised = false;
+    gic->clearInt(intNum);
+}
+
+void
+Sp805::serialize(CheckpointOut &cp) const
+{
+    SERIALIZE_SCALAR(timeoutInterval);
+    SERIALIZE_SCALAR(timeoutStartTick);
+    SERIALIZE_SCALAR(persistedValue);
+    SERIALIZE_SCALAR(enabled);
+    SERIALIZE_SCALAR(resetEnabled);
+    SERIALIZE_SCALAR(intRaised);
+    SERIALIZE_SCALAR(writeAccessEnabled);
+    SERIALIZE_SCALAR(integrationTestEnabled);
+
+    bool ev_scheduled = timeoutEvent.scheduled();
+    SERIALIZE_SCALAR(ev_scheduled);
+    if (ev_scheduled)
+        SERIALIZE_SCALAR(timeoutEvent.when());
+}
+
+void
+Sp805::unserialize(CheckpointIn &cp)
+{
+    UNSERIALIZE_SCALAR(timeoutInterval);
+    UNSERIALIZE_SCALAR(timeoutStartTick);
+    UNSERIALIZE_SCALAR(persistedValue);
+    UNSERIALIZE_SCALAR(enabled);
+    UNSERIALIZE_SCALAR(resetEnabled);
+    UNSERIALIZE_SCALAR(intRaised);
+    UNSERIALIZE_SCALAR(writeAccessEnabled);
+    UNSERIALIZE_SCALAR(integrationTestEnabled);
+
+    bool ev_scheduled;
+    UNSERIALIZE_SCALAR(ev_scheduled);
+    if (ev_scheduled) {
+        Tick when;
+        UNSERIALIZE_SCALAR(when);
+        reschedule(timeoutEvent, when, true);
+    }
+}
+
+Sp805 *
+Sp805Params::create()
+{
+    return new Sp805(this);
+}
diff --git a/src/dev/arm/watchdog_sp805.hh b/src/dev/arm/watchdog_sp805.hh
new file mode 100644
index 000000000..93654e7b7
--- /dev/null
+++ b/src/dev/arm/watchdog_sp805.hh
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2020 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: Adrian Herrera
+ */
+
+#ifndef __DEV_ARM_WATCHDOG_SP805_HH__
+#define __DEV_ARM_WATCHDOG_SP805_HH__
+
+#include "dev/arm/amba_device.hh"
+
+class Sp805Params;
+
+/**
+ * @file
+ * Arm Watchdog Module (SP805)
+ * Reference:
+ *     Arm Watchdog Module (SP805) - Technical Reference Manual - rev. r1p0
+ *     Doc. ID: ARM DDI 0270B
+ */
+class Sp805 : public AmbaIntDevice
+{
+  public:
+    Sp805(Sp805Params const* params);
+
+    void serialize(CheckpointOut &cp) const override;
+    void unserialize(CheckpointIn &cp) override;
+
+  protected:
+    Tick read(PacketPtr pkt) override;
+    Tick write(PacketPtr pkt) override;
+
+  private:
+    enum Offset : Addr {
+        WDOGLOAD      = 0x000,
+        WDOGVALUE     = 0x004,
+        WDOGCONTROL   = 0x008,
+        WDOGINTCLR    = 0x00c,
+        WDOGRIS       = 0x010,
+        WDOGMIS       = 0x014,
+        // 0x018 - 0xbfc -> Reserved
+        WDOGLOCK      = 0xc00,
+        // 0xc04 - 0xefc -> Reserved
+        WDOGITCR      = 0xf00,
+        WDOGITOP      = 0xf04,
+        // 0xf08 - 0xfdc -> Reserved
+        // 0xfe0 - 0xfff -> CoreSight / Peripheral ID (AMBA ID)
+    };
+
+    /** Timeout interval (in cycles) as specified in WdogLoad */
+    uint32_t timeoutInterval;
+
+    /** Timeout start tick to keep track of the counter value */
+    Tick timeoutStartTick;
+
+    /** Value as persisted when the watchdog is stopped */
+    uint32_t persistedValue;
+
+    /** Indicates if watchdog (counter and interrupt) is enabled */
+    bool enabled;
+
+    /** Indicates if reset behaviour is enabled when counter reaches 0 */
+    bool resetEnabled;
+
+    /** Indicates if an interrupt has been raised by the counter reaching 0 */
+    bool intRaised;
+
+    /** Indicates if write access to registers is enabled */
+    bool writeAccessEnabled;
+
+    /** Indicates if integration test harness is enabled */
+    bool integrationTestEnabled;
+
+    /** Timeout event, triggered when the counter value reaches 0 */
+    EventFunctionWrapper timeoutEvent;
+
+    /** Returns the current counter value */
+    uint32_t value(void) const;
+
+    /** Triggered when value reaches 0 */
+    void timeoutExpired(void);
+
+    /** Restarts the counter to the current timeout interval */
+    void restartCounter(void);
+
+    /** Stops the counter when watchdog becomes disabled */
+    void stopCounter(void);
+
+    /**
+     * Raises an interrupt. If there is already a pending interrupt and
+     * reset behaviour is enabled, asserts system reset
+     */
+    void sendInt(void);
+
+    /** Clears any active interrupts */
+    void clearInt(void);
+
+    /** If written into WdogLock, registers are unlocked for writes */
+    static constexpr uint32_t WDOGLOCK_MAGIC = 0x1acce551;
+};
+
+#endif // __DEV_ARM_WATCHDOG_SP805_HH__