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/*
* Copyright (c) 2012, 2015, 2017, 2019 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.
*
* Copyright (c) 2006 The Regents of The University of Michigan
* 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
* 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,
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "dev/dma_device.hh"
#include <algorithm>
#include <cassert>
#include <cstring>
#include <utility>
#include "base/logging.hh"
#include "base/trace.hh"
#include "debug/DMA.hh"
#include "debug/Drain.hh"
#include "sim/clocked_object.hh"
#include "sim/system.hh"
namespace gem5
{
DmaPort::DmaPort(ClockedObject *dev, System *s,
uint32_t sid, uint32_t ssid)
: RequestPort(dev->name() + ".dma"),
device(dev), sys(s), requestorId(s->getRequestorId(dev)),
sendEvent([this]{ sendDma(); }, dev->name()),
defaultSid(sid), defaultSSid(ssid), cacheLineSize(s->cacheLineSize())
{ }
void
DmaPort::handleRespPacket(PacketPtr pkt, Tick delay)
{
// Should always see a response with a sender state.
assert(pkt->isResponse());
// Get the DMA sender state.
auto *state = dynamic_cast<DmaReqState*>(pkt->senderState);
assert(state);
handleResp(state, pkt->getAddr(), pkt->req->getSize(), delay);
delete pkt;
}
void
DmaPort::handleResp(DmaReqState *state, Addr addr, Addr size, Tick delay)
{
DPRINTF(DMA, "Received response %s for addr: %#x size: %d nb: %d," \
" tot: %d sched %d\n",
MemCmd(state->cmd).toString(), addr, size,
state->numBytes, state->totBytes,
state->completionEvent ?
state->completionEvent->scheduled() : 0);
// Update the number of bytes received based on the request rather
// than the packet as the latter could be rounded up to line sizes.
state->numBytes += size;
assert(state->totBytes >= state->numBytes);
// If we have reached the total number of bytes for this DMA request,
// then signal the completion and delete the sate.
if (state->totBytes == state->numBytes) {
assert(pendingCount != 0);
pendingCount--;
if (state->completionEvent) {
delay += state->delay;
device->schedule(state->completionEvent, curTick() + delay);
}
delete state;
}
// We might be drained at this point, if so signal the drain event.
if (pendingCount == 0)
signalDrainDone();
}
PacketPtr
DmaPort::DmaReqState::createPacket()
{
RequestPtr req = std::make_shared<Request>(
gen.addr(), gen.size(), flags, id);
req->setStreamId(sid);
req->setSubstreamId(ssid);
req->taskId(context_switch_task_id::DMA);
PacketPtr pkt = new Packet(req, cmd);
if (data)
pkt->dataStatic(data + gen.complete());
pkt->senderState = this;
return pkt;
}
bool
DmaPort::recvTimingResp(PacketPtr pkt)
{
// We shouldn't ever get a cacheable block in Modified state.
assert(pkt->req->isUncacheable() ||
!(pkt->cacheResponding() && !pkt->hasSharers()));
handleRespPacket(pkt);
return true;
}
DmaDevice::DmaDevice(const Params &p)
: PioDevice(p), dmaPort(this, sys, p.sid, p.ssid)
{ }
void
DmaDevice::init()
{
panic_if(!dmaPort.isConnected(),
"DMA port of %s not connected to anything!", name());
PioDevice::init();
}
DrainState
DmaPort::drain()
{
if (pendingCount == 0) {
return DrainState::Drained;
} else {
DPRINTF(Drain, "DmaPort not drained\n");
return DrainState::Draining;
}
}
void
DmaPort::recvReqRetry()
{
assert(transmitList.size());
trySendTimingReq();
}
void
DmaPort::dmaAction(Packet::Command cmd, Addr addr, int size, Event *event,
uint8_t *data, uint32_t sid, uint32_t ssid, Tick delay,
Request::Flags flag)
{
DPRINTF(DMA, "Starting DMA for addr: %#x size: %d sched: %d\n", addr, size,
event ? event->scheduled() : -1);
// One DMA request sender state for every action, that is then
// split into many requests and packets based on the block size,
// i.e. cache line size.
transmitList.push_back(
new DmaReqState(cmd, addr, cacheLineSize, size,
data, flag, requestorId, sid, ssid, event, delay));
pendingCount++;
// In zero time, also initiate the sending of the packets for the request
// we have just created. For atomic this involves actually completing all
// the requests.
sendDma();
}
void
DmaPort::dmaAction(Packet::Command cmd, Addr addr, int size, Event *event,
uint8_t *data, Tick delay, Request::Flags flag)
{
dmaAction(cmd, addr, size, event, data,
defaultSid, defaultSSid, delay, flag);
}
void
DmaPort::trySendTimingReq()
{
// Send the next packet for the first DMA request on the transmit list,
// and schedule the following send if it is successful
DmaReqState *state = transmitList.front();
PacketPtr pkt = inRetry ? inRetry : state->createPacket();
inRetry = nullptr;
DPRINTF(DMA, "Trying to send %s addr %#x\n", pkt->cmdString(),
pkt->getAddr());
// Check if this was the last packet now, since hypothetically the packet
// response may come immediately, and state may be deleted.
bool last = state->gen.last();
if (!sendTimingReq(pkt))
inRetry = pkt;
if (!inRetry) {
// If that was the last packet from this request, pop it from the list.
if (last)
transmitList.pop_front();
else
state->gen.next();
DPRINTF(DMA, "-- Done\n");
// If there is more to do, then do so.
if (!transmitList.empty()) {
// This should ultimately wait for as many cycles as the device
// needs to send the packet, but currently the port does not have
// any known width so simply wait a single cycle.
device->schedule(sendEvent, device->clockEdge(Cycles(1)));
}
} else {
DPRINTF(DMA, "-- Failed, waiting for retry\n");
}
DPRINTF(DMA, "TransmitList: %d, inRetry: %d\n",
transmitList.size(), inRetry ? 1 : 0);
}
bool
DmaPort::sendAtomicReq(DmaReqState *state)
{
PacketPtr pkt = state->createPacket();
DPRINTF(DMA, "Sending DMA for addr: %#x size: %d\n",
state->gen.addr(), state->gen.size());
Tick lat = sendAtomic(pkt);
// Check if we're done, since handleResp may delete state.
bool done = !state->gen.next();
handleRespPacket(pkt, lat);
return done;
}
bool
DmaPort::sendAtomicBdReq(DmaReqState *state)
{
bool done = false;
auto bd_it = memBackdoors.contains(state->gen.addr());
if (bd_it == memBackdoors.end()) {
// We don't have a backdoor for this address, so use a packet.
PacketPtr pkt = state->createPacket();
DPRINTF(DMA, "Sending DMA for addr: %#x size: %d\n",
state->gen.addr(), state->gen.size());
MemBackdoorPtr bd = nullptr;
Tick lat = sendAtomicBackdoor(pkt, bd);
// If we got a backdoor, record it.
if (bd && memBackdoors.insert(bd->range(), bd) != memBackdoors.end()) {
// Invalidation callback which finds this backdoor and removes it.
auto callback = [this](const MemBackdoor &backdoor) {
for (auto it = memBackdoors.begin();
it != memBackdoors.end(); it++) {
if (it->second == &backdoor) {
memBackdoors.erase(it);
return;
}
}
panic("Got invalidation for unknown memory backdoor.");
};
bd->addInvalidationCallback(callback);
}
// Check if we're done now, since handleResp may delete state.
done = !state->gen.next();
handleRespPacket(pkt, lat);
} else {
// We have a backdoor that can at least partially satisfy this request.
DPRINTF(DMA, "Handling DMA for addr: %#x size %d through backdoor\n",
state->gen.addr(), state->gen.size());
const auto *bd = bd_it->second;
// Offset of this access into the backdoor.
const Addr offset = state->gen.addr() - bd->range().start();
// How many bytes we still need.
const Addr remaining = state->totBytes - state->gen.complete();
// How many bytes this backdoor can provide, starting from offset.
const Addr available = bd->range().size() - offset;
// How many bytes we're going to handle through this backdoor.
const Addr handled = std::min(remaining, available);
// If there's a buffer for data, read/write it.
if (state->data) {
uint8_t *bd_data = bd->ptr() + offset;
uint8_t *state_data = state->data + state->gen.complete();
if (MemCmd(state->cmd).isRead())
memcpy(state_data, bd_data, handled);
else
memcpy(bd_data, state_data, handled);
}
// Advance the chunk generator past this region of memory.
state->gen.setNext(state->gen.addr() + handled);
// Check if we're done now, since handleResp may delete state.
done = !state->gen.next();
handleResp(state, state->gen.addr(), handled);
}
return done;
}
void
DmaPort::sendDma()
{
// Some kind of selection between access methods. More work is going to
// have to be done to make switching actually work.
assert(transmitList.size());
if (sys->isTimingMode()) {
// If we are either waiting for a retry or are still waiting after
// sending the last packet, then do not proceed.
if (inRetry || sendEvent.scheduled()) {
DPRINTF(DMA, "Can't send immediately, waiting to send\n");
return;
}
trySendTimingReq();
} else if (sys->isAtomicMode()) {
const bool bypass = sys->bypassCaches();
// Send everything there is to send in zero time.
while (!transmitList.empty()) {
DmaReqState *state = transmitList.front();
transmitList.pop_front();
bool done = state->gen.done();
while (!done)
done = bypass ? sendAtomicBdReq(state) : sendAtomicReq(state);
}
} else {
panic("Unknown memory mode.");
}
}
Port &
DmaDevice::getPort(const std::string &if_name, PortID idx)
{
if (if_name == "dma") {
return dmaPort;
}
return PioDevice::getPort(if_name, idx);
}
DmaReadFifo::DmaReadFifo(DmaPort &_port, size_t size,
unsigned max_req_size,
unsigned max_pending,
Request::Flags flags)
: maxReqSize(max_req_size), fifoSize(size),
reqFlags(flags), port(_port), cacheLineSize(port.sys->cacheLineSize()),
buffer(size)
{
freeRequests.resize(max_pending);
for (auto &e : freeRequests)
e.reset(new DmaDoneEvent(this, max_req_size));
}
DmaReadFifo::~DmaReadFifo()
{
for (auto &p : pendingRequests) {
DmaDoneEvent *e(p.release());
if (e->done()) {
delete e;
} else {
// We can't kill in-flight DMAs, so we'll just transfer
// ownership to the event queue so that they get freed
// when they are done.
e->kill();
}
}
}
void
DmaReadFifo::serialize(CheckpointOut &cp) const
{
assert(pendingRequests.empty());
SERIALIZE_CONTAINER(buffer);
SERIALIZE_SCALAR(endAddr);
SERIALIZE_SCALAR(nextAddr);
}
void
DmaReadFifo::unserialize(CheckpointIn &cp)
{
UNSERIALIZE_CONTAINER(buffer);
UNSERIALIZE_SCALAR(endAddr);
UNSERIALIZE_SCALAR(nextAddr);
}
bool
DmaReadFifo::tryGet(uint8_t *dst, size_t len)
{
if (buffer.size() >= len) {
buffer.read(dst, len);
resumeFill();
return true;
} else {
return false;
}
}
void
DmaReadFifo::get(uint8_t *dst, size_t len)
{
panic_if(!tryGet(dst, len), "Buffer underrun in DmaReadFifo::get()");
}
void
DmaReadFifo::startFill(Addr start, size_t size)
{
assert(atEndOfBlock());
nextAddr = start;
endAddr = start + size;
resumeFill();
}
void
DmaReadFifo::stopFill()
{
// Prevent new DMA requests by setting the next address to the end
// address. Pending requests will still complete.
nextAddr = endAddr;
// Flag in-flight accesses as canceled. This prevents their data
// from being written to the FIFO.
for (auto &p : pendingRequests)
p->cancel();
}
void
DmaReadFifo::resumeFill()
{
// Don't try to fetch more data if we are draining. This ensures
// that the DMA engine settles down before we checkpoint it.
if (drainState() == DrainState::Draining)
return;
const bool old_eob(atEndOfBlock());
if (port.sys->bypassCaches())
resumeFillBypass();
else
resumeFillTiming();
if (!old_eob && atEndOfBlock())
onEndOfBlock();
}
void
DmaReadFifo::resumeFillBypass()
{
const size_t fifo_space = buffer.capacity() - buffer.size();
if (fifo_space >= cacheLineSize || buffer.capacity() < cacheLineSize) {
const size_t block_remaining = endAddr - nextAddr;
const size_t xfer_size = std::min(fifo_space, block_remaining);
std::vector<uint8_t> tmp_buffer(xfer_size);
assert(pendingRequests.empty());
DPRINTF(DMA, "Direct bypass startAddr=%#x xfer_size=%#x " \
"fifo_space=%#x block_remaining=%#x\n",
nextAddr, xfer_size, fifo_space, block_remaining);
port.dmaAction(MemCmd::ReadReq, nextAddr, xfer_size, nullptr,
tmp_buffer.data(), 0, reqFlags);
buffer.write(tmp_buffer.begin(), xfer_size);
nextAddr += xfer_size;
}
}
void
DmaReadFifo::resumeFillTiming()
{
size_t size_pending(0);
for (auto &e : pendingRequests)
size_pending += e->requestSize();
while (!freeRequests.empty() && !atEndOfBlock()) {
const size_t req_size(std::min(maxReqSize, endAddr - nextAddr));
if (buffer.size() + size_pending + req_size > fifoSize)
break;
DmaDoneEventUPtr event(std::move(freeRequests.front()));
freeRequests.pop_front();
assert(event);
event->reset(req_size);
port.dmaAction(MemCmd::ReadReq, nextAddr, req_size, event.get(),
event->data(), 0, reqFlags);
nextAddr += req_size;
size_pending += req_size;
pendingRequests.emplace_back(std::move(event));
}
}
void
DmaReadFifo::dmaDone()
{
const bool old_active(isActive());
handlePending();
resumeFill();
if (old_active && !isActive())
onIdle();
}
void
DmaReadFifo::handlePending()
{
while (!pendingRequests.empty() && pendingRequests.front()->done()) {
// Get the first finished pending request
DmaDoneEventUPtr event(std::move(pendingRequests.front()));
pendingRequests.pop_front();
if (!event->canceled())
buffer.write(event->data(), event->requestSize());
// Move the event to the list of free requests
freeRequests.emplace_back(std::move(event));
}
if (pendingRequests.empty())
signalDrainDone();
}
DrainState
DmaReadFifo::drain()
{
return pendingRequests.empty() ?
DrainState::Drained : DrainState::Draining;
}
DmaReadFifo::DmaDoneEvent::DmaDoneEvent(DmaReadFifo *_parent, size_t max_size)
: parent(_parent), _data(max_size, 0)
{
}
void
DmaReadFifo::DmaDoneEvent::kill()
{
parent = nullptr;
setFlags(AutoDelete);
}
void
DmaReadFifo::DmaDoneEvent::cancel()
{
_canceled = true;
}
void
DmaReadFifo::DmaDoneEvent::reset(size_t size)
{
assert(size <= _data.size());
_done = false;
_canceled = false;
_requestSize = size;
}
void
DmaReadFifo::DmaDoneEvent::process()
{
if (!parent)
return;
assert(!_done);
_done = true;
parent->dmaDone();
}
} // namespace gem5