dev-amdgpu: Add memory manager readRequest method

This method reads arbitrary sized requests from *device* memory with the
ability to call a callback after the last chunk, similar to writeRequest
method.

Change-Id: I8fc22c45b650a632ea48dbed1e978ceeda34ffdd
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/62712
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/amdgpu/memory_manager.cc

@@ -82,6 +82,35 @@ AMDGPUMemoryManager::writeRequest(Addr addr, uint8_t *data, int size,
     }
 }
 
+void
+AMDGPUMemoryManager::readRequest(Addr addr, uint8_t *data, int size,
+                                 Request::Flags flag, Event *callback)
+{
+    assert(data);
+    uint8_t *dataPtr = data;
+
+    ChunkGenerator gen(addr, size, cacheLineSize);
+    for (; !gen.done(); gen.next()) {
+        RequestPtr req = std::make_shared<Request>(gen.addr(), gen.size(),
+                                                   flag, _requestorId);
+
+        PacketPtr pkt = Packet::createRead(req);
+        pkt->dataStatic<uint8_t>(dataPtr);
+        dataPtr += gen.size();
+
+        // Only issue the callback on the last request completing
+        pkt->pushSenderState(new GPUMemPort::SenderState(
+                    gen.last() ? callback : nullptr, addr));
+
+        if (!_gpuMemPort.sendTimingReq(pkt)) {
+            DPRINTF(AMDGPUMem, "Request to %#lx needs retry\n", gen.addr());
+            _gpuMemPort.retries.push_back(pkt);
+        } else {
+            DPRINTF(AMDGPUMem, "Read request to %#lx sent\n", gen.addr());
+        }
+    }
+}
+
 bool
 AMDGPUMemoryManager::GPUMemPort::recvTimingResp(PacketPtr pkt)
 {

src/dev/amdgpu/memory_manager.hh

@@ -89,6 +89,19 @@ class AMDGPUMemoryManager : public ClockedObject
     void writeRequest(Addr addr, uint8_t *data, int size,
                       Request::Flags flag = 0, Event *callback = nullptr);
 
+    /**
+     * Read size amount of data from device memory at addr using flags and
+     * callback.
+     *
+     * @param addr Device address to read.
+     * @param data Pointer to data to read into.
+     * @param size Number of bytes to read.
+     * @param flag Additional request flags for read packets.
+     * @param callback Event callback to call after all bytes are read.
+     */
+    void readRequest(Addr addr, uint8_t *data, int size,
+                     Request::Flags flag = 0, Event *callback = nullptr);
+
     /**
      * Get the requestorID for the memory manager. This ID is used for all
      * packets which should be routed through the device network.