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.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.