3 files changed, 95 insertions, 3 deletions

diff --git a/src/video_core/engines/maxwell_3d.cpp b/src/video_core/engines/maxwell_3d.cpp
index ccdb310f0..9f699399f 100644
--- a/src/video_core/engines/maxwell_3d.cpp
+++ b/src/video_core/engines/maxwell_3d.cpp
@@ -2,12 +2,50 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include "common/assert.h"
 #include "video_core/engines/maxwell_3d.h"
 
 namespace Tegra {
 namespace Engines {
 
-void Maxwell3D::WriteReg(u32 method, u32 value) {}
+Maxwell3D::Maxwell3D(MemoryManager& memory_manager) : memory_manager(memory_manager) {}
 
+void Maxwell3D::WriteReg(u32 method, u32 value) {
+    ASSERT_MSG(method < Regs::NUM_REGS,
+               "Invalid Maxwell3D register, increase the size of the Regs structure");
+
+    regs.reg_array[method] = value;
+
+#define MAXWELL3D_REG_INDEX(field_name) (offsetof(Regs, field_name) / sizeof(u32))
+
+    switch (method) {
+    case MAXWELL3D_REG_INDEX(query.query_get): {
+        ProcessQueryGet();
+        break;
+    }
+    default:
+        break;
+    }
+
+#undef MAXWELL3D_REG_INDEX
+}
+
+void Maxwell3D::ProcessQueryGet() {
+    GPUVAddr sequence_address = regs.query.QueryAddress();
+    // Since the sequence address is given as a GPU VAddr, we have to convert it to an application
+    // VAddr before writing.
+    VAddr address = memory_manager.PhysicalToVirtualAddress(sequence_address);
+
+    switch (regs.query.query_get.mode) {
+    case Regs::QueryMode::Write: {
+        // Write the current query sequence to the sequence address.
+        u32 sequence = regs.query.query_sequence;
+        Memory::Write32(address, sequence);
+        break;
+    }
+    default:
+        UNIMPLEMENTED_MSG("Query mode %u not implemented", regs.query.query_get.mode.Value());
+    }
+}
 } // namespace Engines
 } // namespace Tegra
diff --git a/src/video_core/engines/maxwell_3d.h b/src/video_core/engines/maxwell_3d.h
index 0f4ae1328..5cd2ecd20 100644
--- a/src/video_core/engines/maxwell_3d.h
+++ b/src/video_core/engines/maxwell_3d.h
@@ -4,19 +4,73 @@
 
 #pragma once
 
+#include "common/bit_field.h"
+#include "common/common_funcs.h"
 #include "common/common_types.h"
+#include "video_core/memory_manager.h"
 
 namespace Tegra {
 namespace Engines {
 
 class Maxwell3D final {
 public:
-    Maxwell3D() = default;
+    Maxwell3D(MemoryManager& memory_manager);
     ~Maxwell3D() = default;
 
     /// Write the value to the register identified by method.
     void WriteReg(u32 method, u32 value);
+
+    /// Register structure of the Maxwell3D engine.
+    /// TODO(Subv): This structure will need to be made bigger as more registers are discovered.
+    struct Regs {
+        static constexpr size_t NUM_REGS = 0xE36;
+
+        enum class QueryMode : u32 {
+            Write = 0,
+            Sync = 1,
+        };
+
+        union {
+            struct {
+                INSERT_PADDING_WORDS(0x6C0);
+                struct {
+                    u32 query_address_high;
+                    u32 query_address_low;
+                    u32 query_sequence;
+                    union {
+                        u32 raw;
+                        BitField<0, 2, QueryMode> mode;
+                        BitField<4, 1, u32> fence;
+                        BitField<12, 4, u32> unit;
+                    } query_get;
+
+                    GPUVAddr QueryAddress() const {
+                        return static_cast<GPUVAddr>(
+                            (static_cast<GPUVAddr>(query_address_high) << 32) | query_address_low);
+                    }
+                } query;
+                INSERT_PADDING_WORDS(0x772);
+            };
+            std::array<u32, NUM_REGS> reg_array;
+        };
+    } regs{};
+
+    static_assert(sizeof(Regs) == Regs::NUM_REGS * sizeof(u32), "Maxwell3D Regs has wrong size");
+
+private:
+    /// Handles a write to the QUERY_GET register.
+    void ProcessQueryGet();
+
+    MemoryManager& memory_manager;
 };
 
+#define ASSERT_REG_POSITION(field_name, position)                                                  \
+    static_assert(offsetof(Maxwell3D::Regs, field_name) == position * 4,                           \
+                  "Field " #field_name " has invalid position")
+
+ASSERT_REG_POSITION(query, 0x6C0);
+
+#undef ASSERT_REG_POSITION
+
 } // namespace Engines
 } // namespace Tegra
diff --git a/src/video_core/gpu.h b/src/video_core/gpu.h
index a961f3fd4..ba7781756 100644
--- a/src/video_core/gpu.h
+++ b/src/video_core/gpu.h
@@ -26,7 +26,7 @@ class GPU final {
 public:
     GPU() {
         memory_manager = std::make_unique<MemoryManager>();
-        maxwell_3d = std::make_unique<Engines::Maxwell3D>();
+        maxwell_3d = std::make_unique<Engines::Maxwell3D>(*memory_manager);
         fermi_2d = std::make_unique<Engines::Fermi2D>();
         maxwell_compute = std::make_unique<Engines::MaxwellCompute>();
     }