From a5a1253185fc6b3231e30477ebb8dba5375ac936 Mon Sep 17 00:00:00 2001
From: squidbus <175574877+squidbus@users.noreply.github.com>
Date: Sat, 25 Jan 2025 04:12:18 -0800
Subject: [PATCH] liverpool: Implement PM4 MEM_SEMAPHORE. (#2235)

---
 src/video_core/amdgpu/liverpool.cpp | 24 ++++++++++++
 src/video_core/amdgpu/pm4_cmds.h    | 61 +++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/src/video_core/amdgpu/liverpool.cpp b/src/video_core/amdgpu/liverpool.cpp
index 8355dd1e6..2f40d4136 100644
--- a/src/video_core/amdgpu/liverpool.cpp
+++ b/src/video_core/amdgpu/liverpool.cpp
@@ -636,6 +636,18 @@ Liverpool::Task Liverpool::ProcessGraphics(std::span<const u32> dcb, std::span<c
                 }
                 break;
             }
+            case PM4ItOpcode::MemSemaphore: {
+                const auto* mem_semaphore = reinterpret_cast<const PM4CmdMemSemaphore*>(header);
+                if (mem_semaphore->IsSignaling()) {
+                    mem_semaphore->Signal();
+                } else {
+                    while (!mem_semaphore->Signaled()) {
+                        YIELD_GFX();
+                    }
+                    mem_semaphore->Decrement();
+                }
+                break;
+            }
             case PM4ItOpcode::AcquireMem: {
                 // const auto* acquire_mem = reinterpret_cast<PM4CmdAcquireMem*>(header);
                 break;
@@ -848,6 +860,18 @@ Liverpool::Task Liverpool::ProcessCompute(std::span<const u32> acb, u32 vqid) {
             }
             break;
         }
+        case PM4ItOpcode::MemSemaphore: {
+            const auto* mem_semaphore = reinterpret_cast<const PM4CmdMemSemaphore*>(header);
+            if (mem_semaphore->IsSignaling()) {
+                mem_semaphore->Signal();
+            } else {
+                while (!mem_semaphore->Signaled()) {
+                    YIELD_ASC(vqid);
+                }
+                mem_semaphore->Decrement();
+            }
+            break;
+        }
         case PM4ItOpcode::WaitRegMem: {
             const auto* wait_reg_mem = reinterpret_cast<const PM4CmdWaitRegMem*>(header);
             ASSERT(wait_reg_mem->engine.Value() == PM4CmdWaitRegMem::Engine::Me);
diff --git a/src/video_core/amdgpu/pm4_cmds.h b/src/video_core/amdgpu/pm4_cmds.h
index 311f4d4d0..e92ba17fa 100644
--- a/src/video_core/amdgpu/pm4_cmds.h
+++ b/src/video_core/amdgpu/pm4_cmds.h
@@ -884,4 +884,65 @@ struct PM4CmdDrawIndexIndirectMulti {
     u32 draw_initiator; ///< Draw Initiator Register
 };
 
+struct PM4CmdMemSemaphore {
+    enum class ClientCode : u32 {
+        CommandProcessor = 0u,
+        CommandBuffer = 1u,
+        DataBuffer = 2u,
+    };
+    enum class Select : u32 {
+        SignalSemaphore = 6u,
+        WaitSemaphore = 7u,
+    };
+    enum class SignalType : u32 {
+        Increment = 0u,
+        Write = 1u,
+    };
+
+    PM4Type3Header header; ///< header
+    union {
+        u32 dw1;
+        BitField<3, 29, u32> addr_lo; ///< Semaphore address bits [31:3]
+    };
+    union {
+        u32 dw2;
+        BitField<0, 8, u32> addr_hi;             ///< Semaphore address bits [39:32]
+        BitField<16, 1, u32> use_mailbox;        ///< Enables waiting until mailbox is written to
+        BitField<20, 1, SignalType> signal_type; ///< Indicates the type of signal sent
+        BitField<24, 2, ClientCode> client_code;
+        BitField<29, 3, Select> sem_sel; ///< Indicates whether to do a signal or wait operation
+    };
+
+    template <typename T>
+    [[nodiscard]] T Address() const {
+        return std::bit_cast<T>(u64(addr_lo) << 3 | (u64(addr_hi) << 32));
+    }
+
+    [[nodiscard]] bool IsSignaling() const {
+        return sem_sel == Select::SignalSemaphore;
+    }
+
+    [[nodiscard]] bool Signaled() const {
+        return *Address<u64*>() > 0;
+    }
+
+    void Decrement() const {
+        *Address<u64*>() -= 1;
+    }
+
+    void Signal() const {
+        auto* ptr = Address<u64*>();
+        switch (signal_type) {
+        case SignalType::Increment:
+            *ptr += 1;
+            break;
+        case SignalType::Write:
+            *ptr = 1;
+            break;
+        default:
+            UNREACHABLE_MSG("Unknown signal type {}", static_cast<u32>(signal_type.Value()));
+        }
+    }
+};
+
 } // namespace AmdGpu