From 28e7a806b4dc38b9f8ee8508aeeb39782d9e597f Mon Sep 17 00:00:00 2001
From: Maxim Poliakovski <maximumspatium@googlemail.com>
Date: Mon, 12 Feb 2024 02:38:08 +0100
Subject: [PATCH] grandcentral: use MeshStub on machines without MESH.

---
 devices/common/scsi/mesh.h      | 10 ++++++++++
 devices/ioctrl/grandcentral.cpp |  4 +++-
 devices/ioctrl/macio.h          |  1 +
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/devices/common/scsi/mesh.h b/devices/common/scsi/mesh.h
index 1909bb7..2a5a20b 100644
--- a/devices/common/scsi/mesh.h
+++ b/devices/common/scsi/mesh.h
@@ -109,6 +109,16 @@ enum SeqState : uint32_t {
 
 }; // namespace MeshScsi
 
+class MeshStub : public HWComponent {
+public:
+    MeshStub()  = default;
+    ~MeshStub() = default;
+
+    // registers access
+    uint8_t read(uint8_t reg_offset) { return 0; };
+    void   write(uint8_t reg_offset, uint8_t value) {};
+};
+
 class MeshController : public HWComponent {
 public:
     MeshController(uint8_t mesh_id) {
diff --git a/devices/ioctrl/grandcentral.cpp b/devices/ioctrl/grandcentral.cpp
index 10826b2..9479060 100644
--- a/devices/ioctrl/grandcentral.cpp
+++ b/devices/ioctrl/grandcentral.cpp
@@ -70,7 +70,9 @@ GrandCentral::GrandCentral() : PCIDevice("mac-io/grandcentral"), InterruptCtrl()
     // connect MESH (internal SCSI)
     this->mesh = dynamic_cast<MeshController*>(gMachineObj->get_comp_by_name("MeshTnt"));
     if (this->mesh == nullptr) {
-        LOG_F(WARNING, "%s: Mesh not found, install MeshStub", this->name.c_str());
+        LOG_F(WARNING, "%s: Mesh not found, using MeshStub instead", this->name.c_str());
+        this->mesh_stub = std::unique_ptr<MeshStub>(new MeshStub());
+        this->mesh = dynamic_cast<MeshController*>(this->mesh_stub.get());
     } else {
         this->mesh_dma = std::unique_ptr<DMAChannel> (new DMAChannel());
         this->mesh_dma->register_dma_int(this, this->register_dma_int(IntSrc::DMA_SCSI_MESH));
diff --git a/devices/ioctrl/macio.h b/devices/ioctrl/macio.h
index 2d2cac1..5db9fac 100644
--- a/devices/ioctrl/macio.h
+++ b/devices/ioctrl/macio.h
@@ -135,6 +135,7 @@ private:
 
     // subdevice objects
     std::unique_ptr<AwacsScreamer>      awacs;   // AWACS audio codec instance
+    std::unique_ptr<MeshStub>           mesh_stub = nullptr;
 
     NVram*              nvram;      // NVRAM module
     MaceController*     mace;