riscv: Implement partial CLINT and SYSCON.

native/projects/riscv/CMakeLists.txt

@@ -8,6 +8,9 @@ project(riscv_emu
 add_library(riscv
 	src/Bus.cpp
 	src/CPU.cpp
+	src/System.cpp
+	
+	src/Devices/SysconDevice.cpp
 	src/Devices/RamDevice.cpp
 )
 

native/projects/riscv/README.md

@@ -1,11 +1,11 @@
 # riscv
 
-This is the RISC-V emulation core that LCPU uses in its native emulation module.
+This is a simple RISC-V RV32IMA emulation library.
 
 This is based off [cnlohr/mini-rv32ima](https://github.com/cnlohr/mini-rv32ima), but:
 
 - Rewritten in C++20 (because I like sanity)
-- Cleaned up somewhat
+- Cleaned up vastly
 - Moved *ALL* device and MMIO code to seperate interfaces
-	- Re-implemented the timer device and the UART as said oop interface
-		- Lua devices use a wrapper which can contain lua callbacks
+
+Depends on lucore.

native/projects/riscv/include/riscv/Bus.hpp

@@ -16,6 +16,7 @@ namespace riscv {
 		struct Device {
 			enum class BasicType {
 				Device,		 // do not upcast.
+				Cpu,		 // upcast to CPU is safe.
 				PlainMemory, // upcast to MemoryDevice is safe.
 				Mmio		 // upcast to MmioDevice is safe.
 			};
@@ -34,16 +35,22 @@ namespace riscv {
 			/// This function is called by the bus to clock devices.
 			virtual void Clock() {}
 
+			// ability to interrupt
+
+			// probably some reset functionality later on
+
 			template <class T>
 			constexpr bool IsA() {
-				if(std::is_same_v<T, Bus::MemoryDevice*>) {
+				if constexpr (std::is_same_v<T, CPU*>) {
+					return this->Type() == BasicType::Cpu;
+				} else if constexpr (std::is_same_v<T, Bus::MemoryDevice*>) {
 					return this->Type() == BasicType::PlainMemory;
-				} else if(std::is_same_v<T, Bus::MmioDevice*>) {
+				} else if constexpr (std::is_same_v<T, Bus::MmioDevice*>) {
 					return this->Type() == BasicType::Mmio;
+				} else {
+					// Invalid types should do this.
+					return false;
 				}
-
-				// Invalid types should do this.
-				return false;
 			}
 
 			template <class T>
@@ -121,12 +128,16 @@ namespace riscv {
 		void PokeWord(AddressT address, u32 value);
 
 	   private:
+	   	// TODO: version which takes Device::BasicType
 		Bus::Device* FindDeviceForAddress(AddressT address) const;
 
-		/// All devices attached to the bus
+		CPU* cpu;
+
+		/// All plain memory or mmio devices attached to the bus
 		std::vector<Device*> devices;
 
 		// TODO: if these end up being a hotpath replace with ankerl::unordered_dense
+		// (or just use the [devices] vector, probably.)
 		std::unordered_map<AddressT, MemoryDevice*> mapped_devices;
 		std::unordered_map<AddressT, MmioDevice*> mmio_devices;
 	};

native/projects/riscv/include/riscv/CPU.hpp

@@ -4,7 +4,7 @@
 namespace riscv {
 
 	/// The CPU core.
-	struct CPU {
+	struct CPU : Bus::Device {
 		/// CPU core state.
 		struct State {
 			u32 gpr[32];
@@ -13,11 +13,6 @@ namespace riscv {
 			u32 cyclel;
 			u32 cycleh;
 
-			u32 timerl;
-			u32 timerh;
-			u32 timermatchl;
-			u32 timermatchh;
-
 			u32 mscratch;
 			u32 mtvec;
 			u32 mie;
@@ -38,14 +33,18 @@ namespace riscv {
 
 		State& GetState() { return state; }
 
+		bool Clocked() const override { return true; } 
+		void Clock() override;
 
 		// TODO: Handlers for CSR read/write
 
-		u32 Step(u32 elapsedMicroseconds, u32 instCount);
-
 	   private:
 		State state;
 		Bus* bus;
+
+		u32 Step(u32 elapsedMicroseconds, u32 instCount);
+
+		// todo: counters for chrono/inst count.
 	};
 
 } // namespace riscv

native/projects/riscv/include/riscv/Devices/ClntDevice.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <riscv/Bus.hpp>
+
+namespace riscv::devices {
+
+	/// Partial implementation of a CLINT.
+	/// The timer device is implemented, SIP is not.
+	struct ClntDevice : public Bus::MmioDevice {
+		constexpr static AddressT BASE_ADDRESS = 0x11000000;
+
+		AddressT Base() const override { return BASE_ADDRESS; }
+		AddressT Size() const override { return 0xbfff; }
+
+		bool Clocked() const override { return true; } 
+		void Clock() override;
+
+
+		u32 Peek(AddressT address) override;
+		void Poke(AddressT address, u32 value) override;
+
+	private:
+		u32 timerCountHigh;
+		u32 timerCountLow;
+
+		u32 timerMatchHigh;
+		u32 timerMatchLow;	
+	};
+
+}

native/projects/riscv/include/riscv/Devices/RamDevice.hpp

@@ -1,3 +1,5 @@
+#pragma once
+
 #include <riscv/Bus.hpp>
 
 namespace riscv::devices {

native/projects/riscv/include/riscv/Devices/SysconDevice.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <riscv/Bus.hpp>
+
+namespace riscv { struct System; }
+
+namespace riscv::devices {
+	/// RISC-V SYSCON device. This will later talk to the system to tell it things.
+	struct SysconDevice : public Bus::MmioDevice {
+		constexpr static AddressT BASE_ADDRESS = 0x11100000;
+
+		SysconDevice(System* system);
+
+		AddressT Size() const override { return sizeof(u32); } // I think this is right?
+
+		u32 Peek(AddressT address) override;
+		void Poke(AddressT address, u32 value) override;
+	private:
+		System* system;
+	};
+}

native/projects/riscv/include/riscv/System.hpp

@@ -1,15 +1,15 @@
 #include <riscv/Bus.hpp>
+#include <riscv/CPU.hpp>
 #include <riscv/Devices/RamDevice.hpp>
+#include <riscv/Devices/SysconDevice.hpp>
+#include <riscv/Devices/ClntDevice.hpp>
 
 namespace riscv {
 
-	// fwd decls
-	struct CPU;
-
 	/// a system.
 	struct System {
-
-		/// Create
+		/// Create a basic system with the basic periphials created.
+		/// All other periphials should be managed by the creator of this System
 		static System* WithMemory(AddressT ramSize);
 
 		~System();
@@ -23,18 +23,20 @@ namespace riscv {
 		Bus* GetBus();
 
 	   private:
-	   	
 		/// How many Cycle() calls will the bus get
 		/// (also decides ipsRate)
-	   	u32 cycleRate;
+		u32 cycleRate;
 
 		/// How many instructions will the CPU execute each step
 		u32 ipsRate;
 
-		// Most of our basic required devices.
-		CPU* cpu;
 		Bus* bus;
+
+		// Required devices.
+		CPU* cpu;
 		devices::RamDevice* ram;
-	}
+		devices::SysconDevice* syscon;
+		devices::ClntDevice* clnt;
+	};
 
 } // namespace riscv

native/projects/riscv/include/riscv/Types.hpp

@@ -8,4 +8,6 @@ namespace riscv {
 	/// A type that can repressent address space or address space offsets.
 	using AddressT = u32;
 
+	
+
 } // namespace riscv

native/projects/riscv/src/Bus.cpp

@@ -1,5 +1,6 @@
 #include <algorithm>
 #include <riscv/Bus.hpp>
+#include <riscv/CPU.hpp>
 
 namespace riscv {
 
@@ -13,6 +14,11 @@ namespace riscv {
 		if(!device)
 			return false;
 
+		if(device->IsA<CPU*>()) {
+			cpu = device->Upcast<CPU*>();
+			return true;
+		}
+
 		if(device->IsA<MemoryDevice*>()) {
 			auto* upcasted = device->Upcast<MemoryDevice*>();
 
@@ -47,6 +53,8 @@ namespace riscv {
 			if(device->Clocked())
 				device->Clock();
 		}
+
+		cpu->Clock();
 	}
 
 	u8 Bus::PeekByte(AddressT address) {

native/projects/riscv/src/CPU.cpp

@@ -0,0 +1,9 @@
+#include <riscv/CPU.hpp>
+
+namespace riscv {
+
+	void CPU::Clock() {
+		// do the thing
+	}
+
+} // namespace riscv

native/projects/riscv/src/Devices/ClntDevice.cpp

@@ -0,0 +1,52 @@
+#include <riscv/Devices/ClntDevice.hpp>
+#include <lucore/Logger.hpp>
+
+namespace riscv::devices {
+
+		/// anonymous enum to make documenting stuff easier
+		/// could be done with constexpr but Lazy lilypad
+		enum : AddressT {
+			MATCHL_ADDRESS = ClntDevice::BASE_ADDRESS + 0x4000,
+			MATCHH_ADDRESS = ClntDevice::BASE_ADDRESS + 0x4004,
+
+			TIMERL_ADDRESS = ClntDevice::BASE_ADDRESS + 0xbff8,
+			TIMERH_ADDRESS = ClntDevice::BASE_ADDRESS + 0xbffc,
+		};
+
+		void ClntDevice::Clock() {
+			// TODO: handle timer
+			// If match low and high match the timer during a clock
+			// we should fire the interrupt, otherwise not do so
+		}
+
+
+		u32 ClntDevice::Peek(AddressT address) {
+			switch(address) {
+				case TIMERL_ADDRESS:
+					return timerCountLow;
+
+				case TIMERH_ADDRESS:
+					return timerCountHigh;
+				
+				default:
+					return 0x0;
+			}
+		}
+
+		void ClntDevice::Poke(AddressT address, u32 value) {
+			switch(address) {
+				case MATCHL_ADDRESS:
+					timerMatchLow = value;
+					break;
+				case MATCHH_ADDRESS:
+					timerMatchHigh = value;
+					break;
+
+					// ?
+				default:
+					lucore::LogInfo("CLNT({}) unhandled poke @ 0x{:08x} : 0x{:08x}", static_cast<void*>(this), address, value);
+					break;
+			}
+		}
+
+}

native/projects/riscv/src/Devices/SysconDevice.cpp

@@ -0,0 +1,30 @@
+#include <riscv/Devices/SysconDevice.hpp>
+#include <riscv/System.hpp>
+
+#include <lucore/Logger.hpp>
+
+namespace riscv::devices {
+
+	SysconDevice::SysconDevice(System* system) : system(system) {
+	}
+
+	u32 SysconDevice::Peek(AddressT address) {
+
+		lucore::LogInfo("SYSCON({}) Peek @ 0x{:08x}", static_cast<void*>(this), address);
+		return -1;
+	}
+
+	void SysconDevice::Poke(AddressT address, u32 value) {
+		lucore::LogInfo("SYSCON({}) Poke @ 0x{:08x}: 0x{:08x}", static_cast<void*>(this), address, value);
+		/*
+			if(address == BASE_ADDRESS) {
+				if(value == 0x5555)
+					system->PowerOff();
+				else if (value == 0x7777)
+					system->Reset();
+			}
+		*/
+		return;
+	}
+
+} // namespace riscv::devices