From 078a10dcdb14f5dd3137f99a7f3a3f006901182f Mon Sep 17 00:00:00 2001
From: TheLastRar <TheLastRar@users.noreply.github.com>
Date: Sun, 13 Oct 2024 16:28:18 +0100
Subject: [PATCH] DEV9: Implement ATA pending interrupts

---
 pcsx2/DEV9/ATA/ATA.h                          |  2 ++
 pcsx2/DEV9/ATA/ATA_State.cpp                  | 25 ++++++++++++++++---
 pcsx2/DEV9/ATA/Commands/ATA_CmdDMA.cpp        |  4 ++-
 .../ATA/Commands/ATA_CmdExecuteDeviceDiag.cpp |  9 +++++--
 pcsx2/DEV9/ATA/Commands/ATA_CmdNoData.cpp     |  1 +
 pcsx2/DEV9/ATA/Commands/ATA_CmdPIOData.cpp    |  6 ++++-
 6 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/pcsx2/DEV9/ATA/ATA.h b/pcsx2/DEV9/ATA/ATA.h
index 456e94f1bc..e49d6425a1 100644
--- a/pcsx2/DEV9/ATA/ATA.h
+++ b/pcsx2/DEV9/ATA/ATA.h
@@ -96,6 +96,8 @@ private:
 
 	u8 regStatus; //ReadOnly. When read via AlternateStatus pending interrupts are not cleared
 
+	bool pendingInterrupt = false;
+
 	//Transfer
 	//Write Buffer(s)
 	bool awaitFlush = false;
diff --git a/pcsx2/DEV9/ATA/ATA_State.cpp b/pcsx2/DEV9/ATA/ATA_State.cpp
index a96444adb2..4207c3a5d9 100644
--- a/pcsx2/DEV9/ATA/ATA_State.cpp
+++ b/pcsx2/DEV9/ATA/ATA_State.cpp
@@ -380,6 +380,7 @@ u16 ATA::Read(u32 addr, int width)
 			return regSelect;
 		case ATA_R_STATUS:
 			// Clear irqcause
+			pendingInterrupt = false;
 			dev9.irqcause &= ~ATA_INTR_INTRQ;
 			[[fallthrough]];
 		case ATA_R_ALT_STATUS:
@@ -437,21 +438,38 @@ void ATA::Write(u32 addr, u16 value, int width)
 			regHcyl = static_cast<u8>(value);
 			break;
 		case ATA_R_SELECT:
+		{
 			//DevCon.WriteLn("DEV9: ATA: ATA_R_SELECT %dbit write %x", width, value);
+			const int oldDev = GetSelectedDevice();
+			const int newDev = (value >> 4) & 1;
+			// Suppress INTRQ when not selected device
+			if (oldDev == 0 && newDev == 1)
+			{
+				dev9.irqcause &= ~ATA_INTR_INTRQ;
+			}
+			else if (oldDev == 1 && newDev == 0)
+			{
+				if (regControlEnableIRQ && pendingInterrupt)
+					_DEV9irq(ATA_INTR_INTRQ, 1);
+			}
+
 			regSelect = static_cast<u8>(value);
-			//bus->ifs[0].select = (val & ~0x10) | 0xa0;
-			//bus->ifs[1].select = (val | 0x10) | 0xa0;
 			break;
+		}
 		case ATA_R_CONTROL:
 			//DevCon.WriteLn("DEV9: ATA: ATA_R_CONTROL %dbit write %x", width, value);
 			if ((value & 0x2) != 0)
 			{
-				// Suppress all IRQ
+				// Suppress INTRQ
 				dev9.irqcause &= ~ATA_INTR_INTRQ;
 				regControlEnableIRQ = false;
 			}
 			else
+			{
+				if (GetSelectedDevice() == 0 && regControlEnableIRQ == false && pendingInterrupt)
+					_DEV9irq(ATA_INTR_INTRQ, 1);
 				regControlEnableIRQ = true;
+			}
 
 			if ((value & 0x4) != 0)
 			{
@@ -467,6 +485,7 @@ void ATA::Write(u32 addr, u16 value, int width)
 			//DevCon.WriteLn("DEV9: ATA: ATA_R_CMD %dbit write %x", width, value);
 			regCommand = value;
 			regControlHOBRead = false;
+			pendingInterrupt = false;
 			dev9.irqcause &= ~ATA_INTR_INTRQ;
 			IDE_ExecCmd(value);
 			break;
diff --git a/pcsx2/DEV9/ATA/Commands/ATA_CmdDMA.cpp b/pcsx2/DEV9/ATA/Commands/ATA_CmdDMA.cpp
index c240e942f7..8b3ace0c03 100644
--- a/pcsx2/DEV9/ATA/Commands/ATA_CmdDMA.cpp
+++ b/pcsx2/DEV9/ATA/Commands/ATA_CmdDMA.cpp
@@ -23,6 +23,7 @@ void ATA::PostCmdDMADataToHost()
 	dmaReady = false;
 
 	dev9.irqcause &= ~SPD_INTR_ATA_FIFO_DATA;
+	pendingInterrupt = true;
 	if (regControlEnableIRQ)
 		_DEV9irq(ATA_INTR_INTRQ, 1);
 	//PCSX2 Will Start DMA
@@ -66,8 +67,9 @@ void ATA::PostCmdDMADataFromHost()
 	if (fetWriteCacheEnabled)
 	{
 		regStatus &= ~ATA_STAT_BUSY;
+		pendingInterrupt = true;
 		if (regControlEnableIRQ)
-			_DEV9irq(ATA_INTR_INTRQ, 1); //0x6C
+			_DEV9irq(ATA_INTR_INTRQ, 1);
 	}
 	else
 		awaitFlush = true;
diff --git a/pcsx2/DEV9/ATA/Commands/ATA_CmdExecuteDeviceDiag.cpp b/pcsx2/DEV9/ATA/Commands/ATA_CmdExecuteDeviceDiag.cpp
index 00c0a9441b..f21f0e648a 100644
--- a/pcsx2/DEV9/ATA/Commands/ATA_CmdExecuteDeviceDiag.cpp
+++ b/pcsx2/DEV9/ATA/Commands/ATA_CmdExecuteDeviceDiag.cpp
@@ -8,6 +8,7 @@ void ATA::PreCmdExecuteDeviceDiag()
 {
 	regStatus |= ATA_STAT_BUSY;
 	regStatus &= ~ATA_STAT_READY;
+	pendingInterrupt = false;
 	dev9.irqcause &= ~ATA_INTR_INTRQ;
 	//dev9.spd.regIntStat &= unchecked((UInt16)~DEV9Header.ATA_INTR_DMA_RDY); //Is this correct?
 }
@@ -21,8 +22,12 @@ void ATA::PostCmdExecuteDeviceDiag(bool sendIRQ)
 
 	// If Device Diagnostics is performed as part of a reset
 	// then we don't raise an IRQ or set pending interrupt
-	if (regControlEnableIRQ && sendIRQ)
-		_DEV9irq(ATA_INTR_INTRQ, 1);
+	if (sendIRQ)
+	{
+		pendingInterrupt = true;
+		if (regControlEnableIRQ)
+			_DEV9irq(ATA_INTR_INTRQ, 1);
+	}
 }
 
 //GENRAL FEATURE SET
diff --git a/pcsx2/DEV9/ATA/Commands/ATA_CmdNoData.cpp b/pcsx2/DEV9/ATA/Commands/ATA_CmdNoData.cpp
index e92e19cb93..97d5aa0f69 100644
--- a/pcsx2/DEV9/ATA/Commands/ATA_CmdNoData.cpp
+++ b/pcsx2/DEV9/ATA/Commands/ATA_CmdNoData.cpp
@@ -8,6 +8,7 @@ void ATA::PostCmdNoData()
 {
 	regStatus &= ~ATA_STAT_BUSY;
 
+	pendingInterrupt = true;
 	if (regControlEnableIRQ)
 		_DEV9irq(ATA_INTR_INTRQ, 1);
 }
diff --git a/pcsx2/DEV9/ATA/Commands/ATA_CmdPIOData.cpp b/pcsx2/DEV9/ATA/Commands/ATA_CmdPIOData.cpp
index d2db7052ad..36650c3d47 100644
--- a/pcsx2/DEV9/ATA/Commands/ATA_CmdPIOData.cpp
+++ b/pcsx2/DEV9/ATA/Commands/ATA_CmdPIOData.cpp
@@ -15,8 +15,12 @@ void ATA::DRQCmdPIODataToHost(u8* buff, int buffLen, int buffIndex, int size, bo
 	regStatus &= ~ATA_STAT_BUSY;
 	regStatus |= ATA_STAT_DRQ;
 
+	// Only set pendingInterrupt if nIEN is cleared
 	if (regControlEnableIRQ && sendIRQ)
-		_DEV9irq(ATA_INTR_INTRQ, 1); //0x6c cycles before
+	{
+		pendingInterrupt = true;
+		_DEV9irq(ATA_INTR_INTRQ, 1);
+	}
 }
 void ATA::PostCmdPIODataToHost()
 {