From a1a23add718137b43519394121336c187e6e6020 Mon Sep 17 00:00:00 2001
From: Patrick Mackinlay <pmackinlay@hotmail.com>
Date: Tue, 2 Oct 2018 13:59:39 +0700
Subject: [PATCH] ncr5390: various fixes (nw)

Several important fixes that help Sun4 (can now boot Solaris 2.3 from CD-ROM) and Jazz work better.
* Fix stupid virtual/override errors preventing ncr53c90a+ from working properly.
* Start DMA after arbitration/selection is completed for "select with..." commands.
* Trigger an interrupt on SCSI bus reset (if enabled).
---
 src/devices/machine/ncr5390.cpp | 16 +++++++++++++---
 src/devices/machine/ncr5390.h   | 18 +++++++++---------
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/devices/machine/ncr5390.cpp b/src/devices/machine/ncr5390.cpp
index 135bcdb9705..62c62a038b6 100644
--- a/src/devices/machine/ncr5390.cpp
+++ b/src/devices/machine/ncr5390.cpp
@@ -407,10 +407,15 @@ void ncr5390_device::step(bool timeout)
 
 	case DISC_SEL_ARBITRATION_INIT:
 		// wait until a command is in the fifo
-		if (!fifo_pos && dma_command && !(status & S_TC0))
+		if (!fifo_pos && dma_command && !(status & S_TC0)) {
+			// dma starts after bus arbitration/selection is complete
+			dma_set(DMA_OUT);
+			step(false);
 			break;
+		}
 
-		command_length = derive_msg_size(fifo[0]);
+		// "with atn" variants have a message byte before the command descriptor
+		command_length = (c == CD_SELECT) ? derive_msg_size(fifo[0]) : 1;
 		state = DISC_SEL_ARBITRATION;
 		step(false);
 		break;
@@ -850,6 +855,12 @@ void ncr5390_device::start_command()
 	case CM_RESET_BUS:
 		LOGMASKED(LOG_COMMAND, "Reset SCSI bus\n");
 		reset_soft();
+		// FIXME: this interrupt should be generated when the reset is reflected
+		// back into the device, and not when the device starts the scsi reset
+		if (!(config & 0x40)) {
+			istatus = I_SCSI_RESET;
+			check_irq();
+		}
 		break;
 
 	case CD_RESELECT:
@@ -867,7 +878,6 @@ void ncr5390_device::start_command()
 			"Select with ATN and stop sequence\n");
 		seq = 0;
 		state = DISC_SEL_ARBITRATION_INIT;
-		dma_set(dma_command ? DMA_OUT : DMA_NONE);
 		arbitrate();
 		break;
 
diff --git a/src/devices/machine/ncr5390.h b/src/devices/machine/ncr5390.h
index d39b352ddb7..bf301bed266 100644
--- a/src/devices/machine/ncr5390.h
+++ b/src/devices/machine/ncr5390.h
@@ -35,7 +35,7 @@ public:
 	DECLARE_WRITE8_MEMBER(fifo_w);
 	DECLARE_READ8_MEMBER(command_r);
 	DECLARE_WRITE8_MEMBER(command_w);
-	DECLARE_READ8_MEMBER(status_r);
+	virtual DECLARE_READ8_MEMBER(status_r);
 	DECLARE_WRITE8_MEMBER(bus_id_w);
 	DECLARE_READ8_MEMBER(istatus_r);
 	DECLARE_WRITE8_MEMBER(timeout_w);
@@ -236,7 +236,7 @@ protected:
 	void check_irq();
 
 protected:
-	void reset_soft();
+	virtual void reset_soft();
 
 private:
 	void reset_disconnect();
@@ -262,19 +262,19 @@ public:
 
 	virtual void map(address_map &map) override;
 
-	DECLARE_READ8_MEMBER(status_r);
+	virtual DECLARE_READ8_MEMBER(status_r) override;
 
 	DECLARE_READ8_MEMBER(conf2_r) { return config2; };
 	DECLARE_WRITE8_MEMBER(conf2_w) { config2 = data; };
 
-	DECLARE_READ8_MEMBER(read) override;
-	DECLARE_WRITE8_MEMBER(write) override;
+	virtual DECLARE_READ8_MEMBER(read) override;
+	virtual DECLARE_WRITE8_MEMBER(write) override;
 
 protected:
 	ncr53c90a_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock);
 
 	virtual void device_start() override;
-	void reset_soft();
+	virtual void reset_soft() override;
 
 	virtual bool check_valid_command(uint8_t cmd) override;
 
@@ -298,12 +298,12 @@ public:
 	DECLARE_WRITE8_MEMBER(conf3_w) { config3 = data; };
 	DECLARE_WRITE8_MEMBER(fifo_align_w) { fifo_align = data; };
 
-	DECLARE_READ8_MEMBER(read) override;
-	DECLARE_WRITE8_MEMBER(write) override;
+	virtual DECLARE_READ8_MEMBER(read) override;
+	virtual DECLARE_WRITE8_MEMBER(write) override;
 
 protected:
 	virtual void device_start() override;
-	void reset_soft();
+	virtual void reset_soft() override;
 
 private:
 	u8 config3;