From 3b6dae34113b43cfc0485310326123cef7483a42 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Wed, 3 Jun 2015 01:03:14 +0100
Subject: [PATCH] dragondos: get read side of driver working

With these changes we can now read dragondos floppies fairly reliably. We
need to optimise the wait for the initial DRQ as now and then we don't quite
make it in the clocks allowed and end up retrying

Writes blow up at the end of the second write in a FIRQ storm, not sure why
yet. Possibly its up to us to disable FIRQ in the NMI handler ?
---
 Kernel/platform-dragon-nx32/devfd.c  | 14 ++++----------
 Kernel/platform-dragon-nx32/floppy.s | 23 +++++++++++++++++------
 2 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/Kernel/platform-dragon-nx32/devfd.c b/Kernel/platform-dragon-nx32/devfd.c
index 56e48230..dd0a78a8 100644
--- a/Kernel/platform-dragon-nx32/devfd.c
+++ b/Kernel/platform-dragon-nx32/devfd.c
@@ -55,9 +55,6 @@ static int fd_transfer(uint8_t minor, bool is_read, uint8_t rawflag)
     uint8_t *driveptr = fd_tab + minor;
     uint8_t cmd[7];
 
-    if(rawflag)
-        goto bad2;
-
     fd_motor_busy();		/* Touch the motor timer first so we don't
                                    go and turn it off as we are doing this */
     if (fd_selected != minor) {
@@ -76,7 +73,8 @@ static int fd_transfer(uint8_t minor, bool is_read, uint8_t rawflag)
         dptr = (uint16_t)udata.u_base;
         block = udata.u_offset >> 9;
         nblock = udata.u_count >> 8;
-    }
+    } else
+        goto bad2;
 
 //    kprintf("Issue command: drive %d\n", minor);
     cmd[0] = rawflag;
@@ -89,15 +87,11 @@ static int fd_transfer(uint8_t minor, bool is_read, uint8_t rawflag)
         
     while (nblock) {
         for (tries = 0; tries < 4 ; tries++) {
-            kprintf("fd sector %d track %d\n", cmd[3], cmd[2]);
             err = fd_operation(cmd, driveptr);
             if (err == 0)
                 break;
-            kprintf("fd error %d\n", err);
-            if (tries > 1) {
-                kputs("fd reset\n");
+            if (tries > 1)
                 fd_reset(driveptr);
-            }
         }
         /* FIXME: should we try the other half and then bale out ? */
         if (tries == 4)
@@ -111,7 +105,7 @@ static int fd_transfer(uint8_t minor, bool is_read, uint8_t rawflag)
         nblock--;
     }
     fd_motor_idle();
-    return 1;
+    return 0;
 bad:
     kprintf("fd%d: error %x\n", minor, err);
 bad2:
diff --git a/Kernel/platform-dragon-nx32/floppy.s b/Kernel/platform-dragon-nx32/floppy.s
index 245ccfeb..ef37dfad 100644
--- a/Kernel/platform-dragon-nx32/floppy.s
+++ b/Kernel/platform-dragon-nx32/floppy.s
@@ -107,6 +107,7 @@ fdsetup:
 ;
 	beq	fdiosetup
 
+	lda	TRACK,x
 	sta	<FDCDATA	; target
 	;
 	;	So we can verify
@@ -155,15 +156,15 @@ noprecomp:
 	sty	nmivector	; so our NMI handler will clean up
 	ldy	#0		; timeout handling
 	orcc	#0x50		; irqs off or we'll miss bytes
+	ldb	DIRECT,x
+	cmpb	#0x01		; read ?
+	beq	fdio_in_1
+	cmpb	#0x02
+	beq	wait_drq_1	; write
 	sta	<FDCREG		; issue the command
 	nop			; give the FDC a moment to think
 	exg	a,a
 	exg	a,a
-	ldb	DIRECT,x
-	cmpb	#0x01		; read ?
-	beq	fdio_in
-	cmpb	#0x02
-	beq	wait_drq	; write
 ;
 ;	Status registers
 ;
@@ -176,6 +177,11 @@ fdxferdone:
 ;
 ;	Relies on B being 2...
 ;
+wait_drq_1:
+	sta	<FDCREG		; issue the command
+	nop			; give the FDC a moment to think
+	exg	a,a
+	exg	a,a
 wait_drq:
 	bitb	<FDCREG
 	bne	drq_on
@@ -207,6 +213,11 @@ drq_go:
 ;
 ;	Read from the disk
 ;
+fdio_in_1:
+	sta	<FDCREG		; issue the command
+	nop			; give the FDC a moment to think
+	exg	a,a
+	exg	a,a
 fdio_in:
 	ldx	DATA,x
 fdio_dwait:
@@ -412,4 +423,4 @@ pia_stash:
 	.byte	0
 	.byte	0
 _fd_tab:
-	.byte	0,0,0,0
+	.byte	0xFF,0xFF,0xFF,0xFF
-- 
2.34.1