m68k: Mac IRQ prep

Make sure that there are no slot IRQs asserted before leaving the nubus
handler. If there are and we don't then the nubus gets wedged because this
prevents a CA1 transition, which means no more nubus IRQs.

Make the interrupt dispatch loops terminate sooner.

Explicitly initialise the VIA latches to make the code more easily understood.

Also some cleanups.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 9 deletions

diff --git a/arch/m68k/mac/psc.c b/arch/m68k/mac/psc.c
index 401147985a9..1dba88247c6 100644
--- a/arch/m68k/mac/psc.c
+++ b/arch/m68k/mac/psc.c
@@ -131,11 +131,8 @@ irqreturn_t psc_irq(int irq, void *dev_id)
 {
 	int pIFR	= pIFRbase + ((int) dev_id);
 	int pIER	= pIERbase + ((int) dev_id);
-	int base_irq;
-	int irq_bit,i;
-	unsigned char events;
-
-	base_irq = irq << 3;
+	int irq_num;
+	unsigned char irq_bit, events;
 
 #ifdef DEBUG_IRQS
 	printk("psc_irq: irq %d pIFR = 0x%02X pIER = 0x%02X\n",
@@ -146,14 +143,18 @@ irqreturn_t psc_irq(int irq, void *dev_id)
 	if (!events)
 		return IRQ_NONE;
 
-	for (i = 0, irq_bit = 1 ; i < 4 ; i++, irq_bit <<= 1) {
-	        if (events & irq_bit) {
+	irq_num = irq << 3;
+	irq_bit = 1;
+	do {
+		if (events & irq_bit) {
 			psc_write_byte(pIER, irq_bit);
 			psc_write_byte(pIFR, irq_bit);
-			m68k_handle_int(base_irq + i);
+			m68k_handle_int(irq_num);
 			psc_write_byte(pIER, irq_bit | 0x80);
 		}
-	}
+		irq_num++;
+		irq_bit <<= 1;
+	} while (events >= irq_bit);
 	return IRQ_HANDLED;
 }