SONIC interrupt handling

Install the built-in macsonic interrupt handler on both IRQs when using
via_alt_mapping. Otherwise the rare interrupt that still comes from the
nubus slot will wedge the nubus.

$ cat /proc/interrupts
auto       2:      89176 via2
auto       3:     744367 sonic
auto       4:          0 scc
auto       6:     318363 via1
auto       7:          0 NMI
mac        9:     119413 framebuffer vbl
mac       10:       1971 ADB
mac       14:     198517 timer
mac       17:      89104 nubus
mac       19:         72 Mac ESP SCSI
mac       56:        629 sonic
mac       62:    1142593 ide0

Version 1 of this patch had a bug where a nubus sonic card would register
two interrupt handlers. Only a built-in sonic needs both.

Versions 2 and 3 needed some cleanups, as Raylynn Knight and Christoph
Hellwig pointed out (thanks).

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/net/macsonic.c b/drivers/net/macsonic.c
index c78a7e2..e9ecdbf 100644
--- a/drivers/net/macsonic.c
+++ b/drivers/net/macsonic.c
@@ -130,6 +130,46 @@
 		addr[i] = bitrev8(addr[i]);
 }
 
+static irqreturn_t macsonic_interrupt(int irq, void *dev_id)
+{
+	irqreturn_t result;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	result = sonic_interrupt(irq, dev_id);
+	local_irq_restore(flags);
+	return result;
+}
+
+static int macsonic_open(struct net_device* dev)
+{
+	if (request_irq(dev->irq, &sonic_interrupt, IRQ_FLG_FAST, "sonic", dev)) {
+		printk(KERN_ERR "%s: unable to get IRQ %d.\n", dev->name, dev->irq);
+		return -EAGAIN;
+	}
+	/* Under the A/UX interrupt scheme, the onboard SONIC interrupt comes
+	 * in at priority level 3. However, we sometimes get the level 2 inter-
+	 * rupt as well, which must prevent re-entrance of the sonic handler.
+	 */
+	if (dev->irq == IRQ_AUTO_3)
+		if (request_irq(IRQ_NUBUS_9, &macsonic_interrupt, IRQ_FLG_FAST, "sonic", dev)) {
+			printk(KERN_ERR "%s: unable to get IRQ %d.\n", dev->name, IRQ_NUBUS_9);
+			free_irq(dev->irq, dev);
+			return -EAGAIN;
+		}
+	return sonic_open(dev);
+}
+
+static int macsonic_close(struct net_device* dev)
+{
+	int err;
+	err = sonic_close(dev);
+	free_irq(dev->irq, dev);
+	if (dev->irq == IRQ_AUTO_3)
+		free_irq(IRQ_NUBUS_9, dev);
+	return err;
+}
+
 int __init macsonic_init(struct net_device* dev)
 {
 	struct sonic_local* lp = netdev_priv(dev);
@@ -160,8 +200,8 @@
 	lp->rra_laddr = lp->rda_laddr + (SIZEOF_SONIC_RD * SONIC_NUM_RDS
 	                     * SONIC_BUS_SCALE(lp->dma_bitmode));
 
-	dev->open = sonic_open;
-	dev->stop = sonic_close;
+	dev->open = macsonic_open;
+	dev->stop = macsonic_close;
 	dev->hard_start_xmit = sonic_send_packet;
 	dev->get_stats = sonic_get_stats;
 	dev->set_multicast_list = &sonic_multicast_list;
@@ -572,8 +612,6 @@
 module_param(sonic_debug, int, 0);
 MODULE_PARM_DESC(sonic_debug, "macsonic debug level (1-4)");
 
-#define SONIC_IRQ_FLAG IRQ_FLG_FAST
-
 #include "sonic.c"
 
 static int __devexit mac_sonic_device_remove (struct platform_device *pdev)