[POWERPC] 4xx: rework UIC cascade irq handling

This is a UIC cascade handler rework to use set_irq_chained_handler() for
cascade, just like othe ppc platforms do. With current implementation we have
additional redirection for irq handler and we call generic_handle_irq twice
(once for the primary uic and the other time for handling cascade interrupt).
This causes Ingo's realtime support patch to stop working on 4xx.

Not sure of any other possible problems though, but with
set_irq_chained_handler() we can abolish "struct irqaction cascade" from the
chip descriptor and call generic_handle_irq() once, directly for cascade irq.

Signed-off-by: Valentine Barshak <vbarshak@ru.mvista.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/sysdev/uic.c

@@ -53,9 +53,6 @@ struct uic {
 
 	/* The remapper for this UIC */
 	struct irq_host	*irqhost;
-
-	/* For secondary UICs, the cascade interrupt's irqaction */
-	struct irqaction cascade;
 };
 
 static void uic_unmask_irq(unsigned int virq)
@@ -221,23 +218,36 @@ static struct irq_host_ops uic_host_ops = {
 	.xlate	= uic_host_xlate,
 };
 
-irqreturn_t uic_cascade(int virq, void *data)
+void uic_irq_cascade(unsigned int virq, struct irq_desc *desc)
 {
-	struct uic *uic = data;
+	struct uic *uic = get_irq_data(virq);
 	u32 msr;
 	int src;
 	int subvirq;
 
+	spin_lock(&desc->lock);
+	if (desc->status & IRQ_LEVEL)
+		desc->chip->mask(virq);
+	else
+		desc->chip->mask_ack(virq);
+	spin_unlock(&desc->lock);
+
 	msr = mfdcr(uic->dcrbase + UIC_MSR);
 	if (!msr) /* spurious interrupt */
-		return IRQ_HANDLED;
+		goto uic_irq_ret;
 
 	src = 32 - ffs(msr);
 
 	subvirq = irq_linear_revmap(uic->irqhost, src);
 	generic_handle_irq(subvirq);
 
-	return IRQ_HANDLED;
+uic_irq_ret:
+	spin_lock(&desc->lock);
+	if (desc->status & IRQ_LEVEL)
+		desc->chip->ack(virq);
+	if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
+		desc->chip->unmask(virq);
+	spin_unlock(&desc->lock);
 }
 
 static struct uic * __init uic_init_one(struct device_node *node)
@@ -325,7 +335,6 @@ void __init uic_init_tree(void)
 		if (interrupts) {
 			/* Secondary UIC */
 			int cascade_virq;
-			int ret;
 
 			uic = uic_init_one(np);
 			if (! uic)
@@ -334,15 +343,8 @@ void __init uic_init_tree(void)
 
 			cascade_virq = irq_of_parse_and_map(np, 0);
 
-			uic->cascade.handler = uic_cascade;
-			uic->cascade.name = "UIC cascade";
-			uic->cascade.dev_id = uic;
-
-			ret = setup_irq(cascade_virq, &uic->cascade);
-			if (ret)
-				printk(KERN_ERR "Failed to setup_irq(%d) for "
-				       "UIC%d cascade\n", cascade_virq,
-				       uic->index);
+			set_irq_data(cascade_virq, uic);
+			set_irq_chained_handler(cascade_virq, uic_irq_cascade);
 
 			/* FIXME: setup critical cascade?? */
 		}