microblaze: Change NO_IRQ to 0

As has been discussed many times[1], Using NO_IRQ set to anything other
than 0 is bug waiting to happen since many drivers follow the pattern
"if (!irq)" for testing whether or not an irq has been set.

This patch changes the Microblaze NO_IRQ setting from -1 to 0 to bring
it in line with most of the rest of the kernel.  It also prepares for
Microblaze eventually supporting multiple interrupt controllers by
breaking the assumption that hwirq# == Linux IRQ#.  The Linux IRQ
number is just a cookie with no guarantee of a direct relationship
with the hardware irq arrangement.

At this point, Microblaze interrupt handling only supports only one
instance of one kind of interrupt controller (xilinx_intc).  This change
shouldn't affect any architecture code outside of the interrupt
controller driver and the irq_of mapping.

Updated to 3.2 and to use irq_data.hwirq by Rob Herring.
Tested and fixed by Michal Simek.

[1] http://lkml.org/lkml/2005/11/21/221

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 6 insertions, 5 deletions

diff --git a/arch/microblaze/kernel/irq.c b/arch/microblaze/kernel/irq.c
index e5d63a89b9b2..bbebcae72c02 100644
--- a/arch/microblaze/kernel/irq.c
+++ b/arch/microblaze/kernel/irq.c
@@ -33,11 +33,12 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
 	irq_enter();
 	irq = get_irq(regs);
 next_irq:
-	BUG_ON(irq == -1U);
-	generic_handle_irq(irq);
+	BUG_ON(!irq);
+	/* Substract 1 because of get_irq */
+	generic_handle_irq(irq + IRQ_OFFSET - NO_IRQ_OFFSET);
 
 	irq = get_irq(regs);
-	if (irq != -1U) {
+	if (irq) {
 		pr_debug("next irq: %d\n", irq);
 		++concurrent_irq;
 		goto next_irq;
@@ -52,13 +53,13 @@ next_irq:
   intc without any cascades or any connection that's why mapping is 1:1 */
 unsigned int irq_create_mapping(struct irq_host *host, irq_hw_number_t hwirq)
 {
-	return hwirq;
+	return hwirq + IRQ_OFFSET;
 }
 EXPORT_SYMBOL_GPL(irq_create_mapping);
 
 unsigned int irq_create_of_mapping(struct device_node *controller,
 				   const u32 *intspec, unsigned int intsize)
 {
-	return intspec[0];
+	return intspec[0] + IRQ_OFFSET;
 }
 EXPORT_SYMBOL_GPL(irq_create_of_mapping);