[RFC PATCH 18/24] arm: irq: do not assume NR_IRQS to be defined

[Venkatraman S]

From: Venkatraman S <venkat at linaro.org>

If SPARSE_IRQ is defined, NR_IRQS will not necessarily be
relevant. Use the number populated in machine descriptor.

Note: HARDIRQ_BITS is defined as a constant independent of NR_IRQS.
Needs review if this assumption makes sense.

Signed-off-by: Venkatraman S <venkat at linaro.org>
---
 arch/arm/common/gic.c          |    8 ++++----
 arch/arm/include/asm/hardirq.h |    6 ++++++
 arch/arm/kernel/irq.c          |    8 +++++++-
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
index 4ddd0a6..6fb5fa4 100644
--- a/arch/arm/common/gic.c
+++ b/arch/arm/common/gic.c
@@ -28,7 +28,7 @@
 #include <linux/smp.h>
 #include <linux/cpumask.h>
 #include <linux/io.h>
-
+#include <linux/irqnr.h>
 #include <asm/irq.h>
 #include <asm/mach/irq.h>
 #include <asm/hardware/gic.h>
@@ -231,7 +231,7 @@ static void gic_handle_cascade_irq(unsigned int irq, struct irq_desc *desc)
 		goto out;
 
 	cascade_irq = gic_irq + chip_data->irq_offset;
-	if (unlikely(gic_irq < 32 || gic_irq > 1020 || cascade_irq >= NR_IRQS))
+	if (unlikely(gic_irq < 32 || gic_irq > 1020 || cascade_irq >= nr_irqs))
 		do_bad_IRQ(cascade_irq, desc);
 	else
 		generic_handle_irq(cascade_irq);
@@ -312,8 +312,8 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
 	 * Limit number of interrupts registered to the platform maximum
 	 */
 	irq_limit = gic->irq_offset + gic_irqs;
-	if (WARN_ON(irq_limit > NR_IRQS))
-		irq_limit = NR_IRQS;
+	if (WARN_ON(irq_limit > nr_irqs))
+		irq_limit = nr_irqs;
 
 	/*
 	 * Setup the Linux IRQ subsystem.
diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h
index 89ad180..4bea5c0 100644
--- a/arch/arm/include/asm/hardirq.h
+++ b/arch/arm/include/asm/hardirq.h
@@ -30,6 +30,10 @@ u64 smp_irq_stat_cpu(unsigned int cpu);
 
 #define arch_irq_stat_cpu	smp_irq_stat_cpu
 
+#ifndef NR_IRQS
+/* FIXME: Need a better way to derive HARDIRQ_BITS */
+#define HARDIRQ_BITS 10
+#else
 #if NR_IRQS > 512
 #define HARDIRQ_BITS	10
 #elif NR_IRQS > 256
@@ -47,6 +51,8 @@ u64 smp_irq_stat_cpu(unsigned int cpu);
 # error HARDIRQ_BITS is too low!
 #endif
 
+#endif
+
 #define __ARCH_IRQ_EXIT_IRQS_DISABLED	1
 
 #endif /* __ASM_HARDIRQ_H */
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 83bbad0..12ffa9d 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -124,7 +124,13 @@ void __init init_IRQ(void)
 #ifdef CONFIG_SPARSE_IRQ
 int __init arch_probe_nr_irqs(void)
 {
-	nr_irqs = machine_desc->nr_irqs ? machine_desc->nr_irqs : NR_IRQS;
+	if (machine_desc->nr_irqs)
+		nr_irqs = machine_desc->nr_irqs;
+	#ifdef NR_IRQS
+	else
+		nr_irqs = NR_IRQS;
+	#endif
+	WARN_ON(nr_irqs);
 	return nr_irqs;
 }
 #endif
-- 
1.7.1