[PATCH] genirq: add IRQ_NOREQUEST support

Enable platforms to disable request_irq() for certain interrupts.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/linux/irq.h

@@ -41,6 +41,7 @@
 #endif
 
 #define IRQ_NOPROBE	512	/* IRQ is not valid for probing */
+#define IRQ_NOREQUEST	1024	/* IRQ cannot be requested */
 /**
  * struct hw_interrupt_type - hardware interrupt type descriptor
  *

kernel/irq/manage.c

@@ -141,7 +141,7 @@ int can_request_irq(unsigned int irq, unsigned long irqflags)
 {
 	struct irqaction *action;
 
-	if (irq >= NR_IRQS)
+	if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
 		return 0;
 
 	action = irq_desc[irq].action;
@@ -356,6 +356,8 @@ int request_irq(unsigned int irq,
 		return -EINVAL;
 	if (irq >= NR_IRQS)
 		return -EINVAL;
+	if (irq_desc[irq].status & IRQ_NOREQUEST)
+		return -EINVAL;
 	if (!handler)
 		return -EINVAL;