[MIPS] Make irq number allocator generally available for fixing EV64120.

Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/kernel/irq.c

···
 #include <asm/system.h>
 #include <asm/uaccess.h>
 
+static unsigned long irq_map[NR_IRQS / BITS_PER_LONG];
+
+int __devinit allocate_irqno(void)
+{
+	int irq;
+
+again:
+	irq = find_first_zero_bit(irq_map, NR_IRQS);
+
+	if (irq >= NR_IRQS)
+		return -ENOSPC;
+
+	if (test_and_set_bit(irq, irq_map))
+		goto again;
+
+	return irq;
+}
+
+EXPORT_SYMBOL_GPL(allocate_irqno);
+
+/*
+ * Allocate the 16 legacy interrupts for i8259 devices.  This happens early
+ * in the kernel initialization so treating allocation failure as BUG() is
+ * ok.
+ */
+void __init alloc_legacy_irqno(void)
+{
+	int i;
+
+	for (i = 0; i <= 16; i++)
+		BUG_ON(test_and_set_bit(i, irq_map));
+}
+
+void __devinit free_irqno(unsigned int irq)
+{
+	smp_mb__before_clear_bit();
+	clear_bit(irq, irq_map);
+	smp_mb__after_clear_bit();
+}
+
+EXPORT_SYMBOL_GPL(free_irqno);
+
 /*
  * 'what should we do if we get a hw irq event on an illegal vector'.
  * each architecture has to answer this themselves.

arch/mips/sgi-ip27/ip27-irq.c

···
 	.end		= end_bridge_irq,
 };
 
-static unsigned long irq_map[NR_IRQS / BITS_PER_LONG];
-
-int allocate_irqno(void)
-{
-	int irq;
-
-again:
-	irq = find_first_zero_bit(irq_map, NR_IRQS);
-
-	if (irq >= NR_IRQS)
-		return -ENOSPC;
-
-	if (test_and_set_bit(irq, irq_map))
-		goto again;
-
-	return irq;
-}
-
-void free_irqno(unsigned int irq)
-{
-	clear_bit(irq, irq_map);
-}
-
 void __devinit register_bridge_irq(unsigned int irq)
 {
 	irq_desc[irq].status	= IRQ_DISABLED;

arch/mips/sgi-ip27/ip27-timer.c

···
 	.name		= "timer"
 };
 
-extern int allocate_irqno(void);
-
 void __init plat_timer_setup(struct irqaction *irq)
 {
 	int irqno  = allocate_irqno();

include/asm-mips/irq.h

···
                           unsigned long hwmask);
 #endif /* CONFIG_MIPS_MT_SMTC */
 
+extern int allocate_irqno(void);
+extern void alloc_legacy_irqno(void);
+extern void free_irqno(unsigned int irq);
+
 #endif /* _ASM_IRQ_H */