OMAP3: ack spurious IRQs in get_irqnr_and_base

This prevents spurious interrupts from repeating unacked and
thus locking the system, while still allowing the spurious
bad irq error message to be show on console.
Signed-off-by: Lauri Leukkunen <lauri.leukkunen@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/include/mach/entry-macro.S

@@ -87,7 +87,26 @@
 		ldr	\irqnr, [\base, #0xd8] /* IRQ pending reg 3 */
 		cmp	\irqnr, #0x0
 2222:
-		ldrne	\irqnr, [\base, #INTCPS_SIR_IRQ_OFFSET]
+#if defined(CONFIG_ARCH_OMAP34XX)
+		mov	\tmp, \irqnr
+#endif
+ 		ldrne	\irqnr, [\base, #INTCPS_SIR_IRQ_OFFSET]
+#if defined(CONFIG_ARCH_OMAP34XX)
+		mov	\irqstat, \irqnr
+		bic	\irqstat, \irqstat, #0x7f /* check for spurious flag */
+		cmp	\irqstat, #0x0
+		beq	2223f
+		mov	\irqstat, #0x1 /* Ack the spurious irq, this lets it
+					* generate a bad irq error message,
+					* but prevents infinitely repeating
+					* irq.
+					*/
+		str	\irqstat, [\base, #0x48] /* INTC_CONTROL register */
+2223:
+		cmp	\tmp, #0x0 /* set conditional back to what it was
+				    * before spurious test
+				    */
+#endif
 
 		.endm