[ARM PATCH] 2373/1: S3C2410 - fix possible loop in irq macro

Patch from Ben Dooks

If we read the INTPEND register and get the wrong
result (details below) then it looks like a possible
loop to go back and re-read it after calculating
the possible correct value for it.

It seems that the INTPEND register, which should
show the unique number of the interrupt that we
need to handle. However, it seems that this register
can show the wrong interrupt under certain conditions.

Shannon's research shows that it is very possible that
the occurence of an external interrupt can end up
merging with the base interrupt number, causing
the wrong result in the register.

This patch also fixes the end position of the #ifdef
block and ensures as many registers as possible are
stacked before calling printk() for debug.

Original patch for 2.6.9 by Shannon Holland re-written
for 2.6.10 by Ben Dooks.

Signed-off-by: Shannon Holland                             
Signed-off-by: Ben Dooks                                 
Signed-off-by: Russell King

include/asm-arm/arch-s3c2410/entry-macro.S

@@ -8,11 +8,12 @@
  * warranty of any kind, whether express or implied.
  */
 
-		.macro	get_irqnr_and_base, irqnr, irqstat, base, tmp
 
-30000:
+	.macro	get_irqnr_and_base, irqnr, irqstat, base, tmp
+
 		mov	\tmp, #S3C2410_VA_IRQ
 		ldr	\irqnr, [ \tmp, #0x14 ]		@ get irq no
+30000:
 		teq	\irqnr, #4
 		teqne	\irqnr, #5
 		beq	1002f				@ external irq reg
@@ -29,15 +30,17 @@
 		tst	\irqstat, #1
 		bne	20002f
 
+		/* debug/warning if we get an invalud response from the
+		 * INTOFFSET register */
 #if 1
-		stmfd	r13!, { r0 - r4 , r14 }
-		ldr	r1,	[ \tmp, #0x14 ]		@ intoffset
+		stmfd	r13!, { r0 - r4 , r8-r12, r14 }
+		ldr	r1,	[ \tmp, #0x14 ]		@ INTOFFSET
 		ldr	r2,	[ \tmp, #0x10 ]		@ INTPND
 		ldr	r3,	[ \tmp, #0x00 ]		@ SRCPND
 		adr	r0, 20003f
 		bl	printk
 		b	20004f
-#endif
+
 20003:
 		.ascii	"<7>irq: err - bad offset %d, intpnd=%08x, srcpnd=%08x\n"
 		.byte	0
@@ -45,7 +48,8 @@
 20004:
 		mov	r1, #1
 		mov	\tmp, #S3C2410_VA_IRQ
-		ldmfd	r13!, { r0 - r4 , r14 }
+		ldmfd	r13!, { r0 - r4 , r8-r12, r14 }
+#endif
 
 		@ try working out interript number for ourselves
 		mov	\irqnr, #0