[MIPS] IRQ cleanups

This is a big irq cleanup patch.

* Use set_irq_chip() to register irq_chip.
* Initialize .mask, .unmask, .mask_ack field.  Functions for these
  method are already exist in most case.
* Do not initialize .startup, .shutdown, .enable, .disable fields if
  default routines provided by irq_chip_set_defaults() were suitable.
* Remove redundant irq_desc initializations.
* Remove unnecessary local_irq_save/local_irq_restore, spin_lock.

With this cleanup, it would be easy to switch to slightly lightwait
irq flow handlers (handle_level_irq(), etc.) instead of __do_IRQ().

Though whole this patch is quite large, changes in each irq_chip are
not quite simple.  Please review and test on your platform.  Thanks.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/jazz/irq.c

@@ -28,14 +28,6 @@ static void enable_r4030_irq(unsigned int irq)
 	spin_unlock_irqrestore(&r4030_lock, flags);
 }
 
-static unsigned int startup_r4030_irq(unsigned int irq)
-{
-	enable_r4030_irq(irq);
-	return 0; /* never anything pending */
-}
-
-#define shutdown_r4030_irq	disable_r4030_irq
-
 void disable_r4030_irq(unsigned int irq)
 {
 	unsigned int mask = ~(1 << (irq - JAZZ_PARALLEL_IRQ));
@@ -47,8 +39,6 @@ void disable_r4030_irq(unsigned int irq)
 	spin_unlock_irqrestore(&r4030_lock, flags);
 }
 
-#define mask_and_ack_r4030_irq disable_r4030_irq
-
 static void end_r4030_irq(unsigned int irq)
 {
 	if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
@@ -57,11 +47,10 @@ static void end_r4030_irq(unsigned int irq)
 
 static struct irq_chip r4030_irq_type = {
 	.typename = "R4030",
-	.startup = startup_r4030_irq,
-	.shutdown = shutdown_r4030_irq,
-	.enable = enable_r4030_irq,
-	.disable = disable_r4030_irq,
-	.ack = mask_and_ack_r4030_irq,
+	.ack = disable_r4030_irq,
+	.mask = disable_r4030_irq,
+	.mask_ack = disable_r4030_irq,
+	.unmask = enable_r4030_irq,
 	.end = end_r4030_irq,
 };
 
@@ -69,12 +58,8 @@ void __init init_r4030_ints(void)
 {
 	int i;
 
-	for (i = JAZZ_PARALLEL_IRQ; i <= JAZZ_TIMER_IRQ; i++) {
-		irq_desc[i].status     = IRQ_DISABLED;
-		irq_desc[i].action     = 0;
-		irq_desc[i].depth      = 1;
-		irq_desc[i].chip    = &r4030_irq_type;
-	}
+	for (i = JAZZ_PARALLEL_IRQ; i <= JAZZ_TIMER_IRQ; i++)
+		set_irq_chip(i, &r4030_irq_type);
 
 	r4030_write_reg16(JAZZ_IO_IRQ_ENABLE, 0);
 	r4030_read_reg16(JAZZ_IO_IRQ_SOURCE);		/* clear pending IRQs */