[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/vr41xx/common/icu.c

@@ -417,14 +417,7 @@ void vr41xx_disable_bcuint(void)
 
 EXPORT_SYMBOL(vr41xx_disable_bcuint);
 
-static unsigned int startup_sysint1_irq(unsigned int irq)
-{
-	icu1_set(MSYSINT1REG, 1 << SYSINT1_IRQ_TO_PIN(irq));
-
-	return 0; /* never anything pending */
-}
-
-static void shutdown_sysint1_irq(unsigned int irq)
+static void disable_sysint1_irq(unsigned int irq)
 {
 	icu1_clear(MSYSINT1REG, 1 << SYSINT1_IRQ_TO_PIN(irq));
 }
@@ -434,9 +427,6 @@ static void enable_sysint1_irq(unsigned int irq)
 	icu1_set(MSYSINT1REG, 1 << SYSINT1_IRQ_TO_PIN(irq));
 }
 
-#define disable_sysint1_irq	shutdown_sysint1_irq
-#define ack_sysint1_irq		shutdown_sysint1_irq
-
 static void end_sysint1_irq(unsigned int irq)
 {
 	if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
@@ -445,22 +435,14 @@ static void end_sysint1_irq(unsigned int irq)
 
 static struct irq_chip sysint1_irq_type = {
 	.typename	= "SYSINT1",
-	.startup	= startup_sysint1_irq,
-	.shutdown	= shutdown_sysint1_irq,
-	.enable		= enable_sysint1_irq,
-	.disable	= disable_sysint1_irq,
-	.ack		= ack_sysint1_irq,
+	.ack		= disable_sysint1_irq,
+	.mask		= disable_sysint1_irq,
+	.mask_ack	= disable_sysint1_irq,
+	.unmask		= enable_sysint1_irq,
 	.end		= end_sysint1_irq,
 };
 
-static unsigned int startup_sysint2_irq(unsigned int irq)
-{
-	icu2_set(MSYSINT2REG, 1 << SYSINT2_IRQ_TO_PIN(irq));
-
-	return 0; /* never anything pending */
-}
-
-static void shutdown_sysint2_irq(unsigned int irq)
+static void disable_sysint2_irq(unsigned int irq)
 {
 	icu2_clear(MSYSINT2REG, 1 << SYSINT2_IRQ_TO_PIN(irq));
 }
@@ -470,9 +452,6 @@ static void enable_sysint2_irq(unsigned int irq)
 	icu2_set(MSYSINT2REG, 1 << SYSINT2_IRQ_TO_PIN(irq));
 }
 
-#define disable_sysint2_irq	shutdown_sysint2_irq
-#define ack_sysint2_irq		shutdown_sysint2_irq
-
 static void end_sysint2_irq(unsigned int irq)
 {
 	if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
@@ -481,11 +460,10 @@ static void end_sysint2_irq(unsigned int irq)
 
 static struct irq_chip sysint2_irq_type = {
 	.typename	= "SYSINT2",
-	.startup	= startup_sysint2_irq,
-	.shutdown	= shutdown_sysint2_irq,
-	.enable		= enable_sysint2_irq,
-	.disable	= disable_sysint2_irq,
-	.ack		= ack_sysint2_irq,
+	.ack		= disable_sysint2_irq,
+	.mask		= disable_sysint2_irq,
+	.mask_ack	= disable_sysint2_irq,
+	.unmask		= enable_sysint2_irq,
 	.end		= end_sysint2_irq,
 };
 
@@ -723,10 +701,10 @@ static int __init vr41xx_icu_init(void)
 	icu2_write(MGIUINTHREG, 0xffff);
 
 	for (i = SYSINT1_IRQ_BASE; i <= SYSINT1_IRQ_LAST; i++)
-		irq_desc[i].chip = &sysint1_irq_type;
+		set_irq_chip(i, &sysint1_irq_type);
 
 	for (i = SYSINT2_IRQ_BASE; i <= SYSINT2_IRQ_LAST; i++)
-		irq_desc[i].chip = &sysint2_irq_type;
+		set_irq_chip(i, &sysint2_irq_type);
 
 	cascade_irq(INT0_IRQ, icu_get_irq);
 	cascade_irq(INT1_IRQ, icu_get_irq);