[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>

1 files changed, 5 insertions, 22 deletions

diff --git a/arch/mips/sgi-ip27/ip27-timer.c b/arch/mips/sgi-ip27/ip27-timer.c
index 5e82a268e3c9..86ba7fc10c38 100644
--- a/arch/mips/sgi-ip27/ip27-timer.c
+++ b/arch/mips/sgi-ip27/ip27-timer.c
@@ -172,15 +172,6 @@ static __init unsigned long get_m48t35_time(void)
         return mktime(year, month, date, hour, min, sec);
 }
 
-static unsigned int startup_rt_irq(unsigned int irq)
-{
-        return 0;
-}
-
-static void shutdown_rt_irq(unsigned int irq)
-{
-}
-
 static void enable_rt_irq(unsigned int irq)
 {
 }
@@ -189,21 +180,16 @@ static void disable_rt_irq(unsigned int irq)
 {
 }
 
-static void mask_and_ack_rt(unsigned int irq)
-{
-}
-
 static void end_rt_irq(unsigned int irq)
 {
 }
 
 static struct irq_chip rt_irq_type = {
         .typename       = "SN HUB RT timer",
-        .startup        = startup_rt_irq,
-        .shutdown       = shutdown_rt_irq,
-        .enable         = enable_rt_irq,
-        .disable        = disable_rt_irq,
-        .ack            = mask_and_ack_rt,
+        .ack            = disable_rt_irq,
+        .mask           = disable_rt_irq,
+        .mask_ack       = disable_rt_irq,
+        .unmask         = enable_rt_irq,
         .end            = end_rt_irq,
 };
 
@@ -221,10 +207,7 @@ void __init plat_timer_setup(struct irqaction *irq)
         if (irqno < 0)
                 panic("Can't allocate interrupt number for timer interrupt");
 
-        irq_desc[irqno].status  = IRQ_DISABLED;
-        irq_desc[irqno].action  = NULL;
-        irq_desc[irqno].depth   = 1;
-        irq_desc[irqno].chip    = &rt_irq_type;
+        set_irq_chip(irqno, &rt_irq_type);
 
         /* over-write the handler, we use our own way */
         irq->handler = no_action;