x86: Simplify timer_ack magic in time_32.c

Let the compiler optimize the timer_ack magic away in the 32bit timer
interrupt and put the same code into time_64.c. It's optimized out for
CONFIG_X86_IO_APIC on 32bit and for 64bit because timer_ack is const 0
in both cases.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c
index 45914f8844a7..35e0a925da56 100644
--- a/arch/x86/kernel/time_64.c
+++ b/arch/x86/kernel/time_64.c
@@ -51,6 +51,20 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
 {
         inc_irq_stat(irq0_irqs);
 
+        /* Optimized out for !IO_APIC and x86_64 */
+        if (timer_ack) {
+                /*
+                 * Subtle, when I/O APICs are used we have to ack timer IRQ
+                 * manually to deassert NMI lines for the watchdog if run
+                 * on an 82489DX-based system.
+                 */
+                spin_lock(&i8259A_lock);
+                outb(0x0c, PIC_MASTER_OCW3);
+                /* Ack the IRQ; AEOI will end it automatically. */
+                inb(PIC_MASTER_POLL);
+                spin_unlock(&i8259A_lock);
+        }
+
         global_clock_event->event_handler(global_clock_event);
 
 #ifdef CONFIG_MCA