[PATCH] clockevents: i386 drivers

Add clockevent drivers for i386: lapic (local) and PIT/HPET (global).  Update
the timer IRQ to call into the PIT/HPET driver's event handler and the
lapic-timer IRQ to call into the lapic clockevent driver.  The assignement of
timer functionality is delegated to the core framework code and replaces the
compile and runtime evalution in do_timer_interrupt_hook()

Use the clockevents broadcast support and implement the lapic_broadcast
function for ACPI.

No changes to existing functionality.

[ kdump fix from Vivek Goyal <vgoyal@in.ibm.com> ]
[ fixes based on review feedback from Arjan van de Ven <arjan@infradead.org> ]
Cleanups-from: Adrian Bunk <bunk@stusta.de>
Build-fixes-from: Andrew Morton <akpm@osdl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 88 insertions, 8 deletions

diff --git a/arch/i386/kernel/i8253.c b/arch/i386/kernel/i8253.c
index 9a0060b92e32..a6bc7bb38834 100644
--- a/arch/i386/kernel/i8253.c
+++ b/arch/i386/kernel/i8253.c
@@ -2,7 +2,7 @@
  * i8253.c  8253/PIT functions
  *
  */
-#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 #include <linux/spinlock.h>
 #include <linux/jiffies.h>
 #include <linux/sysdev.h>
@@ -19,17 +19,97 @@
 DEFINE_SPINLOCK(i8253_lock);
 EXPORT_SYMBOL(i8253_lock);
 
-void setup_pit_timer(void)
+/*
+ * HPET replaces the PIT, when enabled. So we need to know, which of
+ * the two timers is used
+ */
+struct clock_event_device *global_clock_event;
+
+/*
+ * Initialize the PIT timer.
+ *
+ * This is also called after resume to bring the PIT into operation again.
+ */
+static void init_pit_timer(enum clock_event_mode mode,
+                           struct clock_event_device *evt)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&i8253_lock, flags);
+
+        switch(mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                /* binary, mode 2, LSB/MSB, ch 0 */
+                outb_p(0x34, PIT_MODE);
+                udelay(10);
+                outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
+                udelay(10);
+                outb(LATCH >> 8 , PIT_CH0);     /* MSB */
+                break;
+
+        case CLOCK_EVT_MODE_ONESHOT:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        case CLOCK_EVT_MODE_UNUSED:
+                /* One shot setup */
+                outb_p(0x38, PIT_MODE);
+                udelay(10);
+                break;
+        }
+        spin_unlock_irqrestore(&i8253_lock, flags);
+}
+
+/*
+ * Program the next event in oneshot mode
+ *
+ * Delta is given in PIT ticks
+ */
+static int pit_next_event(unsigned long delta, struct clock_event_device *evt)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&i8253_lock, flags);
-        outb_p(0x34,PIT_MODE);          /* binary, mode 2, LSB/MSB, ch 0 */
-        udelay(10);
-        outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
-        udelay(10);
-        outb(LATCH >> 8 , PIT_CH0);     /* MSB */
+        outb_p(delta & 0xff , PIT_CH0); /* LSB */
+        outb(delta >> 8 , PIT_CH0);     /* MSB */
         spin_unlock_irqrestore(&i8253_lock, flags);
+
+        return 0;
+}
+
+/*
+ * On UP the PIT can serve all of the possible timer functions. On SMP systems
+ * it can be solely used for the global tick.
+ *
+ * The profiling and update capabilites are switched off once the local apic is
+ * registered. This mechanism replaces the previous #ifdef LOCAL_APIC -
+ * !using_apic_timer decisions in do_timer_interrupt_hook()
+ */
+struct clock_event_device pit_clockevent = {
+        .name           = "pit",
+        .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+        .set_mode       = init_pit_timer,
+        .set_next_event = pit_next_event,
+        .shift          = 32,
+        .irq            = 0,
+};
+
+/*
+ * Initialize the conversion factor and the min/max deltas of the clock event
+ * structure and register the clock event source with the framework.
+ */
+void __init setup_pit_timer(void)
+{
+        /*
+         * Start pit with the boot cpu mask and make it global after the
+         * IO_APIC has been initialized.
+         */
+        pit_clockevent.cpumask = cpumask_of_cpu(0);
+        pit_clockevent.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, 32);
+        pit_clockevent.max_delta_ns =
+                clockevent_delta2ns(0x7FFF, &pit_clockevent);
+        pit_clockevent.min_delta_ns =
+                clockevent_delta2ns(0xF, &pit_clockevent);
+        clockevents_register_device(&pit_clockevent);
+        global_clock_event = &pit_clockevent;
 }
 
 /*
@@ -46,7 +126,7 @@ static cycle_t pit_read(void)
         static u32 old_jifs;
 
         spin_lock_irqsave(&i8253_lock, flags);
-        /*
+        /*
          * Although our caller may have the read side of xtime_lock,
          * this is now a seqlock, and we are cheating in this routine
          * by having side effects on state that we cannot undo if