3 files changed, 100 insertions, 8 deletions

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 330343bcb67e..d8d3e02b912c 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -1,11 +1,14 @@
 config CLKSRC_I8253
         bool
 
+config CLKEVT_I8253
+        bool
+
 config I8253_LOCK
         bool
 
 config CLKBLD_I8253
-        def_bool y if CLKSRC_I8253 || I8253_LOCK
+        def_bool y if CLKSRC_I8253 || CLKEVT_I8253 || I8253_LOCK
 
 config CLKSRC_MMIO
         bool
diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c
index e594f52eb88e..27c49e60b7d6 100644
--- a/drivers/clocksource/i8253.c
+++ b/drivers/clocksource/i8253.c
@@ -1,13 +1,14 @@
 /*
  * i8253 PIT clocksource
  */
-#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/spinlock.h>
 #include <linux/timex.h>
 #include <linux/module.h>
 #include <linux/i8253.h>
+#include <linux/smp.h>
 
 /*
  * Protects access to I/O ports
@@ -47,15 +48,15 @@ static cycle_t i8253_read(struct clocksource *cs)
          * count), it cannot be newer.
          */
         jifs = jiffies;
-        outb_pit(0x00, PIT_MODE);       /* latch the count ASAP */
-        count = inb_pit(PIT_CH0);       /* read the latched count */
-        count |= inb_pit(PIT_CH0) << 8;
+        outb_p(0x00, PIT_MODE); /* latch the count ASAP */
+        count = inb_p(PIT_CH0); /* read the latched count */
+        count |= inb_p(PIT_CH0) << 8;
 
         /* VIA686a test code... reset the latch if count > max + 1 */
         if (count > LATCH) {
-                outb_pit(0x34, PIT_MODE);
-                outb_pit(PIT_LATCH & 0xff, PIT_CH0);
-                outb_pit(PIT_LATCH >> 8, PIT_CH0);
+                outb_p(0x34, PIT_MODE);
+                outb_p(PIT_LATCH & 0xff, PIT_CH0);
+                outb_p(PIT_LATCH >> 8, PIT_CH0);
                 count = PIT_LATCH - 1;
         }
 
@@ -97,3 +98,89 @@ int __init clocksource_i8253_init(void)
         return clocksource_register_hz(&i8253_cs, PIT_TICK_RATE);
 }
 #endif
+
+#ifdef CONFIG_CLKEVT_I8253
+/*
+ * 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)
+{
+        raw_spin_lock(&i8253_lock);
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                /* binary, mode 2, LSB/MSB, ch 0 */
+                outb_p(0x34, PIT_MODE);
+                outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
+                outb_p(LATCH >> 8 , PIT_CH0);           /* MSB */
+                break;
+
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        case CLOCK_EVT_MODE_UNUSED:
+                if (evt->mode == CLOCK_EVT_MODE_PERIODIC ||
+                    evt->mode == CLOCK_EVT_MODE_ONESHOT) {
+                        outb_p(0x30, PIT_MODE);
+                        outb_p(0, PIT_CH0);
+                        outb_p(0, PIT_CH0);
+                }
+                break;
+
+        case CLOCK_EVT_MODE_ONESHOT:
+                /* One shot setup */
+                outb_p(0x38, PIT_MODE);
+                break;
+
+        case CLOCK_EVT_MODE_RESUME:
+                /* Nothing to do here */
+                break;
+        }
+        raw_spin_unlock(&i8253_lock);
+}
+
+/*
+ * 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)
+{
+        raw_spin_lock(&i8253_lock);
+        outb_p(delta & 0xff , PIT_CH0); /* LSB */
+        outb_p(delta >> 8 , PIT_CH0);           /* MSB */
+        raw_spin_unlock(&i8253_lock);
+
+        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.
+ */
+struct clock_event_device i8253_clockevent = {
+        .name           = "pit",
+        .features       = CLOCK_EVT_FEAT_PERIODIC,
+        .set_mode       = init_pit_timer,
+        .set_next_event = pit_next_event,
+};
+
+/*
+ * 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 clockevent_i8253_init(bool oneshot)
+{
+        if (oneshot)
+                i8253_clockevent.features |= CLOCK_EVT_FEAT_ONESHOT;
+        /*
+         * Start pit with the boot cpu mask. x86 might make it global
+         * when it is used as broadcast device later.
+         */
+        i8253_clockevent.cpumask = cpumask_of(smp_processor_id());
+
+        clockevents_config_and_register(&i8253_clockevent, PIT_TICK_RATE,
+                                        0xF, 0x7FFF);
+}
+#endif
diff --git a/include/linux/i8253.h b/include/linux/i8253.h
index 76039c86ab58..487d50c7db39 100644
--- a/include/linux/i8253.h
+++ b/include/linux/i8253.h
@@ -24,6 +24,8 @@
 #define outb_pit        outb_p
 
 extern raw_spinlock_t i8253_lock;
+extern struct clock_event_device i8253_clockevent;
+extern void clockevent_i8253_init(bool oneshot);
 
 extern void setup_pit_timer(void);