*
*/
#include <linux/clockchips.h>
-#include <linux/init.h>
#include <linux/interrupt.h>
+#include <linux/spinlock.h>
#include <linux/jiffies.h>
#include <linux/module.h>
-#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
-#include <asm/smp.h>
-#include <asm/delay.h>
#include <asm/i8253.h>
-#include <asm/io.h>
+#include <asm/hpet.h>
+#include <asm/smp.h>
DEFINE_SPINLOCK(i8253_lock);
EXPORT_SYMBOL(i8253_lock);
+#ifdef CONFIG_X86_32
+static void pit_disable_clocksource(void);
+#else
+static inline void pit_disable_clocksource(void) { }
+#endif
+
/*
* HPET replaces the PIT, when enabled. So we need to know, which of
* the two timers is used
static void init_pit_timer(enum clock_event_mode mode,
struct clock_event_device *evt)
{
- unsigned long flags;
-
- spin_lock_irqsave(&i8253_lock, flags);
+ spin_lock(&i8253_lock);
- switch(mode) {
+ 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(LATCH >> 8 , PIT_CH0); /* MSB */
+ outb_pit(0x34, PIT_MODE);
+ outb_pit(LATCH & 0xff , PIT_CH0); /* LSB */
+ outb_pit(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);
+ outb_pit(0x30, PIT_MODE);
+ outb_pit(0, PIT_CH0);
+ outb_pit(0, PIT_CH0);
}
+ pit_disable_clocksource();
break;
case CLOCK_EVT_MODE_ONESHOT:
/* One shot setup */
- outb_p(0x38, PIT_MODE);
+ pit_disable_clocksource();
+ outb_pit(0x38, PIT_MODE);
break;
case CLOCK_EVT_MODE_RESUME:
/* Nothing to do here */
break;
}
- spin_unlock_irqrestore(&i8253_lock, flags);
+ spin_unlock(&i8253_lock);
}
/*
*/
static int pit_next_event(unsigned long delta, struct clock_event_device *evt)
{
- unsigned long flags;
-
- spin_lock_irqsave(&i8253_lock, flags);
- outb_p(delta & 0xff , PIT_CH0); /* LSB */
- outb(delta >> 8 , PIT_CH0); /* MSB */
- spin_unlock_irqrestore(&i8253_lock, flags);
+ spin_lock(&i8253_lock);
+ outb_pit(delta & 0xff , PIT_CH0); /* LSB */
+ outb_pit(delta >> 8 , PIT_CH0); /* MSB */
+ 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.
*
- * The profiling and update capabilites are switched off once the local apic is
+ * The profiling and update capabilities 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 = {
+static struct clock_event_device pit_ce = {
.name = "pit",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_mode = init_pit_timer,
* Start pit with the boot cpu mask and make it global after the
* IO_APIC has been initialized.
*/
- pit_clockevent.cpumask = cpumask_of_cpu(smp_processor_id());
- 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;
+ pit_ce.cpumask = cpumask_of(smp_processor_id());
+ pit_ce.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, pit_ce.shift);
+ pit_ce.max_delta_ns = clockevent_delta2ns(0x7FFF, &pit_ce);
+ pit_ce.min_delta_ns = clockevent_delta2ns(0xF, &pit_ce);
+
+ clockevents_register_device(&pit_ce);
+ global_clock_event = &pit_ce;
}
#ifndef CONFIG_X86_64
* to just read by itself. So use jiffies to emulate a free
* running counter:
*/
-static cycle_t pit_read(void)
+static cycle_t pit_read(struct clocksource *cs)
{
+ static int old_count;
+ static u32 old_jifs;
unsigned long flags;
int count;
u32 jifs;
- static int old_count;
- static u32 old_jifs;
spin_lock_irqsave(&i8253_lock, flags);
/*
* count), it cannot be newer.
*/
jifs = jiffies;
- outb_p(0x00, PIT_MODE); /* latch the count ASAP */
- count = inb_p(PIT_CH0); /* read the latched count */
- count |= inb_p(PIT_CH0) << 8;
+ outb_pit(0x00, PIT_MODE); /* latch the count ASAP */
+ count = inb_pit(PIT_CH0); /* read the latched count */
+ count |= inb_pit(PIT_CH0) << 8;
/* VIA686a test code... reset the latch if count > max + 1 */
if (count > LATCH) {
- outb_p(0x34, PIT_MODE);
- outb_p(LATCH & 0xff, PIT_CH0);
- outb(LATCH >> 8, PIT_CH0);
+ outb_pit(0x34, PIT_MODE);
+ outb_pit(LATCH & 0xff, PIT_CH0);
+ outb_pit(LATCH >> 8, PIT_CH0);
count = LATCH - 1;
}
* Previous attempts to handle these cases intelligently were
* buggy, so we just do the simple thing now.
*/
- if (count > old_count && jifs == old_jifs) {
+ if (count > old_count && jifs == old_jifs)
count = old_count;
- }
+
old_count = count;
old_jifs = jifs;
return (cycle_t)(jifs * LATCH) + count;
}
-static struct clocksource clocksource_pit = {
- .name = "pit",
- .rating = 110,
- .read = pit_read,
- .mask = CLOCKSOURCE_MASK(32),
- .mult = 0,
- .shift = 20,
+static struct clocksource pit_cs = {
+ .name = "pit",
+ .rating = 110,
+ .read = pit_read,
+ .mask = CLOCKSOURCE_MASK(32),
+ .mult = 0,
+ .shift = 20,
};
+static void pit_disable_clocksource(void)
+{
+ /*
+ * Use mult to check whether it is registered or not
+ */
+ if (pit_cs.mult) {
+ clocksource_unregister(&pit_cs);
+ pit_cs.mult = 0;
+ }
+}
+
static int __init init_pit_clocksource(void)
{
- if (num_possible_cpus() > 1) /* PIT does not scale! */
+ /*
+ * Several reasons not to register PIT as a clocksource:
+ *
+ * - On SMP PIT does not scale due to i8253_lock
+ * - when HPET is enabled
+ * - when local APIC timer is active (PIT is switched off)
+ */
+ if (num_possible_cpus() > 1 || is_hpet_enabled() ||
+ pit_ce.mode != CLOCK_EVT_MODE_PERIODIC)
return 0;
- clocksource_pit.mult = clocksource_hz2mult(CLOCK_TICK_RATE, 20);
- return clocksource_register(&clocksource_pit);
+ pit_cs.mult = clocksource_hz2mult(CLOCK_TICK_RATE, pit_cs.shift);
+
+ return clocksource_register(&pit_cs);
}
arch_initcall(init_pit_clocksource);
-#endif
+#endif /* !CONFIG_X86_64 */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff