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Diffstat (limited to 'drivers/clocksource/i8253.c')
-rw-r--r--drivers/clocksource/i8253.c114
1 files changed, 106 insertions, 8 deletions
diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c
index 225c1761b372..27c49e60b7d6 100644
--- a/drivers/clocksource/i8253.c
+++ b/drivers/clocksource/i8253.c
@@ -1,14 +1,25 @@
/*
* 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>
-#include <asm/i8253.h>
+/*
+ * Protects access to I/O ports
+ *
+ * 0040-0043 : timer0, i8253 / i8254
+ * 0061-0061 : NMI Control Register which contains two speaker control bits.
+ */
+DEFINE_RAW_SPINLOCK(i8253_lock);
+EXPORT_SYMBOL(i8253_lock);
+#ifdef CONFIG_CLKSRC_I8253
/*
* Since the PIT overflows every tick, its not very useful
* to just read by itself. So use jiffies to emulate a free
@@ -37,15 +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;
}
@@ -86,3 +97,90 @@ 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