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yaml
---
r: 257195
b: refs/heads/master
c: e6220bd
h: refs/heads/master
i:
  257193: abc22fd
  257191: 8496752
v: v3
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Thomas Gleixner committed Jul 1, 2011
1 parent 4857578 commit 855007b
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Showing 4 changed files with 101 additions and 9 deletions.
2 changes: 1 addition & 1 deletion [refs]
Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 21f07f4f5718449c85c29827ff6fb0cf35a6c96e
refs/heads/master: e6220bdc9485c5ea972f9e0e6d062a05934bb74b
5 changes: 4 additions & 1 deletion trunk/drivers/clocksource/Kconfig
Original file line number Diff line number Diff line change
@@ -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
101 changes: 94 additions & 7 deletions trunk/drivers/clocksource/i8253.c
Original file line number Diff line number Diff line change
@@ -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
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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
2 changes: 2 additions & 0 deletions trunk/include/linux/i8253.h
Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand Down

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