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i8253: Create common clockevent implementation 

arm, mips and x86 implement i8253 based clockevents. All the same code
copied. Create a common implementation in drivers/clocksource/i8253.c.

About time to rename drivers/clocksource/ to something else.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20110609130621.921710458@linutronix.de
This commit is contained in:
Thomas Gleixner 2011-06-09 13:08:25 +00:00
parent 21f07f4f57
commit e6220bdc94
3 changed files with 100 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
drivers/clocksource/Kconfig
View File

@ -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
drivers/clocksource/i8253.c
View File

@ -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

2
include/linux/i8253.h
View File

@ -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);