mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-02 11:36:42 +07:00
61ee9a4ba0
Let the core do the work. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Reviewed-by: Ingo Molnar <mingo@elte.hu> Link: http://lkml.kernel.org/r/%3C20110518210136.545615675%40linutronix.de%3E
133 lines
3.2 KiB
C
133 lines
3.2 KiB
C
/*
|
|
* 8253/PIT functions
|
|
*
|
|
*/
|
|
#include <linux/clockchips.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/jiffies.h>
|
|
#include <linux/module.h>
|
|
#include <linux/timex.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/init.h>
|
|
#include <linux/io.h>
|
|
|
|
#include <asm/i8253.h>
|
|
#include <asm/hpet.h>
|
|
#include <asm/smp.h>
|
|
|
|
DEFINE_RAW_SPINLOCK(i8253_lock);
|
|
EXPORT_SYMBOL(i8253_lock);
|
|
|
|
/*
|
|
* HPET replaces the PIT, when enabled. So we need to know, which of
|
|
* the two timers is used
|
|
*/
|
|
struct clock_event_device *global_clock_event;
|
|
|
|
/*
|
|
* 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_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_pit(0x30, PIT_MODE);
|
|
outb_pit(0, PIT_CH0);
|
|
outb_pit(0, PIT_CH0);
|
|
}
|
|
break;
|
|
|
|
case CLOCK_EVT_MODE_ONESHOT:
|
|
/* One shot setup */
|
|
outb_pit(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_pit(delta & 0xff , PIT_CH0); /* LSB */
|
|
outb_pit(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.
|
|
*
|
|
* 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()
|
|
*/
|
|
static struct clock_event_device pit_ce = {
|
|
.name = "pit",
|
|
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
|
|
.set_mode = init_pit_timer,
|
|
.set_next_event = pit_next_event,
|
|
.irq = 0,
|
|
};
|
|
|
|
/*
|
|
* 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 setup_pit_timer(void)
|
|
{
|
|
/*
|
|
* Start pit with the boot cpu mask and make it global after the
|
|
* IO_APIC has been initialized.
|
|
*/
|
|
pit_ce.cpumask = cpumask_of(smp_processor_id());
|
|
|
|
clockevents_config_and_register(&pit_ce, CLOCK_TICK_RATE, 0xF, 0x7FFF);
|
|
global_clock_event = &pit_ce;
|
|
}
|
|
|
|
#ifndef CONFIG_X86_64
|
|
static int __init init_pit_clocksource(void)
|
|
{
|
|
/*
|
|
* 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;
|
|
|
|
return clocksource_i8253_init();
|
|
}
|
|
arch_initcall(init_pit_clocksource);
|
|
#endif /* !CONFIG_X86_64 */
|