i8253: Create common clockevent implementation (e6220bdc) · Commits · 戴 / test

drivers/clocksource/Kconfig

+4 −1

Original line number	Diff line number	Diff line
		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

drivers/clocksource/i8253.c

+94 −7

Original line number	Diff line number	Diff line
		/*
		* 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

include/linux/i8253.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -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);

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