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Commit ab0e08f1 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: hpet: Cleanup the clockevents init and register code 



No need to recalculate the frequency and the conversion factors over
and over. Calculate the frequency once and use the new config/register
interface and let the core code do the math.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Link: http://lkml.kernel.org/r/%3C20110518210136.646482357%40linutronix.de%3E
parent 61ee9a4b

arch/x86/kernel/hpet.c

+16 −56
Original line number Diff line number Diff line
@@ -217,7 +217,7 @@ static void hpet_reserve_platform_timers(unsigned int id) { } 
/*

 * Common hpet info

 */

static unsigned long hpet_period;

static unsigned long hpet_freq;



static void hpet_legacy_set_mode(enum clock_event_mode mode,

			  struct clock_event_device *evt);
@@ -232,7 +232,6 @@ static struct clock_event_device hpet_clockevent = { 
	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,

	.set_mode	= hpet_legacy_set_mode,

	.set_next_event = hpet_legacy_next_event,

	.shift		= 32,

	.irq		= 0,

	.rating		= 50,

};
@@ -289,29 +288,13 @@ static void hpet_legacy_clockevent_register(void) 
	/* Start HPET legacy interrupts */

	hpet_enable_legacy_int();



	/*

	 * The mult factor is defined as (include/linux/clockchips.h)

	 *  mult/2^shift = cyc/ns (in contrast to ns/cyc in clocksource.h)

	 * hpet_period is in units of femtoseconds (per cycle), so

	 *  mult/2^shift = cyc/ns = 10^6/hpet_period

	 *  mult = (10^6 * 2^shift)/hpet_period

	 *  mult = (FSEC_PER_NSEC << hpet_clockevent.shift)/hpet_period

	 */

	hpet_clockevent.mult = div_sc((unsigned long) FSEC_PER_NSEC,

				      hpet_period, hpet_clockevent.shift);

	/* Calculate the min / max delta */

	hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,

							   &hpet_clockevent);

	/* Setup minimum reprogramming delta. */

	hpet_clockevent.min_delta_ns = clockevent_delta2ns(HPET_MIN_PROG_DELTA,

							   &hpet_clockevent);



	/*

	 * Start hpet with the boot cpu mask and make it

	 * global after the IO_APIC has been initialized.

	 */

	hpet_clockevent.cpumask = cpumask_of(smp_processor_id());

	clockevents_register_device(&hpet_clockevent);

	clockevents_config_and_register(&hpet_clockevent, hpet_freq,

					HPET_MIN_PROG_DELTA, 0x7FFFFFFF);

	global_clock_event = &hpet_clockevent;

	printk(KERN_DEBUG "hpet clockevent registered\n");

}
@@ -549,7 +532,6 @@ static int hpet_setup_irq(struct hpet_dev *dev) 
static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)

{

	struct clock_event_device *evt = &hdev->evt;

	uint64_t hpet_freq;



	WARN_ON(cpu != smp_processor_id());

	if (!(hdev->flags & HPET_DEV_VALID))
@@ -571,24 +553,10 @@ static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu) 


	evt->set_mode = hpet_msi_set_mode;

	evt->set_next_event = hpet_msi_next_event;

	evt->shift = 32;



	/*

	 * The period is a femto seconds value. We need to calculate the

	 * scaled math multiplication factor for nanosecond to hpet tick

	 * conversion.

	 */

	hpet_freq = FSEC_PER_SEC;

	do_div(hpet_freq, hpet_period);

	evt->mult = div_sc((unsigned long) hpet_freq,

				      NSEC_PER_SEC, evt->shift);

	/* Calculate the max delta */

	evt->max_delta_ns = clockevent_delta2ns(0x7FFFFFFF, evt);

	/* 5 usec minimum reprogramming delta. */

	evt->min_delta_ns = 5000;



	evt->cpumask = cpumask_of(hdev->cpu);

	clockevents_register_device(evt);



	clockevents_config_and_register(evt, hpet_freq, HPET_MIN_PROG_DELTA,

					0x7FFFFFFF);

}



#ifdef CONFIG_HPET
@@ -792,7 +760,6 @@ static struct clocksource clocksource_hpet = { 
static int hpet_clocksource_register(void)

{

	u64 start, now;

	u64 hpet_freq;

	cycle_t t1;



	/* Start the counter */
@@ -819,24 +786,7 @@ static int hpet_clocksource_register(void) 
		return -ENODEV;

	}



	/*

	 * The definition of mult is (include/linux/clocksource.h)

	 * mult/2^shift = ns/cyc and hpet_period is in units of fsec/cyc

	 * so we first need to convert hpet_period to ns/cyc units:

	 *  mult/2^shift = ns/cyc = hpet_period/10^6

	 *  mult = (hpet_period * 2^shift)/10^6

	 *  mult = (hpet_period << shift)/FSEC_PER_NSEC

	 */



	/* Need to convert hpet_period (fsec/cyc) to cyc/sec:

	 *

	 * cyc/sec = FSEC_PER_SEC/hpet_period(fsec/cyc)

	 * cyc/sec = (FSEC_PER_NSEC * NSEC_PER_SEC)/hpet_period

	 */

	hpet_freq = FSEC_PER_SEC;

	do_div(hpet_freq, hpet_period);

	clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);



	return 0;

}
@@ -845,7 +795,9 @@ static int hpet_clocksource_register(void) 
 */

int __init hpet_enable(void)

{

	unsigned long hpet_period;

	unsigned int id;

	u64 freq;

	int i;



	if (!is_hpet_capable())
@@ -883,6 +835,14 @@ int __init hpet_enable(void) 
	if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)

		goto out_nohpet;



	/*

	 * The period is a femto seconds value. Convert it to a

	 * frequency.

	 */

	freq = FSEC_PER_SEC;

	do_div(freq, hpet_period);

	hpet_freq = freq;



	/*

	 * Read the HPET ID register to retrieve the IRQ routing

	 * information and the number of channels