arch/arm/mach-pxa/time.c - kernel/msm-4.19 - Gitiles

 /*
  * arch/arm/mach-pxa/time.c
  *
  * PXA clocksource, clockevents, and OST interrupt handlers.
  * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>.
  *
  * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001
  * by MontaVista Software, Inc.  (Nico, your code rocks!)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/clockchips.h>
 #include <linux/sched.h>

 #include <asm/div64.h>
 #include <asm/cnt32_to_63.h>
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>
 #include <asm/arch/pxa-regs.h>
 #include <asm/mach-types.h>

 /*
  * This is PXA's sched_clock implementation. This has a resolution
  * of at least 308 ns and a maximum value of 208 days.
  *
  * The return value is guaranteed to be monotonic in that range as
  * long as there is always less than 582 seconds between successive
  * calls to sched_clock() which should always be the case in practice.
  */

 #define OSCR2NS_SCALE_FACTOR 10

 static unsigned long oscr2ns_scale;

 static void __init set_oscr2ns_scale(unsigned long oscr_rate)
 {
 	unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR;
 	do_div(v, oscr_rate);
 	oscr2ns_scale = v;
 	/*
 	 * We want an even value to automatically clear the top bit
 	 * returned by cnt32_to_63() without an additional run time
 	 * instruction. So if the LSB is 1 then round it up.
 	 */
 	if (oscr2ns_scale & 1)
 		oscr2ns_scale++;
 }

 unsigned long long sched_clock(void)
 {
 	unsigned long long v = cnt32_to_63(OSCR);
 	return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR;
 }


 static irqreturn_t
 pxa_ost0_interrupt(int irq, void *dev_id)
 {
 	int next_match;
 	struct clock_event_device *c = dev_id;

 	if (c->mode == CLOCK_EVT_MODE_ONESHOT) {
 		/* Disarm the compare/match, signal the event. */
 		OIER &= ~OIER_E0;
 		OSSR = OSSR_M0;
 		c->event_handler(c);
 	} else if (c->mode == CLOCK_EVT_MODE_PERIODIC) {
 		/* Call the event handler as many times as necessary
 		 * to recover missed events, if any (if we update
 		 * OSMR0 and OSCR0 is still ahead of us, we've missed
 		 * the event).  As we're dealing with that, re-arm the
 		 * compare/match for the next event.
 		 *
 		 * HACK ALERT:
 		 *
 		 * There's a latency between the instruction that
 		 * writes to OSMR0 and the actual commit to the
 		 * physical hardware, because the CPU doesn't (have
 		 * to) run at bus speed, there's a write buffer
 		 * between the CPU and the bus, etc. etc.  So if the
 		 * target OSCR0 is "very close", to the OSMR0 load
 		 * value, the update to OSMR0 might not get to the
 		 * hardware in time and we'll miss that interrupt.
 		 *
 		 * To be safe, if the new OSMR0 is "very close" to the
 		 * target OSCR0 value, we call the event_handler as
 		 * though the event actually happened.  According to
 		 * Nico's comment in the previous version of this
 		 * code, experience has shown that 6 OSCR ticks is
 		 * "very close" but he went with 8.  We will use 16,
 		 * based on the results of testing on PXA270.
 		 *
 		 * To be doubly sure, we also tell clkevt via
 		 * clockevents_register_device() not to ask for
 		 * anything that might put us "very close".
 	 */
 #define MIN_OSCR_DELTA 16
 		do {
 			OSSR = OSSR_M0;
 			next_match = (OSMR0 += LATCH);
 			c->event_handler(c);
 		} while (((signed long)(next_match - OSCR) <= MIN_OSCR_DELTA)
 			 && (c->mode == CLOCK_EVT_MODE_PERIODIC));
 	}

 	return IRQ_HANDLED;
 }

 static int
 pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
 {
 	unsigned long flags, next, oscr;

 	raw_local_irq_save(flags);
 	OIER |= OIER_E0;
 	next = OSCR + delta;
 	OSMR0 = next;
 	oscr = OSCR;
 	raw_local_irq_restore(flags);

 	return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
 }

 static void
 pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
 {
 	unsigned long irqflags;

 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
 		raw_local_irq_save(irqflags);
 		OSSR = OSSR_M0;
 		OIER |= OIER_E0;
 		OSMR0 = OSCR + LATCH;
 		raw_local_irq_restore(irqflags);
 		break;

 	case CLOCK_EVT_MODE_ONESHOT:
 		raw_local_irq_save(irqflags);
 		OIER &= ~OIER_E0;
 		OSSR = OSSR_M0;
 		raw_local_irq_restore(irqflags);
 		break;

 	case CLOCK_EVT_MODE_UNUSED:
 	case CLOCK_EVT_MODE_SHUTDOWN:
 		/* initializing, released, or preparing for suspend */
 		raw_local_irq_save(irqflags);
 		OIER &= ~OIER_E0;
 		OSSR = OSSR_M0;
 		raw_local_irq_restore(irqflags);
 		break;

 	case CLOCK_EVT_MODE_RESUME:
 		break;
 	}
 }

 static struct clock_event_device ckevt_pxa_osmr0 = {
 	.name		= "osmr0",
 	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 	.shift		= 32,
 	.rating		= 200,
 	.cpumask	= CPU_MASK_CPU0,
 	.set_next_event	= pxa_osmr0_set_next_event,
 	.set_mode	= pxa_osmr0_set_mode,
 };

 static cycle_t pxa_read_oscr(void)
 {
 	return OSCR;
 }

 static struct clocksource cksrc_pxa_oscr0 = {
 	.name           = "oscr0",
 	.rating         = 200,
 	.read           = pxa_read_oscr,
 	.mask           = CLOCKSOURCE_MASK(32),
 	.shift          = 20,
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };

 static struct irqaction pxa_ost0_irq = {
 	.name		= "ost0",
 	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 	.handler	= pxa_ost0_interrupt,
 	.dev_id		= &ckevt_pxa_osmr0,
 };

 static void __init pxa_timer_init(void)
 {
 	unsigned long clock_tick_rate;

 	OIER = 0;
 	OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;

 	if (cpu_is_pxa21x() || cpu_is_pxa25x())
 		clock_tick_rate = 3686400;
 	else if (machine_is_mainstone())
 		clock_tick_rate = 3249600;
 	else
 		clock_tick_rate = 3250000;

 	set_oscr2ns_scale(clock_tick_rate);

 	ckevt_pxa_osmr0.mult =
 		div_sc(clock_tick_rate, NSEC_PER_SEC, ckevt_pxa_osmr0.shift);
 	ckevt_pxa_osmr0.max_delta_ns =
 		clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0);
 	ckevt_pxa_osmr0.min_delta_ns =
 		clockevent_delta2ns(MIN_OSCR_DELTA, &ckevt_pxa_osmr0) + 1;

 	cksrc_pxa_oscr0.mult =
 		clocksource_hz2mult(clock_tick_rate, cksrc_pxa_oscr0.shift);

 	setup_irq(IRQ_OST0, &pxa_ost0_irq);

 	clocksource_register(&cksrc_pxa_oscr0);
 	clockevents_register_device(&ckevt_pxa_osmr0);
 }

 #ifdef CONFIG_PM
 static unsigned long osmr[4], oier;

 static void pxa_timer_suspend(void)
 {
 	osmr[0] = OSMR0;
 	osmr[1] = OSMR1;
 	osmr[2] = OSMR2;
 	osmr[3] = OSMR3;
 	oier = OIER;
 }

 static void pxa_timer_resume(void)
 {
 	OSMR0 = osmr[0];
 	OSMR1 = osmr[1];
 	OSMR2 = osmr[2];
 	OSMR3 = osmr[3];
 	OIER = oier;

 	/*
 	 * OSCR0 is the system timer, which has to increase
 	 * monotonically until it rolls over in hardware.  The value
 	 * (OSMR0 - LATCH) is OSCR0 at the most recent system tick,
 	 * which is a handy value to restore to OSCR0.
 	 */
 	OSCR = OSMR0 - LATCH;
 }
 #else
 #define pxa_timer_suspend NULL
 #define pxa_timer_resume NULL
 #endif

 struct sys_timer pxa_timer = {
 	.init		= pxa_timer_init,
 	.suspend	= pxa_timer_suspend,
 	.resume		= pxa_timer_resume,
 };
	/*
	* arch/arm/mach-pxa/time.c
	*
	* PXA clocksource, clockevents, and OST interrupt handlers.
	* Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>.
	*
	* Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001
	* by MontaVista Software, Inc. (Nico, your code rocks!)
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/clockchips.h>
	#include <linux/sched.h>

	#include <asm/div64.h>
	#include <asm/cnt32_to_63.h>
	#include <asm/mach/irq.h>
	#include <asm/mach/time.h>
	#include <asm/arch/pxa-regs.h>
	#include <asm/mach-types.h>

	/*
	* This is PXA's sched_clock implementation. This has a resolution
	* of at least 308 ns and a maximum value of 208 days.
	*
	* The return value is guaranteed to be monotonic in that range as
	* long as there is always less than 582 seconds between successive
	* calls to sched_clock() which should always be the case in practice.
	*/

	#define OSCR2NS_SCALE_FACTOR 10

	static unsigned long oscr2ns_scale;

	static void __init set_oscr2ns_scale(unsigned long oscr_rate)
	{
	unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR;
	do_div(v, oscr_rate);
	oscr2ns_scale = v;
	/*
	* We want an even value to automatically clear the top bit
	* returned by cnt32_to_63() without an additional run time
	* instruction. So if the LSB is 1 then round it up.
	*/
	if (oscr2ns_scale & 1)
	oscr2ns_scale++;
	}

	unsigned long long sched_clock(void)
	{
	unsigned long long v = cnt32_to_63(OSCR);
	return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR;
	}


	static irqreturn_t
	pxa_ost0_interrupt(int irq, void *dev_id)
	{
	int next_match;
	struct clock_event_device *c = dev_id;

	if (c->mode == CLOCK_EVT_MODE_ONESHOT) {
	/* Disarm the compare/match, signal the event. */
	OIER &= ~OIER_E0;
	OSSR = OSSR_M0;
	c->event_handler(c);
	} else if (c->mode == CLOCK_EVT_MODE_PERIODIC) {
	/* Call the event handler as many times as necessary
	* to recover missed events, if any (if we update
	* OSMR0 and OSCR0 is still ahead of us, we've missed
	* the event). As we're dealing with that, re-arm the
	* compare/match for the next event.
	*
	* HACK ALERT:
	*
	* There's a latency between the instruction that
	* writes to OSMR0 and the actual commit to the
	* physical hardware, because the CPU doesn't (have
	* to) run at bus speed, there's a write buffer
	* between the CPU and the bus, etc. etc. So if the
	* target OSCR0 is "very close", to the OSMR0 load
	* value, the update to OSMR0 might not get to the
	* hardware in time and we'll miss that interrupt.
	*
	* To be safe, if the new OSMR0 is "very close" to the
	* target OSCR0 value, we call the event_handler as
	* though the event actually happened. According to
	* Nico's comment in the previous version of this
	* code, experience has shown that 6 OSCR ticks is
	* "very close" but he went with 8. We will use 16,
	* based on the results of testing on PXA270.
	*
	* To be doubly sure, we also tell clkevt via
	* clockevents_register_device() not to ask for
	* anything that might put us "very close".
	*/
	#define MIN_OSCR_DELTA 16
	do {
	OSSR = OSSR_M0;
	next_match = (OSMR0 += LATCH);
	c->event_handler(c);
	} while (((signed long)(next_match - OSCR) <= MIN_OSCR_DELTA)
	&& (c->mode == CLOCK_EVT_MODE_PERIODIC));
	}

	return IRQ_HANDLED;
	}

	static int
	pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
	{
	unsigned long flags, next, oscr;

	raw_local_irq_save(flags);
	OIER \|= OIER_E0;
	next = OSCR + delta;
	OSMR0 = next;
	oscr = OSCR;
	raw_local_irq_restore(flags);

	return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
	}

	static void
	pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
	{
	unsigned long irqflags;

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
	raw_local_irq_save(irqflags);
	OSSR = OSSR_M0;
	OIER \|= OIER_E0;
	OSMR0 = OSCR + LATCH;
	raw_local_irq_restore(irqflags);
	break;

	case CLOCK_EVT_MODE_ONESHOT:
	raw_local_irq_save(irqflags);
	OIER &= ~OIER_E0;
	OSSR = OSSR_M0;
	raw_local_irq_restore(irqflags);
	break;

	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
	/* initializing, released, or preparing for suspend */
	raw_local_irq_save(irqflags);
	OIER &= ~OIER_E0;
	OSSR = OSSR_M0;
	raw_local_irq_restore(irqflags);
	break;

	case CLOCK_EVT_MODE_RESUME:
	break;
	}
	}

	static struct clock_event_device ckevt_pxa_osmr0 = {
	.name = "osmr0",
	.features = CLOCK_EVT_FEAT_PERIODIC \| CLOCK_EVT_FEAT_ONESHOT,
	.shift = 32,
	.rating = 200,
	.cpumask = CPU_MASK_CPU0,
	.set_next_event = pxa_osmr0_set_next_event,
	.set_mode = pxa_osmr0_set_mode,
	};

	static cycle_t pxa_read_oscr(void)
	{
	return OSCR;
	}

	static struct clocksource cksrc_pxa_oscr0 = {
	.name = "oscr0",
	.rating = 200,
	.read = pxa_read_oscr,
	.mask = CLOCKSOURCE_MASK(32),
	.shift = 20,
	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
	};

	static struct irqaction pxa_ost0_irq = {
	.name = "ost0",
	.flags = IRQF_DISABLED \| IRQF_TIMER \| IRQF_IRQPOLL,
	.handler = pxa_ost0_interrupt,
	.dev_id = &ckevt_pxa_osmr0,
	};

	static void __init pxa_timer_init(void)
	{
	unsigned long clock_tick_rate;

	OIER = 0;
	OSSR = OSSR_M0 \| OSSR_M1 \| OSSR_M2 \| OSSR_M3;

	if (cpu_is_pxa21x() \|\| cpu_is_pxa25x())
	clock_tick_rate = 3686400;
	else if (machine_is_mainstone())
	clock_tick_rate = 3249600;
	else
	clock_tick_rate = 3250000;

	set_oscr2ns_scale(clock_tick_rate);

	ckevt_pxa_osmr0.mult =
	div_sc(clock_tick_rate, NSEC_PER_SEC, ckevt_pxa_osmr0.shift);
	ckevt_pxa_osmr0.max_delta_ns =
	clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0);
	ckevt_pxa_osmr0.min_delta_ns =
	clockevent_delta2ns(MIN_OSCR_DELTA, &ckevt_pxa_osmr0) + 1;

	cksrc_pxa_oscr0.mult =
	clocksource_hz2mult(clock_tick_rate, cksrc_pxa_oscr0.shift);

	setup_irq(IRQ_OST0, &pxa_ost0_irq);

	clocksource_register(&cksrc_pxa_oscr0);
	clockevents_register_device(&ckevt_pxa_osmr0);
	}

	#ifdef CONFIG_PM
	static unsigned long osmr[4], oier;

	static void pxa_timer_suspend(void)
	{
	osmr[0] = OSMR0;
	osmr[1] = OSMR1;
	osmr[2] = OSMR2;
	osmr[3] = OSMR3;
	oier = OIER;
	}

	static void pxa_timer_resume(void)
	{
	OSMR0 = osmr[0];
	OSMR1 = osmr[1];
	OSMR2 = osmr[2];
	OSMR3 = osmr[3];
	OIER = oier;

	/*
	* OSCR0 is the system timer, which has to increase
	* monotonically until it rolls over in hardware. The value
	* (OSMR0 - LATCH) is OSCR0 at the most recent system tick,
	* which is a handy value to restore to OSCR0.
	*/
	OSCR = OSMR0 - LATCH;
	}
	#else
	#define pxa_timer_suspend NULL
	#define pxa_timer_resume NULL
	#endif

	struct sys_timer pxa_timer = {
	.init = pxa_timer_init,
	.suspend = pxa_timer_suspend,
	.resume = pxa_timer_resume,
	};