arch/tile/kernel/time.c - maze/linux - Git at Google

 /*
  * Copyright 2010 Tilera Corporation. All Rights Reserved.
  *
  *   This program is free software; you can redistribute it and/or
  *   modify it under the terms of the GNU General Public License
  *   as published by the Free Software Foundation, version 2.
  *
  *   This program is distributed in the hope that it will be useful, but
  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  *   NON INFRINGEMENT.  See the GNU General Public License for
  *   more details.
  *
  * Support the cycle counter clocksource and tile timer clock event device.
  */

 #include <linux/time.h>
 #include <linux/timex.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
 #include <linux/hardirq.h>
 #include <linux/sched.h>
 #include <linux/smp.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <asm/irq_regs.h>
 #include <asm/traps.h>
 #include <hv/hypervisor.h>
 #include <arch/interrupts.h>
 #include <arch/spr_def.h>


 /*
  * Define the cycle counter clock source.
  */

 /* How many cycles per second we are running at. */
 static cycles_t cycles_per_sec __write_once;

 cycles_t get_clock_rate(void)
 {
 	return cycles_per_sec;
 }

 #if CHIP_HAS_SPLIT_CYCLE()
 cycles_t get_cycles(void)
 {
 	unsigned int high = __insn_mfspr(SPR_CYCLE_HIGH);
 	unsigned int low = __insn_mfspr(SPR_CYCLE_LOW);
 	unsigned int high2 = __insn_mfspr(SPR_CYCLE_HIGH);

 	while (unlikely(high != high2)) {
 		low = __insn_mfspr(SPR_CYCLE_LOW);
 		high = high2;
 		high2 = __insn_mfspr(SPR_CYCLE_HIGH);
 	}

 	return (((cycles_t)high) << 32) | low;
 }
 EXPORT_SYMBOL(get_cycles);
 #endif

 /*
  * We use a relatively small shift value so that sched_clock()
  * won't wrap around very often.
  */
 #define SCHED_CLOCK_SHIFT 10

 static unsigned long sched_clock_mult __write_once;

 static cycles_t clocksource_get_cycles(struct clocksource *cs)
 {
 	return get_cycles();
 }

 static struct clocksource cycle_counter_cs = {
 	.name = "cycle counter",
 	.rating = 300,
 	.read = clocksource_get_cycles,
 	.mask = CLOCKSOURCE_MASK(64),
 	.shift = 22,   /* typical value, e.g. x86 tsc uses this */
 	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
 };

 /*
  * Called very early from setup_arch() to set cycles_per_sec.
  * We initialize it early so we can use it to set up loops_per_jiffy.
  */
 void __init setup_clock(void)
 {
 	cycles_per_sec = hv_sysconf(HV_SYSCONF_CPU_SPEED);
 	sched_clock_mult =
 		clocksource_hz2mult(cycles_per_sec, SCHED_CLOCK_SHIFT);
 	cycle_counter_cs.mult =
 		clocksource_hz2mult(cycles_per_sec, cycle_counter_cs.shift);
 }

 void __init calibrate_delay(void)
 {
 	loops_per_jiffy = get_clock_rate() / HZ;
 	pr_info("Clock rate yields %lu.%02lu BogoMIPS (lpj=%lu)\n",
 		loops_per_jiffy/(500000/HZ),
 		(loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy);
 }

 /* Called fairly late in init/main.c, but before we go smp. */
 void __init time_init(void)
 {
 	/* Initialize and register the clock source. */
 	clocksource_register(&cycle_counter_cs);

 	/* Start up the tile-timer interrupt source on the boot cpu. */
 	setup_tile_timer();
 }


 /*
  * Define the tile timer clock event device.  The timer is driven by
  * the TILE_TIMER_CONTROL register, which consists of a 31-bit down
  * counter, plus bit 31, which signifies that the counter has wrapped
  * from zero to (2**31) - 1.  The INT_TILE_TIMER interrupt will be
  * raised as long as bit 31 is set.
  *
  * The TILE_MINSEC value represents the largest range of real-time
  * we can possibly cover with the timer, based on MAX_TICK combined
  * with the slowest reasonable clock rate we might run at.
  */

 #define MAX_TICK 0x7fffffff   /* we have 31 bits of countdown timer */
 #define TILE_MINSEC 5         /* timer covers no more than 5 seconds */

 static int tile_timer_set_next_event(unsigned long ticks,
 				     struct clock_event_device *evt)
 {
 	BUG_ON(ticks > MAX_TICK);
 	__insn_mtspr(SPR_TILE_TIMER_CONTROL, ticks);
 	arch_local_irq_unmask_now(INT_TILE_TIMER);
 	return 0;
 }

 /*
  * Whenever anyone tries to change modes, we just mask interrupts
  * and wait for the next event to get set.
  */
 static void tile_timer_set_mode(enum clock_event_mode mode,
 				struct clock_event_device *evt)
 {
 	arch_local_irq_mask_now(INT_TILE_TIMER);
 }

 /*
  * Set min_delta_ns to 1 microsecond, since it takes about
  * that long to fire the interrupt.
  */
 static DEFINE_PER_CPU(struct clock_event_device, tile_timer) = {
 	.name = "tile timer",
 	.features = CLOCK_EVT_FEAT_ONESHOT,
 	.min_delta_ns = 1000,
 	.rating = 100,
 	.irq = -1,
 	.set_next_event = tile_timer_set_next_event,
 	.set_mode = tile_timer_set_mode,
 };

 void __cpuinit setup_tile_timer(void)
 {
 	struct clock_event_device *evt = &__get_cpu_var(tile_timer);

 	/* Fill in fields that are speed-specific. */
 	clockevents_calc_mult_shift(evt, cycles_per_sec, TILE_MINSEC);
 	evt->max_delta_ns = clockevent_delta2ns(MAX_TICK, evt);

 	/* Mark as being for this cpu only. */
 	evt->cpumask = cpumask_of(smp_processor_id());

 	/* Start out with timer not firing. */
 	arch_local_irq_mask_now(INT_TILE_TIMER);

 	/* Register tile timer. */
 	clockevents_register_device(evt);
 }

 /* Called from the interrupt vector. */
 void do_timer_interrupt(struct pt_regs *regs, int fault_num)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
 	struct clock_event_device *evt = &__get_cpu_var(tile_timer);

 	/*
 	 * Mask the timer interrupt here, since we are a oneshot timer
 	 * and there are now by definition no events pending.
 	 */
 	arch_local_irq_mask(INT_TILE_TIMER);

 	/* Track time spent here in an interrupt context */
 	irq_enter();

 	/* Track interrupt count. */
 	__get_cpu_var(irq_stat).irq_timer_count++;

 	/* Call the generic timer handler */
 	evt->event_handler(evt);

 	/*
 	 * Track time spent against the current process again and
 	 * process any softirqs if they are waiting.
 	 */
 	irq_exit();

 	set_irq_regs(old_regs);
 }

 /*
  * Scheduler clock - returns current time in nanosec units.
  * Note that with LOCKDEP, this is called during lockdep_init(), and
  * we will claim that sched_clock() is zero for a little while, until
  * we run setup_clock(), above.
  */
 unsigned long long sched_clock(void)
 {
 	return clocksource_cyc2ns(get_cycles(),
 				  sched_clock_mult, SCHED_CLOCK_SHIFT);
 }

 int setup_profiling_timer(unsigned int multiplier)
 {
 	return -EINVAL;
 }

 /*
  * Use the tile timer to convert nsecs to core clock cycles, relying
  * on it having the same frequency as SPR_CYCLE.
  */
 cycles_t ns2cycles(unsigned long nsecs)
 {
 	struct clock_event_device *dev = &__get_cpu_var(tile_timer);
 	return ((u64)nsecs * dev->mult) >> dev->shift;
 }
	/*
	* Copyright 2010 Tilera Corporation. All Rights Reserved.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation, version 2.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	* NON INFRINGEMENT. See the GNU General Public License for
	* more details.
	*
	* Support the cycle counter clocksource and tile timer clock event device.
	*/

	#include <linux/time.h>
	#include <linux/timex.h>
	#include <linux/clocksource.h>
	#include <linux/clockchips.h>
	#include <linux/hardirq.h>
	#include <linux/sched.h>
	#include <linux/smp.h>
	#include <linux/delay.h>
	#include <linux/module.h>
	#include <asm/irq_regs.h>
	#include <asm/traps.h>
	#include <hv/hypervisor.h>
	#include <arch/interrupts.h>
	#include <arch/spr_def.h>


	/*
	* Define the cycle counter clock source.
	*/

	/* How many cycles per second we are running at. */
	static cycles_t cycles_per_sec __write_once;

	cycles_t get_clock_rate(void)
	{
	return cycles_per_sec;
	}

	#if CHIP_HAS_SPLIT_CYCLE()
	cycles_t get_cycles(void)
	{
	unsigned int high = __insn_mfspr(SPR_CYCLE_HIGH);
	unsigned int low = __insn_mfspr(SPR_CYCLE_LOW);
	unsigned int high2 = __insn_mfspr(SPR_CYCLE_HIGH);

	while (unlikely(high != high2)) {
	low = __insn_mfspr(SPR_CYCLE_LOW);
	high = high2;
	high2 = __insn_mfspr(SPR_CYCLE_HIGH);
	}

	return (((cycles_t)high) << 32) \| low;
	}
	EXPORT_SYMBOL(get_cycles);
	#endif

	/*
	* We use a relatively small shift value so that sched_clock()
	* won't wrap around very often.
	*/
	#define SCHED_CLOCK_SHIFT 10

	static unsigned long sched_clock_mult __write_once;

	static cycles_t clocksource_get_cycles(struct clocksource *cs)
	{
	return get_cycles();
	}

	static struct clocksource cycle_counter_cs = {
	.name = "cycle counter",
	.rating = 300,
	.read = clocksource_get_cycles,
	.mask = CLOCKSOURCE_MASK(64),
	.shift = 22, /* typical value, e.g. x86 tsc uses this */
	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
	};

	/*
	* Called very early from setup_arch() to set cycles_per_sec.
	* We initialize it early so we can use it to set up loops_per_jiffy.
	*/
	void __init setup_clock(void)
	{
	cycles_per_sec = hv_sysconf(HV_SYSCONF_CPU_SPEED);
	sched_clock_mult =
	clocksource_hz2mult(cycles_per_sec, SCHED_CLOCK_SHIFT);
	cycle_counter_cs.mult =
	clocksource_hz2mult(cycles_per_sec, cycle_counter_cs.shift);
	}

	void __init calibrate_delay(void)
	{
	loops_per_jiffy = get_clock_rate() / HZ;
	pr_info("Clock rate yields %lu.%02lu BogoMIPS (lpj=%lu)\n",
	loops_per_jiffy/(500000/HZ),
	(loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy);
	}

	/* Called fairly late in init/main.c, but before we go smp. */
	void __init time_init(void)
	{
	/* Initialize and register the clock source. */
	clocksource_register(&cycle_counter_cs);

	/* Start up the tile-timer interrupt source on the boot cpu. */
	setup_tile_timer();
	}


	/*
	* Define the tile timer clock event device. The timer is driven by
	* the TILE_TIMER_CONTROL register, which consists of a 31-bit down
	* counter, plus bit 31, which signifies that the counter has wrapped
	* from zero to (2**31) - 1. The INT_TILE_TIMER interrupt will be
	* raised as long as bit 31 is set.
	*
	* The TILE_MINSEC value represents the largest range of real-time
	* we can possibly cover with the timer, based on MAX_TICK combined
	* with the slowest reasonable clock rate we might run at.
	*/

	#define MAX_TICK 0x7fffffff /* we have 31 bits of countdown timer */
	#define TILE_MINSEC 5 /* timer covers no more than 5 seconds */

	static int tile_timer_set_next_event(unsigned long ticks,
	struct clock_event_device *evt)
	{
	BUG_ON(ticks > MAX_TICK);
	__insn_mtspr(SPR_TILE_TIMER_CONTROL, ticks);
	arch_local_irq_unmask_now(INT_TILE_TIMER);
	return 0;
	}

	/*
	* Whenever anyone tries to change modes, we just mask interrupts
	* and wait for the next event to get set.
	*/
	static void tile_timer_set_mode(enum clock_event_mode mode,
	struct clock_event_device *evt)
	{
	arch_local_irq_mask_now(INT_TILE_TIMER);
	}

	/*
	* Set min_delta_ns to 1 microsecond, since it takes about
	* that long to fire the interrupt.
	*/
	static DEFINE_PER_CPU(struct clock_event_device, tile_timer) = {
	.name = "tile timer",
	.features = CLOCK_EVT_FEAT_ONESHOT,
	.min_delta_ns = 1000,
	.rating = 100,
	.irq = -1,
	.set_next_event = tile_timer_set_next_event,
	.set_mode = tile_timer_set_mode,
	};

	void __cpuinit setup_tile_timer(void)
	{
	struct clock_event_device *evt = &__get_cpu_var(tile_timer);

	/* Fill in fields that are speed-specific. */
	clockevents_calc_mult_shift(evt, cycles_per_sec, TILE_MINSEC);
	evt->max_delta_ns = clockevent_delta2ns(MAX_TICK, evt);

	/* Mark as being for this cpu only. */
	evt->cpumask = cpumask_of(smp_processor_id());

	/* Start out with timer not firing. */
	arch_local_irq_mask_now(INT_TILE_TIMER);

	/* Register tile timer. */
	clockevents_register_device(evt);
	}

	/* Called from the interrupt vector. */
	void do_timer_interrupt(struct pt_regs *regs, int fault_num)
	{
	struct pt_regs *old_regs = set_irq_regs(regs);
	struct clock_event_device *evt = &__get_cpu_var(tile_timer);

	/*
	* Mask the timer interrupt here, since we are a oneshot timer
	* and there are now by definition no events pending.
	*/
	arch_local_irq_mask(INT_TILE_TIMER);

	/* Track time spent here in an interrupt context */
	irq_enter();

	/* Track interrupt count. */
	__get_cpu_var(irq_stat).irq_timer_count++;

	/* Call the generic timer handler */
	evt->event_handler(evt);

	/*
	* Track time spent against the current process again and
	* process any softirqs if they are waiting.
	*/
	irq_exit();

	set_irq_regs(old_regs);
	}

	/*
	* Scheduler clock - returns current time in nanosec units.
	* Note that with LOCKDEP, this is called during lockdep_init(), and
	* we will claim that sched_clock() is zero for a little while, until
	* we run setup_clock(), above.
	*/
	unsigned long long sched_clock(void)
	{
	return clocksource_cyc2ns(get_cycles(),
	sched_clock_mult, SCHED_CLOCK_SHIFT);
	}

	int setup_profiling_timer(unsigned int multiplier)
	{
	return -EINVAL;
	}

	/*
	* Use the tile timer to convert nsecs to core clock cycles, relying
	* on it having the same frequency as SPR_CYCLE.
	*/
	cycles_t ns2cycles(unsigned long nsecs)
	{
	struct clock_event_device *dev = &__get_cpu_var(tile_timer);
	return ((u64)nsecs * dev->mult) >> dev->shift;
	}