arch/arm/mach-omap1/time.c - maze/linux - Git at Google

 /*
  * linux/arch/arm/mach-omap1/time.c
  *
  * OMAP Timers
  *
  * Copyright (C) 2004 Nokia Corporation
  * Partial timer rewrite and additional dynamic tick timer support by
  * Tony Lindgen <tony@atomide.com> and
  * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
  *
  * MPU timer code based on the older MPU timer code for OMAP
  * Copyright (C) 2000 RidgeRun, Inc.
  * Author: Greg Lonnon <glonnon@ridgerun.com>
  *
  * 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; either version 2 of the License, or (at your
  * option) any later version.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
  * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * You should have received a copy of the  GNU General Public License along
  * with this program; if not, write  to the Free Software Foundation, Inc.,
  * 675 Mass Ave, Cambridge, MA 02139, USA.
  */

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

 #include <asm/system.h>
 #include <asm/hardware.h>
 #include <asm/io.h>
 #include <asm/leds.h>
 #include <asm/irq.h>
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>

 struct sys_timer omap_timer;

 /*
  * ---------------------------------------------------------------------------
  * MPU timer
  * ---------------------------------------------------------------------------
  */
 #define OMAP_MPU_TIMER_BASE		OMAP_MPU_TIMER1_BASE
 #define OMAP_MPU_TIMER_OFFSET		0x100

 /* cycles to nsec conversions taken from arch/i386/kernel/timers/timer_tsc.c,
  * converted to use kHz by Kevin Hilman */
 /* convert from cycles(64bits) => nanoseconds (64bits)
  *  basic equation:
  *		ns = cycles / (freq / ns_per_sec)
  *		ns = cycles * (ns_per_sec / freq)
  *		ns = cycles * (10^9 / (cpu_khz * 10^3))
  *		ns = cycles * (10^6 / cpu_khz)
  *
  *	Then we use scaling math (suggested by george at mvista.com) to get:
  *		ns = cycles * (10^6 * SC / cpu_khz / SC
  *		ns = cycles * cyc2ns_scale / SC
  *
  *	And since SC is a constant power of two, we can convert the div
  *  into a shift.
  *			-johnstul at us.ibm.com "math is hard, lets go shopping!"
  */
 static unsigned long cyc2ns_scale;
 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */

 static inline void set_cyc2ns_scale(unsigned long cpu_khz)
 {
 	cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
 }

 static inline unsigned long long cycles_2_ns(unsigned long long cyc)
 {
 	return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
 }

 /*
  * MPU_TICKS_PER_SEC must be an even number, otherwise machinecycles_to_usecs
  * will break. On P2, the timer count rate is 6.5 MHz after programming PTV
  * with 0. This divides the 13MHz input by 2, and is undocumented.
  */
 #if defined(CONFIG_MACH_OMAP_PERSEUS2) || defined(CONFIG_MACH_OMAP_FSAMPLE)
 /* REVISIT: This ifdef construct should be replaced by a query to clock
  * framework to see if timer base frequency is 12.0, 13.0 or 19.2 MHz.
  */
 #define MPU_TICKS_PER_SEC		(13000000 / 2)
 #else
 #define MPU_TICKS_PER_SEC		(12000000 / 2)
 #endif

 #define MPU_TIMER_TICK_PERIOD		((MPU_TICKS_PER_SEC / HZ) - 1)

 typedef struct {
 	u32 cntl;			/* CNTL_TIMER, R/W */
 	u32 load_tim;			/* LOAD_TIM,   W */
 	u32 read_tim;			/* READ_TIM,   R */
 } omap_mpu_timer_regs_t;

 #define omap_mpu_timer_base(n)						\
 ((volatile omap_mpu_timer_regs_t*)IO_ADDRESS(OMAP_MPU_TIMER_BASE +	\
 				 (n)*OMAP_MPU_TIMER_OFFSET))

 static inline unsigned long omap_mpu_timer_read(int nr)
 {
 	volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
 	return timer->read_tim;
 }

 static inline void omap_mpu_timer_start(int nr, unsigned long load_val)
 {
 	volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);

 	timer->cntl = MPU_TIMER_CLOCK_ENABLE;
 	udelay(1);
 	timer->load_tim = load_val;
         udelay(1);
 	timer->cntl = (MPU_TIMER_CLOCK_ENABLE | MPU_TIMER_AR | MPU_TIMER_ST);
 }

 unsigned long omap_mpu_timer_ticks_to_usecs(unsigned long nr_ticks)
 {
 	unsigned long long nsec;

 	nsec = cycles_2_ns((unsigned long long)nr_ticks);
 	return (unsigned long)nsec / 1000;
 }

 /*
  * Last processed system timer interrupt
  */
 static unsigned long omap_mpu_timer_last = 0;

 /*
  * Returns elapsed usecs since last system timer interrupt
  */
 static unsigned long omap_mpu_timer_gettimeoffset(void)
 {
 	unsigned long now = 0 - omap_mpu_timer_read(0);
 	unsigned long elapsed = now - omap_mpu_timer_last;

 	return omap_mpu_timer_ticks_to_usecs(elapsed);
 }

 /*
  * Elapsed time between interrupts is calculated using timer0.
  * Latency during the interrupt is calculated using timer1.
  * Both timer0 and timer1 are counting at 6MHz (P2 6.5MHz).
  */
 static irqreturn_t omap_mpu_timer_interrupt(int irq, void *dev_id,
 					struct pt_regs *regs)
 {
 	unsigned long now, latency;

 	write_seqlock(&xtime_lock);
 	now = 0 - omap_mpu_timer_read(0);
 	latency = MPU_TICKS_PER_SEC / HZ - omap_mpu_timer_read(1);
 	omap_mpu_timer_last = now - latency;
 	timer_tick(regs);
 	write_sequnlock(&xtime_lock);

 	return IRQ_HANDLED;
 }

 static struct irqaction omap_mpu_timer_irq = {
 	.name		= "mpu timer",
 	.flags		= IRQF_DISABLED | IRQF_TIMER,
 	.handler	= omap_mpu_timer_interrupt,
 };

 static unsigned long omap_mpu_timer1_overflows;
 static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id,
 					     struct pt_regs *regs)
 {
 	omap_mpu_timer1_overflows++;
 	return IRQ_HANDLED;
 }

 static struct irqaction omap_mpu_timer1_irq = {
 	.name		= "mpu timer1 overflow",
 	.flags		= IRQF_DISABLED,
 	.handler	= omap_mpu_timer1_interrupt,
 };

 static __init void omap_init_mpu_timer(void)
 {
 	set_cyc2ns_scale(MPU_TICKS_PER_SEC / 1000);
 	omap_timer.offset = omap_mpu_timer_gettimeoffset;
 	setup_irq(INT_TIMER1, &omap_mpu_timer1_irq);
 	setup_irq(INT_TIMER2, &omap_mpu_timer_irq);
 	omap_mpu_timer_start(0, 0xffffffff);
 	omap_mpu_timer_start(1, MPU_TIMER_TICK_PERIOD);
 }

 /*
  * Scheduler clock - returns current time in nanosec units.
  */
 unsigned long long sched_clock(void)
 {
 	unsigned long ticks = 0 - omap_mpu_timer_read(0);
 	unsigned long long ticks64;

 	ticks64 = omap_mpu_timer1_overflows;
 	ticks64 <<= 32;
 	ticks64 |= ticks;

 	return cycles_2_ns(ticks64);
 }

 /*
  * ---------------------------------------------------------------------------
  * Timer initialization
  * ---------------------------------------------------------------------------
  */
 static void __init omap_timer_init(void)
 {
 	omap_init_mpu_timer();
 }

 struct sys_timer omap_timer = {
 	.init		= omap_timer_init,
 	.offset		= NULL,		/* Initialized later */
 };
	/*
	* linux/arch/arm/mach-omap1/time.c
	*
	* OMAP Timers
	*
	* Copyright (C) 2004 Nokia Corporation
	* Partial timer rewrite and additional dynamic tick timer support by
	* Tony Lindgen <tony@atomide.com> and
	* Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
	*
	* MPU timer code based on the older MPU timer code for OMAP
	* Copyright (C) 2000 RidgeRun, Inc.
	* Author: Greg Lonnon <glonnon@ridgerun.com>
	*
	* 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; either version 2 of the License, or (at your
	* option) any later version.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
	* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
	* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, write to the Free Software Foundation, Inc.,
	* 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

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

	#include <asm/system.h>
	#include <asm/hardware.h>
	#include <asm/io.h>
	#include <asm/leds.h>
	#include <asm/irq.h>
	#include <asm/mach/irq.h>
	#include <asm/mach/time.h>

	struct sys_timer omap_timer;

	/*
	* ---------------------------------------------------------------------------
	* MPU timer
	* ---------------------------------------------------------------------------
	*/
	#define OMAP_MPU_TIMER_BASE OMAP_MPU_TIMER1_BASE
	#define OMAP_MPU_TIMER_OFFSET 0x100

	/* cycles to nsec conversions taken from arch/i386/kernel/timers/timer_tsc.c,
	* converted to use kHz by Kevin Hilman */
	/* convert from cycles(64bits) => nanoseconds (64bits)
	* basic equation:
	* ns = cycles / (freq / ns_per_sec)
	* ns = cycles * (ns_per_sec / freq)
	* ns = cycles * (10^9 / (cpu_khz * 10^3))
	* ns = cycles * (10^6 / cpu_khz)
	*
	* Then we use scaling math (suggested by george at mvista.com) to get:
	* ns = cycles * (10^6 * SC / cpu_khz / SC
	* ns = cycles * cyc2ns_scale / SC
	*
	* And since SC is a constant power of two, we can convert the div
	* into a shift.
	* -johnstul at us.ibm.com "math is hard, lets go shopping!"
	*/
	static unsigned long cyc2ns_scale;
	#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */

	static inline void set_cyc2ns_scale(unsigned long cpu_khz)
	{
	cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
	}

	static inline unsigned long long cycles_2_ns(unsigned long long cyc)
	{
	return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
	}

	/*
	* MPU_TICKS_PER_SEC must be an even number, otherwise machinecycles_to_usecs
	* will break. On P2, the timer count rate is 6.5 MHz after programming PTV
	* with 0. This divides the 13MHz input by 2, and is undocumented.
	*/
	#if defined(CONFIG_MACH_OMAP_PERSEUS2) \|\| defined(CONFIG_MACH_OMAP_FSAMPLE)
	/* REVISIT: This ifdef construct should be replaced by a query to clock
	* framework to see if timer base frequency is 12.0, 13.0 or 19.2 MHz.
	*/
	#define MPU_TICKS_PER_SEC (13000000 / 2)
	#else
	#define MPU_TICKS_PER_SEC (12000000 / 2)
	#endif

	#define MPU_TIMER_TICK_PERIOD ((MPU_TICKS_PER_SEC / HZ) - 1)

	typedef struct {
	u32 cntl; /* CNTL_TIMER, R/W */
	u32 load_tim; /* LOAD_TIM, W */
	u32 read_tim; /* READ_TIM, R */
	} omap_mpu_timer_regs_t;

	#define omap_mpu_timer_base(n) \
	((volatile omap_mpu_timer_regs_t*)IO_ADDRESS(OMAP_MPU_TIMER_BASE + \
	(n)*OMAP_MPU_TIMER_OFFSET))

	static inline unsigned long omap_mpu_timer_read(int nr)
	{
	volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
	return timer->read_tim;
	}

	static inline void omap_mpu_timer_start(int nr, unsigned long load_val)
	{
	volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);

	timer->cntl = MPU_TIMER_CLOCK_ENABLE;
	udelay(1);
	timer->load_tim = load_val;
	udelay(1);
	timer->cntl = (MPU_TIMER_CLOCK_ENABLE \| MPU_TIMER_AR \| MPU_TIMER_ST);
	}

	unsigned long omap_mpu_timer_ticks_to_usecs(unsigned long nr_ticks)
	{
	unsigned long long nsec;

	nsec = cycles_2_ns((unsigned long long)nr_ticks);
	return (unsigned long)nsec / 1000;
	}

	/*
	* Last processed system timer interrupt
	*/
	static unsigned long omap_mpu_timer_last = 0;

	/*
	* Returns elapsed usecs since last system timer interrupt
	*/
	static unsigned long omap_mpu_timer_gettimeoffset(void)
	{
	unsigned long now = 0 - omap_mpu_timer_read(0);
	unsigned long elapsed = now - omap_mpu_timer_last;

	return omap_mpu_timer_ticks_to_usecs(elapsed);
	}

	/*
	* Elapsed time between interrupts is calculated using timer0.
	* Latency during the interrupt is calculated using timer1.
	* Both timer0 and timer1 are counting at 6MHz (P2 6.5MHz).
	*/
	static irqreturn_t omap_mpu_timer_interrupt(int irq, void *dev_id,
	struct pt_regs *regs)
	{
	unsigned long now, latency;

	write_seqlock(&xtime_lock);
	now = 0 - omap_mpu_timer_read(0);
	latency = MPU_TICKS_PER_SEC / HZ - omap_mpu_timer_read(1);
	omap_mpu_timer_last = now - latency;
	timer_tick(regs);
	write_sequnlock(&xtime_lock);

	return IRQ_HANDLED;
	}

	static struct irqaction omap_mpu_timer_irq = {
	.name = "mpu timer",
	.flags = IRQF_DISABLED \| IRQF_TIMER,
	.handler = omap_mpu_timer_interrupt,
	};

	static unsigned long omap_mpu_timer1_overflows;
	static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id,
	struct pt_regs *regs)
	{
	omap_mpu_timer1_overflows++;
	return IRQ_HANDLED;
	}

	static struct irqaction omap_mpu_timer1_irq = {
	.name = "mpu timer1 overflow",
	.flags = IRQF_DISABLED,
	.handler = omap_mpu_timer1_interrupt,
	};

	static __init void omap_init_mpu_timer(void)
	{
	set_cyc2ns_scale(MPU_TICKS_PER_SEC / 1000);
	omap_timer.offset = omap_mpu_timer_gettimeoffset;
	setup_irq(INT_TIMER1, &omap_mpu_timer1_irq);
	setup_irq(INT_TIMER2, &omap_mpu_timer_irq);
	omap_mpu_timer_start(0, 0xffffffff);
	omap_mpu_timer_start(1, MPU_TIMER_TICK_PERIOD);
	}

	/*
	* Scheduler clock - returns current time in nanosec units.
	*/
	unsigned long long sched_clock(void)
	{
	unsigned long ticks = 0 - omap_mpu_timer_read(0);
	unsigned long long ticks64;

	ticks64 = omap_mpu_timer1_overflows;
	ticks64 <<= 32;
	ticks64 \|= ticks;

	return cycles_2_ns(ticks64);
	}

	/*
	* ---------------------------------------------------------------------------
	* Timer initialization
	* ---------------------------------------------------------------------------
	*/
	static void __init omap_timer_init(void)
	{
	omap_init_mpu_timer();
	}

	struct sys_timer omap_timer = {
	.init = omap_timer_init,
	.offset = NULL, /* Initialized later */
	};