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/*
* 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.
*/
#ifdef CONFIG_MACH_OMAP_PERSEUS2
/* 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 = SA_INTERRUPT | SA_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 = SA_INTERRUPT,
.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 */
};
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