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linux-sg2042/arch/arm/mach-omap1/time.c

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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 <linux/clk.h>
#include <linux/err.h>
#include <linux/clocksource.h>
#include <linux/clockchips.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>
#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;
}
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_set_autoreset(int nr)
{
volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
timer->cntl = timer->cntl | MPU_TIMER_AR;
}
static inline void omap_mpu_remove_autoreset(int nr)
{
volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
timer->cntl = timer->cntl & ~MPU_TIMER_AR;
}
static inline void omap_mpu_timer_start(int nr, unsigned long load_val,
int autoreset)
{
volatile omap_mpu_timer_regs_t* timer = omap_mpu_timer_base(nr);
unsigned int timerflags = (MPU_TIMER_CLOCK_ENABLE | MPU_TIMER_ST);
if (autoreset) timerflags |= MPU_TIMER_AR;
timer->cntl = MPU_TIMER_CLOCK_ENABLE;
udelay(1);
timer->load_tim = load_val;
udelay(1);
timer->cntl = timerflags;
}
/*
* ---------------------------------------------------------------------------
* MPU timer 1 ... count down to zero, interrupt, reload
* ---------------------------------------------------------------------------
*/
static int omap_mpu_set_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
omap_mpu_timer_start(0, cycles, 0);
return 0;
}
static void omap_mpu_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
omap_mpu_set_autoreset(0);
break;
case CLOCK_EVT_MODE_ONESHOT:
omap_mpu_remove_autoreset(0);
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
break;
}
}
static struct clock_event_device clockevent_mpu_timer1 = {
.name = "mpu_timer1",
.features = CLOCK_EVT_FEAT_PERIODIC, CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.set_next_event = omap_mpu_set_next_event,
.set_mode = omap_mpu_set_mode,
};
static irqreturn_t omap_mpu_timer1_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_mpu_timer1;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction omap_mpu_timer1_irq = {
.name = "mpu_timer1",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = omap_mpu_timer1_interrupt,
};
static __init void omap_init_mpu_timer(unsigned long rate)
{
set_cyc2ns_scale(rate / 1000);
setup_irq(INT_TIMER1, &omap_mpu_timer1_irq);
omap_mpu_timer_start(0, (rate / HZ) - 1, 1);
clockevent_mpu_timer1.mult = div_sc(rate, NSEC_PER_SEC,
clockevent_mpu_timer1.shift);
clockevent_mpu_timer1.max_delta_ns =
clockevent_delta2ns(-1, &clockevent_mpu_timer1);
clockevent_mpu_timer1.min_delta_ns =
clockevent_delta2ns(1, &clockevent_mpu_timer1);
clockevent_mpu_timer1.cpumask = cpumask_of_cpu(0);
clockevents_register_device(&clockevent_mpu_timer1);
}
/*
* ---------------------------------------------------------------------------
* MPU timer 2 ... free running 32-bit clock source and scheduler clock
* ---------------------------------------------------------------------------
*/
static unsigned long omap_mpu_timer2_overflows;
static irqreturn_t omap_mpu_timer2_interrupt(int irq, void *dev_id)
{
omap_mpu_timer2_overflows++;
return IRQ_HANDLED;
}
static struct irqaction omap_mpu_timer2_irq = {
.name = "mpu_timer2",
.flags = IRQF_DISABLED,
.handler = omap_mpu_timer2_interrupt,
};
static cycle_t mpu_read(void)
{
return ~omap_mpu_timer_read(1);
}
static struct clocksource clocksource_mpu = {
.name = "mpu_timer2",
.rating = 300,
.read = mpu_read,
.mask = CLOCKSOURCE_MASK(32),
.shift = 24,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init omap_init_clocksource(unsigned long rate)
{
static char err[] __initdata = KERN_ERR
"%s: can't register clocksource!\n";
clocksource_mpu.mult
= clocksource_khz2mult(rate/1000, clocksource_mpu.shift);
setup_irq(INT_TIMER2, &omap_mpu_timer2_irq);
omap_mpu_timer_start(1, ~0, 1);
if (clocksource_register(&clocksource_mpu))
printk(err, clocksource_mpu.name);
}
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
unsigned long ticks = 0 - omap_mpu_timer_read(1);
unsigned long long ticks64;
ticks64 = omap_mpu_timer2_overflows;
ticks64 <<= 32;
ticks64 |= ticks;
return cycles_2_ns(ticks64);
}
/*
* ---------------------------------------------------------------------------
* Timer initialization
* ---------------------------------------------------------------------------
*/
static void __init omap_timer_init(void)
{
struct clk *ck_ref = clk_get(NULL, "ck_ref");
unsigned long rate;
BUG_ON(IS_ERR(ck_ref));
rate = clk_get_rate(ck_ref);
clk_put(ck_ref);
/* PTV = 0 */
rate /= 2;
omap_init_mpu_timer(rate);
omap_init_clocksource(rate);
}
struct sys_timer omap_timer = {
.init = omap_timer_init,
};
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