timer32k.c

来自「omap3 linux 2.6 用nocc去除了冗余代码」· C语言 代码 · 共 307 行

/*
 * linux/arch/arm/plat-omap/timer32k.c
 *
 * OMAP 32K Timer
 *
 * Copyright (C) 2004 - 2005 Nokia Corporation
 * Partial timer rewrite and additional dynamic tick timer support by
 * Tony Lindgen <[e-mail]> and
 * Tuukka Tikkanen <[e-mail]>
 * OMAP Dual-mode timer framework support by Timo Teras
 *
 * MPU timer code based on the older MPU timer code for OMAP
 * Copyright (C) 2000 RidgeRun, Inc.
 * Author: Greg Lonnon <[e-mail]>
 *
 * 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/err.h>
#include <linux/clk.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>
#include <asm/arch/dmtimer.h>

struct sys_timer omap_timer;

struct clk* sync_32k_clk;
unsigned long long last_tick;
unsigned int oneshot;


/*
 * ---------------------------------------------------------------------------
 * 32KHz OS timer
 *
 * This currently works only on 16xx, as 1510 does not have the continuous
 * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
 * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
 * on 1510 would be possible, but the timer would not be as accurate as
 * with the 32KHz synchronized timer.
 * ---------------------------------------------------------------------------
 */

#define TIMER_32K_SYNCHRONIZED		0x48320010

/* 16xx specific defines */
#define OMAP1_32K_TIMER_BASE		0xfffb9000
#define OMAP1_32K_TIMER_CR		0x08
#define OMAP1_32K_TIMER_TVR		0x00
#define OMAP1_32K_TIMER_TCR		0x04

#define OMAP_32K_TICKS_PER_SEC		(32768)

/*
 * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
 * so with HZ = 128, TVR = 255.
 */
#define OMAP_32K_TIMER_TICK_PERIOD	((OMAP_32K_TICKS_PER_SEC / HZ) - 1)

#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)			\
				(((nr_jiffies) * (clock_rate)) / HZ)


static struct omap_dm_timer *gptimer;

inline void omap_32k_timer_start(unsigned long load_val)
{
	if (oneshot)
		omap_dm_timer_set_load(gptimer, 0, 0xffffffff - load_val);
	else
		omap_dm_timer_set_load(gptimer, 1, 0xffffffff - load_val);
	omap_dm_timer_start(gptimer);
}

static inline void omap_32k_timer_stop(void)
{
	omap_dm_timer_stop(gptimer);
}

static inline void omap_32k_timer_ack_irq(void)
{
	u32 status = omap_dm_timer_read_status(gptimer);
	omap_dm_timer_write_status(gptimer, status);
}


static void omap_32k_timer_set_mode(enum clock_event_mode mode,
				    struct clock_event_device *evt)
{
	omap_32k_timer_stop();

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		oneshot = 0;
		omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
		break;
	case CLOCK_EVT_MODE_ONESHOT:
		oneshot = 1;
		break;
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		break;
	}
}

int omap_set_next_event(unsigned long cycles, struct clock_event_device *evt)
{
	omap_32k_timer_start(cycles);
	return 0;
}

static struct clock_event_device clockevent_32k_timer = {
	.name		= "32k-timer",
	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
	.shift		= 32,
	.set_next_event = omap_set_next_event,
	.set_mode	= omap_32k_timer_set_mode,
};

/*
 * The 32KHz synchronized timer is an additional timer on 16xx.
 * It is always running.
 */
inline unsigned long omap_32k_sync_timer_read(void)
{
	return omap_readl(TIMER_32K_SYNCHRONIZED);
}

/*
 * Rounds down to nearest usec. Note that this will overflow for larger values.
 */
inline unsigned long omap_32k_ticks_to_usecs(unsigned long ticks_32k)
{
	return (ticks_32k * 5*5*5*5*5*5) >> 9;
}

/*
 * Rounds down to nearest nsec.
 */
inline unsigned long long omap_32k_ticks_to_nsecs(unsigned long ticks_32k)
{
	return (unsigned long long) ticks_32k * 1000 * 5*5*5*5*5*5 >> 9;
}

/*
 * Returns current time from boot in nsecs. It's OK for this to wrap
 * around for now, as it's just a relative time stamp.
 */
unsigned long long sched_clock(void)
{
	return omap_32k_ticks_to_nsecs(omap_32k_sync_timer_read());
}

static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = &clockevent_32k_timer;
	omap_32k_timer_ack_irq();

	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static struct irqaction omap_32k_timer_irq = {
	.name		= "32KHz timer",
	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
	.handler	= omap_32k_timer_interrupt,
};

static __init void omap_init_32k_timer(void)
{
	int ret;
	if (cpu_class_is_omap1())
		setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
	sync_32k_clk = clk_get(NULL,"sync_32k_ick");
	ret = clk_enable(sync_32k_clk);
	BUG_ON(ret != 0);

	/* REVISIT: Check 24xx TIOCP_CFG settings after idle works */
	if (cpu_class_is_omap2()) {
		gptimer = omap_dm_timer_request_specific(1);
		BUG_ON(gptimer == NULL);

		omap_dm_timer_set_source(gptimer, OMAP_TIMER_SRC_32_KHZ);
		setup_irq(omap_dm_timer_get_irq(gptimer), &omap_32k_timer_irq);
		omap_dm_timer_set_int_enable(gptimer,
			OMAP_TIMER_INT_CAPTURE | OMAP_TIMER_INT_OVERFLOW |
			OMAP_TIMER_INT_MATCH);
	}

	clockevent_32k_timer.mult = div_sc(OMAP_32K_TICKS_PER_SEC,
					   NSEC_PER_SEC,
					   clockevent_32k_timer.shift);
	clockevent_32k_timer.max_delta_ns =
		clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer);
	clockevent_32k_timer.min_delta_ns =
		clockevent_delta2ns(1, &clockevent_32k_timer);

	clockevent_32k_timer.cpumask = cpumask_of_cpu(0);
	clockevents_register_device(&clockevent_32k_timer);
	

}

void omap_disable_system_timer(void)
{
	omap_dm_timer_set_int_enable(gptimer,0);
	omap_dm_timer_stop(gptimer);
	while(omap_dm_timer_read_reg(gptimer, OMAP_TIMER_WRITE_PEND_REG));
	omap_32k_timer_ack_irq();
	omap_32k_timer_ack_irq();
	last_tick = omap_32k_sync_timer_read();
}

void omap_enable_system_timer(void)
{
	unsigned long long now = omap_32k_sync_timer_read();
	unsigned long long tick_cnt = 0;
	unsigned long rem;
	unsigned long long rem_u64;
	struct timespec sleeptime;

	omap_dm_timer_set_int_enable(gptimer,
		OMAP_TIMER_INT_CAPTURE | OMAP_TIMER_INT_OVERFLOW |
		OMAP_TIMER_INT_MATCH);
	omap_dm_timer_start(gptimer);
	/* wait for all the writes to complete as we are running in 
	*posted mode */
	while(omap_dm_timer_read_reg(gptimer, OMAP_TIMER_WRITE_PEND_REG));

	tick_cnt = (now - last_tick);
	do_div(tick_cnt, OMAP_32K_TIMER_TICK_PERIOD+1);

        /* Fix up the wall time */
	rem = do_div(tick_cnt,HZ);
	sleeptime.tv_sec = tick_cnt;
	rem_u64 = 1000000000UL;
	rem_u64 = rem_u64*rem;
	do_div(rem_u64,HZ);

	sleeptime.tv_nsec = rem_u64;

	if (!(in_atomic() || irqs_disabled()))
		write_seqlock_irq(&xtime_lock);

	xtime.tv_sec += sleeptime.tv_sec;
	xtime.tv_nsec += sleeptime.tv_nsec;

	/* nsec may have overflowed 1 sec */
	while (xtime.tv_nsec >= 1000000000) {
		xtime.tv_nsec -= 1000000000;
		xtime.tv_sec++;
	}

	if (!(in_atomic() || irqs_disabled()))
		write_sequnlock_irq(&xtime_lock);

	omap_32k_timer_ack_irq();
}

/*
 * ---------------------------------------------------------------------------
 * Timer initialization
 * ---------------------------------------------------------------------------
 */
static void __init omap_timer_init(void)
{
	omap_dm_timer_init();
	omap_init_32k_timer();
}

struct sys_timer omap_timer = {
	.init		= omap_timer_init,
};