time.h

来自「优龙2410linux2.6.8内核源代码」· C头文件 代码 · 共 157 行

/*
 *  linux/include/asm-arm/arch-integrator/time.h
 *
 * 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 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.  See the
 * GNU General Public License for more details.
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <asm/system.h>
#include <asm/leds.h>
#include <asm/mach-types.h>

/*
 * Where is the timer (VA)?
 */
#define TIMER0_VA_BASE (IO_ADDRESS(INTEGRATOR_CT_BASE)+0x00000000)
#define TIMER1_VA_BASE (IO_ADDRESS(INTEGRATOR_CT_BASE)+0x00000100)
#define TIMER2_VA_BASE (IO_ADDRESS(INTEGRATOR_CT_BASE)+0x00000200)
#define VA_IC_BASE     IO_ADDRESS(INTEGRATOR_IC_BASE) 

/*
 * How long is the timer interval?
 */
#define TIMER_INTERVAL	(TICKS_PER_uSEC * mSEC_10)
#if TIMER_INTERVAL >= 0x100000
#define TICKS2USECS(x)	(256 * (x) / TICKS_PER_uSEC)
#elif TIMER_INTERVAL >= 0x10000
#define TICKS2USECS(x)	(16 * (x) / TICKS_PER_uSEC)
#else
#define TICKS2USECS(x)	((x) / TICKS_PER_uSEC)
#endif

#define TIMER_CTRL_IE	(1 << 5)			/* Interrupt Enable */

/*
 * What does it look like?
 */
typedef struct TimerStruct {
	unsigned long TimerLoad;
	unsigned long TimerValue;
	unsigned long TimerControl;
	unsigned long TimerClear;
} TimerStruct_t;

extern unsigned long (*gettimeoffset)(void);

static unsigned long timer_reload;

/*
 * Returns number of ms since last clock interrupt.  Note that interrupts
 * will have been disabled by do_gettimeoffset()
 */
static unsigned long integrator_gettimeoffset(void)
{
	volatile TimerStruct_t *timer1 = (TimerStruct_t *)TIMER1_VA_BASE;
	unsigned long ticks1, ticks2, status;

	/*
	 * Get the current number of ticks.  Note that there is a race
	 * condition between us reading the timer and checking for
	 * an interrupt.  We get around this by ensuring that the
	 * counter has not reloaded between our two reads.
	 */
	ticks2 = timer1->TimerValue & 0xffff;
	do {
		ticks1 = ticks2;
		status = __raw_readl(VA_IC_BASE + IRQ_RAW_STATUS);
		ticks2 = timer1->TimerValue & 0xffff;
	} while (ticks2 > ticks1);

	/*
	 * Number of ticks since last interrupt.
	 */
	ticks1 = timer_reload - ticks2;

	/*
	 * Interrupt pending?  If so, we've reloaded once already.
	 */
	if (status & (1 << IRQ_TIMERINT1))
		ticks1 += timer_reload;

	/*
	 * Convert the ticks to usecs
	 */
	return TICKS2USECS(ticks1);
}

/*
 * IRQ handler for the timer
 */
static irqreturn_t
integrator_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	volatile TimerStruct_t *timer1 = (volatile TimerStruct_t *)TIMER1_VA_BASE;

	// ...clear the interrupt
	timer1->TimerClear = 1;

	do_leds();
	do_timer(regs);
	do_profile(regs);

	return IRQ_HANDLED;
}

/*
 * Set up timer interrupt, and return the current time in seconds.
 */
void __init time_init(void)
{
	volatile TimerStruct_t *timer0 = (volatile TimerStruct_t *)TIMER0_VA_BASE;
	volatile TimerStruct_t *timer1 = (volatile TimerStruct_t *)TIMER1_VA_BASE;
	volatile TimerStruct_t *timer2 = (volatile TimerStruct_t *)TIMER2_VA_BASE;
	unsigned int timer_ctrl = 0x80 | 0x40;	/* periodic */

	if (machine_is_integrator()) {
		timer_reload = 1000000 * TICKS_PER_uSEC / HZ;
	} else if (machine_is_cintegrator()) {
		timer_reload = 1000000 / HZ;
		timer_ctrl |= TIMER_CTRL_IE;
	}
	if (timer_reload > 0x100000) {
		timer_reload >>= 8;
		timer_ctrl |= 0x08; /* /256 */
	} else if (timer_reload > 0x010000) {
		timer_reload >>= 4;
		timer_ctrl |= 0x04; /* /16 */
	}

	/*
	 * Initialise to a known state (all timers off)
	 */
	timer0->TimerControl = 0;
	timer1->TimerControl = 0;
	timer2->TimerControl = 0;

	timer1->TimerLoad    = timer_reload;
	timer1->TimerValue   = timer_reload;
	timer1->TimerControl = timer_ctrl;

	/* 
	 * Make irqs happen for the system timer
	 */
	timer_irq.handler = integrator_timer_interrupt;
	setup_irq(IRQ_TIMERINT1, &timer_irq);
	gettimeoffset = integrator_gettimeoffset;
}