[deliverable/linux.git] / arch / arm / mach-at91rm9200 / time.c

/*
 * linux/arch/arm/mach-at91rm9200/time.c
 *
 *  Copyright (C) 2003 SAN People
 *  Copyright (C) 2003 ATMEL
 *
 * 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 <linux/config.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>

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

static unsigned long last_crtr;

/*
 * The ST_CRTR is updated asynchronously to the master clock.  It is therefore
 *  necessary to read it twice (with the same value) to ensure accuracy.
 */
static inline unsigned long read_CRTR(void) {
	unsigned long x1, x2;

	do {
		x1 = at91_sys_read(AT91_ST_CRTR);
		x2 = at91_sys_read(AT91_ST_CRTR);
	} while (x1 != x2);

	return x1;
}

/*
 * Returns number of microseconds since last timer interrupt.  Note that interrupts
 * will have been disabled by do_gettimeofday()
 *  'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
 *  'tick' is usecs per jiffy (linux/timex.h).
 */
static unsigned long at91rm9200_gettimeoffset(void)
{
	unsigned long elapsed;

	elapsed = (read_CRTR() - last_crtr) & AT91_ST_ALMV;

	return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
}

/*
 * IRQ handler for the timer.
 */
static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	if (at91_sys_read(AT91_ST_SR) & AT91_ST_PITS) {	/* This is a shared interrupt */
		write_seqlock(&xtime_lock);

		while (((read_CRTR() - last_crtr) & AT91_ST_ALMV) >= LATCH) {
			timer_tick(regs);
			last_crtr = (last_crtr + LATCH) & AT91_ST_ALMV;
		}

		write_sequnlock(&xtime_lock);

		return IRQ_HANDLED;
	}
	else
		return IRQ_NONE;		/* not handled */
}

static struct irqaction at91rm9200_timer_irq = {
	.name		= "at91_tick",
	.flags		= SA_SHIRQ | SA_INTERRUPT | SA_TIMER,
	.handler	= at91rm9200_timer_interrupt
};

/*
 * Set up timer interrupt.
 */
void __init at91rm9200_timer_init(void)
{
	/* Disable all timer interrupts */
	at91_sys_write(AT91_ST_IDR, AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
	(void) at91_sys_read(AT91_ST_SR);	/* Clear any pending interrupts */

	/*
	 * Make IRQs happen for the system timer.
	 */
	setup_irq(AT91_ID_SYS, &at91rm9200_timer_irq);

	/* Set initial alarm to 0 */
	at91_sys_write(AT91_ST_RTAR, 0);

	/* Real time counter incremented every 30.51758 microseconds */
	at91_sys_write(AT91_ST_RTMR, 1);

	/* Set Period Interval timer */
	at91_sys_write(AT91_ST_PIMR, LATCH);

	/* Change the kernel's 'tick' value to 10009 usec. (the default is 10000) */
	tick_usec = (LATCH * 1000000) / CLOCK_TICK_RATE;

	/* Enable Period Interval Timer interrupt */
	at91_sys_write(AT91_ST_IER, AT91_ST_PITS);
}

struct sys_timer at91rm9200_timer = {
	.init		= at91rm9200_timer_init,
	.offset		= at91rm9200_gettimeoffset,
};
Commit	Line	Data
73a59c1c SP	1	/*
	2	* linux/arch/arm/mach-at91rm9200/time.c
	3	*
	4	* Copyright (C) 2003 SAN People
	5	* Copyright (C) 2003 ATMEL
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20	*/
	21
	22	#include <linux/config.h>
	23	#include <linux/init.h>
	24	#include <linux/interrupt.h>
	25	#include <linux/kernel.h>
	26	#include <linux/sched.h>
	27	#include <linux/time.h>
	28
	29	#include <asm/hardware.h>
	30	#include <asm/io.h>
	31	#include <asm/irq.h>
	32	#include <asm/mach/time.h>
	33
963151f2 AV	34	static unsigned long last_crtr;
963151f2 AV	35
73a59c1c SP	36	/*
	37	* The ST_CRTR is updated asynchronously to the master clock. It is therefore
	38	* necessary to read it twice (with the same value) to ensure accuracy.
	39	*/
	40	static inline unsigned long read_CRTR(void) {
	41	unsigned long x1, x2;
	42
	43	do {
	44	x1 = at91_sys_read(AT91_ST_CRTR);
	45	x2 = at91_sys_read(AT91_ST_CRTR);
	46	} while (x1 != x2);
	47
	48	return x1;
	49	}
	50
	51	/*
	52	* Returns number of microseconds since last timer interrupt. Note that interrupts
	53	* will have been disabled by do_gettimeofday()
	54	* 'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
	55	* 'tick' is usecs per jiffy (linux/timex.h).
	56	*/
	57	static unsigned long at91rm9200_gettimeoffset(void)
	58	{
	59	unsigned long elapsed;
	60
963151f2	61	elapsed = (read_CRTR() - last_crtr) & AT91_ST_ALMV;
73a59c1c SP	62
	63	return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
	64	}
	65
	66	/*
	67	* IRQ handler for the timer.
	68	*/
	69	static irqreturn_t at91rm9200_timer_interrupt(int irq, void dev_id, struct pt_regs regs)
	70	{
73a59c1c SP	71	if (at91_sys_read(AT91_ST_SR) & AT91_ST_PITS) { /* This is a shared interrupt */
	72	write_seqlock(&xtime_lock);
	73
963151f2	74	while (((read_CRTR() - last_crtr) & AT91_ST_ALMV) >= LATCH) {
73a59c1c	75	timer_tick(regs);
963151f2	76	last_crtr = (last_crtr + LATCH) & AT91_ST_ALMV;
39806805	77	}
73a59c1c SP	78
	79	write_sequnlock(&xtime_lock);
	80
	81	return IRQ_HANDLED;
	82	}
	83	else
	84	return IRQ_NONE; /* not handled */
	85	}
	86
	87	static struct irqaction at91rm9200_timer_irq = {
	88	.name = "at91_tick",
963151f2	89	.flags = SA_SHIRQ \| SA_INTERRUPT \| SA_TIMER,
73a59c1c SP	90	.handler = at91rm9200_timer_interrupt
	91	};
	92
	93	/*
	94	* Set up timer interrupt.
	95	*/
	96	void __init at91rm9200_timer_init(void)
	97	{
	98	/* Disable all timer interrupts */
	99	at91_sys_write(AT91_ST_IDR, AT91_ST_PITS \| AT91_ST_WDOVF \| AT91_ST_RTTINC \| AT91_ST_ALMS);
	100	(void) at91_sys_read(AT91_ST_SR); /* Clear any pending interrupts */
	101
	102	/*
	103	* Make IRQs happen for the system timer.
	104	*/
	105	setup_irq(AT91_ID_SYS, &at91rm9200_timer_irq);
	106
	107	/* Set initial alarm to 0 */
	108	at91_sys_write(AT91_ST_RTAR, 0);
	109
	110	/* Real time counter incremented every 30.51758 microseconds */
	111	at91_sys_write(AT91_ST_RTMR, 1);
	112
	113	/* Set Period Interval timer */
	114	at91_sys_write(AT91_ST_PIMR, LATCH);
	115
	116	/* Change the kernel's 'tick' value to 10009 usec. (the default is 10000) */
	117	tick_usec = (LATCH * 1000000) / CLOCK_TICK_RATE;
	118
	119	/* Enable Period Interval Timer interrupt */
	120	at91_sys_write(AT91_ST_IER, AT91_ST_PITS);
	121	}
	122
	123	struct sys_timer at91rm9200_timer = {
	124	.init = at91rm9200_timer_init,
	125	.offset = at91rm9200_gettimeoffset,
	126	};