[net-next-2.6.git] / arch / i386 / lib / delay.c

/*
 *	Precise Delay Loops for i386
 *
 *	Copyright (C) 1993 Linus Torvalds
 *	Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
 *
 *	The __delay function must _NOT_ be inlined as its execution time
 *	depends wildly on alignment on many x86 processors. The additional
 *	jump magic is needed to get the timing stable on all the CPU's
 *	we have to worry about.
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/delay.h>

#include <asm/processor.h>
#include <asm/delay.h>
#include <asm/timer.h>

#ifdef CONFIG_SMP
# include <asm/smp.h>
#endif

/* simple loop based delay: */
static void delay_loop(unsigned long loops)
{
	int d0;

	__asm__ __volatile__(
		"\tjmp 1f\n"
		".align 16\n"
		"1:\tjmp 2f\n"
		".align 16\n"
		"2:\tdecl %0\n\tjns 2b"
		:"=&a" (d0)
		:"0" (loops));
}

/* TSC based delay: */
static void delay_tsc(unsigned long loops)
{
	unsigned long bclock, now;

	rdtscl(bclock);
	do {
		rep_nop();
		rdtscl(now);
	} while ((now-bclock) < loops);
}

/*
 * Since we calibrate only once at boot, this
 * function should be set once at boot and not changed
 */
static void (*delay_fn)(unsigned long) = delay_loop;

void use_tsc_delay(void)
{
	delay_fn = delay_tsc;
}

int read_current_timer(unsigned long *timer_val)
{
	if (delay_fn == delay_tsc) {
		rdtscl(*timer_val);
		return 0;
	}
	return -1;
}

void __delay(unsigned long loops)
{
	delay_fn(loops);
}

inline void __const_udelay(unsigned long xloops)
{
	int d0;

	xloops *= 4;
	__asm__("mull %0"
		:"=d" (xloops), "=&a" (d0)
		:"1" (xloops), "0"
		(cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4)));

	__delay(++xloops);
}

void __udelay(unsigned long usecs)
{
	__const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
}

void __ndelay(unsigned long nsecs)
{
	__const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
}

EXPORT_SYMBOL(__delay);
EXPORT_SYMBOL(__const_udelay);
EXPORT_SYMBOL(__udelay);
EXPORT_SYMBOL(__ndelay);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Precise Delay Loops for i386
	3	*
	4	* Copyright (C) 1993 Linus Torvalds
	5	* Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
	6	*
	7	* The __delay function must _NOT_ be inlined as its execution time
	8	* depends wildly on alignment on many x86 processors. The additional
	9	* jump magic is needed to get the timing stable on all the CPU's
	10	* we have to worry about.
	11	*/
	12
6f84fa2f	13	#include <linux/module.h>
1da177e4 LT	14	#include <linux/sched.h>
1da177e4 LT	15	#include <linux/delay.h>
6f84fa2f	16
1da177e4 LT	17	#include <asm/processor.h>
	18	#include <asm/delay.h>
	19	#include <asm/timer.h>
	20
	21	#ifdef CONFIG_SMP
6f84fa2f	22	# include <asm/smp.h>
1da177e4 LT	23	#endif
1da177e4 LT	24
6f84fa2f JS	25	/* simple loop based delay: */
	26	static void delay_loop(unsigned long loops)
	27	{
	28	int d0;
	29
	30	__asm__ __volatile__(
	31	"\tjmp 1f\n"
	32	".align 16\n"
	33	"1:\tjmp 2f\n"
	34	".align 16\n"
	35	"2:\tdecl %0\n\tjns 2b"
	36	:"=&a" (d0)
	37	:"0" (loops));
	38	}
	39
	40	/* TSC based delay: */
	41	static void delay_tsc(unsigned long loops)
	42	{
	43	unsigned long bclock, now;
	44
	45	rdtscl(bclock);
	46	do {
	47	rep_nop();
	48	rdtscl(now);
	49	} while ((now-bclock) < loops);
	50	}
	51
	52	/*
	53	* Since we calibrate only once at boot, this
	54	* function should be set once at boot and not changed
	55	*/
	56	static void (*delay_fn)(unsigned long) = delay_loop;
	57
	58	void use_tsc_delay(void)
	59	{
	60	delay_fn = delay_tsc;
	61	}
	62
	63	int read_current_timer(unsigned long *timer_val)
	64	{
	65	if (delay_fn == delay_tsc) {
	66	rdtscl(*timer_val);
	67	return 0;
	68	}
	69	return -1;
	70	}
1da177e4 LT	71
	72	void __delay(unsigned long loops)
	73	{
6f84fa2f	74	delay_fn(loops);
1da177e4 LT	75	}
	76
	77	inline void __const_udelay(unsigned long xloops)
	78	{
	79	int d0;
6f84fa2f	80
1da177e4 LT	81	xloops *= 4;
	82	__asm__("mull %0"
	83	:"=d" (xloops), "=&a" (d0)
6f84fa2f JS	84	:"1" (xloops), "0"
	85	(cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4)));
	86
	87	__delay(++xloops);
1da177e4 LT	88	}
	89
	90	void __udelay(unsigned long usecs)
	91	{
6f84fa2f	92	__const_udelay(usecs * 0x000010c7); /* 2*32 / 1000000 (rounded up) /
1da177e4 LT	93	}
	94
	95	void __ndelay(unsigned long nsecs)
	96	{
6f84fa2f	97	__const_udelay(nsecs * 0x00005); /* 2*32 / 1000000000 (rounded up) /
1da177e4	98	}
129f6946 AD	99
	100	EXPORT_SYMBOL(__delay);
	101	EXPORT_SYMBOL(__const_udelay);
	102	EXPORT_SYMBOL(__udelay);
	103	EXPORT_SYMBOL(__ndelay);