android_kernel_motorola_sm6225/include/asm-i386/mach-default/mach_timer.h
john stultz 539eb11e6e [PATCH] Time: i386 Conversion - part 2: Rework TSC Support
As part of the i386 conversion to the generic timekeeping infrastructure, this
introduces a new tsc.c file.  The code in this file replaces the TSC
initialization, management and access code currently in timer_tsc.c (which
will be removed) that we want to preserve.

The code also introduces the following functionality:

o tsc_khz: like cpu_khz but stores the TSC frequency on systems that do not
  change TSC frequency w/ CPU frequency

o check/mark_tsc_unstable: accessor/modifier flag for TSC timekeeping
  usability

o minor cleanups to calibration math.

This patch also includes a one line __cpuinitdata fix from Zwane Mwaikambo.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 09:58:21 -07:00

50 lines
1.5 KiB
C

/*
* include/asm-i386/mach-default/mach_timer.h
*
* Machine specific calibrate_tsc() for generic.
* Split out from timer_tsc.c by Osamu Tomita <tomita@cinet.co.jp>
*/
/* ------ Calibrate the TSC -------
* Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
* Too much 64-bit arithmetic here to do this cleanly in C, and for
* accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
* output busy loop as low as possible. We avoid reading the CTC registers
* directly because of the awkward 8-bit access mechanism of the 82C54
* device.
*/
#ifndef _MACH_TIMER_H
#define _MACH_TIMER_H
#define CALIBRATE_TIME_MSEC 30 /* 30 msecs */
#define CALIBRATE_LATCH \
((CLOCK_TICK_RATE * CALIBRATE_TIME_MSEC + 1000/2)/1000)
static inline void mach_prepare_counter(void)
{
/* Set the Gate high, disable speaker */
outb((inb(0x61) & ~0x02) | 0x01, 0x61);
/*
* Now let's take care of CTC channel 2
*
* Set the Gate high, program CTC channel 2 for mode 0,
* (interrupt on terminal count mode), binary count,
* load 5 * LATCH count, (LSB and MSB) to begin countdown.
*
* Some devices need a delay here.
*/
outb(0xb0, 0x43); /* binary, mode 0, LSB/MSB, Ch 2 */
outb_p(CALIBRATE_LATCH & 0xff, 0x42); /* LSB of count */
outb_p(CALIBRATE_LATCH >> 8, 0x42); /* MSB of count */
}
static inline void mach_countup(unsigned long *count_p)
{
unsigned long count = 0;
do {
count++;
} while ((inb_p(0x61) & 0x20) == 0);
*count_p = count;
}
#endif /* !_MACH_TIMER_H */