mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-26 22:24:09 +08:00
1164dd0099
We are getting rid of subarchitecture support - move the hook files to asm/. (These are now stale and should be replaced with more explicit runtime mechanisms - but the transition is simpler this way.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
49 lines
1.5 KiB
C
49 lines
1.5 KiB
C
/*
|
|
* 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 _ASM_X86_MACH_DEFAULT_MACH_TIMER_H
|
|
#define _ASM_X86_MACH_DEFAULT_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 /* _ASM_X86_MACH_DEFAULT_MACH_TIMER_H */
|