cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mach_timer.h (1590B)


      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 *  Machine specific calibrate_tsc() for generic.
      4 *  Split out from timer_tsc.c by Osamu Tomita <tomita@cinet.co.jp>
      5 */
      6/* ------ Calibrate the TSC ------- 
      7 * Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
      8 * Too much 64-bit arithmetic here to do this cleanly in C, and for
      9 * accuracy's sake we want to keep the overhead on the CTC speaker (channel 2)
     10 * output busy loop as low as possible. We avoid reading the CTC registers
     11 * directly because of the awkward 8-bit access mechanism of the 82C54
     12 * device.
     13 */
     14#ifndef _ASM_X86_MACH_DEFAULT_MACH_TIMER_H
     15#define _ASM_X86_MACH_DEFAULT_MACH_TIMER_H
     16
     17#define CALIBRATE_TIME_MSEC 30 /* 30 msecs */
     18#define CALIBRATE_LATCH	\
     19	((PIT_TICK_RATE * CALIBRATE_TIME_MSEC + 1000/2)/1000)
     20
     21static inline void mach_prepare_counter(void)
     22{
     23       /* Set the Gate high, disable speaker */
     24	outb((inb(0x61) & ~0x02) | 0x01, 0x61);
     25
     26	/*
     27	 * Now let's take care of CTC channel 2
     28	 *
     29	 * Set the Gate high, program CTC channel 2 for mode 0,
     30	 * (interrupt on terminal count mode), binary count,
     31	 * load 5 * LATCH count, (LSB and MSB) to begin countdown.
     32	 *
     33	 * Some devices need a delay here.
     34	 */
     35	outb(0xb0, 0x43);			/* binary, mode 0, LSB/MSB, Ch 2 */
     36	outb_p(CALIBRATE_LATCH & 0xff, 0x42);	/* LSB of count */
     37	outb_p(CALIBRATE_LATCH >> 8, 0x42);       /* MSB of count */
     38}
     39
     40static inline void mach_countup(unsigned long *count_p)
     41{
     42	unsigned long count = 0;
     43	do {
     44		count++;
     45	} while ((inb_p(0x61) & 0x20) == 0);
     46	*count_p = count;
     47}
     48
     49#endif /* _ASM_X86_MACH_DEFAULT_MACH_TIMER_H */