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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hwtimer.c (4911B)

      1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
      2/******************************************************************************
      3 *
      4 * Name: hwtimer.c - ACPI Power Management Timer Interface
      5 *
      6 * Copyright (C) 2000 - 2022, Intel Corp.
      7 *
      8 *****************************************************************************/
      9
     10#define EXPORT_ACPI_INTERFACES
     11
     12#include <acpi/acpi.h>
     13#include "accommon.h"
     14
     15#define _COMPONENT          ACPI_HARDWARE
     16ACPI_MODULE_NAME("hwtimer")
     17
     18#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
     19/******************************************************************************
     20 *
     21 * FUNCTION:    acpi_get_timer_resolution
     22 *
     23 * PARAMETERS:  resolution          - Where the resolution is returned
     24 *
     25 * RETURN:      Status and timer resolution
     26 *
     27 * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
     28 *
     29 ******************************************************************************/
     30acpi_status acpi_get_timer_resolution(u32 * resolution)
     31{
     32	ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
     33
     34	if (!resolution) {
     35		return_ACPI_STATUS(AE_BAD_PARAMETER);
     36	}
     37
     38	if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
     39		*resolution = 24;
     40	} else {
     41		*resolution = 32;
     42	}
     43
     44	return_ACPI_STATUS(AE_OK);
     45}
     46
     47ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
     48
     49/******************************************************************************
     50 *
     51 * FUNCTION:    acpi_get_timer
     52 *
     53 * PARAMETERS:  ticks               - Where the timer value is returned
     54 *
     55 * RETURN:      Status and current timer value (ticks)
     56 *
     57 * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
     58 *
     59 ******************************************************************************/
     60acpi_status acpi_get_timer(u32 * ticks)
     61{
     62	acpi_status status;
     63	u64 timer_value;
     64
     65	ACPI_FUNCTION_TRACE(acpi_get_timer);
     66
     67	if (!ticks) {
     68		return_ACPI_STATUS(AE_BAD_PARAMETER);
     69	}
     70
     71	/* ACPI 5.0A: PM Timer is optional */
     72
     73	if (!acpi_gbl_FADT.xpm_timer_block.address) {
     74		return_ACPI_STATUS(AE_SUPPORT);
     75	}
     76
     77	status = acpi_hw_read(&timer_value, &acpi_gbl_FADT.xpm_timer_block);
     78	if (ACPI_SUCCESS(status)) {
     79
     80		/* ACPI PM Timer is defined to be 32 bits (PM_TMR_LEN) */
     81
     82		*ticks = (u32)timer_value;
     83	}
     84
     85	return_ACPI_STATUS(status);
     86}
     87
     88ACPI_EXPORT_SYMBOL(acpi_get_timer)
     89
     90/******************************************************************************
     91 *
     92 * FUNCTION:    acpi_get_timer_duration
     93 *
     94 * PARAMETERS:  start_ticks         - Starting timestamp
     95 *              end_ticks           - End timestamp
     96 *              time_elapsed        - Where the elapsed time is returned
     97 *
     98 * RETURN:      Status and time_elapsed
     99 *
    100 * DESCRIPTION: Computes the time elapsed (in microseconds) between two
    101 *              PM Timer time stamps, taking into account the possibility of
    102 *              rollovers, the timer resolution, and timer frequency.
    103 *
    104 *              The PM Timer's clock ticks at roughly 3.6 times per
    105 *              _microsecond_, and its clock continues through Cx state
    106 *              transitions (unlike many CPU timestamp counters) -- making it
    107 *              a versatile and accurate timer.
    108 *
    109 *              Note that this function accommodates only a single timer
    110 *              rollover. Thus for 24-bit timers, this function should only
    111 *              be used for calculating durations less than ~4.6 seconds
    112 *              (~20 minutes for 32-bit timers) -- calculations below:
    113 *
    114 *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
    115 *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
    116 *
    117 ******************************************************************************/
    118acpi_status
    119acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 *time_elapsed)
    120{
    121	acpi_status status;
    122	u64 delta_ticks;
    123	u64 quotient;
    124
    125	ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
    126
    127	if (!time_elapsed) {
    128		return_ACPI_STATUS(AE_BAD_PARAMETER);
    129	}
    130
    131	/* ACPI 5.0A: PM Timer is optional */
    132
    133	if (!acpi_gbl_FADT.xpm_timer_block.address) {
    134		return_ACPI_STATUS(AE_SUPPORT);
    135	}
    136
    137	if (start_ticks == end_ticks) {
    138		*time_elapsed = 0;
    139		return_ACPI_STATUS(AE_OK);
    140	}
    141
    142	/*
    143	 * Compute Tick Delta:
    144	 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
    145	 */
    146	delta_ticks = end_ticks;
    147	if (start_ticks > end_ticks) {
    148		if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
    149
    150			/* 24-bit Timer */
    151
    152			delta_ticks |= (u64)1 << 24;
    153		} else {
    154			/* 32-bit Timer */
    155
    156			delta_ticks |= (u64)1 << 32;
    157		}
    158	}
    159	delta_ticks -= start_ticks;
    160
    161	/*
    162	 * Compute Duration (Requires a 64-bit multiply and divide):
    163	 *
    164	 * time_elapsed (microseconds) =
    165	 *  (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
    166	 */
    167	status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC,
    168				      ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);
    169
    170	*time_elapsed = (u32)quotient;
    171	return_ACPI_STATUS(status);
    172}
    173
    174ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
    175#endif				/* !ACPI_REDUCED_HARDWARE */