nuttx/boards/x86_64/intel64/qemu-intel64/src/qemu_freq.c
2021-03-09 23:18:28 +08:00

98 lines
3.1 KiB
C

/****************************************************************************
* boards/x86_64/intel64/qemu-intel64/src/qemu_freq.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <stdbool.h>
#include <time.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/board.h>
#include <arch/board/board.h>
/****************************************************************************
* Public Data
****************************************************************************/
extern unsigned long x86_64_timer_freq;
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: x86_64_timer_initialize
*
* Description:
* Initializes all platform-specific timer facilities. This function is
* called early in the initialization sequence by up_initialize().
* On return, the current up-time should be available from
* up_timer_gettime() and the interval timer is ready for use (but not
* actively timing.
*
* Provided by platform-specific code and called from the architecture-
* specific logic.
*
* Input Parameters:
* None
*
* Returned Value:
* None
*
* Assumptions:
* Called early in the initialization sequence before any special
* concurrency protections are required.
*
****************************************************************************/
void x86_64_timer_calibrate_freq(void)
{
#ifdef CONFIG_ARCH_INTEL64_HAVE_TSC_DEADLINE
unsigned long crystal_freq;
unsigned long numerator;
unsigned long denominator;
asm volatile("cpuid"
: "=c" (crystal_freq), "=b" (numerator), "=a" (denominator)
: "a" (X86_64_CPUID_TSC)
: "rdx", "memory");
if (numerator == 0 || denominator == 0 || crystal_freq == 0)
{
x86_64_timer_freq = CONFIG_ARCH_INTEL64_CORE_FREQ_KHZ * 1000L;
}
else
{
x86_64_timer_freq = crystal_freq / denominator * numerator;
}
#else
x86_64_timer_freq = CONFIG_ARCH_INTEL64_APIC_FREQ_KHZ * 1000L;
#endif
}