/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2017 Intel Corporation
 */

#include <fcntl.h>
#include <unistd.h>
#include <cpuid.h>

#include <rte_common.h>

#include "eal_private.h"

static unsigned int
rte_cpu_get_model(uint32_t fam_mod_step)
{
	uint32_t family, model, ext_model;

	family = (fam_mod_step >> 8) & 0xf;
	model = (fam_mod_step >> 4) & 0xf;

	if (family == 6 || family == 15) {
		ext_model = (fam_mod_step >> 16) & 0xf;
		model += (ext_model << 4);
	}

	return model;
}

static int32_t
rdmsr(int msr, uint64_t *val)
{
#ifdef RTE_EXEC_ENV_LINUX
	int fd;
	int ret;

	fd = open("/dev/cpu/0/msr", O_RDONLY);
	if (fd < 0)
		return fd;

	ret = pread(fd, val, sizeof(uint64_t), msr);

	close(fd);

	return ret;
#else
	RTE_SET_USED(msr);
	RTE_SET_USED(val);

	return -1;
#endif
}

static uint32_t
check_model_wsm_nhm(uint8_t model)
{
	switch (model) {
	/* Westmere */
	case 0x25:
	case 0x2C:
	case 0x2F:
	/* Nehalem */
	case 0x1E:
	case 0x1F:
	case 0x1A:
	case 0x2E:
		return 1;
	}

	return 0;
}

static uint32_t
check_model_gdm_dnv(uint8_t model)
{
	switch (model) {
	/* Goldmont */
	case 0x5C:
	/* Denverton */
	case 0x5F:
		return 1;
	}

	return 0;
}

uint64_t
get_tsc_freq_arch(void)
{
	uint64_t tsc_hz = 0;
	uint32_t a, b, c, d, maxleaf;
	uint8_t mult, model;
	int32_t ret;

	/*
	 * Time Stamp Counter and Nominal Core Crystal Clock
	 * Information Leaf
	 */
	maxleaf = __get_cpuid_max(0, NULL);

	if (maxleaf >= 0x15) {
		__cpuid(0x15, a, b, c, d);

		/* EBX : TSC/Crystal ratio, ECX : Crystal Hz */
		if (b && c)
			return c * (b / a);
	}

	__cpuid(0x1, a, b, c, d);
	model = rte_cpu_get_model(a);

	if (check_model_wsm_nhm(model))
		mult = 133;
	else if ((c & bit_AVX) || check_model_gdm_dnv(model))
		mult = 100;
	else
		return 0;

	ret = rdmsr(0xCE, &tsc_hz);
	if (ret < 0)
		return 0;

	return ((tsc_hz >> 8) & 0xff) * mult * 1E6;
}
