113 lines
2.0 KiB
C
113 lines
2.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* (C) 2003 - 2004 Dominik Brodowski <linux@dominikbrodowski.de>
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*
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* Based on code found in
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* linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
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* and originally developed by Jeremy Fitzhardinge.
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*
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* USAGE: simply run it to decode the current settings on CPU 0,
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* or pass the CPU number as argument, or pass the MSR content
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* as argument.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#define MCPU 32
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#define MSR_IA32_PERF_STATUS 0x198
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static int rdmsr(unsigned int cpu, unsigned int msr,
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unsigned int *lo, unsigned int *hi)
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{
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int fd;
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char file[20];
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unsigned long long val;
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int retval = -1;
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*lo = *hi = 0;
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if (cpu > MCPU)
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goto err1;
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sprintf(file, "/dev/cpu/%d/msr", cpu);
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fd = open(file, O_RDONLY);
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if (fd < 0)
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goto err1;
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if (lseek(fd, msr, SEEK_CUR) == -1)
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goto err2;
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if (read(fd, &val, 8) != 8)
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goto err2;
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*lo = (uint32_t )(val & 0xffffffffull);
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*hi = (uint32_t )(val>>32 & 0xffffffffull);
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retval = 0;
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err2:
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close(fd);
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err1:
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return retval;
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}
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static void decode (unsigned int msr)
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{
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unsigned int multiplier;
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unsigned int mv;
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multiplier = ((msr >> 8) & 0xFF);
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mv = (((msr & 0xFF) * 16) + 700);
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printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
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}
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static int decode_live(unsigned int cpu)
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{
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unsigned int lo, hi;
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int err;
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err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);
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if (err) {
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printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
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printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
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printf("or you are not root, or the msr driver is not present\n");
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return 1;
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}
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decode(lo);
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return 0;
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}
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int main (int argc, char **argv)
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{
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unsigned int cpu, mode = 0;
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if (argc < 2)
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cpu = 0;
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else {
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cpu = strtoul(argv[1], NULL, 0);
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if (cpu >= MCPU)
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mode = 1;
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}
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if (mode)
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decode(cpu);
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else
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decode_live(cpu);
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return 0;
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}
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