96 lines
1.8 KiB
C
96 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
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*
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* Based on code found in
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* linux/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
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* and originally developed by Paul Devriendt
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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_FIDVID_STATUS 0xc0010042
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#define MSR_S_HI_CURRENT_VID 0x0000001f
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#define MSR_S_LO_CURRENT_FID 0x0000003f
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static int get_fidvid(uint32_t cpu, uint32_t *fid, uint32_t *vid)
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{
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int err = 1;
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uint64_t msr = 0;
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int fd;
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char file[20];
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if (cpu > MCPU)
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goto out;
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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 out;
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lseek(fd, MSR_FIDVID_STATUS, SEEK_CUR);
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if (read(fd, &msr, 8) != 8)
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goto err1;
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*fid = ((uint32_t )(msr & 0xffffffffull)) & MSR_S_LO_CURRENT_FID;
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*vid = ((uint32_t )(msr>>32 & 0xffffffffull)) & MSR_S_HI_CURRENT_VID;
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err = 0;
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err1:
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close(fd);
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out:
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return err;
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}
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/* Return a frequency in MHz, given an input fid */
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static uint32_t find_freq_from_fid(uint32_t fid)
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{
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return 800 + (fid * 100);
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}
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/* Return a voltage in miliVolts, given an input vid */
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static uint32_t find_millivolts_from_vid(uint32_t vid)
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{
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return 1550-vid*25;
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}
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int main (int argc, char *argv[])
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{
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int err;
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int cpu;
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uint32_t fid, vid;
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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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err = get_fidvid(cpu, &fid, &vid);
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if (err) {
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printf("can't get fid, vid from MSR\n");
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printf("Possible trouble: you don't run a powernow-k8 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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exit(1);
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}
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printf("cpu %d currently at %d MHz and %d mV\n",
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cpu,
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find_freq_from_fid(fid),
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find_millivolts_from_vid(vid));
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return 0;
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}
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