2 * (C) 2003 - 2004 Dominik Brodowski <linux@dominikbrodowski.de>
4 * Licensed under the terms of the GNU GPL License version 2.
6 * Based on code found in
7 * linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
8 * and originally developed by Jeremy Fitzhardinge.
10 * USAGE: simply run it to decode the current settings on CPU 0,
11 * or pass the CPU number as argument, or pass the MSR content
22 #include <sys/types.h>
27 #define MSR_IA32_PERF_STATUS 0x198
29 static int rdmsr(unsigned int cpu, unsigned int msr,
30 unsigned int *lo, unsigned int *hi)
34 unsigned long long val;
42 sprintf(file, "/dev/cpu/%d/msr", cpu);
43 fd = open(file, O_RDONLY);
48 if (lseek(fd, msr, SEEK_CUR) == -1)
51 if (read(fd, &val, 8) != 8)
54 *lo = (uint32_t )(val & 0xffffffffull);
55 *hi = (uint32_t )(val>>32 & 0xffffffffull);
64 static void decode (unsigned int msr)
66 unsigned int multiplier;
69 multiplier = ((msr >> 8) & 0xFF);
71 mv = (((msr & 0xFF) * 16) + 700);
73 printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
76 static int decode_live(unsigned int cpu)
81 err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);
84 printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
85 printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
86 printf("or you are not root, or the msr driver is not present\n");
95 int main (int argc, char **argv)
97 unsigned int cpu, mode = 0;
102 cpu = strtoul(argv[1], NULL, 0);