diff options
Diffstat (limited to 'tools/power/cpupower/utils/helpers/msr.c')
-rw-r--r-- | tools/power/cpupower/utils/helpers/msr.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/tools/power/cpupower/utils/helpers/msr.c b/tools/power/cpupower/utils/helpers/msr.c new file mode 100644 index 0000000000..8b0b6be74b --- /dev/null +++ b/tools/power/cpupower/utils/helpers/msr.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 +#if defined(__i386__) || defined(__x86_64__) + +#include <fcntl.h> +#include <stdio.h> +#include <unistd.h> +#include <stdint.h> + +#include "helpers/helpers.h" + +/* Intel specific MSRs */ +#define MSR_IA32_PERF_STATUS 0x198 +#define MSR_IA32_MISC_ENABLES 0x1a0 +#define MSR_NEHALEM_TURBO_RATIO_LIMIT 0x1ad + +/* + * read_msr + * + * Will return 0 on success and -1 on failure. + * Possible errno values could be: + * EFAULT -If the read/write did not fully complete + * EIO -If the CPU does not support MSRs + * ENXIO -If the CPU does not exist + */ + +int read_msr(int cpu, unsigned int idx, unsigned long long *val) +{ + int fd; + char msr_file_name[64]; + + sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu); + fd = open(msr_file_name, O_RDONLY); + if (fd < 0) + return -1; + if (lseek(fd, idx, SEEK_CUR) == -1) + goto err; + if (read(fd, val, sizeof *val) != sizeof *val) + goto err; + close(fd); + return 0; + err: + close(fd); + return -1; +} + +/* + * write_msr + * + * Will return 0 on success and -1 on failure. + * Possible errno values could be: + * EFAULT -If the read/write did not fully complete + * EIO -If the CPU does not support MSRs + * ENXIO -If the CPU does not exist + */ +int write_msr(int cpu, unsigned int idx, unsigned long long val) +{ + int fd; + char msr_file_name[64]; + + sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu); + fd = open(msr_file_name, O_WRONLY); + if (fd < 0) + return -1; + if (lseek(fd, idx, SEEK_CUR) == -1) + goto err; + if (write(fd, &val, sizeof val) != sizeof val) + goto err; + close(fd); + return 0; + err: + close(fd); + return -1; +} + +unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu) +{ + unsigned long long val; + int ret; + + if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_HAS_TURBO_RATIO)) + return -1; + + ret = read_msr(cpu, MSR_NEHALEM_TURBO_RATIO_LIMIT, &val); + if (ret) + return ret; + return val; +} +#endif |