1 // SPDX-License-Identifier: GPL-2.0-only 2 3 #include <stdio.h> 4 #include <errno.h> 5 #include <stdlib.h> 6 #include <string.h> 7 #include <sys/types.h> 8 #include <sys/stat.h> 9 #include <fcntl.h> 10 #include <unistd.h> 11 12 #include "cpupower_intern.h" 13 #include "acpi_cppc.h" 14 15 /* ACPI CPPC sysfs access ***********************************************/ 16 17 static int acpi_cppc_read_file(unsigned int cpu, const char *fname, 18 char *buf, size_t buflen) 19 { 20 char path[SYSFS_PATH_MAX]; 21 22 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/acpi_cppc/%s", 23 cpu, fname); 24 return cpupower_read_sysfs(path, buf, buflen); 25 } 26 27 static const char * const acpi_cppc_value_files[] = { 28 [HIGHEST_PERF] = "highest_perf", 29 [LOWEST_PERF] = "lowest_perf", 30 [NOMINAL_PERF] = "nominal_perf", 31 [LOWEST_NONLINEAR_PERF] = "lowest_nonlinear_perf", 32 [LOWEST_FREQ] = "lowest_freq", 33 [NOMINAL_FREQ] = "nominal_freq", 34 [REFERENCE_PERF] = "reference_perf", 35 [WRAPAROUND_TIME] = "wraparound_time" 36 }; 37 38 unsigned long acpi_cppc_get_data(unsigned int cpu, enum acpi_cppc_value which) 39 { 40 unsigned long long value; 41 unsigned int len; 42 char linebuf[MAX_LINE_LEN]; 43 char *endp; 44 45 if (which >= MAX_CPPC_VALUE_FILES) 46 return 0; 47 48 len = acpi_cppc_read_file(cpu, acpi_cppc_value_files[which], 49 linebuf, sizeof(linebuf)); 50 if (len == 0) 51 return 0; 52 53 value = strtoull(linebuf, &endp, 0); 54 55 if (endp == linebuf || errno == ERANGE) 56 return 0; 57 58 return value; 59 } 60