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
17static 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
27static 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
38unsigned 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

source code of linux/tools/power/cpupower/lib/acpi_cppc.c