acpi_cppc.c

 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}