xref: /linux/tools/power/cpupower/lib/acpi_cppc.c (revision 4f2c0a4acffbec01079c28f839422e64ddeff004)
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 
acpi_cppc_read_file(unsigned int cpu,const char * fname,char * buf,size_t buflen)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 
acpi_cppc_get_data(unsigned int cpu,enum acpi_cppc_value which)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