// SPDX-License-Identifier: GPL-2.0-only
/*
* (C) 2004-2009 Dominik Brodowski <[email protected]>
* (C) 2011 Thomas Renninger <[email protected]> Novell Inc.
*/
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "cpuidle.h"
#include "cpupower_intern.h"
/*
* helper function to check whether a file under "../cpuX/cpuidle/stateX/" dir
* exists.
* For example the functionality to disable c-states was introduced in later
* kernel versions, this function can be used to explicitly check for this
* feature.
*
* returns 1 if the file exists, 0 otherwise.
*/
static
unsigned int cpuidle_state_file_exists(unsigned int cpu,
unsigned int idlestate,
const char *fname)
{
char path[SYSFS_PATH_MAX];
struct stat statbuf;
snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
cpu, idlestate, fname);
if (stat(path, &statbuf) != 0)
return 0;
return 1;
}
/*
* helper function to read file from /sys into given buffer
* fname is a relative path under "cpuX/cpuidle/stateX/" dir
* cstates starting with 0, C0 is not counted as cstate.
* This means if you want C1 info, pass 0 as idlestate param
*/
static
unsigned int cpuidle_state_read_file(unsigned int cpu,
unsigned int idlestate,
const char *fname, char *buf,
size_t buflen)
{
char path[SYSFS_PATH_MAX];
int fd;
ssize_t numread;
snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
cpu, idlestate, fname);
fd = open(path, O_RDONLY);
if (fd == -1)
return 0;
numread = read(fd, buf, buflen - 1);
if (numread < 1) {
close(fd);
return 0;
}
buf[numread] = '\0';
close(fd);
return (unsigned int) numread;
}
/*
* helper function to write a new value to a /sys file
* fname is a relative path under "../cpuX/cpuidle/cstateY/" dir
*
* Returns the number of bytes written or 0 on error
*/
static
unsigned int cpuidle_state_write_file(unsigned int cpu,
unsigned int idlestate,
const char *fname,
const char *value, size_t len)
{
char path[SYSFS_PATH_MAX];
int fd;
ssize_t numwrite;
snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/cpuidle/state%u/%s",
cpu, idlestate, fname);
fd = open(path, O_WRONLY);
if (fd == -1)
return 0;
numwrite = write(fd, value, len);
if (numwrite < 1) {
close(fd);
return 0;
}
close(fd);
return (unsigned int) numwrite;
}
/* read access to files which contain one numeric value */
enum idlestate_value {
IDLESTATE_USAGE,
IDLESTATE_POWER,
IDLESTATE_LATENCY,
IDLESTATE_RESIDENCY,
IDLESTATE_TIME,
IDLESTATE_DISABLE,
MAX_IDLESTATE_VALUE_FILES
};
static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = {
[IDLESTATE_USAGE] = "usage",
[IDLESTATE_POWER] = "power",
[IDLESTATE_LATENCY] = "latency",
[IDLESTATE_RESIDENCY] = "residency",
[IDLESTATE_TIME] = "time",
[IDLESTATE_DISABLE] = "disable",
};
static
unsigned long long cpuidle_state_get_one_value(unsigned int cpu,
unsigned int idlestate,
enum idlestate_value which)
{
unsigned long long value;
unsigned int len;
char linebuf[MAX_LINE_LEN];
char *endp;
if (which >= MAX_IDLESTATE_VALUE_FILES)
return 0;
len = cpuidle_state_read_file(cpu, idlestate,
idlestate_value_files[which],
linebuf, sizeof(linebuf));
if (len == 0)
return 0;
value = strtoull(linebuf, &endp, 0);
if (endp == linebuf || errno == ERANGE)
return 0;
return value;
}
/* read access to files which contain one string */
enum idlestate_string {
IDLESTATE_DESC,
IDLESTATE_NAME,
MAX_IDLESTATE_STRING_FILES
};
static const char *idlestate_string_files[MAX_IDLESTATE_STRING_FILES] = {
[IDLESTATE_DESC] = "desc",
[IDLESTATE_NAME] = "name",
};
static char *cpuidle_state_get_one_string(unsigned int cpu,
unsigned int idlestate,
enum idlestate_string which)
{
char linebuf[MAX_LINE_LEN];
char *result;
unsigned int len;
if (which >= MAX_IDLESTATE_STRING_FILES)
return NULL;
len = cpuidle_state_read_file(cpu, idlestate,
idlestate_string_files[which],
linebuf, sizeof(linebuf));
if (len == 0)
return NULL;
result = strdup(linebuf);
if (result == NULL)
return NULL;
if (result[strlen(result) - 1] == '\n')
result[strlen(result) - 1] = '\0';
return result;
}
/*
* Returns:
* 1 if disabled
* 0 if enabled
* -1 if idlestate is not available
* -2 if disabling is not supported by the kernel
*/
int cpuidle_is_state_disabled(unsigned int cpu,
unsigned int idlestate)
{
if (cpuidle_state_count(cpu) <= idlestate)
return -1;
if (!cpuidle_state_file_exists(cpu, idlestate,
idlestate_value_files[IDLESTATE_DISABLE]))
return -2;
return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_DISABLE);
}
/*
* Pass 1 as last argument to disable or 0 to enable the state
* Returns:
* 0 on success
* negative values on error, for example:
* -1 if idlestate is not available
* -2 if disabling is not supported by the kernel
* -3 No write access to disable/enable C-states
*/
int cpuidle_state_disable(unsigned int cpu,
unsigned int idlestate,
unsigned int disable)
{
char value[SYSFS_PATH_MAX];
int bytes_written;
if (cpuidle_state_count(cpu) <= idlestate)
return -1;
if (!cpuidle_state_file_exists(cpu, idlestate,
idlestate_value_files[IDLESTATE_DISABLE]))
return -2;
snprintf(value, SYSFS_PATH_MAX, "%u", disable);
bytes_written = cpuidle_state_write_file(cpu, idlestate, "disable",
value, sizeof(disable));
if (bytes_written)
return 0;
return -3;
}
unsigned long cpuidle_state_latency(unsigned int cpu,
unsigned int idlestate)
{
return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_LATENCY);
}
unsigned long cpuidle_state_residency(unsigned int cpu,
unsigned int idlestate)
{
return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_RESIDENCY);
}
unsigned long cpuidle_state_usage(unsigned int cpu,
unsigned int idlestate)
{
return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_USAGE);
}
unsigned long long cpuidle_state_time(unsigned int cpu,
unsigned int idlestate)
{
return cpuidle_state_get_one_value(cpu, idlestate, IDLESTATE_TIME);
}
char *cpuidle_state_name(unsigned int cpu, unsigned int idlestate)
{
return cpuidle_state_get_one_string(cpu, idlestate, IDLESTATE_NAME);
}
char *cpuidle_state_desc(unsigned int cpu, unsigned int idlestate)
{
return cpuidle_state_get_one_string(cpu, idlestate, IDLESTATE_DESC);
}
/*
* Returns number of supported C-states of CPU core cpu
* Negativ in error case
* Zero if cpuidle does not export any C-states
*/
unsigned int cpuidle_state_count(unsigned int cpu)
{
char file[SYSFS_PATH_MAX];
struct stat statbuf;
int idlestates = 1;
snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpuidle");
if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
return 0;
snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU "cpu%u/cpuidle/state0", cpu);
if (stat(file, &statbuf) != 0 || !S_ISDIR(statbuf.st_mode))
return 0;
while (stat(file, &statbuf) == 0 && S_ISDIR(statbuf.st_mode)) {
snprintf(file, SYSFS_PATH_MAX, PATH_TO_CPU
"cpu%u/cpuidle/state%d", cpu, idlestates);
idlestates++;
}
idlestates--;
return idlestates;
}
/* CPUidle general /sys/devices/system/cpu/cpuidle/ sysfs access ********/
/*
* helper function to read file from /sys into given buffer
* fname is a relative path under "cpu/cpuidle/" dir
*/
static unsigned int sysfs_cpuidle_read_file(const char *fname, char *buf,
size_t buflen)
{
char path[SYSFS_PATH_MAX];
snprintf(path, sizeof(path), PATH_TO_CPU "cpuidle/%s", fname);
return cpupower_read_sysfs(path, buf, buflen);
}
/* read access to files which contain one string */
enum cpuidle_string {
CPUIDLE_GOVERNOR,
CPUIDLE_GOVERNOR_RO,
CPUIDLE_DRIVER,
MAX_CPUIDLE_STRING_FILES
};
static const char *cpuidle_string_files[MAX_CPUIDLE_STRING_FILES] = {
[CPUIDLE_GOVERNOR] = "current_governor",
[CPUIDLE_GOVERNOR_RO] = "current_governor_ro",
[CPUIDLE_DRIVER] = "current_driver",
};
static char *sysfs_cpuidle_get_one_string(enum cpuidle_string which)
{
char linebuf[MAX_LINE_LEN];
char *result;
unsigned int len;
if (which >= MAX_CPUIDLE_STRING_FILES)
return NULL;
len = sysfs_cpuidle_read_file(cpuidle_string_files[which],
linebuf, sizeof(linebuf));
if (len == 0)
return NULL;
result = strdup(linebuf);
if (result == NULL)
return NULL;
if (result[strlen(result) - 1] == '\n')
result[strlen(result) - 1] = '\0';
return result;
}
char *cpuidle_get_governor(void)
{
char *tmp = sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR_RO);
if (!tmp)
return sysfs_cpuidle_get_one_string(CPUIDLE_GOVERNOR);
else
return tmp;
}
char *cpuidle_get_driver(void)
{
return sysfs_cpuidle_get_one_string(CPUIDLE_DRIVER);
}
/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */
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