diff options
Diffstat (limited to 'tools/power/cpupower/utils/helpers/sysfs.c')
| -rw-r--r-- | tools/power/cpupower/utils/helpers/sysfs.c | 172 |
1 files changed, 118 insertions, 54 deletions
diff --git a/tools/power/cpupower/utils/helpers/sysfs.c b/tools/power/cpupower/utils/helpers/sysfs.c index c6343024a61..851c7a16ca4 100644 --- a/tools/power/cpupower/utils/helpers/sysfs.c +++ b/tools/power/cpupower/utils/helpers/sysfs.c @@ -37,25 +37,6 @@ unsigned int sysfs_read_file(const char *path, char *buf, size_t buflen) return (unsigned int) numread; } -static unsigned int sysfs_write_file(const char *path, - const char *value, size_t len) -{ - int fd; - ssize_t numwrite; - - 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; -} - /* * Detect whether a CPU is online * @@ -108,6 +89,33 @@ int sysfs_is_cpu_online(unsigned int cpu) /* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */ + +/* CPUidle idlestate specific /sys/devices/system/cpu/cpuX/cpuidle/ access */ + +/* + * 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. + */ +unsigned int sysfs_idlestate_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 @@ -140,6 +148,40 @@ unsigned int sysfs_idlestate_read_file(unsigned int cpu, unsigned int idlestate, 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 sysfs_idlestate_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 { @@ -147,6 +189,7 @@ enum idlestate_value { IDLESTATE_POWER, IDLESTATE_LATENCY, IDLESTATE_TIME, + IDLESTATE_DISABLE, MAX_IDLESTATE_VALUE_FILES }; @@ -155,6 +198,7 @@ static const char *idlestate_value_files[MAX_IDLESTATE_VALUE_FILES] = { [IDLESTATE_POWER] = "power", [IDLESTATE_LATENCY] = "latency", [IDLESTATE_TIME] = "time", + [IDLESTATE_DISABLE] = "disable", }; static unsigned long long sysfs_idlestate_get_one_value(unsigned int cpu, @@ -224,8 +268,59 @@ static char *sysfs_idlestate_get_one_string(unsigned int cpu, 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 sysfs_is_idlestate_disabled(unsigned int cpu, + unsigned int idlestate) +{ + if (sysfs_get_idlestate_count(cpu) <= idlestate) + return -1; + + if (!sysfs_idlestate_file_exists(cpu, idlestate, + idlestate_value_files[IDLESTATE_DISABLE])) + return -2; + return sysfs_idlestate_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 sysfs_idlestate_disable(unsigned int cpu, + unsigned int idlestate, + unsigned int disable) +{ + char value[SYSFS_PATH_MAX]; + int bytes_written; + + if (sysfs_get_idlestate_count(cpu) <= idlestate) + return -1; + + if (!sysfs_idlestate_file_exists(cpu, idlestate, + idlestate_value_files[IDLESTATE_DISABLE])) + return -2; + + snprintf(value, SYSFS_PATH_MAX, "%u", disable); + + bytes_written = sysfs_idlestate_write_file(cpu, idlestate, "disable", + value, sizeof(disable)); + if (bytes_written) + return 0; + return -3; +} + unsigned long sysfs_get_idlestate_latency(unsigned int cpu, - unsigned int idlestate) + unsigned int idlestate) { return sysfs_idlestate_get_one_value(cpu, idlestate, IDLESTATE_LATENCY); } @@ -257,7 +352,7 @@ char *sysfs_get_idlestate_desc(unsigned int cpu, unsigned int idlestate) * Negativ in error case * Zero if cpuidle does not export any C-states */ -int sysfs_get_idlestate_count(unsigned int cpu) +unsigned int sysfs_get_idlestate_count(unsigned int cpu) { char file[SYSFS_PATH_MAX]; struct stat statbuf; @@ -362,22 +457,7 @@ char *sysfs_get_cpuidle_driver(void) */ int sysfs_get_sched(const char *smt_mc) { - unsigned long value; - char linebuf[MAX_LINE_LEN]; - char *endp; - char path[SYSFS_PATH_MAX]; - - if (strcmp("mc", smt_mc) && strcmp("smt", smt_mc)) - return -EINVAL; - - snprintf(path, sizeof(path), - PATH_TO_CPU "sched_%s_power_savings", smt_mc); - if (sysfs_read_file(path, linebuf, MAX_LINE_LEN) == 0) - return -1; - value = strtoul(linebuf, &endp, 0); - if (endp == linebuf || errno == ERANGE) - return -1; - return value; + return -ENODEV; } /* @@ -388,21 +468,5 @@ int sysfs_get_sched(const char *smt_mc) */ int sysfs_set_sched(const char *smt_mc, int val) { - char linebuf[MAX_LINE_LEN]; - char path[SYSFS_PATH_MAX]; - struct stat statbuf; - - if (strcmp("mc", smt_mc) && strcmp("smt", smt_mc)) - return -EINVAL; - - snprintf(path, sizeof(path), - PATH_TO_CPU "sched_%s_power_savings", smt_mc); - sprintf(linebuf, "%d", val); - - if (stat(path, &statbuf) != 0) - return -ENODEV; - - if (sysfs_write_file(path, linebuf, MAX_LINE_LEN) == 0) - return -1; - return 0; + return -ENODEV; } |