cpupower: Add cpuidle parts into library

This more or less is a renaming and moving of functions and should not
introduce any functional change.

cpupower was built from cpufrequtils (which had a C library providing easy
access to cpu frequency platform info). In the meantime it got enhanced
by quite some neat cpuidle userspace tools.

Now the cpu idle functions have been separated and added to the cpupower.so
library.
So beside an already existing public header file:
cpufreq.h
cpupower now also exports these cpu idle functions in:
cpuidle.h

Here again pasted for better review of the interfaces:

======================================
int cpuidle_is_state_disabled(unsigned int cpu,
                                       unsigned int idlestate);
int cpuidle_state_disable(unsigned int cpu, unsigned int idlestate,
                                   unsigned int disable);
unsigned long cpuidle_state_latency(unsigned int cpu,
                                                unsigned int idlestate);
unsigned long cpuidle_state_usage(unsigned int cpu,
                                        unsigned int idlestate);
unsigned long long cpuidle_state_time(unsigned int cpu,
                                                unsigned int idlestate);
char *cpuidle_state_name(unsigned int cpu,
                                unsigned int idlestate);
char *cpuidle_state_desc(unsigned int cpu,
                                unsigned int idlestate);
unsigned int cpuidle_state_count(unsigned int cpu);

char *cpuidle_get_governor(void);
char *cpuidle_get_driver(void);

======================================

Signed-off-by: Thomas Renninger <trenn@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 380 insertions, 0 deletions

diff --git a/tools/power/cpupower/lib/cpuidle.c b/tools/power/cpupower/lib/cpuidle.c
new file mode 100644
index 000000000000..9bd4c7655fdb
--- /dev/null
+++ b/tools/power/cpupower/lib/cpuidle.c
@@ -0,0 +1,380 @@
+/*
+ *  (C) 2004-2009  Dominik Brodowski <linux@dominikbrodowski.de>
+ *  (C) 2011       Thomas Renninger <trenn@novell.com> Novell Inc.
+ *
+ *  Licensed under the terms of the GNU GPL License version 2.
+ */
+
+#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_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_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_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 sysfs_read_file(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 */